NCD062555792_20061012_Sigmons Septic Tank Service_FRBCERCLA RD_Health Consultation-OCR

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Health Consultation
REVIEW OF GROUNDWATER DAT A
(2005 EPA DELINEATION INVESTIGATION)
SIGMON'S SEPTIC TANK SERVICE SITE
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
REGION IV
EPA FACILITY ID: NCD062555792
OCTOBER 12, 2006
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Atlanta, Georgia 30333
Health Consultation: A Note of Explanation
An ATSDR health consultation is a verbal or written response from ATSDR to a specific
request for information about health risks related to a specific site, a chemical release, or
the presence of hazardous material. In order to prevent or mitigate exposures, a
consultation may lead to specific actions, such as restricting use of or replacing water
supplies; intensifying environmental sampling; restricting site access; or removing the
contaminated material.
In addition, consultations may recommend additional public health actions, such as
conducting health surveillance activities to evaluate exposure or trends in adverse health
outcomes; conducting biological indicators of exposure studies to assess exposure; and
providing health education for health care providers and community members. This
concludes the health consultation process for this site, unless additional information is
obtained by ATSDR which, in the Agency's opinion, indicates a need to revise or append
the conclusions previously issued.
You May Contact ATSDR Toll Free at
1-800-CDC-INFO
or
Visit our Home Page at: http://www.atsdr.cdc.gov
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HEAL TH CONSULTATION
REVIEW OF GROUNDWATER DATA
(2005 EPA DELINEATION INVESTIGATION)
SIGMON'S SEPTIC TANK SERVICE SITE
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
REGION IV
EPA FACILITY ID: NCD062555792
Prepared By:
U.S. Department of Health and Human Services
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
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Table of Contents
• Background and Statement of Issues ............................................................................................... 1
Discussion .................................................................................................................................. 3
Environmental Sampling and Chemical Analyses ....................................................................... 3
Rationale for the Selective Screening of Substances in Groundwater.. ................................... 3
Exposure Pathways ...................................................................................................................... 5
Other Public Health Concerns ..................................................................................................... 6
Public Health Implications ........................................................................................................... 6
Child Health Considerations .......................................................................................................... 1 I
Conclusions ................................................................................................................................ 12
Recommendations .......................................................................................................................... 12
Public Health Action Plan .............................................................................................................. 13
Authors ................................................................................................................................ 14
References ....... : ........................................................................................................................ 16
Appendix A. Comparison Values ............................................................................................. A-1
Appendix B. Tables ................................................................................................................... B-1
Table I. Chemical Levels Considered a No Apparent Health Hazard .................................... B-2
Table 2. Chemical Levels Considered a Nonapparent Health Hazard ..................................... B-4
Table Notes. Footnotes for Tables 3 Through 11 .................................................................... 8-6
Table 3. Detected Substances Found in Private Well PW-01.. ................................................ B-7
• Table 4. Detected Substances Found in Private Well PW-03 .................................................. B-8
Table 5. Detected Substances Found in Private Well PW-04 ................................................ B-10
Table 6. Detected Substances Found in Private Well PW-05 ................................................ 8-l l
Table 7. Detected Substances Found in Private Well PW-06 ................................................ B-12
Table 7. Detected Substances Found in Private Well PW-06 ................................................ B-13
Table 9.Detected Substances Found in Private Well PW-07 ................................................. B-14
Table 10. Detected Substances Found in Private Well PW-08 .............................................. B-15
Table 11. Detected Substances Found in Private Well PW-09 .............................................. B-16
Table 12. Detected Substances Found in Private Well PW-I O .............................................. B-17
Table 13. Detected Substances Found in Private Well PW-11 .............................................. B-18
Table 14. Detected Substances Found in Private Well PW-12 .............................................. B-19
Table 15. Detected Substances Found in Private Wells Near the Sigmon Facility ............... B-20
Appendix C. Figures .................................................................................................................. C-1
Figure I. Site layout map, Sigmon's Septic Tank Site, Statesville, North Carolina ............... C-2
Figure 2. Sigmon's Septic Tank Site, Statesville, North Carolina .......................................... C-3
Figure 3. Monitoring and potable well locations, Sigmon's Septic Tank site, Statesville, North
Carolina .............................................................................................................................. C-4
Figure 4. Groundwater potentiometric surface map, May 21, 2004. Sigmon's Septic Tank site,
Statesville, North Carolina ....................................................................................................... C-5
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Background and Statement of Issues
On June 23, 2005, the Agency for Toxic Substances and Disease Registry (ATSDR) received
additional sampling and analysis data of the groundwater medium at the Sigmon Septic Tank
Service Site, a hazardous w_aste site under investigation by the U. S. Environmental Protection
Agency (EPA), Region IV Office, Atlanta, Georgia (John A. Blanchard, Black & Veatch Special
Projects Corporation, EPA Contractor, e-mail of June 2005 copied David S. Sutton, Division of
Health Assessment and Consultation, ATSDR.). The additional data were collected as part ofa
delineation investigation conducted at the site during the week of April 18, 2005. The
investigation was a follow-up action by EPA to its initial delineation investigation (October
2002-April 2004) of the site to reassess lead and nitrate levels in nearby private wells. None of
the wells showed lead concentrations at levels of health concern during the 2005 investigation.
Moreover, EPA has placed the Sigmon Septic Tank Site on its National's Priority List (NPL),
thus the need for cleaning up the site is a priority (70 FR 21644; April 27, 2005). Hazardous
waste sites placed on the NPL must follow the procedural guidelines for cleanup as described
and documented under the Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA), and the Superfund Amendments and Reauthorization Act of 1986
(SARA).
ATSDR reviewed the additional data and assessed whether exposures to substances detected in
the groundwater pose any potential impacts to the health of nearby private well users. The review
served as a follow-up to an earlier request from ATSDR's Division of Regional Operations
(ORO), Region IV Office, Atlanta, Georgia. ORO requested ATSDR to determine the potential
public health impacts that the Sigmon Septic Tank Service Site-a former septic tank service and
waste removal business-would have on nearby private well users. (Benjamin Moore, Division
of Regional Operations, A TSDR, Region 4, e-mail of October 2004 to Susan Moore, Division of
Health Assessment and Consultation, ATSDR.). The request actually originated from the United
States Environmental Protection Agency (EPA), Region IV Office, Atlanta, Georgia. EPA
initially sent analytical results of groundwater samples to ATSDR's ORO Region IV Office for
public health review and evaluation (Warren Dixon, EPA, Region 4, e-mail of October 2004 to
Benjamin Moore, ATSDR, Division of Regional Operations). These earlier groundwater samples
were also collected from the site as a part of the delineation investigations conducted in October
2002 and April 2004. ATSDR completed its assessment for the earlier request and released its
findings in a public health consultation (PHC) (A TSDR 2006).
Sigmon Septic Tank Service Site (CERCLIS No. NCD062555792) is located at 1268 Eufola
Road, approximately 5 miles southwest of Statesville, Iredell County, North Carolina (NCDENR
1998, 2000; Black & Veatch 2004). This site has been listed under several names, including
Sigmon's Septic Tank Service, AAA Enterprises, and Sigmon Environmental Services. Services
provided by the business have included the pumping and removal of septic tank wastes and
heavy sludges for residential, commercial, and industrial customers, installation and repair of
septic tanks, and other waste removal services to various industries.
Both federal and state environmental regulatory agencies have for several years investigated the
groundwater pathway at the site (NCDENR 1998, 2000; Black & Veatch 2004). The earliest that
the site groundwater was sampled began in 1987, at which time water samples were collected
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from on-site monitoring wells. Starting in I 99 I, water samples were collected from nearby
private wells.
ATSDR released a PHC for the site on March 29, 2002, assessing the site's groundwater
pathway. A TSDR determined that the groundwater pathway appeared to be of concern because
two private wells showed nitrate levels greater than I 0,000 parts per billion (ppb) (ATSDR
2002a). Infants (0-6 months) who consume formula prepared with water containing nitrate levels
greater than I 0,000 ppb have an increased risk of higher methemoglobin levels (EPA 1990;
Bosch et al. 1950; Walton 195 I). Similarly, fetuses might be exposed to potential health risks if
pregnant females drink water with comparable nitrate levels (Muhrer et al. 1959; MMWR 1996).
A TSDR released another PHC on April 3, 2006 that assessed the site's groundwater pathway
based on EPA's initial delineation investigation of the site (October 2002-April 2004). ATSDR
determined that the groundwater pathway again appeared to be of concern because two private
wells showed maximum lead levels of 50 and 140 ppb. Although no notable cause surfaced as to
why the groundwater samples contained these high lead levels, some notable causes can be
attributed to either lead plumbing or improper sampling protocol. Whatever the real cause, the
maximum detected levels in the private wells presented the potential of adversely affecting
public health. The table below summarizes ATSDR's assessment of the site's groundwater
pathway thus far:
Groundwater
Sampling Data
1991 -1999
October 2002 -April 2004
April 2005
Public Health Consultation
Release Date
March 29, 2002
April 3, 2006
this report
Figure I shows the Sigmon Septic Tank Service Site and nearby residences. Former waste areas
still remain at the site. These were used for waste handling and disposal during past operations at
the septic tank service facility. These areas include the Lagoon Area, Waste Pile, and Open Pits
(Figure 1 ). These former waste areas are believed to be the chief source of groundwater problems
within the area. In its previous PHC, A TSDR recommended that environmental regulatory
agencies consider removing these areas from the Sigmon Septic Tank Service Site (A TSDR
2002a). EPA is presently considering this recommendation while its site investigations continue.
A TSDR believes that removing the remaining waste areas at the site could reduce or even
eliminate potential releases of hazardous substances to the surrounding soil, groundwater, or
surface water, thereby reducing or eliminating any potential impacts on public health.
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Discussion
Environmental Sampling and Chemical Analyses
ATSDR reviewed groundwater samples collected in April 2005 from 11 private wells. The water
samples were collected as a follow-up response to determine whether the private wells contained
any significant levels of lead and nitrates. The private well owners use the groundwater for
drinking and other domestic purposes ( e.g., washing, bathing, irrigation).
Rationale for the Selective Screening of Substances in Groundwater
The first step in any public health evaluation or assessment process is the application of
conservative screening values to the available sampling data. This phase of the process helps to
rule out any site-specific substances that would not pose a public health hazard under virtually
any plausible exposure scenario. The substances remaining after the preliminary screen would
then require further analysis to evaluate their potential for causing adverse health effects under
site-specific exposure conditions (ATSDR 2005). It is during this second phase of the process
that potential public health hazards are identified. The preliminary screening phase does not
identify toxic exposures; it merely eliminates obviously nontoxic exposures so that the
evaluation of public health implications can focus on a reduced list of substances.
A substance is initially selected for further public health evaluation if its maximum detected level
in groundwater exceeds its most relevant water comparison value (CV). A substance is also
initially selected for further evaluation if it is detected in groundwater and no water CV exists for
the substance. Following this initial screening, the detected concentration(s) of the selected
substance(s) are compared to concentration ranges considered to pose no apparent public health
hazards in the two previous PH Cs released for the site (ATSDR 2002a, 2006), see Tables 1 and
2. To avoid repeating work already done, if the detected concentrations fell within the
concentration ranges previously considered to pose a no apparent public health hazard, the
substances were not reevaluated.
2005 Delineation Investigation
EPA contracted Black and Veatch Special Projects Corporation (Black & Veatch) to conduct
follow-up sampling activities at the Sigmon Septic Tank Service Site in accordance with its
Environmental Investigations Standard Operating Procedures and Quality Assurance Manual
(EPA 1997). In April 2005, samples were taken from the groundwater.
Twelve groundwater samples were collected from 11 private wells (Figures 2 and 3) and were
subsequently analyzed for metals, volatile organic compounds (VOCs), semi-volatile organic
compounds (SVOCs), pesticides/polychlorinated biphenyls (PCBs), and nitrates. Tables 3
through 14 (Appendix B) list the results of these analyses. The results were compared to water
comparison values (CVs) together with the selection screening criteria to determine whether
further analysis was indicated for any of these substances. The following is a summary of
ATSDR's initial public health screen for each private well.
• Private well PW-01. Of the 10 substances detected in the well, none exceeded any
available water CV; nevertheless, 3 substances were found for which CVs were not
available. The concentrations of these 3 substances were within ranges of levels
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previously considered to pose no apparent public health hazard at this site (A TSDR
2002a, 2006). Accordingly, none of the substances in PW-01 were selected for further
public health evaluation (Table 3).
• Private well PW-03. Of the 26 substances detected in the well, 4 showed maximum levels
that exceeded available water CVs; however, 2 of these substances did not require further
public health evaluation because their maximum measured concentrations were within
ranges considered to pose a no apparent public health hazard. Three other substances
were also detected in the well that had no available water CV s; however, all 3 were
within ranges considered to pose a no apparent public health hazard. Thus, two of the
substances detected in PW-03 were selected for further public health evaluation (Table
4). One was nitrates, a previous concern in ATSDR's March 2002 assessment of the
site's groundwater pathway (ATSDR 2002a), and the other was vinyl chloride.
• Private well PW-04. Of the 14 substances detected in this well, none exceeded any
available water CV. That said, 3 of these substances had no available water CV and all 3
were within ranges considered a no apparent public health hazard. Therefore, none of the
substances detected in PW-04 were selected for further evaluation (Table 5).
• Private well PW-05. Only one of the 13 substances detected in this well showed levels
that exceeded available water CVs. This one substance did not require further public
health evaluation because its measured concentration was within a range considered to
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pose a no apparent public health hazard. Three other substances in the well had no •
available water CVs; however, all three had concentrations within ranges previously
considered to pose a no apparent public health hazard. Therefore, none of the substances
detected in PW-05 were selected for further evaluation (Table 6).
• Private well PW-06. Two (duplicate) water samples were collected from well PW-06. In
the first of the two samples, none of the 12 substances detected in the sample exceeded
any available water CVs. Three of these substances had no available water CVs, but all 3
showed measured concentrations within ranges considered not to pose a public health
hazard (Table 7). The second duplicate sample also showed that none of its 12 detected
substances exceeded any available water CVs. Again, three of these substances had no
available water CVs and all 3 showed measured concentrations within ranges considered
not to pose a public health hazard (Table 8). Therefore, none of the substances detected in
PW-06 were selected for further evaluation.
• Private well PW-07. None of the 10 substances detected in this well exceeded the
available water CVs; however, no water CVs were available for 3 of these substances.
The concentrations of all 3 were within ranges considered to pose a no apparent public
health hazard. Therefore, none of the substances detected in this well were selected for
further evaluation (Table 9).
• Private well PW-08. Only one of the 12 substances detected in this well exceeded the
available water CVs; however, no water CVs were available for 3 of the substances. The
concentrations of the 3 were within ranges considered to pose a no apparent public health
hazard. Therefore, only the one substance, bis(2-ethyhexyl)phthalate, detected in well •
PW-08 was selected for further evaluation (Table 10).
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• Private well PW-09. None of the 12 substances detected in this well exceeded the
available water CVs; however, for 3 of these substances no water CVs were available.
The concentrations of all 3 were within ranges considered to pose a no apparent public
health hazard. Therefore, none of the substances detected in this well were selected for
further evaluation (Table 11 ).
• Private well PW-JO. Only one of the 14 substances detected in this well showed levels
that exceeded available water CVs. The one substance did not require further public
healih evaluation because its measured concentration was within the range considered to
pose a no apparent public health hazard. Three of the substances in the well had no
available water CVs; still, all three had concentrations within ranges considered to pose a
no apparent public health hazard. Therefore, none of the substances detected in PW-I 0
were selected for further evaluation (Table 12).
• Private weUPW-11. Only one of the 16 substances detected in this well showed levels
that exceeded available water CVs. This one substance did not require further public
health evaluation because its measured concentration was within the range considered to
pose a no apparent public health hazard. Three of the substances in the well had no
available water CVs; however, all three had concentrations within ranges considered to
pose a no apparent public health hazard. Therefore, none of the substances detected in
PW-I I were selected for further evaluation (Table 13).
• Private well PW-12. None of the 13 substances detected in this well exceeded the
available water CVs; however, no water CVs were available for 3 of these substances .
The concentrations of all 3 were within ranges considered to pose a no apparent public
health hazard. Therefore, none of the substances detected in this well were selected for
further evaluation (Table 14).
Chemicals Selected for Further Public Health Analysis
ATSDR's review of the groundwater analyses of the private wells is summarized in Table 15.
Using Table 15, our environmental health scientists selected certain substances detected in the
private wells for further public health analysis. These substances were categorized as exceeding
available CVs or for which no CVs were available. The following substances were selected for
in-depth public health analysis:
Substances Exceeding Drinking Water CVs
I) Nitrates, 2) Vinyl Chloride, 3) Bis(2-ethyhexyl)phthalate
Substances without Drinking Water CVs
None
Exposure Pathways
Being that the residential community is comprised of long tenn residents and short tenn renters,
A TSDR detennined that the exposures to the chemicals detected in the water samples were
intermediate and chronic (i.e., moderate and long-tenn exposures, respectively) that can occur
via ingestion, inhalation (VOCs), and dennal contact when groundwater is used for drinking,
showering, and bathing, or for other household purposes (NCDENR 1998, 2000). Several studies
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have indicated that exposures to voes can occur during showering and bathing, as chemicals
volatilize and enter the body through inhalation, absorption, or both. Such exposures to voes
may equal or exceed those from ingestion, but usually by no more than a factor of2 (Jo et al.
1990; Kerger et al. 2000; Kezic et al. 1997; Mattie et al. 1994; EPA 1999). Because of the low
frequency ofVOe detection (8%) and the fact that only one (vinyl chloride) of the nine detected
voes had a level that exceeded any available drinking water comparison values, ATSDR
considered voe exposure through inhalation and skin absorption to be minimal or nonexistent.
Thus, ingestion was the primary route of human exposure considered in this PHe. Ingestion is
also the route of exposure for other, nonvolatile substances that were detected at a higher
frequency (e.g., nitrates and metals).
Other Public Health Concerns
The former site operators disposed of septic waste in the former lagoon area. lt remains there to
this day, raising concerns about the former lagoon area becoming an anaerobic ( oxygen-
depleted) environment for the formation of hydrogen sulfide. As part of the federally mandated
cleanup, that material from the former lagoons will be removed and transported to an appropriate
hazardous waste, treatment, and disposal facility. When removing the material from the former
lagoons, however, it is possible that hydrogen sulfide may be released into the atmosphere,
which may place workers and those residents living next to the site at risk. As a precaution
during remediation and cleanup at the site, necessary steps should be taken to prevent any
possible exposures to hydrogen sulfide.
Environmental health scientists from ATSDR visited the site in December 2005 and observed
that private well PW-02 was inoperable and not in use. Even though the well is not currently in
use, this does not restrict it from future use. Because the well is inoperable and not in use,
A TSDR recommends that the well be properly capped and restricted from any future use; past
pre-2000 sampling has shown that the well contained nitrate levels as high as 23,350 ppb. If
future use is planned for the well, ATSDR recommends removal of all potential source areas at
the site and to make necessary improvements in bringing well PW-02 water quality within safe
drinking water standards.
Past sampling data have shown that groundwater is probably flowing in a southerly to
southwesterly direction (see Figure 4). Most recently-in March 2006-groundwater samples
were collected from private wells in areas north, east, and west of the site; however, no samples
were collected in the areas south to southwest of the site. Past sampling data identified two
problem wells•in those areas, PW-02 and PW-03. Both wells contained elevated levels of
nitrates. These nitrates pose a potential health risk to infants 6 months or younger and for the
fetuses of pregnant women. Therefore, it may be wise to delineate further the groundwater
underlying those areas south to southwest of the site.
Public Health Implications
After application of the selective screening criteria for this PHe, three substances were selected
for in-depth analysis. That analysis is an integrated approach that studies site-specific exposures
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in conjunction with substance-specific toxicological, medical, and epidemiologic data (ATSDR •
2005). The three substances were selected because their detected levels in well PW-03 and well
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• PW-08 exceeded available water CV s. (See Appendix A for a description of comparison values
and their proper interpretation.)
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Substances detected in the groundwater through the sampling of the private potable wells were
screened with health-based comparison values (Tables 3-15). Health-based CV s represent those
levels expected to be safe even for sensitive populations, excluding hypersensitive (allergic)
individuals. Exceeding a CV does not indicate that adverse health effects are expected, but it
does reveal substances that may require additional evaluation of factors that influence the
toxicity and likelihood of health effects. Those substances exceeding CVs or for which
comparison values do not exist were further evaluated for potential adverse health effects.
That further evaluation, as described below, identified nitrates as the only substance for which
intervention is recommended. A nitrate level of 13,000 µg/L (ppb) was detected in one specific
well. This level exceeded EPA's maximum contaminant level (MCL) of I 0,000 µg/L. This level
may be a cause of concern for infants 6 months or younger and for the fetuses of pregnant
women.
Nitrates
The toxicity of nitrates is due to their conversion (reduction) to nitrites by bacteria in the
gastrointestinal tract (i.e., intestines). These nitrites then combine with hemoglobin in the blood.
Once combined, the nitrites convert the hemoglobin to methemoglobin, a form of hemoglobin
that cannot carry oxygen. When enough hemoglobin is converted into methemoglobin, the
blood's ability to transport oxygen from the lungs to the tissues is impaired. Infants are
susceptible to methemoglobinemia because the higher pH (nonacidity) of their gastric juice is
more compatible with the growth of nitrate-reducing bacteria in the gut. Older children, with
their more acidic gastric juices, are much less susceptible (Craun et al. 1981 ). Probably the most
important factor that makes infants more susceptible to methemoglobinemia is their inability to
convert methemoglobin back to hemoglobin; they lack the necessary levels of methemoglobin
reductase, a red-blood cell (RBC) enzyme, which makes this metabolic transition possible.
Again, adults and older children do tend to have the necessary levels of this RBC enzyme,
making them less susceptible. The characteristic blueness (cyanosis) oflips and mucous
membranes can be produced by methemoglobin levels between 20% and 45% (Clinical
Toxicology 2001). Methemoglobin levels under 30% produce minimal symptoms (fatigue,
lightheadedness, headache) in healthy children and adults, while levels between 30% and 50%
cause moderate depression of the cardiovascular and central nervous systems ( e.g., weakness,
headache, rapid breathing and heartbeat, mild shortness of breath). Levels between 50% and 70%
cause severe symptoms ( e.g., stupor, slow and abnormal heartbeat, respiratory depression,
convulsions), and levels above 70% are usually fatal (Ellenhom and Barceloux 1988). Any levels
of methemoglobin that might be associated with the maximum detected nitrate levels in water
from private wells at this site are likely to be less than 2%. (See discussion below.)
EPA has developed a chronic oral reference dose for the ingestion of nitrates based on the early
clinical signs ofmethemoglobinemia (cyanosis) in infants ingesting water containing varying
concentrations of nitrate-nitrogen. That RID is equivalent to the observed NOA EL (i.e., No
Observed Adverse Effect Level) of 1,600 µg nitrate-nitrogen/kg/day, which is the dose that
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would be received by a 0-3 month old infant weighing approximately 8.8 pounds (4 kg) and
drinking 0.64 liters/day of water (as formula) containing 10,000 µg/L nitrate-nitrogen.
A primary source of organic nitrates is human sewage, the processing of which formerly
occurred at the site (i.e., removal and handling of septic wastes). Due to high solubility and weak
retention in soil, nitrates and nitrites are very soil-mobile and have a high potential to migrate to
groundwater. Most nitrogenous materials in natural waters tend to be converted to nitrate, so all
sources of combined nitrogen, particularly organic nitrogen and ammonia, should be considered
as potential nitrate sources. Because it does not volatilize, nitrate/nitrite is likely to remain in
water until consumed by plants or other organisms. Ammonium nitrate will be taken up by
bacteria. Nitrate is more persistent in water than is the ammonium ion. Nitrate degradation is
fastest in anaerobic conditions (i.e., little to no oxygen present).
Nitrate was detected at a level above drinking water CVs in one private well, PW-03,
approximately 450 feet southwest of the site. The estimated daily dose of nitrate from water
containing 13,000 ppb (maximum nitrate detection in Private Well PW3) would be 371
µg/kg/day for a 70-kg (i.e., 150 pounds) adult ingesting 2 liters of water per day; 1,300
µg/kg/day for a 10-kg (i.e., 20 pound) child ingesting 1 liter of water per day; and 2,080
µg/kg/day for a 4-kg (i.e., 8 pound) infant ingesting 0.64 liters of water (as formula) per day.
Although the estimated daily dose for a child is slightly higher than the RID, at these dose levels
noncancerous health effects are not expected in adults or children older than 6 months. Although
chronic exposure to levels of nitrates that exceed EPA's RID (in this case, by a factor of2.3) is
not recommended for infants 1-3 months of age, adverse effects would not be likely to occur in
those infants, either. In one study, oral doses of nitrate ranging from 100 µg/kg/day to 15,500
µg/kg/day in 111 infants less than 6 months old was associated with methemoglobin levels as
high as 5.3% (mean 1.6%), but none of the children had the typical symptoms of
methemoglobinemia (Winton et al. 1971). In another study, mean methemoglobin levels were
only 1.3% in infants aged 1-3 months who received water containing 11,000-23,000 µg nitrate-
nitrogen/L (Simon et al. 1964). Also, no clinical signs of methemoglobinemia were detected in
any of these infants. Low levels ofmethemoglobin (0.5 to 2.0%) occur normally and, due to the
large excess capacity of blood to carry oxygen, levels of methemoglobin up to I 0% are seldom
associated with any clinically significant signs such as cyanosis (EPA-IRIS 2006). Most cases of
infant methemoglobinemia are associated with exposure to nitrate in drinking water used to
prepare infants' formula at levels >20,000 ppb of nitrate-nitrogen. Cases have been reported,
however, at levels of 11,000-20,000 ppb nitrate-nitrogen, especially when associated with
concomitant exposure to bacteriologically contaminated water or excess intake of nitrate from
other sources. Therefore, if other sources of drinking water are available, well water from private
well PW-03 should not be used for making infant formula.
The findings from studies investigating the influence of nitrate on the reproductive outcomes in
laboratory animals and livestock have not been consistent; some studies do, however, suggest a
possible connection between nitrate consumption and spontaneous abortions or miscarriages
(Sund et al. 1957; Sleight and Atallah 1968; FDA 1972). One epidemiologic study of humans
has suggested a possible relation between ingestion of drinking water containing elevated nitrate
levels and an increased risk for neural tube defects (Dorsch et al. 1984). Yet another study
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• indicated a possible relation between methemoglobin levels in women during early pregnancy
and subsequent spontaneous abortions (Schmitz 1961 ).
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Public health scientists investigated this possible link between spontaneous abortions and the
ingestion of nitrate-contaminated well water (MMWR 1996). During March 1993, the LaGrange
County (Indiana) Health Department (LCHD) identified three women who reported a total of six
spontaneous abortions during 1991-1993 and who resided in close proximity to each other. Each
of the three women had obtained drinking water from nitrate-contaminated private wells in
LaGrange County. Nitrate was the only well contaminant present at elevated levels. In the wells
from which the three women drank, nitrate levels were 19,000 µg/L; 26,000 µg/L; and 19,200
µg/L. In comparison, for five households in which women reported giving birth to full-term, live-
born infants, drinking water nitrate levels ranged from 1,600 µg/L to 8,400 µg/L (mean: 3.1
µg/L). An investigation of potential sources of nitrate contamination indicated that the probable
source of groundwater contamination was animal waste from a hog-confinement facility. The
facility was approximately½ to 1 mile from the residences of the women who experienced
spontaneous abortions; the facility was, however, approximately 2 miles from the residences of
the women reporting full-term births.
Subsequently, LCHD was notified about a fourth case in which a woman from another part of
LaGrange County had two spontaneous abortions after she had moved into a new home with a
nitrate-contaminated private well. The woman, age 35, lived approximately 10 miles from the
other three women. During 1984-1992 she gave birth to five live infants. But the woman's
doctor also reported to LCHD that the woman had two spontaneous abortions during April and
August 1994, both at 8 weeks' gestation: the first occurred 24 months after the birth of her fifth
child and 44 months after beginning use of a new well. A mean nitrate-Nitrogen level of 28,700
µg/L was detected in water samples collected during August 1994 from the household's well,
which had been used since 1990. A nitrate-Nitrogen level of 1,200 µg/L was detected in a second
well on the property, approximately 100 feet from the first well; during her first four
pregnancies, this well had supplied the woman's drinking water. The only nitrate source
identified near the contaminated well was the family's septic system, which was installed in
sandy soil approximately 70 feet upgradient from the contaminated well. Although the well
probably became contaminated by effluent from the septic tank, when that contamination
occurred is unknown.
Following the investigations, all four women changed to nitrate-free sources of drinking water
(i.e., bottled or reverse-osmosis treated). Subsequently, each delivered one or more full-term, live
infants.
Vinyl Chloride
Vinyl chloride was only detected in one private well, PW-03, with an estimated value of0.21
µg/L. This concentration is one order of magnitude (or 10 times) lower than the MCL of2.0
µg/L, which is set at a conservatively low level to protect the health of sensitive individuals, such
as children and the elderly. The detected level of vinyl chloride exceeded only one water CV,
ATSDR's cancer risk evaluation guide (CREG). The CREG and other similar CVs are the most
conservative of long-term health benchmarks, given that they are based on estimates of O theoretical cancer risk. The level of vinyl chloride detected in well PW-03 would correspond to a
9
dose of 0.021 micrograms per kilogram per day (µg/kg/day) for a I 0-kilogram (kg) child
drinking I liter of water per day (L/day) and 0.006 µg/kg/day for a 70-kg adult drinking 2 L/day.
Both values are well below EPA's reference dose of3 µg/kg/day. (A reference dose is an
estimate of daily exposure to a contaminant unlikely to cause noncancer adverse health effects.)
No drinking water studies of vinyl chloride exposure have been conducted in either humans or
animals; given the high volatility and low water solubility of vinyl chloride, ingestion of drinking
water is not a toxicologically effective route of exposure for this compound. To deliver toxic oral
doses to laboratory animals, investigators must administer vinyl chloride in oil by gavage or in a
diet containing PVC powder. It is from such animal studies that EPA derived its chronic oral
reference dose (RID) of 3 µg/kg/day.
•
Taking into consideration supporting evidence for carcinogenesis, cancer-based CVs for
ingesting vinyl chloride or any carcinogen are derived using the methodology of quantitative risk
assessments. The methodology of quantitative risk assessments usually employs EPA's cancer
slope factors (CSFs) and inhalation unit risks (fURs). CSFs and fURs are computed on the basis
of two limiting assumptions: I) zero-threshold for carcinogens, and 2) low-dose linearity. Zero-
threshold incorporates the assumption that the process of chemical carcinogenesis can cause
cancer and can have an associated cancer risk at any exposure no matter how small or low the
dose-even doses approaching zero (Bogdanffy et al. 2001). Moreover, low-dose linearity
incorporates the assumption that in the low-dose region of a dose-response curve (i.e., the
graphical display of cancer incidence observed over a range of chemical doses in animal or
occupational studies), the rate of change between the carcinogenic response and chemical dose •
approaches a constant and behaves linearly, even down to zero dose. Using statistical models, a
mathematical equation of a straight line can be developed to approximate the linear relationship
of the low-dose region of the dose-response curve. The slope of the resulting straight line is
called a CSF (for dose data) or !UR (for air concentration data). And the straight line can be
extrapolated to any dose or water concentration-no matter how small-to give a corresponding
estimate of cancer risk. Because no actual data points exist in the region of extrapolation (i.e.,
estimated risks of 104 and less), these estimates of cancer risk are theoretical and may not reflect
the true or actual risk, which is in fact unknown and may be as low as zero (EPA 1986, 2003).
Vinyl chloride is a known human carcinogen only under certain circumstances. Vinyl chloride
has been consistently associated with elevated incidences of rare angiosarcomas of the liver in
humans, but only by inhalation and only at the extremely high worker exposures that were once
associated with certain job categories that no longer exist (Zocchetti 2001 ). This same form of
liver cancer has also been produced experimentally in rats treated with chronic oral doses of 300
µg/kg/day. In humans, this dose would be numerically (if not biologically) equivalent to 10,500
µg/L in drinking water for an adult drinking for several decades 2 L/day, or 3,000 µg/L for a
child drinking I L/day over a similar time period. These toxic levels are 14,300 to 50,000 times
higher than the detected level of vinyl chloride in private well PW-03 (i.e., greater than four
orders of magnitude).
Because the level of vinyl chloride did not exceed any CV s for noncancer effects and was not
detected in the other private wells, ATSDR concludes that the vinyl chloride detected in private
well PW-03 does not pose a public health hazard to anyone drinking water from it.
10
•
• Bis(2-ethyhexyl)phthalate (DEHP)
•
•
DEHP was detected in only one private well (PW-08), and at a concentration (6.2 µg/L)-
practically indistinguishable from the MCL of6 µg/L. ATSDR's chronic Minimum Risk Level
(MRL) for DEHP is 60 µg/kg/day. ATSDR's chronic MRLs are derived human no-effect levels
(expressed as doses) that are designed to be conservatively protective against noncancer health
effects for exposure durations of more than I year, up to an entire lifetime. Assuming a 70-kg
adult drinks 2 liters of water a day, and a 10-kg child drinks I liter of water a day, the 60
µg/kg/day MRL for DEHP converts to ATSDR's adult and child chronic drinking water EMEGs
of2000 ug/L and 600 µg/L, respectively. Therefore, ATSDR's chronic drinking water EMEGS
for DEHP exceed by two or more orders of magnitude the only level ofDEHP detected in
private wells water surrounding the site. This indicates that DEHP poses no noncancer hazard.
Under default conditions of exposure over a lifetime, a CREG coincides with a theoretical 1-in-
a-million risk of cancer in humans. ATSDR's CREG of3 ppb was the only one of ATSDR's
CV s in which the single detect of 6.2 ppb did, in fact, exceed. Nevertheless, neither this nor any
other plausible concentration ofDEHP in drinking water is likely to yield a carcinogenic dose in
humans. Most supporting evidence (i.e., animal studies) does not show a causal relationship
between DEHP exposure and cancer in humans. First, the spontaneous incidence of liver tumors
in rodents can be as much as 1-2 orders of magnitude higher than it is in humans (Compare:
Derelanko & Hollinger 1995 and SEER Cancer Statistics Review 1975-2003), which means that
high doses of a nongenotoxic promoting agent like DEHP will, generally speaking, promote
many more spontaneously initiated cells in rodents than the same concentrations ever could in
humans. Second, statistically significant increases in the lifetime incidence ofliver tumors can be
produced in rodents only by high, environmentally irrelevant doses ofDEHP (i.e., hundreds or
thousands of mg/kg/day for life) which are 3-4 orders of magnitude higher than human
exposures in the general population (ATSDR 2002b). Even the highest, short-term human
exposures, (i.e., up to an estimated 2-3 mg/kg/day in hemodialysis patients) are 2-3 orders of
magnitude higher than the lifelong daily doses required to produce liver cancer in rodents
(A TSDR 2002b ). Finally, DEHP evidently produces excess rodent liver tumors via a
nongenotoxic, species-specific mechanism (i.e., induction of peroxisome proliferation by the
monoester metabolite MEHP), which is irrelevant to human beings-"humans are non-
responsive to peroxisome proliferation" (ATSDR 2002b). Thus even if humans had the same
spontaneous incidence of liver tumors as do rodents, and chronic human doses of hundreds or
even thousands of mg/kg/day were possible, DEHP would still not cause cancer in humans, at
least not by the same mechanism that pertains in animals.
Therefore, ATSDR concludes that the single detect of 6.2 µg/L in a private well PW-08 does not
pose a public health hazard.
Child Health Considerations
ATSDR considers children in the· evaluation for all environmental exposures and uses health
guidelines that are protective for children. When evaluating any potential health effects via
ingestion, children are considered a special or sensitive population. Because of their lower body
weight, the same exposure will result in a higher dose as compared to adults. ATSDR's child
11
EMEGs take into account average body weight differences as well as average differences in
child-specific intake rates for various environmental media.
The April 2005 delineation investigation showed an elevated level of nitrates in one private well
located approximately 450 feet southwest of on-site source areas. The level was high enough to
pose an increased risk of elevated methemoglobin levels in very young infants (less than 6
months of age) who drank formula prepared with this water. Another group at similar risk is
pregnant females, drinking the tainted water could adversely affect their fetuses. ATSDR has
evaluated this site in the past and has written several PH Cs. ATSDR again recommends that with
regard to those households whose wells have been affected by nitrates or by other substances that
perhaps migrated from the site, such households should be supplied with an alternative water
source (bottled water or municipal water) or have installed a water filtration/purification system
that yield safe drinking water.
Conclusions
I. During the April 2005 delineation investigation at the Sigmon Septic Tank Service Site,
private well PW-03 showed nitrate levels of 13,000 ppb. This detected level posed an
increased risk of higher methemoglobin levels in very young infants (0--6 months)
drinking formula prepared with water from this well. The sensitive population also
included pregnant females who drank water from this well, which could adversely affect
their fetuses.
2. The vinyl chloride concentration detected in private well PW-03 pose no apparent public
health hazard to residents; however, drinking water from private well PW-03 did pose a
potential health concern to two sensitive subgroups, very young infants (0-6 months) and
pregnant females, if they used the water from the well (i.e., not because of the detected
vinyl chloride level but because of the detected level of nitrates, refer to conclusion #1).
Moreover, the detected level of. bis(2-ethyhexyl)phthalate in private well PW-08 pose no
apparent public health hazard to residents using water from the well.
Recommendations
I. Supply an alternative water source (bottled water) or implement another remedy (e.g.,
installation of a water filtration/purification system) that yields potable water within safe
drinking water standards to households whose private wells are impacted by nitrates or
other substances that could have migrated from the site. Continue this responsive action
until the appropriate investigations are completed, strategies formulated, remedial actions
implemented, and local water supplies are brought within safe drinking standards.
2. Consider removing the source areas from the Sigmon Septic Tank Service facility to
reduce, prevent or both any potential migration of hazardous substances into nearby
private wells.
3. Consider properly capping private well PW-02 ifno future use is intended for the well.
12
•
•
•
• 4. Implement within health safety plan appropriate actions of preventing any possible
•
•
exposures to hydrogen sulfide during remediation and cleanup at the site.
5. Continue routinely to collect and analyze groundwater samples, particularly for nitrates
and lead, from both the monitoring wells and from nearby private wells (notably in the
area of private wells PW-02 and PW-03) until the appropriate investigations are
completed, strategies formulated, remedial actions implemented, and local water supplies
are brought within safe drinking standards.
Public Health Action Plan
1. Follow up with EPA in educating and informing concerned residents about the public
health importance of using an alternative water source (bottled water) or implementing
another remedy (installation of a water filtration/purification system) that yields safe
drinking water until further notified that their own water is within safe drinking water
standards .
13
•
•
Authors
David S. Sutton, PhD, PE
Environmental Health Scientist
Site Assessment Team
Exposure Investigations and Site Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Frank C. Schnell, PhD, DABT
Senior Toxicologist
Exposure Investigations Team
Exposure Investigations and Site Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Reviewers
Susan Moore
Branch Chief
Exposure Investigations and Site Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Peter Kowalski, MPH, CII-1
Lead, Environmental Health Specialist
Site Assessment Team
Exposure Investigations and Site Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
14
Kenneth Orloff, PhD, DABT
Assistant Director of Science
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Annmarie K. DePasquale, MPH
Environmental Health Scientist
Site Assessment Team C
Site and Radiological Assessment Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Jannett P. Smith-George, MSW
Senior Program Management Officer
Team A
Health Promotion and Community Involvement Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Benjamin Moore, MS
Regional Representative
Region IV
Division of Regional Operations
Agency for Toxic Substances and Disease Registry
Wallace K. Sagendorph, JD
Writer Editor
Office of Communication
National Center for Environmental Health
and Agency for Toxic Substances and Disease Registry
15
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•
•
•
•
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20
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•
Appendix A. Comparison Values
ATSDR comparison values (CVs) are media-specific concentrations that are considered to be
safe under default conditions of exposure. They are used as screening values in selecting site-
specific chemicals for further evaluation of their public health implications. Generally, a
chemical is selected for further public health evaluation because its maximum concentration in
air, water, or soil at the site exceeds at least one of ATSDR's CVs. Supplementing this
conservative approach is A TSDR's guidance that requires environmental health scientists to
exercise professional judgment when selecting chemicals for further public health evaluation,
evaluating exposure pathways, and determining the public health implications of site-specific
exposures (ATSDR 1992). A TSDR may also select detected chemical substances for further
public health evaluation and discussion because ATSDR has no CVs for certain specified
chemicals or because the community has expressed special concern about the substance, whether
it exceeds CV s o(not.
It must be emphasized that CVs are not thresholds of toxicity. While concentrations at or below
the relevant CV are generally considered to be safe, it does not automatically follow that any
environmental concentration that exceeds a CV would be expected to produce adverse health
effects. In fact, the whole purpose behind highly conservative, health-based standards and
guidelines is to enable health professionals to recognize and resolve potential public health
problems before they become actual health hazards. For that reason, ATSDR's CVs are typically
I to 3 orders of magnitude (10-1,000 times) lower than the corresponding no-effect levels or
lowest-effect levels on which they are based. The probability that adverse health outcomes will
actually occur depends not on environmental concentrations alone, but on several additional
factors, including site-specific conditions of exposure, individual lifestyle, and genetic factors
affecting the route, magnitude, and duration of actual exposures, and individual physiological
responses to those exposures.
Listed below are the abbreviations for selected CV s and units of measure used within this
document. Following this list of abbreviations are more complete descriptions of the various
comparison values used within this document, as well as a brief discussion on one of ATSDR's
most conservative CV s.
CREG = cancer risk evaluation guide
EMEG = environmental media evaluation guide
LTHA drinking water lifetime health advisory
MCL maximum contaminant level
MCLA = maximum contaminant level action
MRL = minimal risk level
RBC = risk-based concentration
RID reference dose
RMEG reference dose media evaluation guide
A-1
Units of measure
ppm
ppb
ppt
kg
mg
µg
ng
L
=
=
=
=
parts per million, e.g., mg/L (water), mg/kg (soil)
parts per billion, e.g., µg/L (water), µg/kg (soil)
parts per trillion, e.g., ng/L (water) .
kilogram (1,000 grams)
milligram (0.001 gram)
microgram (0.000001 gram)
nanogram (0.000000001 gram)
liter (1,000 milliliters or 1.057 quarts of liquid, or 0.001 m3 of air)
cubic meter (a volume of air equal to 1,000 liters)
Cancer risk evaluation guides (CREGs) are derived by ATSDR. They are estimated chemical
concentrations theoretically expected to cause no more than one excess case of cancer per
million people exposed over a lifetime. CREGs are derived from EPA's cancer slope factors and
therefore reflect estimates of risk based on the assumption of zero threshold and lifetime
exposure. Such estimates are necessarily hypothetical. As stated in EPA's 1986 Guidelines for
Carcinogenic Risk Assessment (EPA 1986), "the true value of the risk is unknown and may be as
low as zero."
Drinking water equivalent levels (DWELs) are lifetime exposure levels specific for drinking
water (assuming that all exposure is from that medium) at which adverse, noncarcinogenic health
effects would not be expected to occur. They are derived from EPA reference doses (RfDs) by
factoring in default ingestion rates and body weights to convert the RID to an equivalent
concentration in drinking water.
Minimal risk levels (MRLs) are ATS DR estimates of daily human exposures to a chemical that
are unlikely to be associated with any appreciable risk of deleterious noncancer effects over a
specified duration of exposure. MRLs are calculated with data from human and animal studies
and are reported for acute (:::14 days), intermediate (15-364 days), and chronic (2:365 days)
exposures. MRLs for oral exposure ingestion) are doses typically expressed in mg/kg/day.
Inhalation MRLs are concentrations typically expressed in either parts per billion (ppb) or µg/m3
(ppt, or parts per trillion). The latter are identical to ATSDR's EMEGs for airborne
contaminants. ATSDR's MRLs are published in ATSDR toxicological profiles for specific
chemicals.
Environmental media evaluation guides (EMEGs) are media-specific concentrations that are
calculated from A TSDR's Minimal Risk Levels by factoring in default body weights and
ingestion rates. Different EMEGs are calculated for adults and children, as well as for acute (:::14
days), intermediate (15-364 days), and chronic (2:365 days) exposures.
EPA reference dose (RID) is an estimate of the daily exposure to a contaminant unlikely to
cause any noncarcinogenic adverse health effects over a lifetime of chronic exposure. Like the
A TSDR MRL, the EPA RID is a dose and is typically expressed in mg/kg/day.
A-2
•
•
•
• Reference dose media evaluation guide (RMEG) is the concentration of a contaminant in air,
water, or soil that ATSDR derives from EPA's RID for that contaminant by factoring in default
values for body weight and the media-specific intake rate. Like ATSDR EMEGs, RMEGs are
calculated for both adults and children.
•
•
Risk-based concentrations (RBCs) are media-specific values derived by the Region III Office
of the U.S. Environmental Protection Agency from EPA RfDs, RfCs, or cancer slope factors, by
factoring in default values for body weight, exposure-duration, and ingestion/inhalation rates.
These values represent levels of chemicals in air, water, soil, and fish that are considered safe
over a Ii fetime of exposure. RBCs for noncarcinogens and carcinogens are analogous to A TSDR
EMEGs and CREGs, respectively.
Lifetime health advisories (L THAs) are calculated from the drinking water equivalent level
(DWEL) and represent the concentration of a substance in drinking water estimated to have
negligible deleterious effects in humans over a lifetime of 70 years, assuming 2 liter per day
water consumption for a 70-kilogram adult. In the absence of chemical-specific data, LTHAs are
20% and I 0% of the corresponding DWELs for noncarcinogenic organic and inorganic
compounds, respectively. LTHAs are not derived for compounds that are potentially
carcinogenic for humans.
Maximum contaminant levels (MCLs) are drinking water standards established by the EPA.
They represent levels of substances in drinking water that EPA deems protective of public health
over a lifetime (70 years) at an adult exposure rate of2 liters of water per day. They differ from
other protective comparison values in that they (I) reflect consideration of both carcinogenic and
noncarcinogenic effects, (2) take into account the availability and economics of water treatment
technology, and (3) are legally enforceable.
Maximum contaminant level action (MCLA) are action levels for drinking water set by EPA
under Superfund. When the relevant action level is exceeded, a regulatory response is triggered.
When screening individual chemical substances, A TSDR staff compares the highest single
concentration of a chemical detected at the site with the appropriate CV available for the most
sensitive of the potentially exposed individuals (usually children). Typically, the cancer risk
evaluation guide (CREG) or chronic environmental media evaluation guide ( cEMEG) is used.
This worst-case approach introduces a high degree of conservatism into the analysis and often
results in the selection of many chemical substances for further public health evaluation that
upon closer scrutiny will not be judged to pose any hazard to human health. In the interest of
public health, it is, however, more prudent to use an environmental screen that identifies many
chemicals for further evaluation that may later be determined to be harmless, as opposed to one
that may overlook even a single potential hazard to public health. The reader should keep in
mind the conservativeness of this approach when interpreting ATSDR's analysis of the potential
health implications of site-specific exposures .
A-3
•
Appendix B. Tables
•
B-1
• • • TABLE 1: Chemical Levels Considered a No Apparent Health Hazard
ATSDR's 2002 Public Health Response for Sigmon's Septic Tank Service Facility
(Summary of Detected Chemical Concentrations found in all Private Wells between 1991 --1999)
' c"'M>CAL ~'"' < 'illillliilf"""c"''M 'Ill'' cc,''' , ;-A<SOR't<% , ,,, ",,
-,,.. •,,,f"1~• •·• "'-:'-' ' -•4-k "•-•' 'i<ft_<. {,~., •~--,.,,., ~-=•""' '='.).:.l •• .,.,_ .. , O'-/~, ... •• • o > •L .. ,, .... --'">•~ .,__,.,,,_ • •
-. sus~,:A~CE_. t~f. _;;,·, ·{ · · •~s,, ... ·,•;.,cON(;EN,;RATl9!'. ,-,,,\· I?('·'-': PU~LJ,C'f:t}t.~J.i:tt~S,9':IQ_l::_U~I~\'!· ·,;i:. ' _. , · ·.. ...,,,. ,,,., /' '" '•(ppb)'*·l"'0 •0 ','\',· 1,,~it·•AS CITED'IN March-,2002··• c:'· · ; . · :-.-tx~· .. ~~.~~ : ·:.~~--€ $;1:i~~:1,;J~~S\ ·;1:---•• <~(>;. ~it:'. _, i;:HEALT~1-rc'ONsuLTATl6Nsi~!J~'~.. -~---_-. :;l{;\~: 7c~,,., .. ,· -.. ·-: ·-· ,, . -... -~ ----·_ ~ ·:.--: . .,: -.. __ .•. . .... :-.. ,-~ .... -·~,· , /·~!ff ,~• .. .,, • · -\"': ,r~•~J;;t/1 :}s:' zO:.~::;;r.:;~~,:If ;,0:l<,0:DetecteCFConcentrattonsri., ~, .nit-;-1,,,,,,?',;rlii , ei:~-. J,.r ,.,.,_ ':,f'., "'-.,, c;--.-~. , ~" , .. , • '~c-;:.> J, ~ "'•' '• •"-c• ,.,1--~,.-:}. ',. -:, .. --~i1f\l{ r~~,;, ; ~~~~:~\tri~~r ~i:1!,~'.I~~~] i~®.i:$i\~~~r1, t~:-P:i~~t:F .{. ·,:: ~~t~f-}1~~ ~-:~ff: ~-/;,,, ~ ,~ :,,t,:;::}'~' • . -• , , ..... ~ -''v, -"·R -~. --~ :f~~. 1,:;~,;! .. "M ! ,,~, '1,Y.>-,,~'M ·c:r '!\""· I~ ""t' '-, ..• ,,,.. .. ~ . ,._ .,,, ~'\1
,,; ,~ . -~--><_t .z,i';'.,1f'.:?: ".'. ¢v,;:>~~~ ',':, ange_-;,.::._':~~rj~ "{i'")i:{t;JI ean;.-1 ~<';J: '%"';',;:Z,~ 8 lanfl'l' ~;: d,,,.:·;;;..\~;.')!';~/ r,, ·-·~~.:1 -... -,,~':::t;'-'1":-i,.:_,.< ·,•
INORGANIC MOITIES
Nitrates I 100 --23,350 I 8,164 8,600 Potential Public Health Concern
Sulfates I 6,000 6,000 6,000 No Apparent Public Health Hazard
METALS
Aluminum 200 --1,700 950 950 No Annarent Public Health Hazard
Barium 16 ·-400 164 90 No Annarent Public Health Hazard
Calcium 21,000 -· 95,000 58,000 58,000 No Annarent Public Health Hazard
Cobalt 1.2--2,6 2.1 2.4 No Annarent Public Health Hazard
Cooper 14 --60 37.6 38 No Annarent Public Health Hazard
Iron 14 --5,500 1,736 195 No Aooarent Public Health Hazard
Lead 2 --28 8.9 4.5 No Aooarent Public Health Hazard
Maqnesium 1,600 -· 12,000 6,983 7,250 No Annarent Public Health Hazard
Manganese 4.2 --830 153.1 78 No Annarent Public Health Hazard
Mercury 1 --7 2.8 1.6 No Annarent Public Health Hazard
Nickel 2,3 --4.2 3,25 3.25 No Annarent Public Health Hazard
Potassium 1,300 --7,000 2,990 2,150 No Annarent Public Health Hazard
Sodium 5,300 ·-15,000 10,150 10,150 No Annarent Public Health Hazard
Zinc 28 --2,500 541 155 No Apparent Public Health Hazard
ORGANIC COMPOUNDS
Acetone 5 --233 71.9 47.5 No Annarent Public Health Hazard
Benzene 0.4 0.4 0.4 No Annarent Public Health Hazard
Bromodichloromethane 3 3 3 No Annarent Public Health Hazard
Chlorobenzene 0.4 0.4 0.4 No Annarent Public Health Hazard
Chloroform 0.6 --39 13.46 0.78 No Annarent Public Health Hazard
Dibromochloromethane 1 1 1 No Annarent Public Health Hazard
1,2-Dichlorobenzene 0,3 -· 48 24 24 No Annarent Public Health Hazard
1,4-Dichlorobenzene 0.27 --44 3.91 0.77 No Annarent Public Health Hazard
1, 1-Dichloroethane 0.4--1.5 0.7 0.6 No Annarent Public Health Hazard
1,2-Dichloroethane 0.53 0.53 0.53 No Annarent Public Health Hazard
cis-1,2-Dichloroethene 0.43 ·-3.5 1.3 0.8 No Annarent Public Health Hazard
Methvlene Chloride 2 2 2 No Apparent Public Health Hazard
B-2
TABLE 1: Chemical Levels Considered a No Apparent Health Hazard
ATSDR's 2002 Public Health Response for Sigmon's Septic Tank Service Facility
(Summary of Detected Chemical Concentrations found in all Private Wells between 1991 --1999)
Tetrachloroethene PCE)
Trichloroethene (TCE
Xylenes
Reference:
•
0.41
0.5
0.5 --5.1 2.2
Agency·for Toxic Substances and Disease Registry. March 29, 2002. Health
Consultation: Sigmon's Septic Tank Service Facility (Review of Groundwater
Data). US DHHS, Public Health Service,-Atlanta, GA.
B-3 • •
• • • TABLE 2: Chemical Levels Considered a No Apparent Health Hazard
ATSDR's 2006 Public Health Response for Sigmon's Septic Tank Service Site
(Summary of Detected Chemical Concentrations found in all Private Wells between October 2002 ·• May 2004)
CHeM>CAC ". ·., .•• , .. v,·• •. ,.,.,.. '•·•"C·•, , , ATSOR' ,, .,,c ,., ,
SUBSTANCE'.;:,_ · ';< .,Ii~f~l,ffi•;I· '.!;;'-~;,1,: CENTRATI · ':> 'Fi~BL_I~ ttEA!,cTH'.C9·~ci!us10~
\ . , -.., ,, "' '" "·"'1",1 "'' ; ' --C. ,.,, ".-~,~~"'' ~-:-..-•
t ·; ~ ,-.:~ ". ;,~~·:~·=.:~;',.:~~·· ~ ,J:·if;,'l~¾,r .~li~:~~.:~. ::-,.,;':\ ,,.:-~•.:~H~t;TH_9o~~Y~IA-W:l!?~:.-f:~: e • . ~'"• ,~.,--_..~.._-, ~,--,, "' .,,_,.~. · • ----• •· .,,---..-•-;' l ~.,,.,' r. .. ~.....,,.,.,-4 ,,,.,.,.., • •;1;,_,._., .(.,:r•,l,-• ,_~. --,: "'·N: -"'-~~!ri.cc_ ~ •• , ~ 'r es:~r,'.r.;rt!'<•~:r.r ,, 11H.-0etected1€oncentrat1onsw->l~'i:tl";:>'f~~-1r,;;.:;~ 1J~•"!• -• ..,..,-...... , ... --::►• • ·~ ,. ~ T •• .s~"'i. ~-. ~-~--,-..... '" •
1 ; • • f',,. '<'.:~•, • ,, ''' • •~ • ,,,,,.,,.,., _ _, ,'►"' ~. ·•' '.l~'"" " ''...t,~,/'"-"'":r,;l• r~•1,,,,.., :,C,
.
-
.,.. . . . ~'!'-tlr"'" ' . ·;,;;;,;;, ·"' ,,;; : ':;M,cri'io.'" '"""",:;,;,.;.'
. " •:;, __ , •· •• [.•~:.-. '>< , it,,,;' Ct,,~. "'•ii'J:i!l>": I ,;,7; il"1''ffC~ "'ill!'iil,"'"" I;\, ,".!j ;,,: t'fj f', .cfi:>,,,.-,\,a;,,•::, , ->~f.<.;,, . ,-,,1 >,. -,_,,: i . 'T;_c,,2\ 7i.Z,:. 2, ;tc~ '<,, ,t•.:,;J,'~ r' ,?._-~,>1.:;!•'•~½•"" '',.,.-''f:~~L "'hl'.',~~,,_,,~'.,.t, •~ !~~•.,-•f~•''!.•<-11'~'~"'•~-•"''•"'~'v~: ~~-•,••;-;,,•• '<>'-1 ,,~,_,_,: ~ ~~,_; : :~~ •!:.}1·: ili,:· 'C, ~~~~%:i;hiR8'nQeyf'':•/~;~;ii, ~~,1,M881lf;f, ~ti ~~~1fM80i3n'~':-; ~ :f.fis~:t }--::1:· ·:,.co-.-•~~:;::t~·=-~;:;>;l~:i:½' t:t~-::-;.;.
METALS
Aluminum 56 --200 107.2 110 No Annarent Public Health Hazard
Arsenic 1.2 --1.2 1.2 1.2 No Annarent Public Health Hazard
Barium 12--130 34 31 No Anoarent Public Health Hazard
Bervllium 0.14--0.14 0.14 0.14 No Annarent Public Health Hazard
Calcium::i 1,700 --39,000 7,989.4 5,900 No Annarent Public Health Hazard
Cobalt 0.08 --3.6 0.27 0.27 No Annarent Public Health Hazard
Copper' 2.8 --270 45.21 45 No Annarent Public Health Hazard
lron 1 37 --250 83.78 79 No Annarent Public Health Hazard
Lead2 1.3--140 6.04 5 Potential Public Health Concern
Magnesium5 390 --6,900 1,217.31 1,350 No Annarent Public Health Hazard
Manganese 1· 5 3.6 --270 11.87 8.2 No Annarent Public Health Hazard
Mercury5 0.98 --2.1 1.43 1.54 No Annarent Public Health Hazard
Nickel 1.3--3.2 2.19 2.4 No Annarent Public Health Hazard
Potassium' 840 --3,100 1,447.75 1,300 No Anoarent Public Health Hazard
Selenium 0.43 --0.43 0.43 0.43 No Annarent Public Health Hazard
Silver 0.07 --0.07 0.07 0.07 No Annarent Public Health Hazard
Sodium' 910 --9,400 3,958.84 4,100 No Annarent Public Health Hazard
Strontium 12--180 26.12 25.5 No Annarent Public Health Hazard
Vanadium 0.45 --1.8 0.9 1.13 No Annarent Public Health Hazard
Yttrium 2.1--2.1 2.1 2.1 No Annarent Public Health Hazard
Zinc 4.9 --3.400 54.82 42 No Apparent Public Health Hazard
VOLATILE ORGANIC COMPOUNDS
Benzene 0.26 --0.26 0.26 0.26 No Annarent Public Health Hazard
Bromoform4 1.6 --1.6 1.6 1.6 No Annarent Public Health Hazard
Carbon Disulfide 1.6--1.6 1.6 1.6 No Anoarent Public Health Hazard
Chlorobenzene 0.54 --0.54 0.54 0.54 No Aooarent Public Health Hazard
Chloroform' 0.32 --0.32 0.32 0.32 No Annarent Public Health Hazard
1,2-Dichlorobenzene 0.17 --0.46 0.28 0.32 No Apparent Public Health Hazard
B-4
.:,
TABLE 2: Chemical Levels Considered a No Apparent Health Hazard
ATSDR's 2006 Public Health Response for Sigmon's Septic Tank Service Site
(Summary of Detected Chemical Concentrations found in all Private Wells between October 2002 --May 2004)
1,4-Dichlorobenzene
1, 1-Dichloroethane
cis-1,2-Dichloroethene
PESTICIDES
-,t·
. ~<?,"•--
· alpha-BHC (Hexach/oroc c/ohexane-AI ha)
Endosulfan 11
Endrin Aldeh de
Endrin Ketone
Gamma-Chlordane
Heptachlor Epoxide
Reference:
•
1 --2.2 1.48 1.6 No A arent Public Health Hazard
0.2 --0.69 0.37 0.45 No A arent Public Health Hazard
0.52 --0.52 0.52 0.52 No A arent Public Health Hazard
0.67 --0.67 0.67 0.67 No A arent Public Health Hazard
0.52 --0.52 0.52 0.52 No A arent Public Health Hazard
0.91 --0.91 0.91 0.91 No A arent Public Health Hazard
0.12--0.12 0.12 0.12 No A arent Public Health Hazard
0.26 --0.39 0.32 0.33 No A arent Public Health Hazard
0.1 --0.21 0.14 0.12 No Apparent Public Health Hazard
0.027 --0.027 0.027 0.027 arent Public Health Hazard
0.011 --0.011 0.011 0.011 arent Public Health Hazard
0.017 --0.017 0.017 0.017 arent Public Health Hazard
0.01 --0.01 0.01 0.01 arent Public Health Hazard
0.011 --0.67 0.086 0.341 arent Public Health Hazard
0.01 --0.032 0.02 0.02 No Apparent Public Health Hazard
Agency for Toxic Substances and Disease Registry. February 2006. Health
Consultation: Sigmon's Septic Tank Service Site (Review of Groundwater Data -
EPA Delineation Investigations of 2002, 2003, and 2004). US DHHS, Public Health
Service; Atlanta, GA.
B-5 • •
• •
TABLE NOTES
Footnotes for Tables 3 through 11
...
A substance is selected for further public health evaluation if its maximum detected level in groundwater exceeds its respective water comparison
value (see blue highlighting). This screening criteria is neglected if the No. 5 disclaimer is specified (see lavender highlighting). Moreover, a
substance may also be selected for further public health evaluation if detected and no available water comparison value exists for the substance
(see yellow highlighting); however, this screening criteria is also neglected if the No. 5 disclaimer is specified (see green highlighting).
Therefore, a response of "Yes" under the column labeled "Further Public Health Evaluation Required" indicated that the substance was further
evaluated by ATSDR health scientists.
CREG: Cancer Risk Evaluation Guide
EMEG: Environmental Media Evaluation Guide (prefixes: a= acute, c
LTHA: Drinking Water Lifetime Health Advisory
IMCL: Maximum Contaminant Level
chronic, and i intermediate)
RBC: Risk Based Concentration (Note, RBC values derived from equations documented in following reference: EPA Region III Risk-Based
Concentration Table. United States Environmental Protection Agency, Region III, 841 Chestnut Street, Philadelphia, PA, 19107. Available on EPA
Region III's Internet website, http://www.epa.gov/reg3hwmd/risk/riskmenu.htm, Background Information -[PDF].)
RMEG: Reference Dose Media Evaluation Guide
lf'pb: parts per billion
1 Listed value in "EPA MCL" column is a Secondary Drinking Water Regulation (SDWR) as set by EPA. SDWRs are unenforceable federal guidelines
regarding taste, odor, color, and other non-aesthetic effects of drinking water. EPA recommends them to States as reasonable goals, but federal law
does not require water supply systems to comply with them. States may, however, adopt their own enforceable regulations governing these concerns.
To be safe, check your State's drinking water regulations.
2 Listed value in "EPA MCL" column is a Maximum Contaminant Level Action (MCLA) for drinking water as set by EPA under Superfund. If the relevant
action level is exceeded, a regulatory response is triggered.
3 Listed value in "EPA MCL" column is a health-based Drinking Water Advisory as set by EPA. The Drinking Water Advisory is based on the assumption
that an individual is placed on a sodium restricted diet of 500 mg/day.
4 Listed value in "EPA MCL" column is a proposed MCL under the 1994 proposed rule for disinfection by products rule; the current MCL for most
trihalomethanes is 100 ppb under the 1996 Drinking Water Advisory Report.
5 Detected concentration(s)are within a range of concentration levels designated for the specific chemical and considered a no apparent public health
hazard as cited in a previous public health consultation released for the Sigmon Septic Tank Service site (ATSDR, 2002).
B-6
TABLE 3
Detected Substances found in Private Well PW-01
CHEMICAL CHEMICAL WATER EPA FURTHER
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL PUBLIC
(ppb) (ppb) (ppb) HEALTH
EVALUATION
Detected REQUIRED
Concentrations
April 18, 2005
METALS
Barium 34 700 child RMEG 2,000 No
Calcium5 2,700 J No
Cobalt 0.11 J 100 child iEMEG No
Copper 28 J 200 child iEMEG 1,300 No
Lead 2 3.7 J 15 No
Magnesium5 500 J No
Manganese' 8.2 300 LTHA 50 No
Potassium' 1,600 J No
Zinc' 35 J 3,000 child iEMEG 5,000 (SDWR) No
CLASSICAL/ NUTRIENTS
Nitrates I 1,2001 20,000 child RMEG 10,0001 No
• • •
• TABLE 4
Detected Substances found in Private Well PW-03
CHEMICAL CHEMICAL WATER EPA
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL
(ppb) (ppb) (ppb)
Detected
Concentrations
April 18, 2005
METALS
Arsenic· "''. ·,-~ .. · ;/t;\;:~1S::-t\t,;\~~ 0.41 J ~''""''W"'-'"~'?lo:oncREG~.i!~;~1t 10
Barium 72 700 child RMEG 2,000
Calciums 48,000
Cobalt 0.79 J 100 child iEMEG
Copper" 1.4 J 200 child iEMEG 1,300
Iron 1 63 J 11,000 RBC 300
Magnesiums 4,300 J
M8ng·anes·e 1.;-~_;-:->--.-"'.'.?c-'?~::1::\ ',: t!~~-~~1~~~~-:fijt 71 300 LTHA ~""ml¥l!.~s:o
Mercury5 0.2 2 LTHA 2
Nickel 1.5 100 LTHA
Potassiums 3,600 J
Silver 0.03 J 50 child RMEG
Sodium' 6,600 20,000
Thallium 0.07 J 0.5 LTHA 2
Vanadium 1.9 30 child iEMEG
Zinc' 2.8 J 3,000 child iEMEG 5,000 (SDWR)
VOLATILE ORGANIC COMPOUNDS
Benzene 0.54 0.6 GREG 5
Chlorobenzene 2.2 100 LTHA 100
1,2-Dichlorobenzene 1.4 600 LTHA 600
1,4-Dichlorobenzene 2.5 75 LTHA 75
1, 1-Dichloroethane 0.84 800 RBC
cis-1,2-Dichloroethene 0.83 70 LTHA 70
1, 1,2-Trichloro-1,2,2-Trifluoroethane /Freon 113) 0.55 300,000 child RMEG
Vinyl Chloride 0.21 J -0.03 GREG 2
Total X,lenes 0.39 J 2,000 child iEMEG 10,000
B-8
•
FURTHER
PUBLIC
HEALTH
EVALUATION
REQUIRED
ll/iNINo ..
No
No
No
No
No
No
~
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
No
TABLE 4
Detected Substances found.in Private Well PW-03
CHEMICAL
SUBSTANCE
CLASSICAL/ NUTRIENTS
~itfatfs
•
CHEMICAL
CONCENTRATIONS
(ppb)
Detected
Concentrations
April 18, 2005
13,000
•
WATER.
COMPARISON VALUES
(ppb)
20,000 child RMEG
''FURTHER··
::PUBLIC
• 9 1-tEALTH
,L_~Ea'Ui~l6 · •;-:-<-.-,.,;,.,,
•
• TABLE 5 •
Detected Substances found in Private Well PW-04
CHEMICAL CHEMICAL WATER EPA FURTHER
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL PUBLIC
(ppb) (ppb) (ppb) HEALTH
EVALUATION
Detected REQUIRED
Concentrations
April 18, 2005
METALS
Barium 100 700 child RMEG 2,0001 No
Bervllium 0.12 J 20 child cEMEG ~~~~w Calciums._ .. : .. ,. ·.· ·. 6,100 • ·: . · ·,r,"'''""'" ''gj . . .. . .. ·, ,,· ... , ,;,-·.j_· ... :~-.'..f@lo'-:"~'·-~-:;~_.: .. .
Cobalt 0.41 J 100 child iEMEG No
Copper" 23 J 200 child iEMEG 1,300 No
Lead2 1.6 J 15 No
Magnesiums ----<•> .. . 2,400 J . ·;_.-:, , ... .. ' .•• ' . ,-•. ,·,~-, ·::'.l ~~ i .-~-.· ~~
Manganese' 19 300 LTHA 50 No
Nickel 1.8 100 LTHA No
Potassiums . · 3,200 J . -. ·r:-: .·.·· :.--.;~ K:~ --& "Jiliil'S<£l . ..
Sodium3 4,300 J 20,000 No
Thallium 0.09 J 0.5 LTHA 2 No
Zinc' 130 J 3,000 child iEMEG 5,000 (SDWR) No
CLASSICAL/ NUTRIENTS
Nitrates I 6,3001 20,000 child RMEG 10,0001 No
B-10
TABLE 6
Detected Substances found in Private Well PW-05
CHEMICAL CHEMICAL WATER EPA FURTHER
SUBSTANCE CON.CENTRA TIONS COMPARISON VALUES MCL PUBLIC
(ppb) (ppb) (ppb) HEALTH
EVALUATION
Detected REQUIRED
Concentrations
April 18, 2005
METALS
Barium 50 700 child RMEG 2,000 No
Calcium' 5,200 No
Cobalt 0.35 J 100 child iEMEG No
Copper2 33 J 200 child iEMEG 1,300 No
Lead2 1.1 J 15 No
Magnesium' 1,100 J No
Manganese' 4.9 300 LTHA 50 No
Nickel 2.3 100 LTHA No
Potassium' 2,000 J No
Thallium 0.06 J 0.5 LTHA 2 No
Zinc 18 J 3,000 child iEMEG 5,000 (SDWR) No
PESTICIDES
rieptachlo(Epoxide c. 0_c:,.<cs·H,;i", .;, /:c.;c,,,C,fS/~,I 0.0095 JI . ,, " , ..... 0,004;CREG"\'.l(';t i~\;'i';, 0.2I~\tZ!i:Nb~~
CLASSICAL/ NUTRIENTS
Nitrates I 1,3001 20,000 child RMEG I 10,0001 No
• • •
• TABLE 7
Detected Substances found in Private Well PW-06
CHEMICAL CHEMICAL WATER EPA
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL
(ppb) (ppb) (ppb)
Detected
Concentrations
April 18, 2005
METALS
Barium 30 700 child RMEG 2,000
Calcium' 3,200 J
Cobalt 0.27 J 100 child iEMEG
Copper" 16 J 200 child iEMEG 1,300
Lead2 1.1 J 15
Magnesium' 710 J
Manganese' 14 300 LTHA 50
Nickel 1.9 100 LTHA
Potassium5 1,400 J
Thallium 0.07 J 0.5 LTHA 2
Zinc' 17 J 3,000 child iEMEG 5,000 (SDWR)
CLASSICAL/ NUTRIENTS
Nitrates I 150 20,000 child RMEG 10,0001
B-12
•
FURTHER
PUBLIC
HEALTH
EVALUATION
REQUIRED
No
No
No
No
No
No
No
No
No
No
No
No
TABLE 8
Detected Substances found in Private Well PW-06 (Duplicate Sample)
CHEMICAL CHEMICAL WATER EPA FURTHER
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL PUBLIC
(ppb) (ppb) (ppb) HEALTH
EVALUATION
-Detected REQUIRED
Concentrations
April 18,.2005
METALS
Barium 30 700 child RMEG 2,000 No
Calciums 3,200 J No
Cobalt 0.28 J 100 child iEMEG No
Copper" 20 J 200 child iEMEG 1,300 No
Lead2 1.3 J 15 No
Magnesiums 710 J No
Manganese' 13 300 LTHA 50 No
Nickel 2 100 LTHA No
Potassiums 1,400 J -No
Thallium 0.07 J 0.5 LTHA 2 No
Zinc·1 20 J 3,000 child iEMEG 5,000 (SDWR) No
CLASSICAL/ NUTRIENTS
Nitrates I 160 20,000 child RMEG 10,000 No
• • •
• TABLE 9
Detected Substances found in Private Well PW-07
METALS
Barium
Calciumf .·
Copper2
Maghesiurji5
Nickel
Pcitassiurri'.· .. ·
Sodium3
Vanadium
Zinc
CHEMICAL
SUBSTANCE
CLASSICAL/ NUTRIENTS
Nitrates
CHEMICAL
CONCENTRATIONS
(ppb)
Detected
Concentrations
April 18, 2005
17
2,300 J
9.8 J
590 J .
0.19 J
1,500 J
5,100
1.2
19 J
640
B-14
WATER
COMPARISON VALUES
(ppb)
700 child RMEG
30 child iEMEG
3,000 child iEMEG
20,000 child RMEG
EPA
MCL
(ppb)
10,000
•
FURTHER
PUBLIC
HEALTH
EVALUATION
REQUIRED
No
No
No
TABLE10
Detected Substances found in Private Well PW-08
CHEMICAL ,·CHEMICAL WATER.. ·EPA FURTHER
. SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL PUBLIC . .. (ppb) (ppb) (ppb) HEALTH
EVALUATION
Detected REQUIRED
Concentrations
April 18, 2005
METALS
Barium 13 700 child RMEG 2,000 No
Calcium5 8,200 No
Copper" 4.5 J 200 child iEMEG 1,300 No
Magnesiums 1,700 J No
Manganese' 1.3 300 LTHA 50 No
Nickel 0.35 J 100 LTHA No
Potassiums 2,100 J No
Sodium3 5,600 20,000 No
Vanadium 2.1 30 child iEMEG No
Zinc' 69 J 3,000 child iEMEG 5,000 (SDWR) No
SEMI-VOLATILE ORGANIC COMPOUNDS
Bis(2-ethyhexyl)phthalate J 6.21 3 CREG .. 61 Yes
CLASSICAL/ NUTRIENTS
Nitrates I 2,0001 20,000 child RMEG 10,0001 No
• • •
• TABLE 11 •
Detected Substances found in Private Well PW-09
CHEMICAL CHEMICAL WATER EPA FURTHER
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL PUBLIC
(ppb) (ppb) (ppb) HEALTH
EVALUATION
Detected REQUIRED
Concentrations
April 18,2005
METALS
Barium 16 700 child RMEG 2,000T No
Beryllium 0.08 J 20 child cEMEG ~, C,aldLitriJ,;,:~~-,-,.,L -~~,~,.u~i.~~:-:i-~:~;.:t~::!u~~-;~~~t-:~.S:·.~::1; 9,600 ,.:_---,-,,,,c; -.)~J;~z~:~J'.a
Cobalt 0.04 J 100 child iEMEG No
Copper" 17 J 200 child iEMEG 1,300 No
Lead2 4.3 J 15 No
Magnesiums.' · ·-, .• ~ c, . ':'.;1[~, ----<.L ·-1,200 J .-'-~:--~~, _·_·:-~"-..... -~::::~, "{;:.·. ./~ ~ .:lffiiB'" .. ·{r_, l)Jo -. f,;
Manganese' 2.7 300 LTHA 50 No
Nickel 0.35 J 100 LTHA No
Potassiums -;-._· .. .. 1,400 J ,, ,:; ,.,, ~-~~· •.iir:,-,111\""'i •" " ,,;;.-. ~--;,}'.~' .' i ,~, -.-
Zinc' 22 J 3,000 child iEMEG 5,000 (SDWR) No
CLASSICAL/ NUTRIENTS
Nitrates -. 6801 20,000 child RMEG I 10,0061 No
B-16
TABLE12
Detected Substances found in Private Well PW-10
CHEMICAL . ·• -CHEMICAL WATER EPA FURTHER
SUBSTANCE CONCENTRATIONS .COMPARISON VALUES MCL PUBLIC
(pp~) (ppb) (ppb) HEALTH
EVALUATION
Detected REQUIRED
C.oncentrations
. April 18,2005
METALS
Barium 11 700 child RMEG 2,000 No
Calcium' 4,600 J No
Cobalt 0.19 J 100 child iEMEG No
Copper" 3.2 J 200 child iEMEG 1,300 No
lron1 -490 11,000 RBC . ·:'>,1300 t(.'.Jfa:No~,jt_.<: -' Lead2 11 J 15 No
Magnesium5 1,100 J No
Manganese1 18 300 LTHA 50 No
Nickel 0.35 J 100 LTHA No
Potassium' 1,700 J No
Sodium' 11,000 20,000 No
Vanadium 1.3 30 child iEMEG No
Zinc' 2,600 J 3,000 child iEMEG 5,000 (SDWR) No
CLASSICAL/ NUTRIENTS
Nitrates I 1,3001 20,000 child RMEG 10,0001 No
• • •
• TABLE13
Detected Substances found in Private Well PW-11
CHEMICAL CHEMICAL WATER
SUBSTANCE CONCENTRATIONS COMPARISON VALUES
(ppb) (ppb)
Detected
Concentrations
April 18, 2005
METALS
Arsenic .. .., ,.,:;." ·.: :,,.,, .. 0.29 J ·',·,•" · "' "0.02°CREG:l!>•i.:,•.,c,;i,:t0 •"c . ., ..
Barium 4.5 J 700 child RMEG
Calciums 10,000
Copper2 20 J 200 child iEMEG
Lead2 2.7 J
Magnesiums 1,500 J
Manganese' 3.6 300 LTHA
Nickel 0.34 J 100 LTHA
Potassiums 2,000 J
Sodium' 8,400
Vanadium 3.2 30 child iEMEG
Zinc' 1,500 J 3,000 child iEMEG
PESTICIDES
alpha-BHC (Hexachlorocvclohexane-Aloha) 0.0042 J 0.006 GREG
beta-BHC (Hexachlorocyc/ohexane-Beta) 0.004 J 0.02 GREG
IL,amma-BHC (Hexach/orocyclohexane-Gamma orLindane) 0.0027 J 0.1 child iEMEG
CLASSICAL/ NUTRIENTS
Nitrates I 1,5001 20,000 child RMEG
8-18
•
EPA FURTHER
MCL PUBLIC
(ppb) HEALTH
EVALUATION
REQUIRED
10 .Yffi~.Nbi.Jf:?(ti
2,000 No
No
1,300 No
15 No
No
50 No
No
No
20,000 No
No
5,000 (SDWR) No
No
No
0.2 No
10,0001 No
TABLE14
Detected Substances found in Private Well PW-12
CHEMICAL CHEMICAL WATER EPA FURTHER
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL PUBLIC
(ppb) (ppb) (ppb) HEALTH
EVALUATION
Detected REQUIRED
Concentrations ..
April 18, 2005
METALS
Barium 29 700 child RMEG 2,000 No
Calciums 3,100 J No
Cobalt 0.16 J 100 child iEMEG No
Copper" 37 J 200 child iEMEG 1,300 No
Iron 1 66 J 11,000 RBC 300 No
Lead2 2.4 J 15 No
Magnesiums 590 J No
Manganese' 25 300 LTHA 50 No
Nickel 0.56 J 100 LTHA No
Potassium' 1,600 J No
Thallium 0.05 J 0.5 LTHA 2 No
Zinc' 8.9 J 3,000 child iEMEG 5,000 (SDWR) No
CLASSICAL/ NUTRIENTS
Nitrates I 3901 20,000 child RMEG 10,0001 No
• • •
• • • TABLE15
Detected Substances found in Private Wells near the Sigmon Facility
(Summary of Detected Chemical Concentrations found in all Private Wells on April 200s:
CHEMICAL CHEMICAL WATER EPA FURTHER
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL PUBLIC
(ppb) (ppb) (ppb) HEALTH
EVALUATION
Detected Concentrations REQUIRED
Detection
Range Mean Median Rate
METALS
rsenic ·,: -., . _,.--... -··'.'c°:.' -'i.'.·•," -··-'( __ }t"\./c•?~~o;.· .. 'i.'';. 0.29 --0.41 0.34 0.35 2/12 .··-: ~' ~-1'.\ --:-:::-?.,;7-'Q.02-.CREG4:~~f9!t 10 ~~-~ NO~:-~
Harium 4.5--100 24.87 29.50 12/12 700 child RMEG 2,000 No
ervlllum 0.08--0.12 0.10 0.10 2/12 20 child cEMEG 4 No
alcium5 2,300 --48,000 8,850.00 5,662.58 12/12 No
obalt 0,04 --0.79 0.22 0.27 9/12 100 child iEMEG No
onner2 1.4--37 12.66 18.50 12/12 200 child iEMEG 1,300 No
rori1-·f:-..,_::', ' ',:./.,. , .. , ·.,.,,_·;• f;:,,·}/·}lit,·•f·:::a,*"~~~~~ 63 --490 126.77 66.00 3/12 11,000 RBG ;;.~ I.. iii3-□-o --N~
ead2 1.1--11 2.42 2.40 9/12 15 No
Aaqnesium5 500 --4,300 1,106.07 1,100.00 12/12 No
,1anaa·nese ,. 5· ··;:"tt~:1_,;:;:i~;/.:_,~,..~i~~ 1.3 --71 9.49 13.00 11/12 300 LTHA MI!.,&&so ~N~
V1ercury5 0.2 --0.2 0.20 0.20 1/12 2 LTHA 2 No
ickel 0.19 --2.3 0.74 0.56 11/12 100 LTHA No
otassium5 1,400 --3,600 1,861.69 1,650.00 12/12 No
ifver 0.03 --0.03 0.03 0.03 1/12 50 child RMEG No
::::odium3 4,300 11,000 6,492.43 6,100.00 6/12 20,000 No
hallium 0.05 --0.09 0.07 0.07 6/12 0.5 LTHA 2 No
anadium 1.2 3.2 1.82 1.90 5/12 30 child iEMEG No
inc 2.8 --2,600 45.47 21.00 12/12 3,000 child iEMEG 5,000 (SDWR) No
OLATILE ORGANIC COMPOUNDS
enzene 0.54 --0.54 0.54 0.54 1/12 0.6 GREG 5 No
hlorobenzene 2.2 --2.2 2.20 2.20 1/12 100 LTHA 100 No
1,2-Dichlorobenzene 1.4 1.4 1.40 1.40 1/12 600 LTHA 600 No
1 ,4-Dichlorobenzene 2.5 --2.5 2.50 2.50 1/12 75 LTHA 75 No
1, 1-Dichloroethane 0.84 --0.84 0.84 0.84 1/12 800 RBG No
llcis-1,2-Dichloroethene 0.83 -0.83 0.83 0.83 1/12 70 LTHA 70 No
1, 1,2-Trichloro-1,2,2-Triffuoroethane <Freon 113) 0.55 --0.55 0.55 0.55 1/12 300,000 child RMEG No
Iv inyl Chloride 0.21 0.21 0.21 0.21 1/12 0.03 GREG 2 Yes
otal Xylenes 0.39 --0.39 0.39 0.39 1/12 2,000 child iEMEG 10,000 No
sEMI-VOLATILE ORGANIC COMPOUNDS
Bis(2-ethyhexyl)phthalate I 6.2 --6,2 6.21 6.21 1/121 3 GREG 61 Yes
PESTICIDES
aloha-BHC (Hexachlorocvclohexane-Aloha) 0.0042 --0.0042 0.0042 0.0042 1/12 0.006 GREG No
beta-BHC (Hexachlorocvclohexane-Beta) 0.004 --0.004 0.004 0.004 1/12 0.02 GREG No
amma-BHC (Hexachlorocvclohexane-Gamma orlindane) 0.0027 --0.0027 0.0027 0.0027 1/12 0.1 child iEMEG 0.2 No
Heptachlor Epoxide · ,. , " _,,_. ·.:.:":'.'tQ-f."";._-·, ~<: ., -~.;-0.0095 --0.0095 0.0095 0.0095 1/12 ;.-, •,0.004 CREG;-:'f'f't• ..,,,->:' 0.2 " '.~-~•\No"t-.t'.:6i
CLASSICAL/ NUTRIENTS
Nitrates I 150 --13,000 1,060.771 1,250.001 12/121 20,000 child RMEG 10,0001 Yes
B-20
•
Appendix C. Figures
•
C-1
•
•
• REP. -USGS 7.5 MINUTE SERIES TOPOGRAPHIC MAP; TROUTMAN, NC 1993.
SITE LAYOUT MAP
SIGMON ·s SEPTIC TANK SITE
STATESVILLE, !REDELL COUNTY, NORTH CAROLINA
I" = 600'
FIGURE
1
•1 81 Iv I \ I r _J l le _J w 3= w tjl SS-PW-07_/ II /\ \ \ \\ 11 _J m ~ 0 a.. '2 ~ a.< ~ Cl :::;; e zz <( 0 51 /111 I \ \ I'\ /"SS-PW-05 ci ~ I 15 tjl SS-Pll-(13 \ \\. \\ ~ 'w'JLLl,.MS POND 3: g l? z Ct'. e 181 \\ I I 11 z Cl •~~·\ :::;; r ~ C • -MV-UC 2 L#IMBERTH FOND "--h SS-P\1-0G ::! 41 \\ C " I I< / "\ 'f I :::; C :? SS-N'J-13JJ cl < ~C~PD ~ " r ~ ,: > ~ "' 0: 0 "' z ~g LAGOCN AR:f:#1 u => 81 I j/[l \ 0 ,= 0 ~ e, " "'~ "'~ . .., z B ,1 ii: II ~ HUSTANG l.Af',E ~ s e; I I> ' ;r--::::, S1 . ~ L.C'loi LAN~ "'~ lkJF"F" "LO SS-,0..., (J ~ SS-H'J-12B SS~V-DS l ~ l.S ~•UI llAVlDSDN POND '\. SS-P\J-o-, ! 21 / ~ II I I 11 I 12 il tjl SS-Pll-01 .../ ~ 11 II I ~z~ I ' SCALE L.EGE:ND I 11" = 300· -$-SHALLOW MONITORINC WE:LL LOCATION [ Flg~r• ] $ DEEP MONITORING WELL LOCATION ~ POTABLE WELL SAMPLE LOCATION .I A B C 0 E F G H
•
•
•
SS-PW-03 ()
SS-MW-13B ~
SS-M 12B~
SS-PW-10 ()
r •
0
< •
~
SS-MW-14
I SS-MW-11C
SS-PW-04~
SS-MW-01
1, Q
SS-MW-10B~
SS-PW-05 ()
Mustang Lane
Low Lane
SS-PW-06
~-z
Legend
-$-Monitoring Well
'-Potable Well
<i z :J 0 a:
<i 0
wI
':::~ "'o :<z z . <i >-f--f--~ s >--o fuo
U)...,
g) u:1 zo ow
" a: (.9-.
Cl)~ ..., > U) w ~
SCALE
1 in. equals 400 ft.
Rgure
3
•
•
----, .
~:.:;:::::::::;;:.::::::~. . /·--..;;: '«..;,If ..
ml SIGMONS SEPTIC TANK SITE
STATESVILLE NORTH CAROLINA
•
•
I . . ,/ ~ --~so,
'
l,
U:GE:ND
2000 1000 0 MM MM M
(~C>0.9J) W,.TtR ELCY,.TIOH
(FEET AMSL., NVGD 29)
2000
-850' -GA OUN fYNATE'.R tUVA TION CONTOURS
(FE£T AMSL, NVCD 29]
--GROUNDWAIER FLOW DIRECTION
GROUNDWATER POTENTIOMETRIC SURFACE MAP
AS MEASURED ON 05-21-20D4
FIGURE
4
•
•
0
Evaluation of Surface Water Data
SIGMON'S SEPTIC TANK SERVICE
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
EPA FACILITY ID: NCD062555792
AUGUST 8, 2006
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Atlanta, Georgia 30333
Health Consultation: A Note of Explanation
An ATSDR health consultation is a verbal or written response from ATSDR to a specific
request for information about health risks related to a specific site, a chemical release, or
the presence of hazardous material. In order to prevent or mitigate exposures, a
consultation may lead to specific actions, such as restricting use of or replacing water
supplies; intensifying environmental sampling; restricting site access; or removing the
contaminated material.
In addition, consultations may recommend additional public health actions, such as
conducting health surveillance activities to evaluate exposure or trends in adverse health
outcomes; conducting biological indicators of exposure studies to assess exposure; and
providing health education for health care providers and community members. This
concludes the health consultation process for this site, unless additional information is
obtained by ATSDR which, in the Agency's opinion, indicates a need to revise or append
the conclusions previously issued.
You May Contact ATSDR TOLL FREE at
l-888-42ATSDR
or
Visit our Home Page at: http://www.atsdr.cdc.gov
•
•
•
•
•
•
HEALTH CONSULTATION
Evaluation of Surface Water Data
SIGMON'S SEPTIC TANK SERVICE
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
EPA FACILITY ID: NCD062555792
Prepared by:
U.S. Department of Health and Human Services
Public Health Service
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Atlanta, Georgia 30333
•
•
STATEMENT OF ISSUES AND BACKGROUND
Statement of Issues
The Agency for Toxic Substances and Disease Registry (ATSDR) prepared this health
consultation to evaluate, based on the information currently available, any known or
potential adverse human health hazards related to exposures to contaminants in surface
water associated with the Sigmon's Septic Tank Site.
Background
The Sigmon's Septic Tank site is located at 1268 Eufola Road, approximately 5 miles
southwest of Statesville, Iredell County, North Carolina. The property comprises
approximately 15 acres. Sigmon's Septic Tank Service, a wholly owned subsidiary of
AAA Enterprises, purchased the property in 1970. The business installed and repaired
septic tanks. In addition, Sigmon's Septic Tank Service pumped septic tank wastes and
heavy sludges from residential, commercial, and industrial customers. From 1978 to
1992, the property owners deposited waste in several unlined lagoons which had been
dug on the property.
Previously, ATSDR has issued six health consultations for the Sigmon's Septic Tank Site
(1,2,3,4,5,6). The health consultations include a review of sampling plans for the site, as
well as evaluations of the available groundwater, surface water, and surface soil data.
The most recent health consultations, released on April 3, 2006 and April 24, 2006,
address recent groundwater and surface soil data, respectively (5,6). This health
consultation is intended to address exposures to on-site and off-site surface water.
Currently, the U.S. Environmental Protection Agency (EPA) continues to investigate the
soil and groundwater conditions at the site. Future health consultations may be prepared
if the evaluation of newly collected data changes previous public health conclusions
made for the site.
Demographics
According to U.S. 2000 Census data, 802 persons live within a one-mile radius of the
site. Approximately 95% of this population, or 760, are white. Also, 81 arc children age
6 and under, and 83 are adults over age 65. A total of323 housing units are in the site
area. Additional demographic information for the community in the vicinity of the site is
presented in the following figure .
D Hazardous Waste Site of Interest D Other Hazardous Waste Site
D One Mile Buffer
0.3 0.6 0.9 Miles
Base Map Source: Geographic Data Technology, May 2005.
I
Site Location Iredell County, NC
TN
Demographic Statistics
Within One Mlle of Site*
-Total Population 802-
White Alone 760
Black Alone 33
Am. Indian & Alaska Native Alone 0-
Asian Alone 0
-Native Hawaiian &
Other Pacific Islander Alone 0
-Some Other Race Alone 5
Two or More Races 4
HisR:anic or Latino""" 9
Children Aged 6 and Younger 81
Adults Aged 65 and Older 83 -Females Aged-15 to 44 176-
Total Housing Units 323
Demographics Statistics Source: 2000 U.S. Census
• Calculated using an area-proportion spabal analysis technique Site Boundary Data Source: ATSDR Public Health GIS Program, May 2005.
Coordinate System {All Panels): NAO 1983 StatePlane North Carolina FIPS 3200 Feet •• People who identify their origin as Hispanic or Latino may be of any race.
GRASPMASTER 9 1 [BETA] -GENERATED: 01-30-2006
□, -4,999°
l£fil 5,000 -9,999"
-10.000 and Allo~~ •
• Per Square M1ie
0030609 -
r-;gA FOR INTERNAL AND EXTERNAL RELEASE \.._~ -~.J}~.B AGENCY FOR TOXIC SUBSTANCES AND DISEASE REGISTRY I UNITED STATES DEPARTMENT OF HEALTH AND HUfv\AN SERVICES
•
•
•
ENVIRONMENTAL DATA
As part of this health consultation, ATSDR evaluates surface water samples collected by
EPA in October 2002 and May 2004. A total of nine surface water samples were
collected by EPA. All surface water samples were analyzed for volatile organic
compounds, semi-volatile organic compounds, metals, and pesticides. Seven surface
water samples were considered in this evaluation and the other two were used for quality
assurance purposes. The available data has undergone EPA's quality assurance/quality
control process and has been determined to be useable (I).
Surface water runoff from the site flows primarily across the Lambreth property to the
Lamberth pond. The Lamberth pond discharges to an intermittent stream west of the site
on the Williams property. Surface water runoff from the southeastern comer of the site
collects in a Lauren Drive grassy swale east of the site and discharges from a culvert
underneath the road to a grassed area in between Lauren Drive and Davidson pond. The
Davidson pond discharges through an outlet pipe to an intermittent stream which
eventually meets other intermittent streams from the other surface water pathways which
flow into the Catawba River (I).
One surface water sample was collected on-site from the pond located on the Sigmon's
Septic Tank Site. One sample was also collected from each of the ponds located on
private, residential property in the vicinity of the site, including the Williams, Davidson,
and Lambreth ponds. In addition, three surface water samples were also collected from a
nearby intermittent stream (I). Sediment samples were also collected at these locations
and evaluated in the surface soil health consultation completed in April 2006 (6).
PATHWAY ANALYSIS
ATSDR's pathways analysis determines whether people have come into contact with
chemicals from a site and whether those contacts were substantial enough to cause harm.
To make this determination, A TSDR identifies exposure pathways or ways in which a
chemical could enter a person's body.
As outlined in ATSDR's Public Health Assessment Guidance Manual, an exposure
pathway contains five major elements:
l. a source of contamination,
2. transport through an environmental medium,
3. a point of exposure,
4. a route of exposure, and
5. an exposed population .
3
If an exposure pathway contains all five elements and exists now or did exist in the past,
the pathway is considered complete. Completed exposure pathways are evaluated to
determine whether health effects could occur. If one or more of the five elements is not
clearly defined but could be present, the exposure pathway is classified as potential (8).
A TSDR has identified the surface water pathway as a completed exposure pathway in
this health consultation. Based on information from EPA, there is no evidence of
individuals eating fish from the Sigmon pond at the current time or in the past. In
addition, fish that people would consume are not likely to be present in the Sigmon pond.
Therefore, the fish consumption pathway is incomplete and poses no public health
hazard.
Other completed or potential pathways may exist for the Sigmon's Septic Tank Site and
have been evaluated in separate health consultations. More detailed information on the
surface water exposure pathway is presented in Table 1.
Table I. Surface Water Exposure Pathway Elements
Source Environmental Point of Route of Exposed Timeframe
Media Exposure Exposure Population
Past Surface water On-site Ingestion Adults and Past
disposal Off-site Inhalation children Present
activities using the
Direct water for Future
Contact recreational
purposes
DISCUSSION
The first step in ATSDR's evaluation process is to select the chemicals of concern, also
described as the chemicals that require further evaluation. ATSDR selects chemicals of
concern on the basis of whether the maximum detected concentrations of the chemical
are found to exceed applicable, health-based comparison values. A chemical found to
exceed a comparison value indicates that a more detailed analysis is necessary for that
chemical. Levels of chemicals greater than comparison values do not necessarily mean
that adverse health effects will occur. The amount of the chemical, the duration of
exposure, the route of exposure (i.e., ingestion, inhalation, and direct skin contact), and
the health status of exposed individuals are also important factors in determining the
potential for adverse health effects. ATSDR has not developed comparison values
specifically for surface water. Therefore, drinking water comparison values were used in
this evaluation. This is a very protective approach because no one uses the surface water
bodies evaluated in this health consultation for drinking water purposes. In addition,
individuals are not expected to swallow large quantities of water during swimming and
wading. A complete discussion of ATSDR's evaluation process is presented in the
appendix of this health consultation.
4
•
•
•
•
•
•
Concentrations of calcium, iron, magnesium, potassium, and sodium were detected in the
surface water samples collected from the ponds and intermittent stream. These elements
occur naturally in the environment and are unlikely to be related to the site. They are also
essential nutrients and are not expected to cause any health-related problems at the levels
at which they were detected. Therefore, calcium, iron, magnesium, potassium, and
sodium have not been considered further in this health consultation.
I
With the exception of the essential nutrients previously discussed, no other chemicals
were detected in surface water at concentrations exceeding comparison values in the
Williams, Lamberth, and Davidson ponds. Only one chemical (Aroclor-1260) was
indicated in surface water above comparison values in the pond located on the Sigmon's
Septic Tank Site property. Aroclor-1260 is part of a group of chemicals known as
polychlorinated biphenyls (or PCBs). Arsenic and manganese were detected above
comparison values in the surface water collected from the intermittent stream. Additional
information about the chemicals detected above comparison values is presented in Table
2 and 3.
Table 2. Surface Water from Sigmon Pond (On-site)-Detected chemical(s) that exceed
comparison values
CONTAMINANT I Milligrams/kilogram (mg/kg) or I sou,c, · parts per million (ppm) FREQUENCY
[ Minimum I Maximum j
DETECTED
Comparison Value
Aroclor-1260 FF! 0.2 Chronic
I
1/1
ChildEMEG
Chronic Child EMEG= Environmental Media Evaluation Guide developed for long-term exposure to the
chemical by children
Frequency of Detection= Number of samples in which chemical was detected/ Total number of samples
collected
Table 3. Surface Water from Intermittent Stream (Off-site)-Detected chemicals that
exceed comparison values
Milligrams/kilogram (mg/kg) or
I SOU,CC CONTAMINANT parts per million (ppm) FREQUENCY
I Minimum I Maximum I Comparison Value DETECTED
I Arsenic 1--o 00094 I 0.00094 I 0.00002 i CREG I 1/3
I Manganese I 0.180 I 1.2 I 0.5 • I Child RMEG I 3/3
Notes:
CREG=Cancer Risk Evaluation Guide
5
RMEG = Reference Media Evaluation Guide developed for exposure to the chemical by children
Frequency of Detection = Number of samples in which chemical was detected/ Total number of samples
collected
PUBLIC HEAL TH IMPLICATIONS
For chemical concentrations found to exceed comparison values, ATSDR performed
calculations referred to as exposure doses and cancer risk estimates. These calculations
estimate the amount of the chemicals of concern that individuals may have been exposed
to and the likelihood of cancer and non-cancer health impacts. They are based on the
types of site-specific activities that individuals may be involved with that result in contact
with chemicals in the surface water. In the event that calculated exposure doses exceed
established health guidelines ( e.g., ATSDR Minimal Risk Levels or EPA Reference
Doses), an in-depth toxicological evaluation is the next step necessary to determine the
likelihood of health effects.
A TSDR has evaluated adults and children who may wade or swim in the Sigmon pond
(on-site) or the intermittent stream (off-site). Unintentional ingestion and direct skin
contact with surface water has been considered. This is considered a conservative
approach because the water may not even be deep enough to swim in at certain times of
the year. Additional information on the exposure scenarios, assumptions and calculations
used to estimate exposures are discussed in the appendix of this health consultation.
No additional evaluation of the Williams, Lamberth, and Davidson ponds has been
completed. Further evaluation is not warranted because none of the chemicals found in
surface water samples collected from these ponds exceeded comparison values.
Therefore, wading and swimming in the Williams, Lamberth, and Davidson ponds poses
no public heath risk.
Non-Cancer Health Effects Evaluation
Only one chemical, Aroclor-1260, was detected in the Sigmon pond (on-site) at a
concentration that exceeds a comparison value. Therefore, site-specific exposure doses
were calculated. The calculated doses for the Sigmon pond were lower than the
established health guidelines.
Arsenic and manganese were the only chemicals found in the intermittent stream ( off-
site) at concentrations that exceed a comparison value. The dose calculations were
determined to be much lower than the established health guidelines.
Therefore, ATSDR concludes that swimming and wading in the Sigmon pond and
the intermittent stream is not expected to result in adverse non-cancer health
effects. A list of the calculated doses and available health guidelines is presented in the
appendix of this health consultation (Table A).
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Cancer Evaluation
The only cancer-causing chemical detected in surface water above comparison values is
arsenic. Arsenic was found in low levels in one of the three samples collected from the
intermittent stream. Studies have indicated that exposure to arsenic causes cancer in
humans. The risk of individuals developing cancer from exposure to arsenic in surface
water was considered in this health consultation. Cancer risk was calculated for residents
and includes exposures occurring during childhood and adulthood.
On the basis of the risk calculations, ATSDR has determined that there is no
increased risk of cancer to residents who swim or wade in the intermittent stream.
A complete list of the calculated cancer risks for surface water is presented in the
appendix of this health consultation (Table 8).
Community Health Concerns
A TSDR held a public availability session on Monday, December 5, 2005 to gather health
concerns from the community surrounding the Sigmon's Septic Tank Site. The public
availability session was held at the Celeste Henkel Elementary School from 6:00 PM to
8:00 PM. A media availability session was held at the same location from 5 :30 PM to 6:00
PM. Representatives from ATSDR and EPA attended the sessions. Flyers were sent out
to residences in the vicinity of the Sigmon's Septic Tank Site to announce the meeting.
Five community members attended the session. Most of the individuals had questions
about EPA's environmental investigation and cleanup planned for the site. No questions
or concerns were raised about surface water on or around the site.
Child Health Considerations
In communities faced with air, water, or food contamination, the many physical
differences between children and adults demand special emphasis. Children could be at
greater risk than are adults from certain kinds of exposures to hazardous substances.
Children play outdoors and sometimes engage in hand-to-mouth behaviors that increase
their exposure potential. Children are shorter than adults; this means they breathe dust,
soil, and vapors close to the ground. A child's lower body weight and higher intake rate
results in a greater dose of hazardous substance per unit of body weight. If toxic exposure
levels are high enough during critical growth stages, the developing body systems of
children can sustain permanent damage. Finally, children are dependent on adults for
access to housing, for access to medical care, and for risk identification. Thus adults need
as much infomiation as possible to make informed decisions regarding their children's
health. On the basis of the evaluation conducted in this health consultation, A TSDR has
determined that children are not at risk for health-related problems from swimming or
wading in surface water in and around the site, including Sigmon pond, Williams pond,
Lamberth pond, Davidson pond, and the intermittent stream.
7
CONCLUSIONS
I. ATSDR has evaluated exposure to chemicals in on-site surface water on the Sigmon's
Septic Tank Site. On the basis of the available data, ATSDR has determined that
exposure to chemicals by adults and children during wading and swimming in
Sigmon pond poses no apparent public health hazard.
2. ATSDR has also evaluated children and adult exposure to chemicals in off-site
surface water, including nearby residential properties. The water bodies include the
Williams, Lamberth, and Davidson ponds, as well as a nearby intermittent stream.
ATSDR has determined that swimming and wading in these surface water bodies is
not expected to result in harmful health effects and poses no apparent public health
hazard.
3. There is no evidence of individuals eating fish from the Sigmon pond at the current
time or in the past. In addition, fish that people would consume are not likely to be
present in the Sigmon pond. Therefore, the fish consumption pathway is incomplete
and poses no public health hazard.
RECOMMENDATIONS
1. The findings of this health consultation are not intended to encourage swimming or
wading in the Sigmon pond located on-site. The site is located on private property
and is currently under investigation by EPA. It is recommended that residents avoid
accessing the property, for any reason, without the owner's consent.
2. If information becomes available about individuals routinely consuming fish from the
Sigmon's pond, it is recommended that EPA collect additional surface water samples
or fish tissue samples . The basis for this recommendation is the detection of
Aroclor-1260 in the one surface water sample collected from the Sigmon pond.
Although this chemical has been found at levels that are not expected to be harmful to
people swimming and wading, studies have found that Aroclor-1260 can accumulate
in fish tissue. Therefore, additional samples would be needed to determine the
potential exposure to people eating fish from Sigmon pond.
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PUBLIC HEAL TH ACTION PLAN
A Public Health Action Plan describes the actions designed to mitigate or prevent adverse
human health effects that might result from exposure to hazardous substances associated
with site contamination. A summary of the public health actions that have been taken
and those completed for the Sigmon's Septic Tank Site are provided below.
Public Health Actions Taken
Previously, ATSDR has issued six health consultations for the Sigmon's Septic Tank Site
(1,2,3,4,5,6). The health consultations include a review of sampling plans for the site, as
well as evaluations of the available groundwater, surface water, and surface soil data.
The most recent health consultations, released on April 3, 2006 and April 24, 2006
address recent groundwater and surface soil data, respectively (5,6).
A TSDR participated in a site tour conducted by EPA and its contractor on Monday,
December 5, 2005. A TSDR examined the conditions of the site and toured the
surrounding community at this time.
ATSDR conducted a public availability session on Monday, December 5, 2005 to gather
health concerns from the community. The public availability session was held at the
Celeste Henkel Elementary School from 6:00 PM to 8:00 PM. Representatives informed
residents about ATSDR's work at the site and gathered community health concerns.
ATSDR also prepared a fact sheet that was mailed to the community in the vicinity of the
site in summer 2006. The fact sheet provides information on ATSDR's work at the site,
the findings of the recent soil and groundwater health consultations, and contacts for
additional information.
Public Health Actions to be Completed
A TSDR will continue to collaborate with the appropriate federal, state, and local
agencies. ATSDR may review new environmental data associated with the Sigmon's
Septic Tank Site. If the data evaluation impacts previous public health conclusions made
for the site, ATSDR will produce additional health consultations .
9
REFERENCES
I. Agency for Toxic Substances and Disease Registry. Health Consultation for
Sigmon's Septic Tank Service. 2001 August 24.
2. Agency for Toxic Substances and Disease Registry. Health Consultation for
Sigmon's Septic Tank Service -Review of Groundwater Data. 2002 March 29.
3. Agency for Toxic Substances and Disease Registry. Health Consultation for
Sigmon's Septic Tank Service -Review of Surface Water Data. 2002 July 09.
4. Agency for Toxic Substances and Disease Registry. Health Consultation for
Sigmon's Septic Tank Service -Review of Sampling Plan. 2005 July 05.
5. Agency for Toxic Substances and Disease Registry. Health Consultation for
Sigmon's Septic Tank Service. 2006 April 03. (Groundwater)
6. Agency for Toxic Substances and Disease Registry. Health Consultation for
Sigmon's Septic Tank Service. 2006 April 24. (Surface soil)
7. US Environmental Protection Agency. Remedial Investigation Report, Operable Unit
I for Sigmon's Septic Tank Service. 2005 August.
8. Agency for Toxic Substances and Disease Registry. Public health assessment
guidance manual. Atlanta: US Department of Health and Human Services; 2005.
10
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ATSDR TEAM
Prepared by:
Annmarie K. DePasquale, MPH
Environmental Health Scientist
Division of Health Assessment and Consultation
Superfund Site Assessment Branch.
Reviewed by:
Benjamin Moore, MS
Regional Representative -Region 4
Division of Regional Operations
Jannett P. Smith-George, MSW
Health Communication Specialist
Division of Health Assessment and Consultation
Health Promotion and Community Involvement Branch
David S. Sutton, Ph.D., PE
Environmental Engineer
Division of Health Assessment and Consultation
Exposure Investigation and Consultation Branch
I I
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Appendix -ATSDR's Evaluation Process
Step 1 Comparison Values and the Screening Process
To evaluate the available data, ATSDR used comparison values (CVs) to determine
which chemicals to examine more closely. CV s are the chemical concentrations found in
a specific media (for example: air, soil, or water) and are used to select chemicals for
further evaluation. CVs incorporate assumptions of daily exposure to the chemical and a
standard amount of air, soil, or water that someone may take into their body each day.
CVs are generated to be conservative and non-site specific. These values are used only to
screen out chemicals that do not need further evaluation; CVs are not intended as
environmental clean-up levels or to indicate that health effects occur at concentrations
that exceed these values.
CVs can be based on either carcinogenic (cancer-causing) or non-carcinogenic effects.
Cancer-based comparison values are calculated from the U.S. Environmental Protection
Agency's (EPA) oral cancer slope factor (CSF) or inhalation risk unit. CVs based on
cancerous effects account for a lifetime exposure (70 years) with a theoretical excess
lifetime cancer risk of I new case per I million exposed people. Non-cancer values are
calculated from ATSDR's Minimal Risk Levels (MRLs), EPA's Reference Doses
(RfDs), or EPA's Reference Concentrations (RfCs). When a cancer and non-cancer CV
exists for the same chemical, the lower of these values is used in the comparison for
conservatism. The chemical and media-specific CV s utilized during the preparation of
this HC are listed below:
An Environmental Media Evaluation Guide (EMEG) is an estimated comparison
concentration for which exposure is unlikely to cause adverse health effects, as
determined by A TSDR from its toxicological profiles for a specific chemical.
A Reference Dose Media Evaluation Gnide (RMEG) is an estimated comparison
concentration that represents concentrations of chemicals (in water, soil, and air) to
which humans may be exposed to without experiencing adverse health effects.
A Cancer Risk Evaluation Guide (CREG) is a comparison concentration that is
based on an excess cancer rate of one in a million persons and is calculated using
EPA's cancer slope factor (CSF).
Step 2 -Evaluation of Public Health Implications
The next step in the evaluation process is to take those contaminants that are above their
respective CVs and further identify which chemicals and exposure situations are likely to
be a health hazard. Therefore, calculations are performed to estimate the possibility of
cancer and non-cancer health problems. The calculations consider the activities of people
living in the community. The assumptions used in the calculations are discussed in the
following sections .
12
Adult Residents
Adult residents were assumed to be exposed to chemicals while swimming or wading in
on-and off-site surface water. They were estimated to engage in these activities twice a
week during the four summer months of the year (or 32 days per year). Unintentional
ingestion and direct skin contact with surface water has been evaluated.
It was assumed that these individuals ingest one-tenth the amount of water ingested for
drinking purposes during swimming, which is equal to 0.10 liters per day (L/day) and
weighed 70 kilograms (kg) (or 153 pounds). The surface area available for direct skin
contact was conservatively considered to be the entire body ( or 18,150 cubic centimeters
[ cm3]). Chemical-specific permeability constants were used when available. When
unavailable, the EPA recommended default permeability constant of0.0010 centimeters
per hour ( cm/hour) was used. Adult residents were assumed to be exposed for 30 years.
Children Residents
Children residents were assumed to be exposed to chemicals while swimming or wading
in on-and off-site surface water. They were estimated to engage in these activities twice
a week during the four summer months of the year (or 32 days per year). Unintentional
ingestion and direct skin contact with surface water has been evaluated.
It was assumed that these individuals ingest one-tenth the amount of water ingested for
drinking purposes during swimming, which is equal to 0.10 liters per day (L/day) and
weighed 23 kilograms (kg) (or 50 pounds). The surface area available for direct skin
contact was conservatively considered to be the entire body ( or 8,545 cm3). Chemical-
specific permeability constants were used when available. When unavailable, the EPA
recommended default permeability constant of 0.0010 centimeters per hour ( cm/hour)
was used. Children residents were assumed to be exposed for 6 years.
The Calculations
In order to evaluate the potential for human exposure to chemicals present at the site and
potential health effects from site-specific activities, ATSDR estimates human exposure to
the site chemicals from different environmental media by calculating exposure doses and
cancer risk estimates. A brief discussion of the calculations is presented below. Separate
calculations have been performed for exposures to adults and children to account for the
different types of exposures each has as described above. The same equations have been
used for the non-cancer and cancer calculations with the indicated modifications. The
equations and the assumptions are based on the EPA Risk Assessment Guidance for
Superfund, Part A 1, EPA Risk Assessment Guidance for Superfund, Part E2 and the EPA
1 U.S. Environmental Protection Agency. Risk Assessment Guidance for Su,perfund. Volume I: Human
Health Evaluation Manual. Part A. December 1989.
2 U.S. Environmental Protection Agency. Risk Assessment Guidance for Superfund. Volume I: Human
Health Evaluation Manual. Part E, Supplemental Guidance for Dermal Exposure. July 2004.
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Exposure Factors Handbook3, unless otherwise specified. A discussion of the cancer and
non-cancer evaluation of exposure is presented following the equations for each pathway.
Incidental Ingestion of Surface Water While Swimming and Wading
Adult and children residents may be exposed to chemicals as a result of unintentionally
swallowing water during swimming and wading. The exposure dose for incidental
ingestion of surface water is
where
CxIRx EFxED Dose(mglkglday)=------
BWx AT
C = maximum detected concentration of a chemical; milligrams per liter (mg/L)
IR= ingestion rate; 0.10 L/day for adults and children
EF = exposure frequency; 32 days/year
ED= exposure duration; 30 years for adults and 6 years for children
BW =bodyweight; 70 kg (or 153 pounds) for adults and 23 kg (or 50 pounds) for
children
AT= averaging time; 10,950 days for adults and 2,190 days for children
Direct Skin {Denna\) Contact with Chemicals Present in Surface Water
Denna! absorption depends on numerous factors, including the area of exposed skin,
anatomical location of the exposed skin, length of contact, concentration of the chemical
in contact with the skin, and other factors. Because chemicals differ greatly in their
potential to be absorbed through the skin, each chemical needs to be evaluated separately.
The exposure dose for direct contact with chemicals in surface water is
D ( lk Id ) CxSAxPCxETxEFxEDxCF ose mg g ay =
. BWx AT
where
C = maximum detected concentration of a chemical; mg/L
S\= surface area exposed; 18,150 square centimeters/day (cm2/day) for adults and 8,545
cm /day for children
PC= permeability constant; 0.43 cm/hour for Aroclor-1260; 0.0010 cm/hour for arsenic
and manganese
ET = exposure time; 2 hours per event for adults and children
3 U.S. Environmental Protection Agency. Exposure Factors Handbook. August 1997.
14
EF = exposure frequency; 32 days/year for adults and children
ED = exposure duration; 30 years for adults and 6 years for children
CF= conversion factor; 0.00 IO liter per cubic centimeters (L/cm3)
BW =bodyweight; 70 kg (or 153 pounds) for adults and 23 kg (or 50 pounds) for
children
AT= averaging time; I 0,950 days for adults and 2,190 days for children
Non-Cancer Health Effects
The doses calculated for exposure to each individual chemical are then compared to an
established health guideline, such as a MRL or RID, in order to assess whether adverse
non-cancer health impacts from exposure are expected. These health guidelines,
developed by ATSDR and EPA, are chemical-specific values that are based on the
available scientific literature and are considered protective of human health. Non-
carcinogenic effects, unlike carcinogenic effects, are believed to have a threshold, that is,
a dose below which adverse health effects will not occur. As a result, the current practice
for deriving health guidelines is to identify, usually from animal toxicology experiments,
a No Observed Adverse Effect Level (or NOAEL), which indicates that no effects are
observed at a particular exposure level. This is the experimental exposure level in animals
(and sometimes humans) at which no adverse toxic effect is observed. The NOAEL is
then modified with an uncertainty ( or safety) factor, which reflects the degree of
uncertainty that exists when experimental animal data are extrapolated to the general
human population. The magnitude of the uncertainty factor considers various factors such
as sensitive subpopulations (for example; children, pregnant women, and the elderly),
extrapolation from animals to humans, and the completeness of available data. Thus,
exposure doses at or below the established health guideline are not expected to result in
adverse health effects because these values are much lower (and more human health
protective) than doses, which do not cause adverse health effects in laboratory animal
studies. For non-cancer health effects, the following health guidelines are described
below in more detail. It is important to consider that the methodology used to develop
these health guidelines does not provide any information on the presence, absence, or
level of cancer risk. Therefore, a separate cancer evaluation is necessary for potentially
cancer-causing chemicals detected in samples at this site. A more detailed discussion of
the evaluation of cancer risks is presented in the following section.
Mi11imal Risk Levels (MRLs)-developed by ATSDR
ATSDR has developed MRLs for contaminants commonly found at hazardous waste
sites. The MRL is an estimate of daily exposure to a contaminant below which non-
cancer, adverse health effects are unlikely to occur. MRLs are developed for different
routes of exposure, such as inhalation and ingestion, and for lengths of exposure, such as
acute (less than 14 days), intermediate ( 15-364 days), and chronic (365 days or greater).
At this time, ATSDR has not developed MRLs for dermal exposure. A complete list of
the available MRLs can be found at http://www.atsdr.cdc.gov/mrls.html.
15
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Refere11ces Doses (RjDs)-developed by EPA
An estimate of the daily, lifetime exposure of human populations to a possible hazard that
is not likely to cause non-cancerous health effects. Rills consider exposures to sensitive
sub-populations, such as the elderly, children, and the developing fetus. EPA Rills have
been developed using information from the available scientific literature and have been
calculated for oral and inhalation exposures. A complete list of the available Rills can be
found at http://www.epa.gov/iris.
lf the estimated exposure dose for a chemical is less than the health guideline value, the
exposure is unlikely to result in non-cancer health effects. Non-cancer health effects from
dermal exposure were evaluated slightly differently than ingestion and inhalation
exposure. Since health guidelines are not available for dermal exposure, the calculated
dermal dose was compared with the oral health guideline value (RID or MRL).
If the calculated exposure dose is greater than the health guideline, the exposure dose is
compared to known toxicological values for the particular chemical and is discussed in
more detail in the text of the health consultation. The known toxicological values are
doses derived from human and animal studies that are presented in the ATSDR
Toxicological Profiles and EPA's Integrated Information System (lRIS). A direct
comparison of site-specific exposure doses to study-derived exposures and doses found to
cause adverse health effects is the basis for deciding whether health effects are likely to
occur. This in-depth evaluation is performed by comparing calculated exposure doses
with known toxicological values, such as the no-observed adverse-effect-level (NOAEL)
and the lowest-observed-adverse-effect-level (LOAEL) from studies used to derive the
MRL or RID for a chemical.
Cancer Risks
Exposure to a cancer-causing compound, even at low concentrations, is assumed to be
associated with some increased risk for evaluation purposes. The estimated excess risk of
developing cancer from exposure to chemicals associated with the site was calculated by
multiplying the site-specific adult exposure doses, with a slight modification, by EPA's
chemical-specific Cancer Slope Factors (CSFs or cancer potency estimates), which are
available at http://www.epa.gov/iris. Calculated dermal doses were compared with the
oral CSFs.
An increased excess lifetime cancer risk is not a specific estimate of expected cancers.
Rather, it is an estimate of the increase in the probability that a person may develop
cancer sometime during his or her lifetime following exposure to a particular chemical.
Therefore, the cancer risk calculation incorporates the equations and parameters
(including the exposure duration and frequency) used to calculate the dose estimates, but
the estimated value is divided by 25,550 days (or the averaging time), which is equal to a
lifetime of exposure (70 years) for 365 days/year.
There arc varying suggestions among the scientific community regarding an acceptable
excess lifetime cancer risk, due to the uncertainties regarding the mechanism of cancer.
The recommendations of many scientists and EPA have been in the risk range of 1 in I
16
million to I in 10,000 (as referred to as I x 10·6 to Ix 10-4) excess cancer cases. An
increased lifetime cancer risk of one in one million or less is generally considered an
insignificant increase in cancer risk. Cancer risk less than I in I 0,000 ( or I x I 0-4) is not
typically considered a health concern. An important consideration when determining
cancer risk estimates is that the risk calculations incorporate several very conservative
assumptions that are expected to overestimate actual exposure scenarios. For example,
the method used to calculate EPA's CSFs assumes that high-dose animal data can be used
to estimate the risk for low dose exposures in humans. As previously stated, the method
also assumes that there is no safe level for exposure. Lastly, the method computes the
95% upper bound for the risk, rather than the average risk, suggesting that the cancer risk
is actually lower, perhaps by several orders of magnitude.
Because of the uncertainties involved with estimating carcinogenic risk, ATSDR also
employs a qualitative approach in evaluating all relevant data. The numerical risk
estimate must be considered in the context of the variables and assumptions involved in
their derivation and in the broader context of biomedical opinion, host factors, and actual
exposure conditions. The actual parameters of environmental exposures have been given
careful and thorough consideration in evaluating the assumptions and variables relating to
both toxicity and exposure. A complete review of the toxicological data regarding the
doses associated with the production of cancer and the site-specific doses is an important
element in determining the likelihood of exposed individuals being at a greater risk for
cancer.
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Appendix, Table A -Summary of Calculated Exposure Doses for Surface Water (Non-cancer Effects)
Sigmon's Septic Tank Site
Ingestion &
Direct Oral Health Exceeds
Contact Dose Guideline Health
(mg/kg/day) (mg/kg/day) Guideline?
Adult Resident -Sigmon Pond
Aroclor-1260 1.40E-05 2.50E-05 No
Child Resident -Sigmon Pond
Aroclor-1260 2.02E-05 2.50E-05 No
Adult Resident -Intermittent Stream
Arsenic 1.61 E-07 3.00E-04 No
Manganese 2.05E-04 5.00E-02 No
Child Resident -Intermittent Stream
Arsenic 4.19E-07 3.00E-04 No
ManQanese 5.35E-04 5.00E-02 No
NOTES:
(a) ATSDR's C/:lronic Oral Minimal Risk Level and EPA's Oral Reference Dose
(b) EPA's Oral Reference Dose
18
Health
Guideline
Source Conclusion
(a) Non-cancer health effects are not expected.
(a) Non-cancer health effects are not expected.
(a) Non-cancer health effects are not expected.
(b) Non-cancer health effects are not expected.
(a) Non-cancer health effects are not expected.
(b) Non-cancer health effects are not exoected.
Appendix, Table B -Summary of Theoretical Cancer Risk for Surface Water
Sigmon's Septic Tank Site
Calculated Theoretical Lifetime Cancer Risk
Ingestion Direct Contact Total Cancer Risk
Intermittent Stream
Residents<11
Arsenic 1.22E-07 3.54E-08 1.57E-07
Total Risk for Contaminants<21 I 1.57E-07
NOTES:
Cancer Risk
Conclusion
No Increased
Cancer Risk
I
<•J The information presented above for residents accounts for exposures to chemicals in surface water occurring during childhood and
adulthood. It is considered a conservative approach that may overestimate risk.
(2) Arsenic is the only chemical detected in surface water above comparison values that has been associated with cancer in human
and animal studies.
19 • • •
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Health Consultation
SIGMON'S SEPTIC TANK SERVICE
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
EPA FACILITY ID: NCD062555792
APRIL 24, 2006
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Atlanta, Georgia 30333
Health Consultation: A Note of Explanation
An A TSDR health consultation is a verbal or written response from ATSDR to a specific
request for information about health risks related to a specific site, a chemical release, or
the presence of hazardous material. In order to prevent or mitigate exposures, a
consultation may lead to specific actions, such as restricting use of or replacing water
supplies; intensifying environmental sampling; restricting site access; or removing the
contaminated material.
In addition, consultations may recommend additional public health actions, such as
conducting health surveillance activities to evaluate exposure or trends in adverse health
outcomes; conducting biological indicators of exposure studies to assess exposure; and
providing health education for health care providers and community members. This
concludes the health consultation process for this site, unless additional information is
obtained by ATSDR which, in the Agency's opinion, indicates a need to revise or append
the conclusions previously issued.
You May Contact ATSDR TOLL FREE at
l-888-42ATSDR
or
Visit our Home Page at: http://www.atsdr.cdc.gov
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HEALTH CONSULTATION
SIGMON'S SEPTIC TANK SERVICE
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
EPA FACILITY ID: NCD062555792
Prepared by:
U.S. Department of Health and Human Services
Public Health Service
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Atlanta, Georgia 30333
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STATEMENT OF ISSUES AND BACKGROUND
Statement of Issues
The Agency for Toxic Substances and Disease Registry (ATSDR) prepared this health
consultation to evaluate, based on the information currently available, any known or
potential adverse human health hazards related to exposures to contaminants in surface
soils at the Sigmon's Septic Tank Site.
Background
The Sigmon's Septic Tank site is located at 1268 Eufola Road, approximately 5 miles
southwest of Statesville, Iredell County, North Carolina. The property comprises
approximately 15 acres. Sigmon's Septic Tank Service, a wholly owned subsidiary of
AAA Enterprises, purchased the property in 1970. The business installed and repaired
septic tanks. In addition, Sigmon's Septic Tank Service pumped septic tank wastes and
heavy sludges from residential, commercial, and industrial customers. From 1978 to
1992, the property owners deposited waste in several unlined lagoons which had been
dug on the property .
Previously, ATSDR has issued five health consultations for the Sigmon's Septic Tank
Site ( 1,2,3,4,5). The health consultations include a review of sampling plans for the site
as well as evaluations of the available groundwater and surface water data. The most
recent health consultation, released on April 3, 2006, evaluates groundwater data
collected in 2002 and 2004 (5). This health consultation is intended to address exposures
to on-site and off-site surface soil. Currently, the U.S. Environmental Protection Agency
(EPA) continues to investigate the soil and groundwater conditions at the site. Future
health consultations may be prepared, as necessary, to evaluate the newly collected data.
Demographics
According to U.S. 2000 Census data, 802 persons live within a one-mile radius of the
site. Approximately 95% of this population, or 760, are white. Also, 81 are children age
6 and under, and 83 are adults over age 65. A total of323 housing units are in the site
area. Additional demographic information for the community in the vicinity of the site is
presented in the following figure .
1
D Hazardous Waste Site of Interest
' D Other Hazardous Waste Site / D One Mile Buffer
0 0.3 0.6 0.9 Miles
Base Map Source: Geographic Data Technology, May 2005.
Site Boundary Data Source: ATSDR Public Health GIS Program, May 2005
Coordinate System (A!I Panels): NAO 1983 StaloP!ano North Carolina FIPS 3200 Feet
.10,000 and Above•
• Per Square Mile
GRASPMASTER 9.1 [BETA]· GENERATED: 01-30-2006
I
TN
Demographic Statistics
W1th1n One Mile of Site*
-Total Population 802
White Alone 760
Black Alone 33 -Am. Indian & Alaska Native Alone 0
Asian Alone 0
-N8tive Hawaiian &
Other Pacific Islander Alone 0
-Some Other Race Alone 5-
Two or More Races 4
HisRanic or Latino** 9
-Children Aged 6 and Younger 81
Adults Aged 65 and Older 83
Females Aged 15 to 44 --176-
Total Housing Units 323
Demographics Statistics Source: 2000 U.S. Census
• Calculated using an area-proportion spa~al analysis technique
-People v.tio identify their origin as Hispanic or Latino may be of any race.
(-AA FOR INTERNAL AND EXTERNAL RELEASE \.._<lr ... -:;,:.!~£~ AGENCY FOR TOXIC SUBSTANCES AND DISEASE REGISTRY I UNITED STATES DEPARTMENT OF HEAL TH AND HUMAN SERVICES
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ENVIRONMENTAL DATA
As part of this health consultation, A TSDR evaluates surface soil samples collected by
EPA in 2002, 2004, and 2005. Forty-nine surface soil samples were located within the
site boundary. An additional fifty-four samples were collected from areas outside the site
boundary and on adjacent residential properties. Samples were collected at depths of 0-
12 inches or 0-6 inches (6). Available data has undergone EPA's quality
assurance/quality control process and has been determined to be useable. All surface soil
samples were analyzed for metals. Approximately 25% of the samples have been
analyzed for dioxins/furans, extractable organic compounds, pesticides/polychlorinated
biphenyls (PCBs) and volatile organic compounds.
PATHWAY ANALYSIS
ATSDR's pathways analysis determines whether people have come into contact with
chemicals from a site and whether those contacts were substantial enough to cause harm.
To make this determination, ATSDR identifies exposure pathways or ways in which a
chemical could enter a person's body.
As outlined in ATSDR's Public Health Assessment Guidance Manual, an exposure
pathway contains five major elements:
I. a source of contamination,
2. transport through an environmental medium,
3. a point of exposure,
4. a route of exposure, and
5. a receptor or a population which could be exposed.
If an exposure pathway contains all five elements and exists now or did exist in the past,
the pathway is considered complete. Completed exposure pathways are evaluated to
determine whether health effects could occur. If one or more of the five elements is not
clearly defined but could be present, the exposure pathway is classified as potential (7).
ATSDR has identified the surface soil pathway as a completed exposure pathway. Other
completed or potential pathways may exist for the Sigmon's Septic Tank Site and may be
evaluated in separate health consultations. More detailed information on the surface soil
exposure pathway is presented in Table I .
3
Table 1. Surface Soil Exposure Pathway Elements
Source Environmental Point of Route of Exposed Timeframe
Media Exposure Exposure Population
Past disposal Surface Soil On-site Ingestion Trespassers Past
activities Inhalation Present
Direct Contact Future
Past disposal Surface Soil Off-site Ingestion Adult and Past
activities Inhalation children Present residents
Direct Contact Future
DISCUSSION
The first step in ATSDR's evaluation process is to select the chemicals of concern, also
described as the chemicals that require further evaluation. ATSDR selects chemicals of
concern on the basis of whether the maximum detected concentrations of the chemical
are found to exceed applicable, health-based comparison values. A chemical found to
exceed a comparison value indicates that a more detailed analysis is necessary for that
chemical. Levels of chemicals greater than comparison values do not necessarily mean
that adverse health effects will occur. The amount of the chemical, the duration of
exposure, the route of exposure (i.e., ingestion, inhalation, and direct skin contact), and
the health status of exposed individuals are also important factors in determining the
potential for adverse health effects. Chemicals detected in surface soil for which no
comparison value exists have been considered further as part of this health consultation.
A complete discussion of ATSDR's evaluation process is presented in the appendix of
this health consultation.
The chemicals of concern in on-site soils at this site are arsenic, vanadium, and
polyaromatic hydrocarbons (PAHs). The PAHs found in on-site surface soil include:
benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene,
benzo(k)fluoranthene, chrysene, indeno(l ,2,3-cd)pyrene, and phenanthrene. More
information about the chemicals detected is presented in Table 2.
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0 Table 2. On-Site Soil Data -Detected chemicals that exceed comparison values or for
which no comparison values are available
Milli grams/kilogram (mg/kg) or
CONTAMINANT p arts per million (ppm) FREQUENCY
[ Minimum ! M f Mean I ~omparison Value I"'""' DETECTED • ax1mum
I I
r---V-a_n_a_d-iu-m--~.~~
Arsenic 4.2 12illl 0.5 I CREG I 21/27
210 Fl 200 Int. Child I 49/49
EMEG
Benzo(a)anthracene I 0.060 0.060 1-: · 1 NA I NA I 1/18
Benzo(a)pyrene .1 0.19 0.19 r-:-1 0.1 I CREG I 1/18
Benzo(b)fluoranthene J 0.041 0.210 ro:083 I NA I NA I 5/18
Benzo(g,h,i)perylene J 0.057 0.40 fo.rrl NA I NA I 2/18
Benzo(k)fluoranthene I 0.044 0.13 I 0.081 J NA I NA I · 2/18
Chrysene I 0.050 0.16 fo.11 I NA I NA I 2/18
lndeno(l,2,3cd)pyrene J 0.047 0.36 fo.wl NA I NA I 2/18
Phenanthrene J 0.067 I - I I I
..
0.067 NA NA 1/18
Notes:
• CREG=Cancer Risk Evaluation Guide
•
Int. Child EMEG=Intermediate Child Environmental Media Evaluation Guide
NA=Not available
A comparison of the chemicals detected in off-site surface soil samples with CVs
indicates that the only chemical of concern is arsenic. More information about the
arsenic detected is presented in Table 3.
Table 3. Off-Site Soil Data -Detected chemicals that exceed comparison values or for
which no comparison values are available
F I ---M--'-'il-li~gr_a_m~s-/k-il-o-gr_a_m_(_m_w __ kg_)_o_r ____ lSO~;C~-
CONTAMINANT . parts per million (ppm) FREQUENCY ~1 · DETECTED [ Minimum I Maximum I Mean Comparison Value
~1--A-r-s-en-ic___ 1.2 3.1 J 1:9j··1 -0.5 . I CREG I 30/39
Notes:
CREG=Cancer Risk Evaluation Guide
5 .
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PUBLIC HEALTH IMPLICATIONS
For chemical concentrations found to exceed comparison values, ATSDR performed
calculations referred to as exposure doses and cancer risk estimates. These calculations
estimate the amount of the chemicals of concern that individuals may have been exposed
to and the likelihood of cancer and non-cancer health impacts. They are based on the
types of site-specific activities that individuals may be involved with that result in contact
with chemicals in the surface soil. In the event that calculated exposure doses exceed
established health guidelines (e.g., ATSDR Minimal Risk Levels or EPA Reference
Doses), an in-depth toxicological evaluation is the next step necessary to determine the
likelihood of health effects.
On the basis of site-specific information, A TSDR has evaluated the trespassers ( on-site
surface soil) and adults and children residents ( off-site surface soil) as part of this health
consultation. Incidental ingestion, inhalation of dust, and direct skin contact has been
evaluated. Information necessary to estimate past exposure to workers is not available.
The average surface soil concentrations were used in the calculations. Additional
information on the exposure scenarios, assumptions and calculations used to estimate
exposures are discussed in the appendix of this health consultation.
Exposure to multiple chemicals was also considered in this health consultation. A TSDR
used the toxicity equivalency factor methodology developed by the EPA to evaluate on-
site surface soil. This methodology is useful when assessing a mixture of chemicals
(with similar chemical structures) for which health guidelines are not available for all of
the detected chemicals. Each of the detected P AHs were adjusted based on their toxicity
compared with benzo(a)pyrene. Benzo(a)pyrene is considered to be the most toxic of the
PAH compounds and has been the focus of much scientific study. The adjusted PAH
mixture is referred to as benzo(a)pyrene equivalents in the remainder of this health
consultation.
Non-Cancer Health Effects Evaluation
As previously stated, calculated exposure doses were compared with the available health
guidelines to determine whether the potential exists for adverse non-cancer health effects.
None of the chemicals detected in on-site soil (arsenic, vanadium, and benzo(a)pyrene
equivalents), were found at levels that exceed the established health guidelines.
Therefore, ATSDR concludes that exposure to chemicals in on-site surface soil by
trespassers is 11ot expected to result in adverse non-cancer health effects.
Arsenic was the only chemical found in off-site surface soil. Exposures to arsenic at the
concentrations found in the vicinity of the site do not exceed health guidelines and are not
expected to be harmful. Therefore, ATSDR concludes that exposure to arsenic in areas
adjace11t to the site and on 11earby residential properties ( off-site) are not expected to
result i11 adverse no11-cancer health effects.
6
A complete list of the calculated doses and available health guidelines is presented in the
appendix of this health consultation (Table A).
Cancer Evaluation
The increased risk of individuals developing cancer from exposure to chemicals in
surface soil was also considered. Cancer risk was calculated for the adult resident
(includes exposure as an adult only) and a combined scenario. The combined approach
considers the potential for chemical exposures occurring as a child, adolescent trespasser,
and as an adult, for conservatism. The combined risk to the adult, adolescent and child is
considered based on site-specific information provided by the community. ATSDR notes
that this approach is very conservative and may overestimate the actual risks of these
individuals.
On the basis of the risk calculations, ATSDR has determined that there is no increased
risk of cancer to adult residents exposed to surface soil. No increased cancer risk was
indicated for the combination of surface soil exposures occurring during childhood,
adolescence, and adulthood.
A complete list of the calculated cancer risks for surface soil is presented in the appendix
of this health consultation (Table B).
Community Health Concerns
A TSDR held a public availability session on Monday, December 5, 2005 to gather health
concerns from the community surrounding the Sigmon's Septic Tank Site. The public
availability session was held at the Celeste Henkel Elementary School from 6:00 PM to
8:00 PM. A media availability session was held at the same location from 5 :30 PM to 6:00
PM. Representatives from ATSDR and EPA attended the sessions. Flyers were sent out
to residences in the vicinity of the Sigmon's Septic Tank Site to announce the meeting.
Five community members attended the session. Most of the individuals had questions
about EPA's environmental investigation and cleanup planned for the site. One soil-
related health concern was received. The question and ATSDR's response are
summarized as follows.
Health Concern: We live near the site and it smelled very badly while the septic
business was in operation. We would like to know if there is anything in the soil that
might be to blame for recent lung and breathing difficulties.
Response: It is unlikely. The site is not active at this time and there are no processes
taking place that would result in the chemicals becoming airborne. In the past,
unpleasant odors associated with septic waste may have occurred at the site. These
odors, while unpleasant, are not likely to have been harmful.
7
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Child Health Considerations
In communities faced with air, water, or food contamination, the many physical
differences between children and adults demand special emphasis. Children could be at
greater risk than are adults from certain kinds of exposure to hazardous substances.
Children play outdoors and sometimes engage in hand-to-mouth behaviors that increase
their exposure potential. Children are shorter than adults; this means they breathe dust,
soil, and vapors close to the ground. A child's lower body weight and higher intake rate
results in a greater dose of hazardous substance per unit of body weight. If toxic exposure
levels are high enough during critical growth stages, the developing body systems of
children can sustain permanent damage. Finally,' children are dependent on adults for
access to housing, for access to medical care, and for risk identification. Thus adults need
as much information as possible to make informed decisions regarding their children's
health.
On the basis of the evaluation conducted in this health consultation, ATSDR has
determined that children are not at risk for health effects from exposure to chemicals in
off-site surface soils. The calculated doses were below the established health guidelines.
Therefore, no harmful effects are expected among children living around the Sigmon's
Septic Tank Site who are exposed to surface soil adjacent to the site and on neighboring
residential properties .
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CONCLUSIONS
I. A TSDR has evaluated exposure to chemicals in on-site surface soil. On the basis of
the available data, A TSDR has determined that exposure to chemicals in on-site
surface soil by individuals trespassing on the site poses no apparent public health
hazard.
2. ATSDR has also evaluated exposure to chemicals in off-site surface soil. ATSDR
has determined exposure to adults and children residents who come in contact with
surface soil adjacent to the site and on neighboring residential properties poses no
apparent public health hazard.
RECOMMENDATIONS
I. The site is located on private property and is currently under investigation by EPA.
Residents should avoid accessing the property .
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PUBLIC HEAL TH ACTION PLAN
A Public Health Action Plan describes the actions designed to mitigate or prevent adverse
human health effects that might result from exposure to hazardous substances associated
with site contamination. A summary of the public health actions that have been taken
and those to be completed for the Sigmon's Septic Tank Site are provided below.
Public Health Actions Taken
Previously, ATSDR has issued five health consultations for the Sigmon's Septic Tank
Site (1,2,3,4,5). The health consultations include a review of sampling plans for the site
as well as evaluations of the available groundwater and surface water data. The most
recent health consultation, released on April 3, 2006, evaluates groundwater data
collected in 2002 and 2004 (5).
ATSDR participated in a site tour conducted by EPA and its contractor on Monday,
December 5, 2005. ATSDR examined the conditions of the site and toured the
surrounding community at this time.
ATSDR conducted a public availability session on Monday, December 5, 2005 to gather
health concerns from the community. The public availability session was held at the
Celeste Henkel Elementary School from 6:00 PM to 8:00 PM. Representatives informed
residents about A TSDR' s work at the site and gathered community health concerns.
ATSDR also prepared a fact sheet that was mailed to the community in the vicinity of the
site in spring 2006. The fact sheet provides information on ATSDR's work at the site,
the findings of the health consultation, and contacts for additional information.
Public Health Actions to be Completed
ATSDR will continue to collaborate with the appropriate federal, state, and local
agencies. ATSDR will review new environmental data associated with the Sigmon's
Septic Tank Site and will include results in future health consultations, as necessary .
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REFERENCES
1.
2.
3.
4.
5.
6.
7.
Agency for Toxic Substances and Disease Registry. Health Consultation for
Sigrnon's Septic Tank Service. 2001 August 24.
Agency for Toxic Substances and Disease Registry. Health Consultation for
Sigrnon's Septic Tank Service -Review of Groundwater Data. 2002 March 29.
Agency for Toxic Substances and Disease Registry. Health Consultation for
Sigrnon's Septic Tank Service -Review of Surface Water Data. 2002 July 09.
Agency for Toxic Substances and Disease Registry. Health Consultation for
Sigrnon's Septic Tank Service-Review of Sampling Plan. 2005 July 05.
Agency for Toxic Substances and Disease Registry. Health Consultation for
Sigrnon's Septic Tank Service. 2006 April 03.
US Environmental Protection Agency. Remedial Investigation Report, Operable Unit
I for Sigrnon's Septic Tank Service. 2005 August.
Agency for Toxic Substances and Disease Registry. Public health assessment
guidance manual. Atlanta: US Department of Health and Human Services; 2005 .
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ATSDRTEAM
Prepared by:
Annmarie K. DePasquale, MPH
Environmental Health Scientist
Division of Health Assessment and Consultation
Superfund Site Assessment Branch.
Reviewed by:
Benjamin Moore, MS
Regional Representative -Region 4
Division of Regional Operations
Jannett P. Smith-George, MSW
Health Communication Specialist
Division of Health Assessment and Consultation
Health Promotion and Community Involvement Branch
David S. Sutton, Ph.D., PE
Environmental Engineer
Division of Health Assessment and Consultation
Exposure Investigation and Consultation Branch
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Appendix -ATSDR's Evaluation Process
Step 1 -Comparison Values and the Screening Process
To evaluate the available data, ATSDR used comparison values (CVs) to determine
which chemicals to examine more closely. CVs are the chemical concentrations found in
a specific media (for example: air, soil, or water) and are used to select chemicals for
further evaluation. CV s incorporate assumptions of daily exposure to the chemical and a
standard amount of soil that someone may inhale or ingest each day. CVs are generated
to be conservative and non-site specific. These values are used only to screen out
chemicals that do not need further evaluation; CVs are not intended as environmental
clean-up levels or to indicate that health effects occur at concentrations that exceed these
values.
CVs can be based on either carcinogenic (cancer-causing) or non-carcinogenic effects.
Cancer-based comparison values are calculated from the U.S. Environmental Protection
Agency's (EPA) oral cancer slope factor (CSF) or inhalation risk unit. CVs based on
cancerous effects account for a lifetime exposure (70 years) with a theoretical excess
lifetime cancer risk of 1 new case per 1 million exposed people. Non-cancer values are
calculated from ATSDR's Minimal Risk Levels (MRLs), EPA's Reference Doses
(RfDs), or EPA's Reference Concentrations (RfCs). When a cancer and non-cancer CV
exists for the same chemical, the lower of these values is used in the comparison for
conservatism. The chemical and media-specific CVs utilized during the preparation of
this HC are listed below:
An Environmental Media Evaluation Guide (EMEG) is an estimated comparison
concentration for which exposure is unlikely to cause adverse health effects, as
determined by ATSDR from its toxicological profiles for a specific chemical.
A Cancer Risk Evaluation Guide (CREG) is a comparison concentration that is
based on an excess cancer rate of one in a million persons and is calculated using
EPA's cancer slope factor (CSF).
Step 2 -Evaluation of Public Health Implications
The next step in the evaluation process is to take those contaminants that are above their
respective CV s and further identify which chemicals and exposure situations are likely to
be a health hazard. Therefore, calculations are performed to estimate the possibility of
cancer and non-cancer health problems. The calculations consider the activities of people
living in the community. The assumptions used in the calculations are discussed in the
following sections.
Adult Residents
Adult residents were assumed to be exposed to chemicals in off-site surface soil while
gardening (3 days per week for 5 months of the year) and doing yard work (2 days per
week for 7 months of the year). Incidental ingestion, inhalation of chemicals in dust
13
generated during activities, and direct skin contact with chemicals in off-site surface soil
has been considered.
It was assumed that these individuals ingest I 00 mg of soil per day (mg/day) and
weighed 70 kilograms (kg) (153 pounds). The surface area available for direct skin
contact is 3,325 cubic centimeters per day (cm2/day) which represents exposure of the
face, hands, and arms. An adherence factor of 0.07 milligrams per cubic centimeter
(mg/cm3) and, when available, a chemical-specific absorption factor was used.
Individuals were assumed to be exposed for 30 years. For inhalation of dust, individuals
were assumed to have an inhalation rate of 0.80 cubic meters per hour (m3 /hour) and be
exposed for 4 hours per event. A default particulate emissions factor of 1.32 x l 0+9 cubic
meter per kilogram (m3 /kg) was also used in the calculations.
Children Residents
Children residents were assumed to be exposed to chemicals while playing in
contaminated soil in their yards or other off-site areas in the summer, fall, and spring ( 4
days of the week for 9 months of the year) as well as the winter (2 days per week for 3
months of the year). Incidental ingestion, inhalation of chemicals in dust generated
during activities, and direct skin contact with chemicals in off-site surface soil while
playing has been considered.
It was assumed that children residents ingest 200 mg/day and weighed 16 kg (35 pounds).
The surface area available for direct skin contact is 4,785 cm2/day in the summer, fall,
and spring months which represents exposure of the face, hands, arms, legs, and feet.
The surface area considered for winter months was 1,880 cm2/day which accounts for·
exposure of the face, hands, and arms. An adherence factor of0.2 mg/cm2 and, when
available, a chemical-specific absorption factor was used. Individuals were assumed to
be exposed for 6 years. For inhalation of dust, individuals were assumed to have an
inhalation rate of 0.42 m3 /hour and be ex~osed for 8 hours per event. A default
particulate emissions factor of 1.32 x IO+ m3 /kg was also used in the calculations.
On-Site Adolescent Trespassers
Adolescent trespassers were assumed to be exposed to chemicals in soil while trespassing
on the site 2 days per week. Incidental ingestion, inhalation of chemicals in dust
generated during activities, and direct skin contact with chemicals in on-site soil has been
considered. It was assumed that these individuals ingested I 00 mg/day and weighed 50
kg (110 pounds). The surface area available for direct skin contact is 7,730 cm2/day in
the summer, fall, and spring months which represents exposure of the face, hands, arms,
and legs. The surface area considered for winter months was 2,950 cm2/day which
2 accounts for exposure of the face, hands, and arms. An adherence factor of 0.2 mg/cm
and, when available, a chemical-specific absorption factor was used. Individuals were
assumed to _be exposed for 5 years. For inhalation of dust, individuals were assumed to
have an inhalation rate of 0.42 m3 /hour and be exposed for 4 hours per event. A default
particulate emissions factor 1.32 x 10+9 m3 /kg was also used in the calculations.
14
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The Calculations 0 In order to evaluate the potential for human exposure to chemicals present at the site and
potential health effects from site-specific activities, A TSDR estimates human exposure to
the site chemicals from different environmental media by calculating exposure doses and
cancer risk estimates. A brief discussion of the calculations is presented below. Separate
calculations have been performed for exposures to adults, adolescents, and children. The
same equations have been used for the non-cancer and cancer calculations with the
indicated modifications. The equations and the assumptions are based on the EPA Risk
Assessment Guidance for Superfund, Part A1 and the EPA Exposure Factors Handbook2,
unless otherwise specified. A discussion of the cancer and non-cancer evaluation of
exposure is presented following the equations for each pathway.
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Incidental Ingestion of Contaminants Present in Soil
(Exposure to adults during gardening; Children during playing)
Adult residents may be exposed to contaminants in soil gardening and yard work via
unintentional ingestion. Children residents may also be exposed to chemicals in soil in
residential yards. The exposure dose for incidental ingestion of soil is
Dose( mg /kg /day)
where
C = chemical concentration ( mg/kg)
IR= ingestion rate (mg/day)
EF = exposure frequency (days/years)
ED= exposure duration (years)
CF = conversion factor ( I x 10-6 kg/mg)
BW = body weight (kg)
AT= averaging time (days)
Cx!Rx EFxEDxCF
BWxAT
Direct Skin (Dermal) Contact with Contaminants Present in Soil
Dermal absorption depends on numerous factors, including the area of exposed skin,
anatomical location of the exposed skin, length of contact, concentration of the chemical
in contact with the skin, and other factors. Because chemicals differ greatly in their
potential to be absorbed through the skin, each chemical needs to be evaluated separately.
1 U.S. Environmental Protection Agency. Risk Assessment Guidance for Superfund. December 1989 .
2 U.S. Environmental Protection Agency. Exposure Factors Handbook. August 1997.
15
The exposure dose for direct contact with chemicals in soil is
( /k Id ) CxSAxAFxABSxEFxEDxCF Dose mg g ay = ------------
BWx AT
where
C = chemical concentration (mg/kg)
SA= surface area exposed (square centimeters/day or cm2/day)
AF = adherence factor (milligrams per square centimeters or mg/cm2)
ABS= Absorption factor (unitless)
ET= exposure time (hours/day)
EF = exposure frequency ( days/year)
ED = exposure duration (years)
CF = conversion factor ( I x 10-6 kg/mg)
BW =bodyweight (kg)
AT= averaging time (days)
Inhalation of Contaminants in Fugitive Dust Generated from Soil
Individuals may generate dust that can be inhaled during gardening, playing, and other
activities with soil and sediment. The dose to evaluate this potential exposure is
Cx!RxETxEFxED Dose(mg/kg/day)
PEFxBWxAT
where
C = chemical concentration ( mg/kg)
IR= inhalation rate (m3/hour)
ET = exposure time (hours/day)
EF = exposure frequency ( days/year)
ED= exposure duration (years)
PEF = particulate emissions factor (m3 /kg)
BW =bodyweight (kg)
AT= averaging time (days)
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Non-Cancer Health Effects
The doses calculated for exposure to each individual chemical are then compared to an
established health guideline, such as a MRL or RID, in order to assess whether adverse
non-cancer health impacts from exposure are expected. These health guidelines,
developed by ATSDR and EPA, are chemical-specific values that are based on the
available scientific literature and are considered protective of human health. Non-
carcinogenic effects, unlike carcinogenic effects, are believed to have a threshold, that is,
a dose below which adverse health effects will not occur. As a result, the current practice
for deriving health guidelines is to identify, usually from animal toxicology experiments,
a No Observed Adverse Effect Level (or NOAEL), which indicates that no effects are
observed at a particular exposure level. This is the experimental exposure level in animals
(and sometimes humans) at which no adverse toxic effect is observed. The NOAEL is
then modified with an uncertainty ( or safety) factor, which reflects the degree of
uncertainty that exists when experimental animal data are extrapolated to the general
human population. The magnitude of the uncertainty factor considers various factors such
as sensitive subpopulations (for example; children, pregnant women, and the elderly),
extrapolation from animals to humans, and the completeness of available data. Thus,
exposure doses at or below the established health guideline are not expected to result in
adverse health effects because these values are much lower (and more human health
protective) than doses, which do not cause adverse health effects in laboratory animal
studies. For non-cancer health effects, the following health guidelines are described
below in more detail. It is important to consider that the methodology used to develop
these health guidelines does not provide any information on the presence, absence, or
level of cancer risk. Therefore, a separate cancer evaluation is necessary for-potentially
cancer-causing chemicals detected in samples at this site. A more detailed discussion of
the evaluation of cancer risks is presented in the following section.
Minimal Risk Levels (MRLs) -developed by ATSDR
A TSDR has developed MRLs for contaminants commonly found at hazardous waste
sites. The MRL is an estimate of daily exposure to a contaminant below which non-
cancer, adverse health effects are unlikely to occur. MRLs are developed for different
routes of exposure, such as inhalation and ingestion, and for lengths of exposure, such as
acute (less than 14 days), intermediate (15-364 days), and chronic (365 days or greater).
At this time, ATSDR has not developed MRLs for dermal exposure. A complete list of
the available MRLs can be found at http://www.atsdr.cdc.gov/mrls.html.
References Doses (RJDs)-developed by EPA
An estimate of the daily, lifetime exposure of human populations to a possible hazard that
is not likely to cause non-cancerous health effects. Rills consider exposures to sensitive
sub-populations, such as the elderly, children, and the developing fetus. EPA RfDs have
been developed using information from the available scientific literature and have been
calculated for oral and inhalation exposures. A complete list of the available RfDs can be
found at http://www.epa.gov/iris.
If the estimated exposure dose for a chemical is less than the health guideline value, the
• exposure is unlikely to result in non-cancer health effects. Non-cancer health effects from
17
dermal exposure were evaluated slightly differently that ingestion and inhalation
exposure. Since health guidelines are not available for dermal exposure, the calculated
dermal dose was compared with the oral health guideline value (RID or MRL).
If the calculated exposure dose is greater than the health guideline, the exposure dose is
compared to known toxicological values for the particular chemical and is discussed in
more detail in the text of the health consultation. The known toxicological values are
doses derived from human and animal studies that are presented in the ATSDR
Toxicological Profiles and EPA's Integrated Information System (IRJS). A direct
comparison of site-specific exposure doses to study-derived exposures and doses found to
cause adverse health effects is the basis for deciding whether health effects are likely to
occur. This in-depth evaluation is performed by comparing calculated exposure doses
with known toxicological values, such as the no-observed adverse-effect-level (NOAEL)
and the lowest-observed-adverse-effect-level (LOAEL) from studies used to derive the
MRL or RID for a chemical.
Cancer Risks
Exposure to a cancer-causing compound, even at low concentrations, is assumed to be
associated with some increased risk for evaluation purposes. The estimated excess risk of
developing cancer from exposure to chemicals associated with the site was calculated by
multiplying the site-specific adult exposure doses, with a slight modification, by EPA's
chemical-specific Cancer Slope Factors (CSFs or cancer potency estimates), which are
available at http://www.epa.gov/iris. Calculated dermal doses were compared with the
oral CSFs.
An increased excess lifetime cancer risk is not a specific estimate of expected cancers.
Rather, it is an estimate of the increase in the probability that a person may develop
cancer sometime during his or her lifetime following exposure to a particular chemical.
Therefore, the cancer risk calculation incorporates the equations and parameters
(including the exposure duration and frequency) used to calculate the dose estimates, but
the estimated value is divided by 25,550 days (or the averaging time), which is equal to a
lifetime of exposure (70 years) for 365 days/year.
There are varying suggestions among the scientific community regarding an acceptable
excess lifetime cancer risk, due to the uncertainties regarding the mechanism of cancer.
The recommendations of many scientists and EPA have been in the risk range of I in I
million to I in I 0,000 (as referred to as I x 10·6 to I x 10-4) excess cancer cases. An
increased lifetime cancer risk of one in one million or less is generally considered an
insignificant increase in cancer risk. Cancer risk less than 1 in 10,000 (or 1 x 10-4) is not
typically considered a health concern. An important consideration when determining
cancer risk estimates is that the risk calculations incorporate several very conservative
assumptions that are expected to overestimate actual exposure scenarios. For example,
the method used to calculate EPA's CSFs assumes that high-dose animal data can be used
to estimate the risk for low dose exposures in humans. As previously stated, the method
also assumes that there is no safe level for exposure. Lastly, the method computes the
18
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95% upper bound for the risk, rather than the average risk, suggesting that the cancer risk
is actually lower, perhaps by several orders of magnitude.
Because of the uncertainties involved with estimating carcinogenic risk, ATSDR employs
a weight-of-evidence approach in evaluating all relevant data. The numerical risk
estimate must be considered in the context of the variables and assumptions involved in
their derivation and in the broader context of biomedical opinion, host factors, and actual
exposure conditions. The actual parameters of environmental exposures have been given
careful and thorough consideration in evaluating the assumptions and variables relating to
both toxicity and exposure. A complete review of the toxicological data regarding the
doses associated with the production of cancer and the site-specific doses is an important
element in determining the likelihood of exposed individuals being at a greater risk for
cancer.
19
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Appendix, Table A -Summary of Calculated Exposure Doses
Sigmon's Septic Tank Site
Ingestion &
Direct Oral Health Exceeds
Contact Dose Guideline Health
(mg/kg/day) (mg/kg/day) Guideline?
Adult Resident -Off-Site Soil Pathwa~
Arsenic 9.44E-07 3.00E-04 No
Child Resident -Off-Site Soil Pathwa~
Arsenic 1.20E-05 3.00E-04 No
Adolescent T res(!asser -Soil Pathwa~
Arsenic 1.19E-06 3.00E-04 No
Vanadium 7.?SE-05 3.00E-03 No
Benzo{a\nvrene Eauivalents 5.74E-07 NA NA
NOTES:
Health Inhalation
Guideline Dose
Source (mg/kg/day)1"'
(c) NA
(c) NA
(c) NA
(d) NA
NA NA
(a) Inhalation doses were calculated only for contaminants with an available inhalation health guideline.
(b) EPA's Inhalation Reference Dose
(c) ATSDR's Chronic Oral Minimal Risk Level and EPA's Oral Reference Dose
(d) ATSDR's Intermediate Oral Minimal Risk Level
NA ;: Not available
20
Inhalation
Health Exceeds
Guldellne Health
(mg/kg/day)''' Guideline?
NA NA
NA NA
NA NA
NA NA
NA NA
Appendix, Table B • Summary of Theoretical Cancer Risk
Sigmon's Septic Tank Site
Calculated Theoretical Lifetime Cancer Risk
Ingestion Direct Contact
Adult Resident It) -Soll Pathway:
Arsenic 6.06E-07 3.15E-08
Total Risk for Contaminants
Combined12>-soil Pathway:
Arsenic 2.26E-06 2.53E-07
Vanadium NA NA
Benzofa'""rene 7.03E-08 9.21E-08
Total Risk for Contaminants
NOTES·
11) Adult Resident Soil Pathway includes the risk from exposure occuring only as an adult.
Cancer Risk
Inhalation of Dust Total Cancer Risk Conclusion
1.48E-10 6.38E-07 No Increased
Cancer Risk
I 6.38E-07 I
3.60E-10 2.51E-06 No Increased
NA NA Cancer Risk
3.81E-13 1.62E-07
I 2.68E-06 I
<2l Combined Soil Pathway includes the risk from exposure occurring as a child resident, adolescent trespasser, and adult resident. The combination of these
pathways was considered based on site-specific infonnation gathered from the community. It is considered a conservative approach that may result in an
overestimation of risk.
21
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Health Consultation
Review of Groundwater Data
(2002 & 2004 EPA Delineation Investigations)
SIGMON'S SEPTIC TANK SERVICE FACILITY
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
EPA FACILITY ID: NCD062555792
APRIL 3, 2006
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Atlanta, Georgia 30333
Health Consultation: A Note of Explanation
An ATSDR health consultation is a verbal or written response from ATSDR to a specific
request for information about health risks related to a specific site, a chemical release, or
the presence of hazardous material. In order to prevent or mitigate exposures, a
consultation may lead to specific actions, such as restricting use of or replacing water
supplies; intensifying environmental sampling; restricting site access; or removing the
contaminated material.
In addition, consultations may recommend additional public health actions, such as
conducting health surveillance activities to evaluate exposure or trends in adverse health
outcomes; conducting biological indicators of exposure studies to assess exposure; and
providing health education for health care providers and community members. This
concludes the health consultation process for this site, unless additional information is
obtained by ATSDR which, in the Agency's opinion, indicates a need to revise or append
the conclusions previously issued.
You May Contact A TSDR TOLL FREE at
1-888-42ATSDR
or
Visit our Home Page at: http://www.atsdr.cdc.gov
•
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HEAL TH CONSULTATION
Review of Groundwater Data
(2002 & 2004 EPA Delineation Investigations)
SIGMON'S SEPTIC TANK SERVICE FACILITY
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
EPA FACILITY ID: NCD062555792
Prepared by:
U.S. Department of Health and Human Services
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Atlanta, Georgia 30333
• Table of Contents
Background and statement of issues ................................................................................................ 1
Discussion ........................................................................................................................................ 2
Environmental sampling and chemical analyses ....................................................................... 2
Rationale for the selective screening of substances in groundwater. ................................... 2
2002 and 2004 delineation investigations ............................................................................ 2
Chemicals selected for further public health analysis .......................................................... 6
Monitoring well data ............................................................................................................. 6
Assessment limitations ......................................................................................................... 8
Exposure pathways .................................................................................................................. 10
Public health implications ........................................................................................................ I 0
Substances without drinking water comparison values ..................................................... 11
Substances exceeding drinking water comparison values ................................................. 13
Child health considerations ............................................................................................................ 13
Conclusions .................................................................................................................................... 14
Recommendations .......................................................................................................................... 14
• Public health action plan ................................................................................................................ 15
Authors .................................... '.: ..................................................................................................... 16
Reviewers ....................................................................................................................................... 16
References ...................................................................................................................................... 17
Selected bibliography ..................................................................................................................... 20
Appendix A. Comparison values ................................................................................................. 23
Appendix B. Tables ....................... :.: ............................................................................................ 26
Table I. Chemical levels considered no apparent health hazard ............................................. 27
Footnotes for Tables 2 through 12 ........................................................................................... 29
Table 2. Detected substances in private well SS-PW-0l ......................................................... 30
Table 3. Detected substances in private well SS-PW-03 ........................................................ .31
Table 4. Detected substances in private well SS-PW-04 ........................................................ .32
Table 5. Detected substances in private well SS-PW-05 ........................................................ .33
Table 6. Detected substances fin private well SS-PW-06 .......... : ............................................. 34 • Table 7. Detected substances in private well SS-PW-07 ......................................................... 35
II
Table 8. Detected substances in private well SS-PW-08 ........................................................ .36 •
Table 9. Detected substances .in private well SS-PW-09.) ..................................................... .37
Table 10. Followup sampling and analyses in private well SS-PW-09 ................................... 38
Table 11. Detected substances in private well SS-PW-I0 ....................................................... 39
Table 12. Detected substances in private wells near the Sigmon facility ............................... .40
Footnotes for Tables 13 through 19 ............ , ........................................................................... .42
Table 13. Detected substances in on-site monitoring well SS-MW-1 IC ............................... .43
Table 14. Detected substances in on-site monitoring well SS-MW-14 .................................. .45
Table 15. Detected substances in off-site monitoring well SS-MW-I0B ............................... .47
Table 16. Detected substances in off-site monitoring well SS-MW-12B ............................... .48
Table 17. Detected substances in on-site monitoring well SS-MW-13B ............................... .49
Table 18. Substances found in on-site monitoring wells near the Sigmon facility .................. 51
Table 19. Substances found in off-site monitoring wells near the Sigmon facility ................ .5-3
Table 20. Matched VOC detections in groundwater wells near the Sigmon facility .............. 54
Appendix C. Figures ...................................................................................................................... 55
Figure I. Site layout map ......................................................................................................... 56
Figure 2. Monitoring well and private well location map -October 2002) ............................ 57
Figure 3. Monitoring well and private well location map -May 2004 ................................... 58
Figure 4. Groundwater potentiometric surface map -May 2004 ............................................ 59
•
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8 Background and Statement of Issues
•
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On October 20, 2004, the Agency for Toxic Substances and Disease Registry (ATSDR) received
a request from its Division of Regional Operations (ORO), Region IV Office, Atlanta, Georgia.
ORO requested A TSDR to determine the potential public health impacts that the Sigmon Septic
Tank Service Site-a former septic tank service and waste removal business-would have on
nearby private wells (Benjamin Moore, Division of Regional Operations, ATSDR, Region 4,
e-mail of October 2004 to Susan Moore, Division of Health Assessment and Consultation,
A TSDR). The request originated from the United States Environmental Protection Agency
(EPA), Region IV Office, Atlanta, Georgia. EPA initially sent analytical results of groundwater
samples to ATSDR's ORO Region IV Office for public health review and evaluation (Warren
Dixon, EPA, Region 4, e-mail of October 2004 to Benjamin Moore, ATSDR, Division of
Regional Operations).
The Sigmon Septic Tank Service Site (CERCLIS No. NCD062555792) is located at 1268 Eufola
Road, approximately 5 miles southwest of Statesville, Iredell County, North Carolina (NCDENR
1998, 2000; Black & Veatch 2004). This site has been listed under several names, including
Sigmon's Septic Tank Service, AAA Enterprises, and Sigmon Environmental Services. Services
provided by the former septic tank service facility have included the pumping and removal of
septic tank wastes and heavy sludges for residential, commercial, and industrial customers,
installation and repair of septic tanks, and other waste removal services to various industries .
Both federal and state environmental regulatory agencies have investigated the groundwater near
the site for several years (NCDENR 1998, 2000; Black & Veatch 2004). ATSDR had previously
determined that the groundwater pathway appeared to be of concern because two private wells
showed nitrate levels greater than 10,000 parts per billion (ppb) (ATSDR 2002). Very young
infants (0-6 months) who consume formula prepared with water containing nitrate levels greater
than 10,000 ppb have an increased risk of higher methemoglobin levels (EPA 1990; Bosch et al.
1950; Walton 1951). Similarly, fetuses might be exposed to potential health risks if pregnant
females drank water with comparable nitrate levels (Dorsch et al. 1984; Arbuckle et al. 1988;
MMWR 1996).
Figure 1 shows the Sigmon Septic Tank Service Site and nearby residences. Former waste areas
still remain at the site. These were used for waste handling and disposal during past operations at
the former septic tank service facility. These areas include the Lagoon Area, Waste Pile, and
Open Pits (Figure 1 ). These former waste areas are believed to be the chief source of
groundwater problems within the area. In its previous public health consultation (PHC), ATSDR
recommended that environmental regulatory agencies consider removing these areas from the
Sigmon Septic Tank Service Site (A TSDR 2002). EPA is presently considering this
recommendation while their delineation investigations continue at the site. ATSDR believes that
removing the remaining waste areas at the site might reduce or even eliminate potential releases
of hazardous substances to the surrounding soil, groundwater, or surface water. A reduction or
elimination of hazardous wastes would in tum lower the potential impact on public health from
contaminants released into the environment.
8 Discussion
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Environmental Sampling and Chemical Analyses
A TSDR reviewed groundwater samples collected in October 2002 and May 2004 from several
private wells and monitoring wells to determine whether any releases of hazardous substances
may be impacting the health of private well users (Black and Veatch 2004). These private well
users utilize the groundwater for drinking and other domestic purposes (washing, bathing,
irrigation, etc.).
Rationale for the Selective Screening of Substances in Groundwater
The first step in any public health evaluation or assessment process is the application of
conservative screening values to the available sampling data. This phase of the process helps to
rule out any site-specific substances that would not pose a public health hazard under virtually any
plausible exposure scenario. The remaining substances require further analysis to evaluate their
potential for causing adverse health effects under site-specific exposure conditions (ATSDR 2005).
It is during this second phase of the process that potential public health hazards are identified. The
preliminary screening phase does not identify toxic exposures; it merely eliminates obviously
nontoxic exposures, so that the evaluation of public health implications can focus on a reduced list
of substances .
A substance is initially selected for further public health evaluation if its maximum detected level
in groundwater exceeds its most relevant water comparison value (CV). A substance is also
initially selected for further evaluation if it is detected in groundwater and no water CV exists for
the substance. Following this initial screening, the detected concentration(s) of the selected
substance(s) are compared to concentration ranges that were considered no apparent public
health hazards in the previous PHC released for the site (A TSDR, 2002). The substances and
their respective concentration ranges considered to pose no apparent public health hazard are
listed in Table 1. If the detected concentrations fell within the concentration ranges considered to
pose no apparent public health hazard, the substances were not reevaluated as to avoid repeating
work already accomplished.
2002 and 2004 delineation investigations
EPA contracted Black and Veatch Special Projects Corporation (Black & Veatch) to conduct
remedial investigation (RJ) sampling activities at the Sigmon Septic Tank Service Site in
accordance with their Environmental Investigations Standard Operating Procedures and Quality
Assurance Manual (EPA 1997). In October 2002 and May 2004, samples were taken from (I)
groundwater, (2) surface water, (3) sediments, (4) surface soil, and (5) subsurface soil.
Groundwater samples were collected from 9 private wells and 5 monitoring wells (Figures 2 and
3). Thirty-one water samples (22 from private wells and 9 from monitoring wells) were collected
from these groundwater wells. Subsequently, these 31 samples ( or some subset thereof) were
analyzed to characterize metals, volatile organic compounds (VOCs), semivolatile organic
2
compounds (SVOCs), and pesticides/polychlorinated biphenyls (PCBs). Tables 2 through 11
(Appendix B) list the analytical results of the water samples collected from the private wells. The
results were compared to water comparison values (CVs) along with the selection screening
criteriato see if further analysis was indicated for any of these substances. The following is a
summary of ATSDR's initial public health screen for each private well.
• Private well SS-P W-0 I. Of the 14 substances in the well, none exceeded any
available water CV; however, 3 substances were found for which there were no ·
available CVs. The concentrations of these 3 substances were within the range of
levels previously considered to pose no apparent public health hazard at this site
(ATSDR 2002). Therefore, none of the substances in SS-PW-01 was selected for
further public health evaluation (Table 2).
• Private weU SS-PW-03. Of the 32 substances in the well, 4 showed maximum
levels that exceeded available water CV s; however, 2 of these substances did not
require further public health evaluation because their maximum measured
concentrations were within the range considered no apparent public health hazard.
Eight other substances were also detected in the well that had no available water
CVs; however, 3 of these were within the range considered no apparent public
health hazard. Seven of the substances in SS-PW-03 were therefore selected for
further public health evaluation (Table 3).
• Private well SS-PW-04. Of the 14 substances detected in this well, none exceeded
any available water CV. However, 4 of these substances had no available water
CVs, 3 of these were within the range considered no apparent public health
hazard. Therefore, only one of the substances in SS-PW-04 was selected for
further evaluation (Table 4).
• Private well SS-PW-05. Only one of the 14 substances in this well showed
maximum levels that exceeded available water CVs. This one substance did
require further public health evaluation. Three other substances in the well had no
available water CV s; however, all three had concentrations within the range
considered no apparent public health hazard. On the basis of the selective
screening criteria used in this. PHC, only 1 of the substances in this well was
selected for further public health evaluation (Table 5).
• Private well SS-PW-06. None of the 16 substances in this well exceeded any
available water CVs; however, 3 of these substances had no available water CVs.
All 3 showed measured concentrations within the range considered not to pose a
public health hazard. Therefore, none of the substances in SS-PW-06 were
selected for further evaluation (Table 6).
• Private well SS-PW-07. None of the 9 substances in this well exceeded the
available water CVs; however, no water CVs were available for 3 of these
3
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substances. The concentrations of all 3 were within the range considered to pose
no apparent public health hazard. Therefore, none of the substances in this well
were selected for further evaluation (Table 7).
Private well SS-PW-08. None of the 15 substances in this well exceeded the
available water CVs; however, no water CVs were available for 5 of these
substances. The concentrations of3 of these substances were within the range
considered no apparent public health hazard and only 2 of the substances in this
well were selected for further evaluation (Table 8).
• Private well SS-PW-09. Two of the 10 substances in this well had maximum
levels that exceeded available water CVs, thus requiring further public health
evaluation. Three other detected substances had no available water CVs, but all 3
were within the range considered no apparent public health hazard. Therefore,
two of the substances in this well were selected for further evaluation (Table 9).
•
Lead levels in this well in October 2002 were 50 parts per billion (ppb ), which
exceeded the maximum contaminant level action (MCLA) of 15 ppb for lead in
drinking water set by EPA under the Superfund statues. Black & Veatch (2004)
. conducted follow-up sampling on March 19, 2003 and April 9, 2003, during
which water samples were collected outdoors at the wellhead and indoors at the
water tap. Seven substances were detected in this well during this round of
sampling (Table 10). None of these exceeded any available water CVs, but water
CVs were unavailable for 2 of these substances. However, these 2 substances
were within the concentration range considered to pose no apparent public health
hazard. The lead levels at the indoor water tap were lower than those measured at
the wellhead, suggesting a possible lead source at the wellhead that should be
assessed further.
Private well SS-PW-10. Two of the 11. substances in this well had maximum
levels exceeding available water CVs, thus requiring further evaluation. Three
other substances detected in the well had no available water CVs. However, all 3
were within the range considered no apparent public health hazard. On this basis,
2 of the substances in this well were selected for further evaluation (Table 11 ).
Tables 13 through 17 (see Appendix B) list the constituents detected in the water samples
collected from the monitoring wells. These results were compared to the relevant CVs. Although
we applied the selection screening criteria to each monitoring well, none of the substances
detected in these wells was selected for further analysis. We believe that the monitoring wells
will never be used for potable or other domestic purposes. Thus, no exposures can occur to any
hazardous substances contained in the wells. Nevertheless, A TSDR recommends routine
sampling and analysis of groundwater samples from both the monitoring wells and nearby
private wells until potential source areas of contamination at the site are removed. This is seen as
a responsive public health action to reduce and/or prevent exposures to hazardous substances that
4
could possibly migrate into nearby private wells. The following briefly summarizes ATSDR's
initial public health screen for each monitoring well.
•
•
Monitoring well SS-MW-11 C. Of the 35 substances detected in this on-site
monitoring well, 7 had maximum levels that exceeded available water CVs and
would have required further public health evaluation (ATSDR 2002). Four other
substances were also detected in the well that would have required further public
health analysis. Although no CVs were available for these substances, all 4 had
concentrations exceeding the range considered to constitute no apparent public
health hazard (Table 13). However, because this monitoring well will not be used
for potable or other domestic purposes, none of these substances was selected for
further evaluation. Otherwise, 11 of the substances detected in this monitoring
well would have required further public health evaluation.
Monitoring well SS-MW-14. Ten of the 33 substances in this on-site monitoring
well had maximum levels that exceeded available water CV s. One of these would
not have required further public health evaluation because its maximum
concentration was within the range considered no apparent public health hazard.
Four other substances in the well had no available water CVs. Again, one of these
would not have required further public health evaluation because its concentration
was within the range considered no apparent public health hazard (Table 14).
Because this monitoring well will not be used for potable or other domestic
purposes, none of these substances was selected for further public health
evaluation. Otherwise, 12 of the detected substances in this monitoring well
would have been selected for further evaluation.
• Monitoring well SS-MW-10B. Of the 18 substances in this off-site monitoring
well, only one had a maximum level that exceeded its available water CV.
However, this concentration was within the range considered no apparent public
health hazard requiring no further evaluation. Three other substances were also
detected in the well for which there were no available water CVs, but all 3 had
concentrations within the range considered to pose no apparent public health
hazard (Table 15). Based on this and the belief this monitoring well will not be
used for potable or other domestic purposes, none of these substances was
selected for further public health evaluation.
• Monitoring well SS-MW-12B. Of the 17 substances detected in this off-site
monitoring well, three substances showed maximum concentrations that exceeded
their available water CVs. Two of these would not require further public health
evaluation because their maximum concentrations were within the range
considered to pose no apparent public health hazard. Four other substances in the
well had no available water CV s. Three of these had concentrations within the
range considered to pose no apparent public health hazard (Table 16). Based on
the belief this monitoring well will not be used for potable or other domestic
5
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purposes, none of these substances was selected for further public health
evaluation. Even if this was not the case, only 2 substances in this well would
have been selected for further evaluation.
• Monitoring well SS-MW-13B. Of the 30 substances detected in this off-site well, 8
had maximum levels that exceeded available water CVs. One of these would not
have required further evaluation because its maximum measured concentration
was within the range considered to pose no apparent public health hazard. Four
other substances were also detected in the well that had no available water CVs.
Two showed concentrations within the range considered to constitute no apparent
public health hazard (Table 17). Because we believe this well will not be used for
potable or other domestic purposes, none of these substances was selected for
evaluation. Otherwise, 9 of the detected substances in this monitoring well would
have been selected for further public health evaluation.
Chemicals Selected for Further Public Health Analysis
ATSDR's review of the groundwater analyses of the private wells is summarized in Table 12.
Using Table 12, our environmental health scientists selected substances detected in the private
wells for further public health analysis. These substances were categorized into 2 groups: those
that exceeded available CVs and those for which there were no available CVs. The following
substances were selected for analysis:
Substances exceeding
drinking water CV s*
Arsenic
Copper
Lead
Zinc
a-BHC1 .
Heptachlor epoxide
* Comparison values
t a-Benzcnehexachloride
Monitoring Well Data
Substances without
drinking water CVs
Yttrium
2-Hexanone
Endosulfan II
Endrin aldehyde
Endrin ketone
y-Chlordane
ATSDR's review of the groundwater analyses of the monitoring wells are summarized in Tables
18 and 19. As noted previously, it is understood that monitoring wells will not be used for
potable or other domestic purposes. Nevertheless, ATS DR still rec·ommends routine sampling
and analysis of groundwater from both the monitoring wells and nearby private wells until
6
potential source areas of contamination at the site are removed. Following the selective screening
criteria used for the potable water wells, ATSDR environmental health scientists noted additional
substances detected in the monitoring wells (highlighted in blue and yellow in Tables 18 and 19)
that were not included in the substances selected for further analysis. Exposures to these
additional substances are minimal to none since the water in these wells is not used for potable
purposes. However, these additional substances could possibly migrate into nearby private wells
that are used for potable and other domestic purposes and they should be continually monitored
until potential sources of contamination at the site are removed. These additional substances are
listed below:
Substances exceeding
drinking water
comparison values
Chromium
Iron*
Manganese*
Mercury
Nickel
Sodium*
Thallium
Vanadium
Benzene
Trichloroethene
Aldrin
[3-BHC1
Heptachlor
Substances without
drinking water
comparison values
Calcium*
Magnesium*
Potassium*
* These substances are essential nutrients and arc typically not harmful under most environmental
exposure scenarios (ATSDR 2005). However, they should still be monitored to ensure that they don
not reach harmful concentrations.
t P-Benzenehexachloride.
A TSDR also reviewed the groundwater analyses in the private wells and monitoring wells to
determine if the number ofVOCs detected in on-site wells were cqmparable to those in the off-
site wells. Only two off-site wells (monitoring well SS-MW-13B and private well SS-PW-03)
showed VOC levels comparable to those in the on-site wells (Table 20). Both wells are south to
7
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•
•
•
southwest of the site, and are believed to be hydraulically downgradient (Figure 4). In a previous
PHC, ATSDR listed two private wells as posing health risks because detected nitrate levels were
greater than 10,000 ppb (ATSDR 2002). These two private wells (SS-PW-02 and SS-PW-03) are
also located south to southwest of the site and are likewise believed to be hydraulically
downgradient. This suggests that substances from the site may be migrating off-site. To err on
the side of public health, we recommend responsive actions to reduce or prevent migration of
these substances from the site (e.g., eliminating all potential source areas). Moreover and until
potential source areas are eliminated at the site, we recommend responsive actions to reduce or
prevent exposures to substances that are perhaps migrating from the site and impacting private
wells. One such responsive action is to install water filtration/purification systems to homes in
close proximity to the site.
Assessment Limitations
We note the following issues regarding the groundwater contamination near the Sigmon Septic
Tank Service Site:
• Nitrates -ATSDR health scientists were especially concerned that none of the samples
were analyzed for nitrates in the private potable wells. In a previous PHC about the site
(A TSDR 2002), A TSDR noted that two private wells containing nitrate levels greater
than I 0,000 ppb posed an increased health risk to very young infants (0-6 months). Both
of these wells (SS-PW-02 and SS-PW-03) appear to be hydraulically downgradient from
the potential source areas at the site (Figure 4; SS-PW-02 is not shown on the figure but
is nearly adjacent to SS-PW-03). Pregnant females and their fetuses also need to be
included in this sensitive population. Sensitive populations are defined as people who
might be more ·sensitive or susceptible to exposures to hazardous substances because of
factors such as age, occupation, sex, or behaviors ( e.g., cigarette smoking). For additional
insight about sensitive populations, please refer to page 13 of this PHC (i.e., "Child
health considerations").
Five wells may possibly be hydraulically connected in the general area where
nitrates might be a problem (ATSDR 2002). Two of the wells are private (SS-
PW-02 and SS-PW-03). The other 3 are monitoring wells (SS-MW-1 lC, SS-MW-
14, and SS-MW-138), 2 of which are on-site and 1 is off-site. No data were
collected for private well SS-PW-02 during October 2002 or May 2004 because it
was dry in October 2002 and was not sampled in May 2004. The only evidence
suggesting that the private well is hydraulically connected to the others are the
nitrate levels measured in the well before and during 1999 (ATSDR 2002).
Lead sources -Lead was detected in 8 private wells near the Sigmon Septic Tank Service
Site. However, only 2 of these (SS-PW-09 and SS-PW-10) contained maximum lead
levels (50 ppb and 140 ppb, respectively) that exceeded EPA's lead action level of 15
ppb. It is noteworthy that when these lead levels were detected (October 2002 and May
2004), they were higher than the levels in on-site monitoring wells SS-MW-11 C and SS-
8
MW-14 (7-16 ppb, respectively), which are relatively close to the source areas.
Therefore, even though lead is a site contaminant, it is possible that other sources, such as
plumbing (lead piping, lead-based solder, and lead-containing water faucets or spigots),
could have contributed to the high measurements. These varied results could also be due
to possible discrepancies in sampling methodology ( e.g., concentration fluctuations
associated with faucet run-time).
Whether or not the potential lead sources are identified, the maximum detected lead
levels in private wells SS-PW-09 and SS-PW-10 do present the potential of adversely
affecting public health. Concerned residents should therefore ask their physicians to
determine their blood lead levels. Meanwhile, residents can take short-term remedies to
reduce lead concentrations in their drinking water and, thus minimize their exposure.
o ](the source o[/ead is in the plumbing. Let the tap water run for 30 seconds to 2
minutes before using it for drinking or cooking. The longer water remains in
pipes, the greater is the likelihood that lead may dissolve into it. Water that has
been in the pipes for more than 4 hours should be flushed for 3 to 5 minutes. For
example, this should be done first thing in the morning and upon arriving home in
the evening. A good indication of when to stop flushing the cold-water tap is
when the water becomes noticeably colder. Use cold water for cooking or making
infant formula because water from the hot-water tap tends to leach lead from the
pipes and plumbing more quickly. This can result in higher lead concentrations in
hot water.
o ](the source o[lead is the groundwater. If the tap water contains lead in excess of
15 ppb even after flushing, residents should consider using bottled water for
drinking or cooking. Alternatively, they might consider a water purification
system that removes lead and other contaminants. Purification systems range in
size and cost from simple water pitcher filtration to purification systems for the
entire household.
• Well construction quality-The Sigmon Septic Tank Service Site is located in a rural
area, and it was therefore difficult to determine when some of these private potable wells
were constructed. Due to the lack of construction details, it was also hard to verify the
integrity of the wells. (Contaminants may enter poorly constructed wells more easily than
well-constructed ones.)
Chlorination by-products -Two VOCs classified as trihalomethanes were detected in two
private wells (chloroform in SS-PW-06 and bromoform in SS-PW-08). Neither of these
chemicals was detected in the on-site monitoring wells close to the source areas.
Trihalomethanes are common by-products of the chlorination of drinking water.
Chlorination is an effective means of treating drinking water for infectious bacteria
(coli forms) and other pathogens. However, guidelines are established to ensure that the
chlorination of non-municipal water sources is done correctly. Therefore, it may be wise
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to contact your county health department to determine if the proper guidelines for
chlorinating such water sources are being followed. Chlorination of the well water would
be a plausible source of the observed trihalomethanes. However, it is also possible that
the trihalomethanes leached from septic tank leaching fields; this is not uncommon in a
rural area with private wells.
Presence of bacteria -Drinking water quality can also be affected by the presence of
bacteria and other pathogens. Unpleasant taste, odor, and water color are not only caused
by elevated levels of metals such as iron and manganese, but also by some types of
bacteria. Due to the type of business formerly conducted at the Sigmon Septic Tank
Service Site and private septic tanks in the area, bacteria could be migrating from on-site
source areas and private septic tanks outside of the site. Prior to the release of a previous
PHC for the site, A TSDR personnel contacted a representative of the Iredell County
Health Department (ICHD). The representative informed ATSDR that none of the nearby
private wells had been sampled or analyzed for fecal or total coliform counts (A TSDR
2002). The representative did state that the ICHD would provide such an analysis at the
request of any concerned well owner.
Exposure Pathways
Exposure to the chemicals detected in the water samples were determined to be intermediate and
chronic (that is, moderate and long-term exposures, respectively) that can occur via ingestion,
inhalation (VOCs), and dermal contact when groundwater is used for drinking, showering and
bathing, or other household purposes. Several studies have indicated that significant exposures to
VOCs can occur during showering and bathing as chemicals volatilize and are subsequently
inhaled and/or absorbed through the skin. Such exposures to VOCs may equal or exceed those
from ingestion, but usually by no more than a factor of 2 (Jo et al. 1990; Kerger, Schmidt &
Paustenbach 2000; Kezic et al. 1997; Mattie et al. 1994; EPA 1999). Because of the low
frequency ofVOC detection (5%-15%) and the fact that none of the detected levels exceeded
any available drinking water comparison values, A TSDR considered VOC exposure through
inhalation and skin absorption to be minimal, if any. Therefore, ingestion was the primary route
of human exposure considered in this PHC; it is also the route of exposure for other, nonvolatile
substances that were detected at a higher frequency (e.g., metals).
Public health implications
The substances discussed below were selected for further evaluation on the basis of the selective
screening criteria for this PHC. Some of these substances were selected merely because their
detected levels in one or more private potable wells exceeded available water CVs. (See
Appendix A for a description of comparison values and their proper interpretation.) The
toxicological evaluations of these substances are based on the best available medical and
toxicological information (A TSDR 2005) .
10
Substances detected in the groundwater through the sampling of private potable wells were
screened with health-based comparison values (Tables 2-12). Health-based CVs represent those
levels expected to be safe even for sensitive populations, excluding hypersensitive (allergic)
individuals. Exceeding a CV does not indicate that adverse health effects are expected, but
identifies substances that may require additional evaluation of factors that may influence the
toxicity and likelihood of health effects. Exposures to potential carcinogens are further evaluated
using risk assessment to describe the increases risk of cancer compared to background levels.
Those substances exceeding CV s or for which comparison values do not exist were further
evaluated for potential adverse health effects.
Further evaluation identified lead as the only substance for which intervention is recommended
for specific water wells. Lead levels of 140 µg/L and 50 µg/L (ppb) were detected in 2 specific
wells. These exceeded the EPA action level for lead of 15 µg/L (EPA 2004a). This action level is
based on the maximum contaminant level (MCL), which is not strictly a health-based screening
level. These levels may be a cause of concern for women of child-bearing age that may become
pregnant, as well as for the fetus and young children. Women of child-bearing age should be
protected because the fetus could be exposed before the mother-to-be learns she is pregnant. A
threshold for effects has not been identified for lead exposures to the fetus or young children.
Cumulative exposures to multiple substances are not considered likely for these wells,
considering the type of substances, the low levels detected, and their modes of action. Adverse
•
health effects due to the potential additive impact of carcinogens and noncarcinogenic substances •
are considered unlikely. ·
Substances without drinking water comparison values
A health-based comparison value has not been developed for the ingestion of 2-hexanone.
2-Hexanone is used as a solvent and is regulated in the workplace where airborne exposure may
occur. Short-chain ketones such as 2-hexanone are of concern mainly due to inhalation and
dermal exposure (Topping et al. 2001). Low levels ofketones can be found in the environment
and 2-hexanone has been reported in milk and cream in the range of 7-18 ppb (ATSDR 1992).
While inhalation is the primary exposure route for adverse health effects, ingestion of very high
levels leads to similar adverse health effects as seen in animals. 2-Hexanone is no longer
manufactured since 1982 but can be found as a waste product, a product of environmental
oxidative degradation, and a mammalian metabolite of n-hexane (A TSDR 1999). The CV of
n-hexane is 420 µg/L for ingesting tap water and inhaling any vapors due to off-gassing (EPA
2004b ). On the basis oflimited laboratory animal data and by comparison to similar chemicals,
exposure to the low maximum level of 0.52 µg/L detected in the water sample is not expected to
result in adverse health effects.
No oral CV exists for yttrium, but the oral toxicity of this metal has been described as low and
the inhalation toxicity varies greatly with the yttrium compound (OSHA). The scientific
literature does not report oral toxicity at site-specific concentrations (2 µg/L, or 2 ppb ). The
lowest published lethal subcutaneous dose in the rat is more than 10 grams per kilogram (I 0
11 •
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million ppb) and adverse effects were not observed in rats dosed intraperitoneally (a more
sensitive route) with 60,000 µg/kg (60,000 parts per billion) of yttrium every other day for 5
months (OSHA). The U.S. Occupational Safety and Health Administration (OSHA) has
established a permissible exposure limit (PEL) for yttrium inhalation of 1,000 µg/m 3 (1,000 ppb)
(OSHA), and the National Institute for Occupational Safety and Health (NIOSH) has established
an immediately dangerous to life and health (IDLH) level of 500,000 µg/m3 (500,000 ppb)
(NIOSH 1995). Such doses resulting from exposures would be extremely high compared to these
site-specific levels. While appropriate studies are not available to determine a safe yttrium oral
exposure level, there is no evidence to expect adverse health effects at the site-specific levels
found here.
"Technical chlordane" is a mixture of at least 23 isomers ( different configurational forms of
chlordane) that include gamma-chlordane (y-chlordane) and other surrogate chemicals. The
approximate composition of technical chlordane is as follows: /rans-chlordane, or y-chlordane,
24%; chlordene isomers, 21.5%; cis-chlordane, or alpha-chlordane (a-chlordane), 19%;
heptachlor, I 0%; nonachlor, 7%; di els-alder adduct of cyclopentadiene and
pentachlorocyclopentadiene, 2%; hexachlorocyclopentadiene, I%; octachlorocyclopentene, I%;
and miscellaneous constituents, 15.5% (]ARC 1979). Because y-chlordane is one of the
components of chlordane, its detected levels were compared to the CVs for chlordane. The
detected levels for y-chlordane did not exceed the noncancer CVs for chlordane (ATSDR's
chronic child environmental media evaluation guide, or EMEG, of6 ppb or EPA's MCL of2
ppb ). One detected water level for y-chlordane did exceed the cancer CV for chlordane
(ATSDR's cancer risk evaluation guide, or CREG, ofO.l ppb), resulting in an increased lifetime
cancer risk of less than I 0-5 (I in I 00,000). However, no adverse health effects are expected at
these detected levels for y-chlordane.
Little is known about the properties of endrin aldehyde (an impurity and breakdown product of
endrin) or endrin ketone (a photodegradation product of endrin when it is exposed to light). As
noted, endrin aldehyde is a minor impurity of the pesticide endrin, which is no longer produced
(ATSDR 1997; Merck 2001). The production and use of endrin may have resulted in the release
of both endrin aldehyde and endrin ketone into the environment, either by the direct release of
endrin or from various waste streams formed in its production. Due to their associated histories
with the pesticide endrin, both endrin aldehyde and endrin ketone are usually considered
surrogates of endrin. Thus, their detected levels are usually compared against the CVs of endrin
as an environmental health screen. None of the detected levels of endrin aldehyde or endrin
ketone exceeded the noncancer comparison values for endrin (ATSDR's chronic child EMEG of
3 ppb or EPA's MCL of2 ppb). Therefore, no adverse health effects are expected from
exposures to endrin aldehyde or endrin ketone at their detected levels in well water here.
Endosulfan is a mixture of two different isomers of the same chemical. Commercially, this
mixture for endosulfan is composed of 70% of endosulfan I and 30% of endosulfan II. The
biological half-life is 1-2 weeks for endosulfan and both isomers are metabolized to endosulfan
sulfate (Accu-Chem). Moreover, endosulfan I and endosulfan II are usually considered
surrogates of the chemical endosulfan. Because the detected water level for endosulfan II does
12
not exceed the noncancer CV for endosulfan (A TSDR chronic child EMEG of 20 ppb ), no
adverse health effects are expected from exposures to endosulfan II at this level in well water.
Substances exceeding drinking water comparison values
The heptachlor epoxide level in one sample exceeded a comparison value for cancer, but not a
noncancer CV. Exposures could result in a slight increase in the risk for developing cancer, but
health effects are unlikely since the risk is less than 10-5 for a lifetime exposure. This
corresponds to a risk of I cancer case in a population of I 00,000 and is likely to be less,
considering the conservative nature of estimating the risk, the use of maximum exposure values,
and an actual less than continuous lifetime exposure.
Moreover, the detected water level in one sample exceeded a cancer comparison value for alpha-
BHC (a-hexachlorocyclohexane) but not a noncancer CV. Exposures could result in a slight
increase in the risk for developing cancer, but health effects are unlikely since the risk is also less
than 10-5 for lifetime exposures.
The water level for arsenic did not exceed noncancer CVs; however, the cancer comparison
value was exceeded, resulting in a slight increase in cancer risk. Nevertheless, health effects are
unlikely, as the increase in cancer risk is less than 10-5 for a lifetime exposure .
. .
Only the maximum detected levels for both copper and zinc slightly exceeded their respective
noncancer comparison values; however, adverse health effects are not expected from lifetime
exposures at these levels.
Child health considerations
ATSDR considers children in the evaluation for all environmental exposures and uses health
guidelines that are protective for children. When evaluating any potential health effects via
ingestion, children are considered a special or sensitive population. Because of their lower body
weight, the same exposure will result in a higher dose compared to adults. Average body weight
differences, as well as average differences in child-specific intake rates for various
environmental media, are taken into account by ATSDR's child EMEGs.
Although not known during the October 2002 and May 2004 delineation investigations, past
nitrate levels in two private wells located directly below the on-site source areas have posed an
increased risk of elevated methemoglobin levels in very young infants (less than 6 months of
age) from drinking formula prepared with this water. Another group at similar risk is pregnant
females carrying fetuses. Current lead levels in two private wells also exceeded the EPA lead
action level of 15 ppb and may potentially pose increased health risks, especially to young
children who drink the well water. However, the sources oflead contamination in these two
wells are also unknown. Regardless of the source, to ensure prudent public health interventions,
A TSDR recommends supplying households whose wells may have been potentially impacted by
13
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nitrates, lead, and/or other substances that perhaps migrated from the site with an alternative
water source (bottled water or connection to a municipal water line) or installing water
filtration/purification systems that yield safe drinking water.
Conclusions
I. During the October 2002 and May 2004 delineation investigations at the Sigmon Septic
Tank Service Site, private wells SS-PW-09 and SS-PW-10 showed maximum lead levels
of 50 and 140 ppb, respectively. These measured levels potentially could adversely affect
the health of individuals using the wells for potable purposes.
2. Although not measured during the October 2002 and May 2004 delineation
investigations, private wells SS-PW-02 and SS-PW-03 had nitrate levels greater than
I 0,000 ppb between 1991 and 1999 (A TSDR 2002). At that time, the maximum detected
nitrate levels in both wells posed an increased risk of higher methemoglobin levels in
very young infants (0-6 months) drinking formula prepared with water from these wells.
The sensitive population also included pregnant females who drank water from these
wells could adversely affect their fetuses.
3. Other substances detected in nearby private wells surrounding the Sigmon Septic Tank
Service Site posed no apparent public health hazard to residents using water from nearby
private wells. The detected substances considered to pose no apparent public hazard are
shown under the following two categories:
• Substances exceeding comparison values -arsenic, copper, zinc, a.-BHC, and
heptachlor epoxide;
• Substances without comparison values -yttrium, 2-hexanone, methyl acetate,
methylcyclohexane, endosulfan II, endrin aldehyde, endrin· ketone, and y-chlordane.
4. ATSDR identified several limitations in the delineation investigations regarding
groundwater contamination found near the Sigmon's Septic Tank Service Site: (I)
unknown presence of nitrates, (2) unknown lead sources, (3) unknown well construction
quality, (4) unknown origin.of chlorination by-products, and (5) unknown presence of
bacterial and other pathogens. It is uncertain what future impact these limitations may
have regarding long-term exposure to groundwater from nearby private wells. However,
these limitations should be addressed in the interest of public health.
Recommendations
I. Consider supplying an alternative water source (bottled water or connection to a
municipal water line) or implementing another remedy (e.g., installation ofa water
14
filtration/purification system) that yields potable water within safe drinking water
standards to households whose private wells may be impacted by nitrates, lead, and/or
other substances that perhaps have migrated from the site. Continue this responsive
action until the appropriate investigations are completed, strategies formulated, remedial
actions implemented, and local water supplies are brought within safe drinking standards.
2. Consider removing the source areas from the Sigmon Septic Tank Service Site to reduce
and/or prevent any potential migration of hazardous substances into nearby private wells.·
3. Consider continuing to routinely collect and analyze groundwater samples, particularly
for nitrates and lead, from both the monitoring wells and nearby private wells until the
appropriate investigations are completed, strategies formulated, remedial actions
implemented, and local water supplies are brought within safe drinking standards.
Public health action plan
I. Follow up with EPA in educating and informing concerned residents about the public
health importance of using an alternative water source (bottled water or connection to a
municipal water line) or implementing another remedy (installation of a water
filtration/purification system) that yields safe drinking water until further notified that
their own water is within safe drinking water standards
2. Follow-up with· EPA and Iredell County Health Department in educating and informing
concerned residents of the public health significance of having drinking water tested for
lead, applying approaches at home to reduce the amount oflead in drinking water, and
checking blood lead levels periodically.
15
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• Authors
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David S. Sutton, PhD, PE
Environmental Health Scientist
Consultations Team
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
David A. Fowler, PhD
Senior Toxicologist
Consultations Team
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Reviewers
Susan Moore
Branch Chief
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Peter Kowalski, MPH, CIH
Team Leader
Consultations Team
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry ·
Benjamin Moore
Regional Representative
Region IV
Division of Regional Operations
Agency for Toxic Substances and Disease Registry
William H. Light, PhD
Environmental Toxicology Writer-Editor
Office of Communication
National Center for Environmental Health
and Agency for Toxic Substances and Disease Registry
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References
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Appendix A
Comparison Values
ATSDR comparison values (CVs) are media-specific concentrations that are considered to be
safe under default conditions of exposure. They are used as screening values in selecting site-
specific chemicals for further evaluation of their public health implications. Generally, a
chemical is selected for further public health evaluation because its maximum concentration in
air, water, or soil at the site exceeds at least one of ATSDR's CVs. Supplementing this
conservative approach is ATSDR's guidance that requires environmental health scientists to
exercise professional judgment when selecting chemicals for further public health evaluation,
evaluating exposure pathways, and determining the public health implications of site-specific
exposures (ATSDR 1992). ATSDR may also select detected chemical substances for further
· public health evaluation and discussion because ATSDR has no CVs for certain specified
chemicals or because the community has expressed special concern about the substance, whether
it exceeds CVs or not.
It must be emphasized that CVs are not thresholds of toxicity. While concentrations at or below
the relevant CV are generally considered to be safe, it does not automatically follow that any
environmental concentration that exceeds a CV would be expected to produce adverse health
effects. In fact, the whole purpose behind highly conservative, health-based standards and
guidelines is to enable health professionals to recognize and resolve potential public health
problems before they become actual health hazards. For that reason, ATSDR's CVs are typically
1 to 3 orders of magnitude (10-1,000 times) lower than the corresponding no-effect levels or
lowest-effect levels on which they are based. The probability that adverse health outcomes will
actually occur depends not on environmental concentrations alone, but on several additional
factors, including site-specific conditions cif exposure, individual lifestyle, and genetic factors
affecting the route, magnitude, and duration of actual exposures, and individual physiological
responses to those exposures.
Listed below are the abbreviations for selected CV s and units of measure used within this
document. Following this list of abbreviations are more complete descriptions of the various
comparison values used within this document, as well as a brief discussion on one of ATSDR's
most conservative CV s.
CREG
EMEG
LTHA
MCL
MCLA
MRL
RBC
RID
RMEG
= cancer risk evaluation guide
= environmental media evaluation guide
= drinking water lifetime health advisory
= maximum contaminant level
= maximum contaminant level action
= minimal risk level
= risk-based concentration
= reference dose
= reference dose media evaluation guide
23
Units of measure
ppm = parts per million, e.g., mg/L (water), mg/kg (soil)
ppb parts per billion, e.g., µg/L (water), µg/kg (soil)
kg kilogram (1,000 grams)
mg = milligram (0.001 gram)
µg microgram (0.000001 gram)
L liter (1,000 milliliters or 1.057 quarts of liquid, or 0.001 m3 of air)
m3 = cubic meter (a volume of air equal to 1,000 liters)
Cancer risk evaluation guides (CREGs) are derived by ATSDR. They are estimated chemical
concentrations theoretically expected to cause no more than one excess case of cancer per
million people exposed over a lifetime. CREGs are derived from EPA's cancer slope factors and
therefore reflect estimates of risk based on the assumption of zero threshold and lifetime
exposure. Such estimates are necessarily hypothetical. As stated in EPA's 1986 Guidelines for
Carcinogenic Risk Assessment (EPA 1986), "the true value of the risk is unknown and may be as
low as zero."
Drinking water equivalent levels (DWELs) are lifetime exposure levels specific for drinking
water (assuming that all exposure is from that medium) at which adverse, noncarcinogenic health
effects would not be expected to occur. They are derived from EPA reference doses (Rills) by
factoring in default ingestion rates and body weights to convert the RID to an equivalent
•
concentration in drinking water. •
Minimal risk levels (MRLs) are ATSDR estimates of daily human exposures to a chemical that
are unlikely fo be associated with any appreciable risk of deleterious noncancer effects over a
specified duration of exposure. MRLs are calculated with data from human and animal studies
and are reported for acute (:::14 days), intermediate (15-364 days), and chronic (c::365 days)
exposures. MRLs for oral exposure ingestion) are doses typically expressed in mg/kg/day.
Inhalation MRLs are concentrations typically expressed in either parts per billion (ppb) or
micrograms per meter cubed (µg/m3). The latter are identical to ATSDR's EMEGs for airborne
contaminants. ATSDR's MRLs are published in ATSDR toxicological profiles for specific
chemicals.
Environmental media evaluation guides (EMEGs) are media-specific concentrations that are
calculated from A TSDR's Minimal Risk Levels by factoring in default body weights and
ingestion rates. Different EMEGs are calculated for adults and children, as well as for acute (SI 4
days), intermediate (15-364 days), and chronic (c::365 days) exposures.
EPA reference dose (RID) is an estimate of the daily exposure to a contaminant unlikely to
cause any noncarcinogenic adverse health effects over a lifetime of chronic exposure. Like the
ATS DR MRL, the EPA RID is a dose and is typically expressed in mg/kg/day.
24 •
•
•
•
Reference dose media evaluation guide (RMEG) is the concentration of a contaminant in air,
water, or soil that ATSDR derives from EPA's RID for that contaminant by factoring in default
values for body weight and the media-specific intake rate. Like ATSDR EMEGs, RMEGs are
calculated for both adults and children.
Risk-based concentrations (RBCs) are media-specific values derived by the Region III Office
of the U.S. Environmental Protection Agency from EPA RfDs, RfCs, or cancer slope factors, by
factoring in default values for body weight, exposure duration, and ingestion/inhalation rates.
These values represent levels of chemicals in air, water, soil, and fish that are considered safe
over a lifetime of exposure. RBCs for noncarcinogens and carcinogens are analogous to ATSDR
EMEGs and CREGs, respectively.
Lifetime health advisories (LTHAs) are calculated from the drinking water equivalent level
(DWEL) and represent the concentration of a substance in drinking water estimated to have
negligible deleterious effects in humans over a lifetime of 70 years, assuming 2 liter per day
water consumption for a 70-kilogram adult. In the absence of chemical-specific data, L THAs are
20% and 10% of the corresponding DWELs for noncarcinogenic organic and inorganic
compounds, respectively. LTHAs are not derived for compounds that are potentially
carcinogenic for humans.
Maximum contaminant levels (MCLs) are drinking water standards established by the EPA.
They represent levels of substances in drinking water that EPA deems protective of public health
over a lifetime (70 years) at an adult exposure rate of2 liters of water per day. They differ from
other protective comparison values in that they(!) reflect consideration of both carcinogenic and
noncarcinogenic effects, (2) take into account the availability and economics of water treatment
technology, and (3) are legally enforceable.
Maximum contaminant level action (MCLA) are action levels for drinking water set by EPA
under Superfund. When the relevant action level is exceeded, a regulatory response is triggered.
When screening individual chemical substances, ATSDR staff compares the highest single
concentration of a chemical detected at the site with the appropriate CV available for the most
sensitive of the potentially exposed individuals (usually children). Typically, the cancer risk
evaluation guide (CREG) or chronic environmental media evaluation guide ( cEMEG) is used.
This worst-case approach introduces a high degree of conservatism into the analysis and often
results in the selection of many chemical substances for further public health evaluation that
upon closer scrutiny will not be judged to pose any hazard to human health. However, in the
interest of public health, it is more prudent to use an environmental screen that identifies many
chemicals for further evaluation that may later be determined to be harmless, as opposed to one
that may overlook even a single potential hazard to public health. The reader should keep in
mind the conservativeness of this approach when interpreting ATSDR's analysis of the potential
health implications of site-specific exposures .
25
• APPENDIX B
•
•
• •
TABLE 1
•
Chemical levels considered no apparent health hazard
ATSDR's 2002 public health conclusions for Sigmon's Septic Tank Service Site
(Summary of chemical concentrations found in all private wells between 1991-1999)
CHEMIC:A_L_ . . . . CHEMICAL
SUBSTANCE . . . CONCENTRATIONS ··-,-··•··-•·· ·::~~r-.......... "' . .,~--•(ppb)· ···_··
• • • • --, __ •• • -,.: • •• 1 -. -_ •· •• :···-·:. Detected concentrations . . .... ,.: . <. ;; ;/ . IC . . . . ·. . < ' ·. " . . . . • .. ,_ ... _,; '"" .. ,.,,.,;,-:-,;-,, .. ::,.;'! ' ... ·.,: ·>; Rarige'.-.,r· •.,.· .. : i''' Mean .
INORGANIC MOITIES
Nitrates I 100-23,350I 8,164
Sulfates l 6,000 6,000
METALS
Aluminum 200-1,700 950
Barium 16-400 164
Calcium 21,000-95,000 58,000
Cobalt 1.2-2.6 2.1
Coooer 14-60 37.6
Iron 14-5,500 1,736
Lead 2 28 8.9
Ma~nesium 1,600-12,000 6,983
Manqanese 4.2-830 153.1
Mercury 1-7 2.8
Nickel 2.3-4.2 3.25
Potassium 1,300-7,000 2,990
Sodium 5,300-15,000 10,150
'-inc 28-2,500 541
ORGANIC COMPOUNDS
ll'.cetone 5-233 71.9
Benzene 0.4 0.4
Bromodichloromethane 3 3
Chlorobenzene 0.4 0.4
Chloroform 0.6-39 13.46
Dibromochloromethane
27
.. _ .• , .. ·. CAT.1?,□ R~ <
PUBLIC HEALTH'CONCLUSION • ~ •••~-,-~-,~,,s....., _ _,_,_,..._,..._~--..., ~~-:•,>::•':''---'. ,,.--" • ,r., V
· AS CITED IN March.2002 ··
HEALTH CONSULTATION. -: . ..
.,.,:·-·--:·:/' -~,,--~'./ ,: .. _,,'.,,\"".'!'~,.-
; · Median• i '' ·: •c;;~:\i~ih,,gii~£iJ(1~~;;;;;.",C } .'
8,6001
6,0001
950
90
58,000
2.4
38
195
4.5
7,250
78
1.6
3.25
2,150
10,150
155
47.5
0.4
3
0.4
0.78
Potential oublic health concern
No apparent public health hazard
No annarent oublic health hazard
No annarent oublic health hazard
No annarent oublic health hazard
No aoparent oublic health hazard
No apparent public health hazard
No annarent public health hazard
No annarent oublic health hazard
No apparent oublic health hazard
No apparent public health hazard
No aoparent public health hazard
No annarent public health hazard
No aoparent oublic health hazard
No aoparent public health hazard
No apparent public health hazard
No apparent public health hazard
No apparent public health hazard
No apparent public health hazard
No aoparent public health hazard
No apparent public health hazard
No annarent public health hazard
TABLE 1 (continued)
Chemical levels considered no apparent health hazard
ATSDR's 2002 public health conclusions for Sigmon's Septic Tank Service Site
(Summary of chemical concentrations found in all private wells between 1991-1999)
CHEMICAL CHEMICAL ATSDR
SUBSTANCE CONCENTRATIONS PUBLIC HEAL TH CONCLUSION
(ppb) AS CITED IN March 2002
HEALTH CONSULTATION
Detected concentrations
Range Mean Median
1,2-Dichlorobenzene 0.3---48 24 24 No annarent public health hazard
1,4-Dichlorobenzene 0.27-44 3.91 0.77 No aooarent public health hazard
1, 1-Dichloroethane 0.4-1.5 0.7 0.6 No aooarent public health hazard
1,2-Dichloroethane 0.53 0.53 0.53 No annarent public health hazard
cis-1,2-Dichloroethene 0.43-3.5 1.3 0.8 No aooarent public health hazard
Meth1 lene chloride 2 2 2 No aooarent public health hazard
Tetrachloroethene (PCE) 0.29-0.53 0.41 0.41 No annarent public health hazard
Trichloroethene ITCE) 0.27-0.89 0.5 0.35 No aooarent public health hazard
Il(vlenes 0.5-5.1 2.2 1.6 No apparent public health hazard
Reference: Agency for Toxic Substances and Disease Registry. March 29, 2002. Health Consultation: Sigmon's Septic Tank Service Facility (Review of
Groundwater Data). US DHHS, Public Health Service; Atlanta, GA
• •
• • • TABLE NOTES
Footnotes for Tables 2 through 12
A substance is selected for further public health evaluation if its maximum detected level in groundwater exceeds its respective water comparison value (see sky blue highlighting). This screening
criteria is not applicable if disclaimer No. 5 is specified (see lavender highlighting}. Moreover, a substance may also be selected for further public health evaluation if detected and no available water
comparison value exists for the substance (see yellow highlighting}; however, this screening criteria is also not applicable if tdisclaimer No. 5 is specified (see lime highlighting). Therefore, a response
of "Yes" under the subheading "Further public health evaluation required" indicates that the substance was further evaluated by ATSDR health scientists.
CREG: Cancer Risk Evaluation Guide
EMEG: Environmental Media Evaluation Guide (prefixes: a= acute, c = chronic, i = intermediate)
L THA: Drinking Water Lifetime Health Advisory
MCL: Maximum Contaminant Level
RBC: Risk Based Concentration. (Note, RBC values derived from equations documented in following reference: EPA Region Ill Risk-based Concentration Table. Philadelphia: United States
Environmental Protection Agency, Region Ill. Available at: hitp:llwww.epa.gov/reg3hwmdlrisklriskmenu.htm. Background Information -[PDF].)
RMEG: Reference Dose Media Evaluation Guide
ppb: parts per billion
Laboratory Qualifiers
A -Analyte analyzed in replicate. Reported value is average of replicates.
AJ -Analyte analyzed in replicate. Reported value is average of replicates. Reported value is an estimate.
J -Identification of analyte is acceptable; reported value is an estimate.
N -Presumptive evidence is present; analyte reported as tentative identification.
NJ -Presumptive evidence is present; analyte reported as tentative identification. Reported value is an estimate.
U -Analyte not detected at or above reporting limit.
1 Listed value in EPA MCL column is a secondary drinking water regulation (SDWR) as set by EPA. SDWRs are unenforceable federal guid~lines regarding taste, odor, color, and other non-aesthetic
effects of drinking water. EPA recommends them to the states as reasonable goals, but federal law does not require water supply systems to comply with them. However, the states may adopt their
own enforceable regulations governing these concerns. To be safe, check your state's drinking water regulations.
2 Listed value in EPA Mel column is a maximum contaminant level action (MCLA) for drinking water as set by EPA under Superfund. If the relevant action level is exceeded, a regulatory response is
triggered.
3 Listed value in EPA MCL column is a health-based drinking water advisory as set by EPA. The drinking water advisory is based on the assumption that an individual is placed on a sodium-restricted
diet of 500 mg/day.
14 Listed value in EPA MCL column is a proposed MCL under the 1994 proposed rule for disinfection by products rule; the current MCL for most trihalomethanes is 100 ppb under the 1996 Drinking
:Water Advisory Report.
5 Detected concentration(s) are within a range of concentrations for the specific chemical considered to be no apparent public health hazard as cited in a previous public health consultation released
ifor the Siemon Seotic Tank Service site tATSDR 2002\. ·
29
• • •
TABLE 2
Substances found in private well 55-PW-01
CHEMICAL CHEMICAL WATER EPA FURTHER
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL PUBLIC
(ppb) (ppb) (ppb) HEALTH
EVALUATION
Detected concentrations REQUIRED
October 2002 October 2002 May 14, 2004 May 14, 2004
(Duplicate) (Duplicate)
METALS
luminum No
Barium 31 31 39
ca1Cfurii5 1,700 1,700 3,200 J
Cobalt 0.08 J
Copper' 78 45 110 J
lron1 90 68
Lead2 12 4.3 7.5 J
400 390 570 J
26 24 7.1
1,200 1,200 1,200 J
3,700 3,600 3,600 J 3,800 J
Strontium 12 12 4,000 LTHA
Zinc 5.6 12 J 3,000 child iEMEG No
VOLATILE ORGANIC COMPOUNDS
Tetrachloroethene PCE 0.12 J 10 L THA 5 No
30
METALS
Arsenit:
Sodium3
Strontium
Vanadium
Yttrium
Zinc
CHEMICAL
SUBSTANCE
VOLATILE ORGANIC COMPOUNDS
Benzene
Chlorobenzene
1,2-Dichlorobenzene
1,4-Dichtorobenzene
1, 1-Dichloroethane
cis-1,2-Dichloroethene
1,2-Dichloropropane
Meth I acetate
Methylcyclohexane
PESTICIDES
alpha;Bl-;lBf aI-ha~HexaC!ilQrOcCIOliexane --
Endrin aldeh de
Endosulfan 11
amma-Chlordane
•
TABLE 3
Substances detected in private well SS-PW-03
CHEMICAL
CONCENTRATIONS
(ppb)
Detected concentrations .
October 2002 -October 2002 May 14, 2004
(Duplicate)
1.2 A
130 A 67
39,000 A 36,000
3.6 A 0.16 J
2.8
250A
6,900 A 3,100 J
270A 20
2.1 A 0,98
3.2
3,100 A 2,600 J
0.43 J
0.07 J
9,400 A 6,000
180 A
OA5J
2.1 A
4.9 J
0,26 J
0.54
0.46 J 0.17 J
2.2 1
0,69 0.2 J
0,52 J
0,67
0,52 J
0,91
0, 12 J
0.027 N
0,017 J
0.011 JN
0.67 J
i
May 14, 2004
(Duplicate)
WATER
COMPARISON VALUES
(ppb)
4,000 LTHA
30 child iEMEG
3,000 child iEMEG
0.6 GREG
100 LTHA
600 LTHA
75 LTHA
800 RBC
70 LTHA
700 child iEMEG
6,100 RBC
EPA
MCL
(ppb)
5,000 (SDWR)
5
100
600
75
70
5
FURTHER '
PUBLIC
HEALTH
EVALUATION
REod1RED
No
No
Yes
No
No
No
No
No
No
No
No
Yes
No
No
Yes
Yes
Yes
•
• • •
TABLE 4
Substances found in private well SS-PW-04
5,000 5,500
0.35 J
34 72 J
5 4.4 J
1,400 2,200 J
8.2 18
1.9
1,900 2,400 J
2,600 4,000 J
trontium 33 4,000 LTHA No
inc 280 330 J 3,000 child iEMEG No
ESTICIDES
ndrin aldeh de 0.D15 NJ Yes
32
CHEMICAL
SUBSTANCE ., ~ "
VOLATILE ORGANIC COMPOUNDS
Methyl-t-butyl ether (MTBE)
PESTICIDES
He-tactiloiTe-oXicle
•
TABLE 5
Substances found in private well SS-PW-05
30 56
3,400 5,300
0.33 J
20 100 J
1.3 3.1 J
700 1,100 J
9.3 5.4
1.3
1,300 1,500 J
1,800 J
18 4,000 LTHA
14 42 3,000 child iEMEG
0.26 J 0.39 J
0.032 0.01
;srURT!:IER .·
<iPUBLIC ,,
itHEALTH·· -~,&;. _·,., .,~-:, _..,. ·' .
. EVALUATION
{~Eqi)1REi>:~
No
No
•
•
METALS
luminum
Barium
CHEMICAL
SUBSTANCE
Calc'fUniil::t~;~)~-~
Cobalt
Copper'
lron1
Lead2
Magne'SiUiii~~
Manganese1
VOLATILE ORGANIC COMPOUNDS
Carbon disulfide
Chloroform
Tetrachloroethene PCE
• TABLE 6
Substances found in private well SS-PW-06
October 2002
1.6
0.32 J
0.1 J
CHEMICAL
CONCENTRATIONS
(ppb)
Detected concentrations
October 2002 May 14, 2004
(Duplicate)
110 J
30
2,900 J
0.27 J
21 J
37 J
1.3 J
660 J
13
2.9
840 J
910 J
20 J
34
May 14, 2004
(Duplicate)
WATER
COMPARISON VALUES
(ppb)
3,000 child iEMEG
1,000 child RMEG
100 child cEMEG
10 LTHA
EPA
MCL
(ppb)
80
5
•
FURTHER
PUBLIC
HEALTH
EVALUATION
REQUIRED
No
No
No
No
METALS
Barium
GaTcium5
Copper'
Zinc
•
CHEMICAL
SUBSTANCE
TABLE 7
Substances found in private well SS-PW-07
October 2002
16
2,200
27
1.5
560
1,500
4,100
16
11
CHEMICAL
CONCENTRATIONS
(ppb)
Detected concentrations
October 2002 May 14, 2004
(Duplicate)
35 •
May 14, 2004
(Duplicate)
. WATER
COMPARISON VALUES
(ppb)
4,000 LTHA
3,000 child iEMEG
EPA
MCL
(ppb)
5,000 SDWR
FURTHER
PUBLIC
HEALTH
EVALUATION
REQUIRED
No
•
• • e
TABLE 8
Substances found in private well SS-PW-08
200
14 15
6,600 6,300
15 70 J
1.6 7.5 J
1,400 1,600 J
3.6
1,700 1,400 J
4,900 5,800 No
36 4,000 LTHA No
Vanadium 1.8 30 child iEMEG No
Zinc 620 200 J 3,000 child iEMEG No
VOLATILE ORGANIC COMPOUNDS
Bromoform 4 CREG No
PESTICIDES
Endrin ketone Yes
amma-Chlordane Yes
36
TABLE 9
Substances found in private well SS-PW-09
25,000 25,000
270 60 J
50 8.3 J
1,800 1,300 J
5.7
1,100J
4,800 3,200 J No
trontium 28 4,000 LTHA No
inc 21 37 J 42 J 3,000 child iEMEG 5,000 SDWR No
• •
•
Zinc
CHEMICAL
SUBSTANCE
•
TABLE 10
Followup sampling and analyses conducted in private well SS-PW-09
CHEMICAL
CONCENTRATIONS
(ppb)
Detected concentrations
March 19, 2003 April 9, 2003 April 9, 2003 April 9, 2003
(Tap unfiltered) (Tap filtered)
22,000 A 21,000 A 21,000 A
40A 64 AJ 36
6A 14 A 1 U
1,900 A 1,900 A 1,900 1,800
5,100 A 5,100 A 5,000 4,700
26A 26 A 25 24
56A 61 A 130 250
38
WATER
COMPARISON VALUES
(ppb)
4,000 LTHA
3,000 child iEMEG
EPA
MCL
(ppb)
20,000
5,000 SDWR
•
FURTHER
PUBLIC
HEALTH
EVALUATION
REQUIRED
No
No
No
TABLE 11
Substances found in private well SS-PW-10
12
4,300 J
37 J
130
140 J
870 J
7.1
1,100 J
5,600
3,400 J 5,000 (SDWR) -Y.~
0.21 J 10 LTHA No
• i •
•
METALS
Silver
Sodium3
Bromoform4
Carbon disulfide
Chlorobenzene
Chloroform4
CHEMICAL
SUBSTANCE
1,2-Dichlorobenzene
1,4-Dichlorobenzene
1, 1-Dichloroethane
cis-1,2-Dichloroethene
1,2-Dichloro ro ane
2-Hexanone
Meth I acetate
•
TABLE12
Substances detected in private wells near the Sigmon Facility
(Summary of chemical concentrations in all private wells from October 2002-May 2004)
CHEMICAL
CONCENTRATIONS
(ppb)
Detected concentrations
Range Mean Median
56-200 107.2 110
1.2 1.2 1.2
12-130 34 31
0.14 0.14 0.14
1,700-39,000 7,989.4 5,900
0.08-3.6 0.27 0.27
2.8-270 45.21 45
37-250 83.78 79
1.3-140 6.04 5
390-6,900 1,217.31 1,350
3.6-270 11.87 8.2
0.98-2.1 1.43 1.54
1.3-3.2 2.19 2.4
840-3, 100 1,447.75 1,300
0.43 0.43 0.43
0.07 0.07 0.07
910-9,400 3,958.84 4,100
12-180 26.12 25.5
0.45--1.8 0.9 1.13
2.1 2.1 2.1
4.9-3,400 54.82 42
0.26 0.26 0.26
1.6 1.6 1.6
1.6 1.6 1.6
0.54 0.54 0.54
0.32 0.32 0.32
0.17-0.46 0.28 0.32
1-2.2 1.48 1.6
0.2-0.69 0.37 0.45
0.52 0.52 0.52
0.67 0.67 0.67
0.52 0.52 0.52
0.91 0.91 0.91
40
Detection
rate
12/12
1/19
1/19
1/19
1/19
2/19
2/19
2/19
1/19
1/19
1/19
1/19
WATER
COMPARISON VALUES
(ppb)
4,000 LTHA
30 child iEMEG
3:QOOJclilia]iEMEG-
0.6 GREG
4 GREG
1000 child RMEG
100 LTHA
100 child cEMEG
600 LTHA
75 LTHA
800 RBG
70 LTHA
700 child iEMEG
6,100 RBG
EPA
MCL
(ppb)
5,000 (SDWR)
5
80
100
80
600
75
70
5
•
FURTHER
PUBLIC
HEALTH
EVALUATION
REQUIRED
No
No
Yes
-Y.es
No
No
No
No
No
No
No
No
No
No
Yes
No
CHEMICAL
SUBSTANCE
Methvlcvclohexane
Methvl-t-but'il ether (MTBE)
Tetrachloroethene (PCE)
PESTICIDES
TABLE 12 (continued)
Substances detected in private wells near the Sigmon Facility
(Summary of chemical concentrations in all private wells from October 2002-May 2004)
:. C ' . .·· .. CHEMICAL, WATER .. ,. ,
' -CONCENTRATIONS COMPARISON VALUES . . (ppb) . "(ppb)
. · . -·' ..
i Detected col1Centrations .. ·
Detection
. Range Mean .. Median rate
0.12 0.12 0.12 1/19 6,300 RBC
0.26-0.39 0.32 0.33 2/19 200 LTHA
0.1-0.21 0.14 0.12 3/19 10 LTHA
81otia::BHE:J(81otia=HexaChlorocYclotiexane)-0.027 0.027 0.027 1/19 0!006lGREG
Endosulfan II 0.011 0.011 0.011 1/19
Endrin aldehvde 0.017 0.017 0.017 1/19
Endrin ketone 0.01 0.01 0.01 1/19
laamma-Chlordane 0.011-0.67 0.086 0.341 2/19
.··
.
He"Pfaclilor'lePoxid-0.01-0.032 0.02 0.02 2119 o:004(GREG~
•
. •.· ;2t:; FURTHER
' ... PUBLIC . (ppp{ .· .· HEALTH
-·,. ' EVALUATION
-REQUIRED
No
No
5 No
-Y.es
Yes
Yes
Yes
Yes
0.2 -Y.es._
•
•
Notes:
• TABLE NOTES
Footnotes for Tables 13 through 19
•
Please note that no substance was selected for further public health evaluation simply because no one is expected to drink water from these monitoring wells. The
tables do indicate where maximum detect levels exceeded their respective _water comparison value (see blue highlighting). This screening criterion, however, could
be not applicable if disclaimer No. 5 was specified (see lavender highlighting). Moreover, the tables also indicate where substances may be selected for further public
health evaluation if detected and no available water comparison value exists for the substance (see yellow highlighting). Likewise, this screening criterion also could
be not applicable if disclaimer No. 5 is specified (see green highlighting).
GREG: Cancer Risk Evaluation Guide
EMEG: Drinking Water Lifetime Health Advisory
L THA: Drinking Water Lifetime Health Advisory
MCL: Maximum Contaminant Level
RBC: Risk-based Concentration (Note, RBC values derived from equations documented in following reference: EPA Region Ill Risk-based Concentration Table.
Philadelphia: United States Environmental Protection Agency. Available at: http://www.epa.gov/reg3hwmdlrisklriskmenu.htm. Background Information -[PDF].)
RMEG: Reference Dose Media Evaluation Guide
ppb: parts per billion
Laboratorv Qualifiers
J -Identification of analyte is acceptable; reported value is an estimate.
N -Presumptive evidence is present; analyte reported as tentative identification.
NJ -Presumptive evidence is present; analyte reported as tentative identification. Reported value is an estimate.
1 Listed value in EPA MCL column is a secondary drinking water regulation (SDWR) as set by EPA. SDWRs are unenforceable federal guidelines regarding taste,
odor, color, and other non-aesthetic effects of drinking water. EPA recommends them to states as reasonable goals, but federal law does not require water supply
systems to comply with them. The states may, however, adopt their own enforceable regulations governing these concerns. To be safe, check your state's drinking
water regulations.
2 Listed value in EPA MCL column is a maximum contaminant level action (MCLA) for drinking water as set by EPA under Superfund. If the relevant action level is
exceeded, a regulatory response is triggered.
3 Listed value in EPA MCL column is a health-based drinking water advisory as set by EPA. The drinking water advisory is based on the assumption that an individual
is placed on a sodium-restricted diet of 500 mg/day.
' Listed value in EPA MCL column is a proposed MCL under the 1994 proposed rule for disinfection by products rule; the current MCL for most trihalomethanes is
100 ppb under the 1996 Drinking Water Advisory Report.
5 Detected concentration(s) are within a range of concentrations for the specific chemical considered to be no apparent public health hazard as cited in a previous
1ublic health consultation released for the Sinmon Sentic Tank Service site (ATSDR, 2002\.
42
• •
TABLE13
Substances found in on-site monitoring well SS-MW-11 C
Calcium
Chromium
CHEMICAL ' ,,.
SUBSTANCE_
1,2-Dichlorobenzene
1,3-Dichlorobenzene
1,4-Dichlorobenzene
1, 1-Dichloroethane
cis-1,2-Dichloroethene
CHEMICAL·
. CONCENTRATIONS
-. (ppl>)
· Detected ·concentrations
October 2002 •· -· May ·14;•2004
100 J
26
260 420
34,000 170,000
0.8 9.8
21 8.5
15 7.6
70,000
100,000
17,000
12
12,000
10,000
19
4.8
1 J
18
2J 0.99 J
0.12 J
18 14 J
1 J
2J 0.35 J
43
WATER
-··· · COMPARISON VALUES
(pp6),
20,000 child iEMEG
0T02(G8EG
700 child RMEG
100 LTHA
100 child iEMEG
600 LTHA
600 LTHA
75 LTHA
800 RBC
70 LTHA
EPA'
•
FURTHER
No
No
100 No
No
100
600 No
No
75 No
No
70 No
TABLE 13 (continued)
Substances found in on-site monitoring well SS-MW-11 C
No
Toluene 66 0.1 J 200 child iEMEG 1,000 No
Total Xylenes 2 J 0.37 J 2,000 child iEMEG 10,000 No
SEMI-VOLATILE ORGANIC COMPOUNDS
1 J 500 child RMEG No
3J 64 5,000 child RMEG No
6J 1.8 J 100 LTHA No
2-Methylnaphthalene 1 J 0.71 J 500 child cEMEG No
PESTICIDES
0!0.06IG:HEG
Endosulfan II
• i •
• •
TABLE14
Detected substances found in on-site monitoring well SS-MW-14
CHEMICAL CHEMICAL WATER EPA
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL
(ppb) (ppb) (ppb)
Detected concentrations
October 2002 May 14, 2004
METALS
Aluminum 19,000 20,000 child iEMEG
Barium 450 700 child RMEG 2,000
Bervllium 2.1 20 child cEMEG 4
Cadmium 1.4 2 child cEMEG 5
Calcium' 62,000
Chromium 7.7 100 LTHA 100
Cobalt 25 100 child iEMEG
Copper' 16 200 child iEMEG 1,300
lron1 9,800 J 11,000 RBC . ·' . ·•·. 300
Lead2• 5 . ~-;~}::T.·:t~;'.~iftf.~~ 16 •··'jj!J/1•••·· ~-(·',~"-.' '.:w--4~-"W-..,: a-15
MaQnesium 35,000
Manganese1 17,000 300 LTHA 50
Mercurv 44 J 2 LTHA 2
Nickel 9.6 100 LTHA
Potassium 7,300
Silver 1.4 50 child RMEG
Sodium' 35,000 20,000
Vanadium 46 30 child iEMEG
Zinc' 46 3,000 child iEMEG 5,000 (SDWR)
VOLATILE ORGANIC COMPOUNDS
Benzene 0.11 J 0.6 GREG 5
Chlorobenzene 0.29 J 100 LTHA 100
1,4-Dichlorobenzene 2.1 J 75 LTHA 75
cis-1,2-Dichloroethene 0.14 J 70 LTHA 70
Methyl-t-butyl ether /MTBE) 1.8 200 LTHA
Total xvlenes 0.56 2,000 child iEMEG 10,000
45
•
FURTHER
PUBLIC
HEALTH
EVALUATION
REQUIRED
No
No
No
No
No
No
No
No
No
~i~-. '~•~N6'.-:t;\;i:.
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
TABLE 14 (continued)
Detected substances found in on-site monitoring well SS-MW-14
CHEMICAL
SUBSTANCE
SEMI-VOLATILE ORGANIC COMPOUNDS
Caprolactam
PESTICIDES
•
CHEMICAL
CONCENTRATIONS
(ppb)
Detected concentrations
October 2002 May 14, 2004
46 •
WATER
COMPARISON VALUES
(ppb)
5,000 child RMEG
0!002{GBEG
0!006lGBEG
0!02{GBEG
0.1 GREG
0TOOBlGBEG
40 LTHA
EPA
MCL
(ppb)
FURTHER
PUBLIC
HEALTH
EVALUATION
REQUIRED
No
•
•
TABLE15
Substances detected in off-site monitoring well SS-MW-1 OB
METALS
luminum
Barium
Cal_ciu
Chrom
Cobalt
Cop
lrori
CHEMICAL
SUBSTANCE
OLATILE ORGANIC COMPOUNDS
Chloroform4
Ethyl benzene
SEMI-VOLATILE ORGANIC COMPOUNDS
Ca rolactam
CHEMICAL
CONCENTRATIONS
(ppb)
Detected concentrations
October 2002 May 14, 2004
1,500
12
6,900
5.5
0.27 J
11
650
1,300
45
7.4
2,300
7,200
2.6
28
47
WATER
COMPARISON VALUES
(ppb)
200 child iEMEG
11,000 RBC
30 child iEMEG
3,000 child iEMEG
100 child cEMEG
700 LTHA
5,000 child RMEG
EPA
MCL
(ppb)
•
FURTHER
PUBLIC
HEALTH
EVALUATION
REQUIRED
No
No
No
No
No
TABLE 16
Substances detected in off-site monitoring well SS-MW-108
CHEMICAL CHEMICAL WATER EPA FURTHER
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL PUBLIC
(ppb) (ppb) (ppb) HEALTH
EVALUATION
Detected concentrations REQUIRED
October 2,002 May 14, 2004
METALS
!Aluminum 700 400 20,000 child iEMEG No
Barium 21 16 700 child RMEG 2,000 No
Calcium5 7,300 3,900 J . No
Chromium 9.1 2.2 100 LTHA 100 No
Cobalt 0.17 J 100 child iEMEG No
Copper' 5.5 0.51 J 200 child iEMEG 1,300 No
1ron\~If': ,:, ,,, (Cf(;'';"'>~~~~,\1§ 720 320 J 11,000 RBC ~·""-~<· ~l~No~~:'"~· """'' : · 300 '-~-~<>i!l: ·' ..
Maanesium5 1,700 890 J No
Manganese'':'·' '> ·.· :,\.';''.'!if'/~/i'imS:.~2%i 230 23 300 LTHA ~',,_>~'}';;~~~50 ~~~NO}_s;:$~::,,
Nickel 9 0.97 J 100 LTHA No
Potassium5 3,600 2,300 J No
Sodium3 8,200 7,300 20,000 No
Vanadium 2.7 1.9 30 child iEMEG No
Zinc 1 4.9 3,000 child iEMEG 5,000 (SDWR) No
~OLATILE ORGANIC COMPOUNDS
Chloroform" I 3J I 100 child cEMEG 80 No
PESTICIDES
beta-BHC (beta-Hexachlorocyclcihexane) I 0.031 NJ I 0.02 GREG I -No
aamma-Chlordane I I 0.0097 NJ I I No
• i •
• •
TABLE17
Substances found in off-site monitoring well SS-MW-138
G.alcju
Gni'orii
Cobalt
Mag
Mao
l)Jicl<
P...o.ta
S_q°diu
Zinc
:;_.:r-iti:~~:=tJ~
. ;--:','.:~f?:·-
VOLATILE ORGANIC COMPOUNDS
Benzene
Chlorobenzene
Chloroethane
Chloroform'
1,2-Dichlorobenzene
1,4-Dichlorobenzene
1, 1-Dichloroethane
cis-1,2-Dichloroethene
Eth !benzene
lsopropylbenzene (Cumene)
Toluene
1,800
260
76,000
160
8.5
67
2,600
7.5
22,000
5,200
130
5,200
22,000
160
7J
5J
1 J
3J
1 J
3J
16
3.7 200 child iEMEG
1,400 J 11,000 RBC
2.6
3,000 child iEMEG
0.49 J 3.6 car. RBC
0.49 J 100 child cEMEG
2.4 600 LTHA
6J 75 LTHA
1.6 800 RBC
5.1 70 LTHA
0.054 J 700 LTHA
0.14 J 1,000 child RMEG
200 child iEMEG
49
•
100
No
80 No
600 No
75 No
No
70 No
700 No
No
1,000 No
TABLE 17 (continued)
Substances found in off-site monitoring well SS-MW-138
CHEMICAL
SUBSTANCE
iinciiioroetljeneJ(tl\BE)
Total xylenes
•
CHEMICAL
CONCENTRATIONS
(ppb)
Detected concentrations
October. 2002 May 14, 2004
34 70
0.046 NJ
WATER
COMPARISON VALUES
(ppb)
0'008.1.CREG
EPA
MCL
(ppb)
FURTHER
PUBLIC
HEALTH
EVALUATION
REQUIRED
•
• • •
TABLE 18
Substances found in on-site monitoring wells near the Sigmon Facility
CHEMICAL CHEMICAL WATER EPA FURTHER
SUBSTANCE CONCENTRATIONS COMPARISON VALUES MCL PUBLIC
(ppb) (ppb) (ppb) HEALTH
EVALUATION
Detected concentrations REQUIRED
Detection
Range Mean Median Rate
METALS
P.luminum 10()-19,000 1,378.4 9,550 2/3 20,000 child iEMEG No
!Arsenic -4 26 10.2 15 2/3 0.02 GREG 10 No
Barium 26()-450 366.28 420 3/3 700 child RMEG 2,000 No
Bervllium 2.1 2.1 2.1 1/3 20 child cEMEG 4 No
Cadmium 1.4 1.4 1.4 1/3 2 child cEMEG 5 No
Calcium5 34,00()-170,000 71,029.68 62,000 3/3 No
Chromium 0.8-9.8 3.92 7.7 3/3 100 LTHA 100 No
Cobalt 8.5-25 16.46 21 3/3 100 child iEMEG No
Conner2 7.6-16 12.22 15 3/3 200 child iEMEG 1,300 No
liori1 6,20()-70,000 16,202.12 9,800 3/3 11,000 RSC 300 No
Lead~·5 . .'''•;)\·~'i:.~·',~~~~ 7.2-16 10.73 11.6 2/3 ~,if~,·t:~~15 lm{1iiffliNo··,._'.$>:·
Maonesium5 35,00()-100,000 54,792.61 47,000 3/3 No
Manqanese1 17,00()-19,000 17,642.11 17,000 3/3 300 LTHA 50 No
Mercury 44 44 44 1/3 2 LTHA 2 No
Nickel 9.6-18 12.75 12 3/3 100 LTHA No
Potassium5 7,300 12,000 10,167.83 12,000 3/3 No
Selenium 0.5 0.5 0.5 1/3 50 child cEMEG 50 No
Silver 1.4 1.4 1.4 1/3 50 child RMEG No
Sodium3 10,00()-160,000 38,258.62 35,000 3/3 20,000 No
hallium 19 19 19 1/3 0.5 LTHA 2 No
vanadium 2.6-46 8.31 4.8 3/3 30 child iEMEG No
1Zinc1 14-46 25.38 30 2/3 3,000 child iEMEG 5,000 (SDWR) No
OLATILE ORGANIC COMPOUNDS
Benzene 0.11 1.4 0.54 1 3/3 0.6 GREG 5 No
Chlorobenzene 0.2~18 3.41 7.6 3/3 100 LTHA 100 No
1,2-Dichlorobenzene 0.99-2 1.41 1.5 2/3 600 LTHA 600 No
1,3-Dichlorobenzene 0.12 0.12 0.12 1/3 600 LTHA No
1,4-Dichlorobenzene 2.1 18 8.09 14 3/3 75 LTHA 75 No
1, 1-Dichloroethane 1 1 1 1/3 800 RSC No
cis-1,2-Dichloroethene 0.14-2 0.46 0.35 3/3 70 LTHA 70 No
thylbenzene 0.097 0.097 0.097 1/3 700 LTHA 700 No
sooronvlbenzene (Cumenel 0.59 0.59 0.59 1/3 1,000 child RMEG No
Methvl-t-butvl ether (MTBE) 1.8 1.8 1.8 1/3 200 LTHA No
I Toluene 0.1--66 2.57 33.05 2/3 200 child iEMEG 1,000 No
otal xvlenes 0."7-, 0.75 0.56 3/3 2,000 child iEMEG 10,000 No
51
TABLE 18 (continued)
Substances found in on-site monitoring wells near the Sigmon Facility
1 1 1/3 500 child RMEG No
3-74 24.22 64 3/3 5,000 child RMEG No
Na hthalene 1.8-6 3.29 3.9 2/3 100 LTHA No
2-Meth !naphthalene 0.71-1 0.84 0.86 213 500 child cEMEG No
PESTICIDES
0.Q3 0.03 0.03 -N-h~Hexacli16roccJOliexane -0.012-0.044 0.023 0.028 -N-~8exaGlil5i'occl61iexane -0.088 0.088 0.088 -N-DDE 0.069 0.069 0.069 No
0.0089 0.0089 0.0089 No
ndrin ketone 0.039 0.039 0.039 1/3 No
9ta"chlo~ 0.061 0.061 0.061 1/3 0'.008IGREG 0.4 -N-etho chlor 0.Q78 0.Q78 0.078 1/3 40 LTHA 40 No
• •
• •
TABLE 19
Substances found in off-site monitoring wells near the Sigmon Facility
Chlorobenzene
Chloroethane
Chloroform4
CHEMICAL
SUBSTANCE
1,2-Dichlorobenzene
1,4-Dichlorobenzene
1, 1-Dichloroethane
cis-1,2-Dichloroethene
Eth benzene
Isa ro !benzene
oluene
riChloro"ettiene
otal xylenes
EMI-VOLATILE ORGANIC COMPOUNDS
aprolactam
PESTICIDES
'et~B88I Deta';l.iexacliloroc clohexarie -
Range
58 --1,800
5 --260
3,900 -86,000
2.2-160
0.17 -9.4
3.7--67
260-2,600
2.1-7.5
890-24,000
15-9,400
0.97-130
1,500-5,200
6,200-22,000
1.3-2.7
4.9-60
0.87-0.87
7-7.3
0.49-0.49
0.077-5
1-2.4
3--j';
1-1.6
3-5.1
0.022--0.054
0.14-0.14
16-16
0.24-0.24
1.1-1.1
34-70
0.031
0.046
0.0097
0.018
:-Cl;IEMl~AL
CONCENTRATIONS
-c<P-Pbl : .
· DeteCied Conce•ritrations
Mean·
477.4
31.87
13,722.25
10.24
1.38
9.29
722.07
3.45
3,233.22
236.4
11.41
2,862.04
10,273.51
2.04
21.13
0.87
7.15
0.49
0.87
1.55
4.24
1.26
3.91
0.034
0.14
16
0.24
1.1
45.28
0.031
0.046
0.0097
0.018
Median
550
18.5
7,100
7.85
4.39
6.95
685
2.6
1,500
137.5
8.2
2,950
7,750
2.25
16
0.87
7.15
0.49
1.75
1.7
4.5
1.3
4.05
0.038
0.14
16
0.24
1.1
39
0.031
0.046
0.0097
0.018
53
Detection
Rate
6/6
6/6
6/6
6/6
6/6
4/6
5/6
1/6
216
1/6
4/6
2/6
2/6
2/6
3/6
WATER
COMPARISON VALUES
(ppb)
30 child iEMEG
3,000 child iEMEG
0'.6IGREG
100 LTHA
3.6 car. RSC
100 child cEMEG
600 LTHA
75 LTHA
800 RBC
70 LTHA
700 LTHA
1,000 child RMEG
200 child iEMEG
0'.02blcar•t<eG
2,000 child iEMEG
5,000 child RMEG
0'02IGREG
EPA
MCL·
(ppbf
•
.F~RTHER
PUBLIC
HEALTH
· .. EVALUATION
~EQUIREO
100 No
No
80 No
600 No
75 No
No
70 No
700 No
No
10,000 No
No
No
No
TABLE 20
Matched VOC detections in groundwater wells near the Sigmon Facility
DETECTED voes . SIMILAR DETECTED voes
IN ON-SITE IN OTHER
MONITORING WELLS GROUNDWATER WELLS
Monitoring Well Other Off-Site Private Well Other Private
SS-MW-13B Monitoring Wells SS-PW-03 Wells
Benzene Benzene Benzene
Chlorobenzene Chlorobenzene Chlorobenzene
1,2-Dichlorobenzene 1,2-Dichlorobenzene 1,2-Dichlorobenzene
1,3-Dichlorobenzene
1,4-Dichlorobenzene 1,4-Dichlorobenzene 1,4-Dichlorobenzene
1, 1-Dichloroethane 1, 1-Dichloroethane 1, 1-Dichloroethane
cis -1,2-Dichloroethene cis-1,2-Dichloroethene cis-1,2-Dichloroethene
Eth1 I benzene Ethylbenzene Ethyl benzene
lsooropvlbenzene lsooropylbenzene
Methyl-T-bufy I ether Methyl-T-butyl ether
Toluene Toluene
Total xvlenes Total xvlenes
Percent matched 83.3% 8.3% 50.0% 8.3%
54 • • •
• APPENDIX C
•
•
•
•
•
SITE LAYOUT MAP
SIGMON 's SEPTIC TANK SITE
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
FIGURE
1
0 • el ~ f \ . . I f ..J II ;:j .. w tjl SS-PV-07.../ II I\\ \ II 11 _, Cll ;5 0 a.. ~ ~ a.< ~ 0 ::; ~ zz < 0 51 1111 I \. tjl ss-Pv-ro 1 \ l!l /tjlSS-Pl/-05 ci~ I 15 ("\ \\ i; 'wJLLIAHS PDND ;;= '3 CJ z a:: 12 181 \ I /181 11 z 0 ••>N·•\\ ::; ,.. > II, C: • V-t1C 2 L#IMBt:RlH FOND ~SS-P\J-06 ~ a " • I I~ "'~--J r X a !il a < YC~PD !, <J r ig F ~ "'"' 0 lg LMiOCN AR~,i u:::, \ Q Fo e, <J "'~ • J ft\ ~ "'~ . w zfj ~ ~ I I> C, iii ~ DUF"r"l.o ~ DAVIDSCH POND (J SS-Ml/-l2E " ~ LS ~o\b "' !;l SS-PW-O'J ! 21 / ~ II 11 I 12 I I ii tjl SS-Pll-m ..../ 'V 11 II I ~z-"-I ' SCALE L. E:O E: ND I 11" = 300' -$-SHAL..L..OW MONITORINC: WE:L.L L.OCATION [ Flg~r• ] -$ DEEP MONITORING WELL LOCATION 1) POT.A.BL!=: WELL SAM PL!=: LOCATION A -B~-I C -0~ I r F G H
•
•
•
SS-PW-03 ()
SS-MW-13B ~
SS-M 12B~
D_"'''°" PoQ
SS-PW-10 ()
SS-PW-04 ft
SS-MW-14
~ SS-MW-01
J SS-MW-11C
'\ Q
SS-PW-09 ()
SS-MW-10B ~
SS-PW-05 ()
ID
Mus.tung Lane
Low Lane
SS-PW-06
r
C
0 r.
Legend
-$-Monitoring Well
--Potable Well
SCALE
1 in. equals 400 ft .
Figure
3
•
2000 LE~CND w-JSDD o MM 2000
1·-2000·
(9D0,9~) WIITCR E LCV.UIOM
(FEEr AMSL. NVGD 29)
-850~ -GROUNOWAIER ELCV (rE£T AWSL, NVCD :~i°M CONIOURS
GROUNDWATER POTENTIOM AS MEASURED ON ~TRIC SURFACE MAP 5-21-2004
GROUNOWAIER FUl W DIRECTION
FIGURE
4
•
Health Consultation
Review of Surface Water Data
SIGMON'S SEPTIC TANK SERVICE FACILITY
(a/k/a SIGMON;S SEPTIC TANK SERVICE)
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
EPA FACILITY ID: NCD062555792
JULY 9, 2002
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Atlanta, Georgia 30333
Health Consultation: A Note of Explanation
An ATSDR health consultation is a verbal or written response from ATSDR to a specific request for
information about health risks related to a specific site, a chemical release, or the presence of
hazardous material. In order to prevent or mitigate exposures, a consultation may lead to specific
actions, such as restricting use of or replacing water supplies; intensifying environmental sampling;
restricting site access; or removing the contaminated material.
In addition, consultations may recommend additional public health actions, such as conducting
health surveillance activities to evaluate exposure or trends in adverse health outcomes; conducting
biological indicators of exposure studies to assess exposure; and providing health education for
health care providers and community members. This concludes the health consultation process for
this site, unless additional information is obtained by ATSDR which, in the Agency's opinion,
indicates a need to revise or append the conclusions previously issued.
You May Contact ATSDR TOLL FREE at
1-888-42ATSDR
or
Visit our Home Page at: http://www.atsdrl.atsdr.cdc.gov
•
•
•
•
HEALTH CONSULTATION
Review of Surface Water Data
SIGMON'S SEPTIC TANK SERVICE FACILITY
(a/k/a SIGMON'S SEPTIC TANK SERVICE)
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
EPA FACILITY ID: NCD062555792
Prepared by:
Exposure Investigation and Consultation Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
• Background and Statement of Issues
•
On June 27, 2001, the Agency for Toxic Substances and Disease Registry (ATSDR) received a
request from the Environmental Protection Agency (EPA). EPA requested ATSDR to determine
if the Sigmon's Septic Tank Service Facility, a septage removal business in operation since 1970,
is affecting the area's nearby streams and other surface water bodies and, therefore, might be a
public health concern to the community. [Benjamin Moore, Office of Regional Operations,
ATSDR, Region 4, to Susan Moore, Division of Health Assessment and Consultation, ATSDR.
Personal communication, 2001].
The Sigmon's Septic Tank Service Facility (CERCLIS No. NCD062555792) is located at 1268
Eufola Road, approximately 5 miles southwest of Statesville, lredell County, North Carolina [NC
DENR 1998, NC DENR 2000]. The facility is currently active under the name Sigmon's
Environmental Services. Its primary business is septage removal. Septic wastes are temporarily
stored in four cylindrical tanks on the property, and the sludges are periodically removed and
transported to a wastewater treatment plant for disposal. The business employs five workers. The
work area includes the area surrounding the storage tanks (see Figure 1, Appendix C). The owner
of the business lives on the property. Public access is not restricted on the south side of the
property (i.e., former lagoon area/waste pile), and unauthorized persons have been reported to
enter the property with recreational vehicles through breaks in the fence.
The site has been listed under several names that include Sigmon's Septic Tank Service, AAA
Enterprises, and Sigmon Environmental Services (current name). Services provided by the
business owners have included the pumping and removal of septic tank wastes and heavy sludges
for various customers (e.g., residential, commercial, and industrial), installation and repair of
septic tanks, and a variety of other waste removal services. A chronological list summarizing the
events that have occurred at the Sigmon's Septic Tank Service Facility follows.
Historical Events at Sigmon's Septic Tank Service Facility
Time Period Event Summary
1970-1978 Wastewaters from the Sigmon's Septic Tank Service Facility originally are
discharged to the City of Statesville wastewater treatment plant.
1973-1974 Sludges from the Sigmon's Septic Tank Service Facility are land applied to
area farmlands.
1978-1992 Sigmon's Septic Tank Service begins disposing of septic wastes into IO on-
site lagoons. During this period, the North Carolina Department of Natural
Resources and Community Development Division of Environmental
Management (DEM) collected groundwater samples from on-site monitoring
wells and from nearby private water wells. Analysis revealed elevated levels
of metallic and organic chemicals .
1
Historical Events at Sigmon's Septic Tank Service Facility
Time Period
1992
1992-1995
1995
Dec. 1995
Dec. 1996
Jan. 1997
Apr. 1997
Aug. 1997
Dec. 1999
Event Summary
DEM and the North Carolina Hazardous Waste Section conducts a site investigation and
sampling to determine if wastes in the on-site lagoons are hazardolls. Because the chemical
constituents of the on-site lagoons did not meet the definition of a hazardous waste, the North
. Carolina Hazardous Waste Section decides the site does not fall under its jurisdiction and refers
the site to the North Carolina Solid Waste Section for further evaluation.
On-site lagoons are non-operational.
DEM requires the on-site lagoons to be closed. Lagoon sludges are excavated and piled in
lagoon area.
DEM refers site to the North Carolina Superfund Section regarding removal options for the
piled sludge in lagoon area.
North Carolina Superfund Section adds the site to the CERCLIS database as one for further
investigation.
North Carolina Superfund Section refers the site to the EPA Emergency Response and Removal
Branch for removal evaluation.
EPA concludes that the site does not meet their criteria for removal eligibility.
North Carolina Superfund Section initiates its investigation of the Sigmon site by conducting
sampling in a combined Preliminary Assessment/Site Inspection (PA/SI). Samples are collected
from the waste pile, open pits, former lagoon area, storage tank area, surface water pathways,
on-site and off-site mm~itoring wells, and nearby private wells.
North Carolina Superfund Section conducts additional sampling at the site through an Expanded
Site Inspection (ES!). Again, samples were collected from the waste pile, former lagoon area,
surface water pathways, an on-site monitoring well, and nearby private wells.
The surface water pathway is of concern because tributaries (i.e., streams and creeks) located
near the site flow into two major recreational fishing waters, the Catawba River and Lake
Norman. Furthermore, analytical results of surface water and sediment samples collected by the
North Carolina Superfund Section during poth the August 1997 PA/SI and December 1999 ESI
sampling events do indicate chemical releases into the surface water bodies located near the site
[NCDENR 1998, NCDENR 2000]. These analytical results may imply that there is potential for
contamination of the biota (i.e., organisms used as food such as fish) to occur within the
recreational fished waters.
Large amounts of waste still remain on the site, which the North Carolina Superfund Section
believes is the source of the contamination. They have recommended to EPA that a non-critical
removal be conducted to address the remaining source areas at the site. Removing these source
areas would result in additional mitigation of potential chemical releases to soil, groundwater,
and surface water pathways [NCDENR 2000].
2
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•
•
•
•
Discussion
ATSDR reviewed analytical results of soil, sediment, and surface water samples. Samples were
analyzed for metals, volatile organic compounds (VOCs), and semi-volatile organic compounds
(SVOCs) to determine if chemicals were being released to nearby surface water features [NC
DENR 1998, NC DENR 2000].
Environmental Sampling and Chemical Analyses
During the August 1997 PA/SI and the December 1999 ESI, sampling of surface water near the
Sigmon's Septic Tank Service Facility included taking samples from drainage ditches,
intermittent streams, ponds, and an unnamed tributary to the Catawba River. Two soil, seven
sediment, and eight surface water samples were collected in 1997. Two soil, six sediment, and
six surface water samples were collected in 1999. Tables 1 and 2, in Appendix B, provide a brief
description of the sample locations and the sample characteristics. Figure 2 shows an areal
perspective of the surface water sampling locations for the August 1997 PA/SI and Figure 3
shows an areal perspective of the surface water sampling locations for the December 1999 ESL
Chemical analyses of collected soil and sediment samples are summarized in Table 3. Of the 31
chemicals detected in soil and sediment samples, maximum detected concentrations for four
chemicals (i.e., arsenic, benzo(a)pyrene, dibenzo(a,h)anthracene, and benzo(b)fluoranthene)
exceeded soil comparison values (CVs) and were selected for further public health evaluation .
Likewise, chemical analyses of surface water samples are summarized in Table 4. Of the 13
chemicals detected in surface water samples, maximum detected concentrations for four
chemicals (i.e., arsenic, iron, lead, and manganese) exceeded drinking water CVs and were
selected for further public health evaluation.
Exposure Pathways and Public Health Implications
This section summarizes the exposure pathways ATSDR considered in conducting its evaluation
of the public health implications posed by chemicals migrating into nearby surface water
features. An exposure pathway is defined as the process by which an individual is exposed to
chemical substances and comprises five elements; (I) source of contamination, (2) environmental
media and transport mechanisms, (3) point of exposure, (4) route of exposure, and (5) receptor
population. There is no impact to public health from chemical substances via an exposure
pathway without exposure.
Soil/Sediment
Residents may be exposed to contaminated soil and sediment either through direct dermal
contact, ingestion, and/or inhalation. Possible human exposure points to soil and sediment could
include recreational or play areas. However, it is believed that recreational activities near the
surface water features are nonexistent or limited .
3
To prevent confusion between soil and sediment, ATSDR defines sediment to be any solid •
material, other than waste material or waste sludge, that lies below a water surface. Two soil
samples that are cited in the health consultation were collected from ditches located south of the
site. These ditches allow surface water runoff to drain from the site. The samples were classified
as soil samples because probably no standing water was present in the ditches at the time the
samples were collected. If standing water was present, the samples would have been classified as
sediment samples. Because of this discrepancy, the term "soil/sediment" is used in this health
consultation to refer to solid material that has been naturally deposited in a waterway, water
body, channel, ditch, wetland, or swell and usually lies on a land feature where solids are
deposited (e.g., a river bank, a beach, a spillway, etc.). Also, the public health implications as
cited in this health consultation is directed toward potential exposures that are likely to occur
outside the site boundaries and not within the site boundaries.
Analytical results indicated that of the 31 chemicals detected in the soil and sediment samples,
none exceeded any non-cancer soil CVs. However, the detected levels of four chemicals (i.e.,
arsenic, benzo(a)pyrene, dibenzo(a,h)anthracene, and benzo(b )fluoranthene) exceeded either the
Cancer Risk Evaluation Guideline (CREG) or cancer-based Risk-Based Concentration (RBC).
As stated, recreational activities near the surface water features are believed to be nonexistent,
therefore, exposure would be infrequent. Furthermore, all four chemicals were detected
infrequently (i.e., analyzed samples showed a detection rate ranging from 13% to 35%). Thus,
lifelong chronic exposure to these soil or sediment contaminants will be substantially lower, and
the cancer risks of these four chemicals from low level chemical exposures in the soil or •
sediment will not pose a cancer hazard to exposed individuals.
Further inspection of the sampling data for the three polycyclic aromatic hydrocarbons (PAHs),
benzo(a)pyrene, dibenzo(a,h)anthracene, and benzo(b)fluoranthene, showed that the chemicals
were detected in two samples (i.e., one soil and one sediment) collected from the property east to
southeast of the site. The property owner owns and operates a roofing business on the eastside
property and the presence of the PAHs could be chemical residuals from day to day operations of
the owner's business, possibly having no direct affiliation with the Sigmon' s Septic Tank Service
Facility.
The level of chemical exposures for the four chemicals (i.e., arsenic, benzo(a)pyrene,
dibenzo(a,h)anthracene, and benzo(b)fluoranthene) selected for further public health evaluation
via the soil and sediment pathway do not pose a public health hazard, because infrequent average
exposures are well below exposure levels known to cause adverse health effects.
Surface Water
The surface water features near the site are not used as a primary water source for potable (i.e.,
drinking) or non-potable (i.e., bathing, showering, laundry, dishwashing, etc.)use. Even though
samples from nearby surface water features surrounding the site did contain chemical pollutants,
these surface water features are located within watersheds where no drinking water intakes exist.
4 •
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•
Furthermore, no drinking water intakes exist within 15 miles downstream of these watersheds
along the Catawba River: One intake does exist on another tributary, Cornelius Creek, that flows
to the Catawba River and is within this 15 mile span of the river (i.e., downstream of the above
watersheds). The intake is located about 9.6 miles southeast of the site and within a different set
of watersheds that characterize surface water runoff differently than those for the site. Thus, it is
expected that this one downstream water intake would not be impacted by chemical pollutants
detected in the surface water features surrounding the Sigmon' s Septic Tank Service Facility.
Considering the above, chronic or long-term exposures to chemicals in the surface water features
surrounding the site probably would not occur.
Acute/intermittent or short-term exposures to chemicals in the surface water can occur via
inadvertent ingestion, inhalation (i.e., VOCs), and dermal contact; however, the level of exposure
is dependent upon the recreational activities (e.g., swimming, wading, water skiing, etc.) that
take place at the surface water source. Such exposures (i.e., acute/intermittent exposures) to
chemicals via surface water features may be very limited near the site because it is unlikely any
recreational activities occur near these surface water features other than fishing in a major fished
water tributary that flows into Catawba River (see Figures 2 and 3) below the fourth probable
entry point (PPE4). Even if other recreational activities do occur sporadically (i.e.,
wading/walking alongside stream, creek, or pond banks), the low intermittent exposures that
might result from such activities would not pose a public health concern. This is based on the fact
that the detected levels for the analyzed chemicals were below CVs applicable to acute and
intermittent exposures. Except for two chemicals, arsenic and manganese, the detected chemical
levels were also below CVs applicable to chronic exposures for non-carcinogenic effects. Similar
to the soil and sediment pathway, lifelong chronic exposure to detectable levels of these
substances in surface water may not be an option at this site. Therefore, the level of chemical
exposures for the four chemicals (i.e., arsenic, iron, lead, and manganese) selected for further
public health evaluation via the surface water pathway also do not pose a public health hazard
because of the infrequent exposures being, on average, well below exposures known to cause
adverse health effects.
Fish
Chronic or long-term exposures to chemicals can occur by eating fish obtained from a
contaminated surface water source.
Several factors contribute to the uncertainty of ATSDR's assessment of the fish exposure
pathway. A TSDR had no data confirming that edible fish existed in the contaminated surface
water features surrounding the site. All streams displayed in Figures 2 and 3, except for the
stream or tributary below PPE4, were intermittent in nature (i.e., periodically dry up some time
during the year). The mean annual flow-rate of the stream below PPE4 is 0.1 cubic feet per
second. These facts make it unlikely that there is enough available water to support a fish habitat.
The stream below PPE4 flows into the Catawba River, a major fished water with a mean annual
flow rate of approximately 2,000 cubic feet per second. Thus, chemical constituents detected in
5
•
surface water samples collected from surface water features near the site would be greatly diluted •
when flowing from these surface water features into the Catawba River. Such flow would also
greatly reduce the chemical levels estimated in the edible tissue of sport fish in. the Catawba
River. One last factor contributing to the uncertainty of assessing the fish exposure pathway is
related to the bio-accumulation of chemicals in sport fish. ATSDR assumed a 100%. bio-
accumulation only in the edible portions (e.g., tissue) of the fish and little to no bio-accumulation
in other portions (e.g., bones, organs). However, this assumption must be considered in proper
perspective. Most of the chemicals detected in the surface water features near the site were
metals, which tend to bio-accumulate more in the bones instead of the tissue.
The public health implications of chronic or long-term exposures to chemicals via edible sport
fish were assessed because it is prudent health practice for ATSDR to use assumptions that
would err on the side of being protective of public health (i.e., assumed surface water features
supported a population of edible fish that migrated into major fished waters).
Bio-Accumulation Estimates for Edible Fish
Fish in surface water features can be exposed to chemical constituents through the water column
and sediments. These chemical constituents in the water column consist of dissolved chemicals
and chemicals associated with suspended solids. Bio-availability is more significant for metals
because most metals exist in both dissolved and suspended fractions of the water column.
The following equation was used to estimate the tissue concentrations in edible fish for
chemicals found in the surface water features located near the Sigmon's Septic Tank Service
Facility:
where,
Clish
cw
BAF
units:
µg/kg
µg/L
Ukg
=
=
=
=
=
=
fish concentration (µg/kg)
water concentration (µg/L)
bio-accumulation factor (Ukg)
microgram per kilogram
microgram per liter, which is equivalent to parts per billion (i.e.,
ppb)
liter per kilogram
In estimating chemical concentrations in edible fish tissue, the BAFs in Table 5.were used along
with the assumption that the measured water concentrations were total water concentrations
[RAIS 2001]. By definition, bio-concentration factors (BCFs) are normally used when deriving
chemical concentrations in fish from water concentrations. BCFs are also used in deriving edible
6
•
•
• fish tissue concentrations because they are easily obtained (i.e., regression models of laboratory
experiments). In keeping with the listed reference, ATSDR used BAFs (see Table 5) instead of
BCFs in its estimates of edible fish tissue concentrations [RAIS 2001).
•
Bio-concentration is defined as the net uptake of a chemical from an organism's surrounding
medium through direct contact (e.g., chemical uptake via the water column by a fish through its
gills); however, BCFs exclude any chemical uptake through the ingestion of contaminated food.
Bio-accumulation, on the other hand, is defined as the net uptake of a chemical from the
environment through all pathways (i.e., includes both direct contact and ingestion of
contaminated food). Therefore, it is important to recognize the distinction between a bio-
concentration factor (BCF) and a bio-accumulation factor (BAF) in both a practical and technical
sense. Since the route of exposure for BCFs is generally assumed to be direct contact, BCF
values are typically generated from controlled laboratory studies where edible fish are only
exposed to the chemical through water. Likewise, using a BCF will tend to underestimate the
concentration in edible fish tissue. The complexity of including the food chain in its derivation,
BAFs are typically generated from field studies or estimated from complex computational
models (e.g., pharmo-kinetic model). Because the BAF considers all environmental pathways for
the net uptake of a chemical, a BAF will tend to overestimate the concentration in edible fish
tissue.
Estimated edible fish tissue concentrations (Table 5) were used to estimate an average daily
potential dose for exposure from eating contaminated fish tissue. The following limiting
assumptions were used in deriving these potential dose estimates: (1) average adult weighs 70 kg
(i.e., 150 lbs) and average child weighs 10 kg (i.e., 20 lbs), (2) chemicals in the contaminated fish
tissue are 100% bio-available, and (3) average adult eats 14.5 grams of sport fish (i.e., only fish
caught via recreational activities) and average child eats 5.63 grams of sport fish every day of the
year [West et. al. 1989, West et. al. 1993). The estimated potential doses are summarized in
Table 6 and compared to ATSDR and EPA oral health guidelines (i.e., Minimal Risk Levels and
Reference Doses, respectively). Of the 13 chemicals evaluated, maximum estimated doses for
three chemicals (i.e., arsenic, iron, and manganese) exceeded oral health guidelines and were
selected for further public health evaluation.
Since the edible fish tissue concentrations presented here are derived estimates using an
empirical equation and very conservative assumptions, public health implications can only be
inferred without actual fish tissue samples.
Based on ATSDR's estimates of chemical concentrations in the edible tissue of sport fish, three
chemicals (i.e., arsenic, iron, and manganese) were selected for further public health evaluation
because their estimated doses either exceeded ATSDR's health guidelines (i.e., MRLs) or EPA
health guidelines (i.e., RfDs).
There is abundant evidence that arsenic bio-accumulates in biota because low levels of arsenic
arc commonly found in seafood, meats, and grains. Fish, shellfish, and other marine foods
7
contain the highest arsenic concentrations and are the largest dietary source of arsenic
[Gunderson 1995, Jelinek and Comeliussen 1977, Tao and Bolger 1999). Marine organisms
especially appear to have the ability to accumulate arsenic naturally present in seawater and food,
rather than due to local pollution [Eisler 1994). Typical arsenic levels in fish and seafood are
usually about 4-5 ppm [Bennett 1986, Schroeder and Balassa 1966], but may be as high as 170
ppm [NAS 1977). The arsenic levels estimated in the edible tissue of sport fish at the site ranged
from 1-5 ppm, which is in line with typical arsenic levels found in fish and seafood. Even though
arsenic is commonly found in fish and seafood, most of the arsenic present is relatively nontoxic
organoarsenical compounds; usually arsenobetaine which does not appear to be harmful to
humans and is excreted, rapidly and unchanged, in urine [Cullen 1998, Dabeka et al. 1993, Eisler
1994, Gebel et al. 1998). Some arsenic found in fish and seafood is of the inorganic form (i.e.,
more toxic), but the estimated amount is low and accounts for 1.5% in fish and 20% in shellfish
[MacIntosh et al. 1997). Therefore, the arsenic levels estimated to bio-accumulate in the edible
tissue of sport fish at the site does not pose a public health hazard.
Iron is one of the most abundant elements present naturally in the Earth's crust, and there is very
little risk of toxicity from iron in natural foods and/or water. This is because (1) iron is an
essential element in the human diet and (2) the body has a number of mechanisms specifically
designed to maintain a relatively constant blood level in the face of wide variations in dietary
intake [Goyer, 1996, pp 715-16]. The estimated daily intake rates of iron for an adult and a child
consuming edible sport fish are listed below. These estimated intake rates are compared to iron's
tolerable upper intake levels (ULs), as established by the Food and Nutrition Board of the
Institute of Medicine, for a broad range of children and adults of various age groups [Institute of
Medicine 2001). The UL is the highest level of daily nutrient intake that is likely to pose no risk
of adverse health effects for almost all individuals in the general population. Because the
estimated intake rate ranges (conservative overestimations of exposure) do not overlap with the
UL ranges, it is not likely that eating sport fish with the estimated iron level will pose a risk of
adverse health effects for the residents living near the Sigmon's Septic Tank Service Facility.
UL Comparison
Element Estimated Daily Intake Rate UL Range UL Range
(mg/day) (mg/day (mg/day
Adult' Child' Adult Child
Iron 2.2-20 0.83 -7.9 40-45 40
Manganese 0.055-7.6 0.021 -2.9 9 -11 2-9
1 Assuming the average adult weighs 70 kg (i.e., 150 lbs.) and eats 14.5 grams of sport
fish per day.
2 Assuming the average child weighs IO kg (i.e., 20 lbs.) and eats 5.63 grams of sport fish
per day.
8
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•
Manganese (Mn) is another essential element in the human diet with very limited toxic potential
via the oral route. The estimated daily intake rates for an adult and a child consuming edible
sport fish are listed above. The estimated daily intake range of Mn for an adult do not overlap the
UL range for adults (i.e., 9-11 mg/day). The estimated child intake rate range does overlap the
UL range for a child; however, further inspection of the data shows that the estimated daily
intake range only overlaps the UL range for children less than 4 years of age (i.e., 2-3 mg/day)
but not for children 4 years and older (i.e., 3-9 mg/day). This slight overlap of the UL, as seen in
the younger children, is of little consequence when considering the bio-availability of different
forms of Mn consumed under different exposure conditions. Inter-individual differences, various
dietary factors, and the form of Mn can have a significant bearing on the dose absorbed from the
gastrointestinal tract. Humans were administered a dose of radio-labeled Mn in an infant formula.
The mean absorption was 5.9% plus or minus 4.8%, with a range of0.8%-16% [Davidsson et al.
1989]. Furthermore, it is unlikely a 2-3 year old child would eat fish from these streams
regularly. Also, many constituents of a vegetarian diet (e.g., tannins, oxalates, phytates, fiber)
have been found to inhibit manganese absorption presumably by forming insoluble complexes in
the gut. In addition, high dietary levels of calcium or phosphorus have been reported to decrease
manganese absorption. It is also recognized that manganese uptake and elimination are under
homeostatic control, generally allowing for a wide range of dietary intakes considered to be safe
[Kies 1987]. Therefore, the Mn levels estimated in the edible tissue of the sport fish existing near
the site are expected to have little to no public health impact.
Lead, another metal, was also considered for further public health evaluation because there are no
available health guidelines for oral ingestion (see Table 6). The U.S. Fish and Wildlife Service
reported on the concentration of metals in a total of 315 composite samples of whole fish
sampled from 109 stations nationwide from early 1985 to late 1994. For lead, the geometric
mean, 85th percentile, and maximum concentrations (µg/kg wet weight) were 110, 220, and
4,880. Using the BAF of 300 IJkg as cited in the health consultation [RAIS 2001],-yielded an
estimated range of fish tissue concentrations of 480to 4,800 µg/kg. Likewise, using EPA's BCF
of 49 IJkg, yielded an estimated range of fish tissue concentrations of 78 to 780 µg/kg. Noting
that lead bio-accumulates more into the bones than in the edible fish tissue and that the estimated
fish tissue concentrations maybe within the normal range of measured concentrations, the lead
levels estimated in the edible tissue of the sport fish existing near the site are also expected to
have little to no public health impact.
Conclusions
The chemicals identified in the nearby surface water features surrounding the Sigmon' s Septic
Tank Service Facility pose no apparent public health hazard to area residents. This conclusion is
based on the following findings:
• exposure frequency is probably intermittent to nonexistent for recreational activities near
the surface water features at the Sigmon's Septic Tank Service Facility,
9
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•
•
no potable use of surface water near the Sigmon's Septic Tank Service Facility is
identified,
levels of chemical exposures in the "soil/sediment" and surface water near the Sigmon's
Septic Tank Service Facility are well below exposure levels known to cause adverse
health effects, and
chemical levels estimated in the edible tissue of sport fish assumed to exist in surface
water features near the Sigmon's Septic Tank Service Facility do not pose a potential
impact to public health.
Recommendations:
No actions due to public health concerns are recommended.
•
•
•
•
•
Prepared by
Environmental Health Scientist
Reviewed by
Branch Chief
Section Chief,
Health Consultation Section
Regional Representative,
Region IV
David S. Sutton, PhD
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
John Abraham, PhD, MPH
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Susan Moore, MS
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Benjamin Moore
Office of Regional Operations
Agency for Toxic Substances and Disease Registry
11
•
References
Agency for Toxic Substances and Disease Registry. 1992. Public health
assessment guidance manual. U.S. Department of Health and Human Services,
Atlanta.
Bennett BG. 1986. Exposure assessment for metals involved in carcinogenesis.
!ARC Sci Publ 71(8):115-27.
Cullen WR. 1998. Arsenic in the environment. In: Bunnett JF, Mikolajczyk M,
editors. Arsenic and old mustard: chemical problems in the destruction of old
arsenical and 'mustard' munitions. Netherlands: Kluwer Academic Publishers.
p.123-34.
Dabeka RW, McKenzie AD, Lacroix GM, et al. 1993. Survey of arsenic in total
diet food composites and estimation of the dietary intake of arsenic by canadian
adults and children. J AOAC Int 76(1):14--25.
Davidsson L, Cederblad A, Lonnerdal B, and Sandstrom B. 1989. Manganese
retention in man: a method for estimating manganese absorption in man. Am J
Clin Nutr 49: 170-9 .
Eisler R. 1994. A review of arsenic hazards to plants and animals with emphasis
on fishery and wildlife. In: Nriagu JO, editor. Arsenic in the environment: part II:
human health and ecosystem effects. New York: John Wiley & Sons, Inc,
p.185-259.
Environmental Protection Agency. Guidelines for Carcinogenic Risk Assessment.
Fed. Reg., 51: 33997-33998, September 24, 1986.
Gebel TW, Suchenwirth RHR, Bolten C, et al. 1998. Human biomonitoring of
arsenic and antimony in case of an elevated geogenic exposure. Environ Health
Perspect 106(1):33-9.
Goyer, RA. l 996. Toxic effects of metals. Chap. 23 In: Klaassen CD, Casarett
and Doull's TOXICOLOGY: The basic science of poisons. 5th ed. New York:
McGraw-Hill. pp 715-716.
Gunderson EL. 1995. Dietary intake of pesticides, selected elements, and other
chemicals: FDA total diet study, June 1984-April 1986. J AOAC Int
78( 4 ):910-21.
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Institute of Medicine, Food and Nutrition Board. 2001. Dietary reference intakes.
Washington, DC: National Academy Press.
Jelinek CF, Comeliussen PE. 1977. Levels of arsenic in the United States food
supply. Environ Health Perspect 19:83-7.
Kies, C. 1987. Manganese bioavailability overview. In: Nutritional bioavailability
of manganese, C. Kies, Ed. ACS Symposium Series 354, American Chemical
Society, Washington, DC.
MacIntosh DL, Williams PL, Hunter DJ, et al. 1997. Evaluation of a food
frequency questionnaire: food composition approach for estimating dietary intake
of inorganic arsenic and methylmercury. Cancer Epidemiol Biomarkers Prev
6(12):1043-50.
National Academy of Sciences. 1977. Arsenic. Drinking water and health.
Washington, DC. p. 316-44, 428-30.
North Carolina Department of Environment and Natural Resources. 1998.
Combined preliminary assessment/site inspection report. Sigmon's Septic Tank
Service. Ref. No. 06611.
North Carolina Department of Environment and Natural Resources. 2000
Expanded site inspection report. Sigmon's Septic Tank Service Ref. No. 040661 l.
Risk Assessment Information System. U.S. Department of Energy (DOE), Office
of Environmental Management, Oak Ridge Operations (ORO) Office. October 23,
2001. http://risk.lsd.oml.gov/rap_hp.shtml. •
Schroeder HA, Balassa JJ. 1966. Abnormal trace metals in man: arsenic. J Chron
Dis 19:85-106.
Tao SS-H, Bolger PM. 1999. Dietary intakes of arsenic in the United States. Food
Addit Contam16:465-72.
West PC, Fly MJ, Marans R, Larkin F. 1989. Michigan sport anglers fish
consumption survey. Michigan Department of Management and Budget. Contract
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West PC, Fly JM, Marans R, Larkin F, Rosenblatt D. 1993. 1991-1992 michigan
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Ann Arbor. Technical Report No. 6.
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Selected Bibliography
Agency for Toxic Substances and Disease Registry. August 1995. Toxicological
Profile for Polycyclic Aromatic Hydrocarbons (Update). US DHHS, Public Health
Service; Atlanta, GA.
Agency for Toxic Substances and Disease Registry. July 1999. Toxicological
Profile for-Lead (Update). US DHHS, Public Health Service; Atlanta, GA.
Agency for Toxic Substances and Disease Registry. September 2000.
Toxicological Profile for Arsenic (Update). US DHHS, Public Health Service;
Atlanta, GA.
Agency for Toxic Substances and Disease Registry. September 2000.
Toxicological Profile for Manganese (Update). US DHHS, Public Health Service;
Atlanta, GA.
Agency for Toxic Substances and Disease Registry. "Soil Comparison Value
Table." US DHHS, Public Health Service; Atlanta, GA. March 30, 2002.
Agency for Toxic Substances and Disease Registry. "Drinking Water Comparison
Value Table." US DHHS, Public Health Service; Atlanta, GA. March 30, 2002.
Environmental Protection Agency. 1991. National Primary Drinking Water
Regulations. Code of Federal Regulations.
Environmental Protection Agency. October 1996. Drinking water regulations and
health advisories. Office of Water. EPA 822-B-96-002.
Environmental Protection Agency. July 30, 1999. Risk Assessment Technical
Background Document for the Chlorinated Aliphatics Listing
Determination-Appendices A-K. Center for Environmental Analysis-Research
Triangle Institute, Research Triangle Park, NC (RTI Project Number
92U-7298-027) and Office of Solid Waste, Washington, DC (EPA Contract
Number 68-W6-0053).
Environmental Protection Agency, Region ill Office. "Risk-Based Concentration
Table." Philadelphia, Pennsylvania. May 8, 2001.
http://www.epa.gov/reg3hwmd/risk/index.htm
14
Environmental Protection Agency, Region IX Office. "Preliminary Remediation
Goal Table." San Francisco, California. Table 2000 Update.
http://www.epa.gov/reg3hwmd/risk/index.htm
Hazardous Substance Data Bank. 2002. National Library of Medicine. National
Toxicology Program. Bethesda, MD.
Integrated Risk Information System. 2002. U.S. Environmental Protection
Agency, Office of Health and Environmental Assessment, Environmental Criteria
and Assessment Office, Cincinnati, OH.
Williams, Gary M., and Weisburger, John H. 1991. "Chemical Carcinogenesis".
Chapter 5 in: Casarett and Doull's TOXICOLOGY: The Basic Science of
Poisons. (Mary O Amdur, John Doull, and Curtis Klaassen, Editors.) Pergamon
Press pp 127-200. [See section entitled "Quantitative Aspects of Carcinogenesis,"
ppl52-155.
15
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APPENDIX A
COMPARISON VALUES
ATSDR comparison values (CVs) are media-specific concentrations that are considered to be
safe under default conditions of exposure. They are used as screening values in selecting site-
specific chemicals for further evaluation of their public health implications. Generally, a
chemical is selected for further public health evaluation because its maximum concentration in
air, water, or soil at the site exceeds at least one of ATSDR's CVs. This approach is conservative
by design. ATSDR may also select detected chemical substances for further public health
evaluation and discussion because ATSDR has no CVs or because the community has expressed
special concern about the substance, whether it exceeds CVs or not.
It cannot be emphasized strongly enough that CVs are not thresholds of toxicity. While
concentrations at or below the relevant CV are generally considered to be safe, it does not
automatically follow that any environmental concentration that exceeds a CV would be expected
to produce adverse health effects. In fact, the whole purpose behind highly conservative, health-
based standards and guidelines is to enable health professionals to recognize and resolve
potential public health problems before they become actual health hazards. For that reason,
A TSDR' s CV s are typically designed to be 1 to 3 orders of magnitude lower (i.e., 10 to 1,000
times lower) than the corresponding no-effect levels or lowest-effect levels on which they are
based. The probability that adverse health outcomes will actually occur depends not on
environmental concentrations alone, but on several additional factors, including site-specific
conditions of exposure, and individual lifestyle and genetic factors that affect the route,
magnitude, and duration of actual exposures.
Listed below are the abbreviations for selected CVs and units of measure used within this
document. Following this list of abbreviations are more complete descriptions of the various
comparison values used within this document, as well as a brief discussion on one of ATSDR's
most conservative CVs.
CREG = Cancer Risk Evaluation Guide
EMEG = Environmental Media Evaluation Guide
LTHA = Drinking Water Lifetime Health Advisory
MCL = Maximum Contaminant Level
MCLA = Maximum Contaminant Level Action.
MRL = Minimal Risk Level
RBC = Risk-Based Concentration
RID = Reference Dose
RMEG = Reference Dose Media Evaluation Guide
16
Units of Measure:
ppm = Parts Per Million [e.g., mg/L (water), mg/kg (soil)]
ppb = Parts Per Billion [e.g., µg/L (water), µg/kg (soil)]
kg = kilogram (1,000 grams)
mg = milligram (0.001 gram)
µg = microgram (0.000001 gram)
L = liter (1000 mL or 1.057 quarts of liquid, or 0.001 m3 of air)
m3 = cubic meter (a volume of air equal to 1,000 liters)
Cancer Risk Evaluation Guides (CREGs) are derived by ATSDR. They are estimated
chemical concentrations theoretically expected to cause no more than one excess cancer in a
million people exposed over a lifetime. CREGs are derived from EPA's cancer slope factors and
therefore reflect estimates of risk based on the assumption of zero threshold and lifetime
exposure. Such estimates are necessarily hypothetical, as stated in EPA 1986 Guidelines for
Carcinogenic Risk Assessment, "the true value of the risk is unknown and may be as low as
zero."
Drinking Water Equivalent Levels (DWELs) are lifetime exposure levels specific for drinking
water (assuming that all exposure is from that medium) at which adverse, noncarcinogenic health
effects would not be expected to occur. They are derived from EPA RIDs by factoring in default
ingestion rates and body weights to convert the RID dose to an equivalent concentration in
drinking water.
Minimal Risk Levels (MRLs) are ATSDR estimates of daily human exposure to a chemical that
are unlikely to be associated with any appreciable risk of deleterious noncancer effects over a
specified duration of exposure. MRLs are calculated using data from human and animal studies
and are reported for acute G; 14 days), intermediate (15-364 days), and chronic (2: 365 days)
exposures. MRLs for oral exposure (i.e., ingestion) are doses and are typically expressed in
mg/kg/day. Inhalation MRLs are concentrations and are typically expressed in either parts per
billion (ppb) or µg/m3• The latter are identical to ATSDR's EMEGs for airborne contaminants.
ATSDR's MRLs are published in ATSDR Toxicological Profiles for specific chemicals.
Environmental Media Evaluation Guides (EMEGs) are media-specific concentrations that are
calculated from ATSDR's Minimal Risk Levels by factoring in default body weights and
ingestion rates. Different EMEGs are calculated for adults and children, as well as for acute G:;14
days), intermediate (15-364 days), and chronic (:?:365 days) exposures.
EPA Reference Dose (RID) is an estimate of the daily exposure to a contaminant unlikely to
cause any non-carcinogenic adverse health effects over a lifetime of chronic exposure. Like the
ATSDR MRL, the EPA RID is a dose and is typically expressed in mg/kg/day ..
Reference Dose Media Evaluation Guide (RMEG) is the concentration of a contaminant in air,
water, or soil that ATSDR derives from EPA's RID for that contaminant by factoring in default
17
•
•
•
•
•
values for body weight and intake rate. RMEGs are calculated for adults and children. RMEGs
are analogous to ATSDR EMEGs.
Risk-Based Concentrations (RBCs) are media-specific values derived by the Region ill Office
of the Environmental Protection Agency from EPA RfDs, RfCs, or cancer slope factors, by
factoring in default values for body weight, exposure duration, and ingestion/inhalation rates.
These values represent levels of chemicals in air, water, soil, and fish that are considered safe
over a lifetime of exposure. RBCs are calculated for adults and children. RBCs for
noncarcinogens and carcinogens are analogous to ATSDR EMEGs and CREGs, respectively.
Lifetime Health Advisories (LTHAs) are calculated from the DWEL (Drinking Water
Equivalent Level) and represent the concentration of a substance in drinking water estimated to
have negligible deleterious effects in humans over a lifetime of 70 years, assuming 2 Uday water
consumption for a 70-kg adult, and taking into account other sources of exposure. In the absence
of chemical-specific data, LTHAs for noncarcinogenic organic and inorganic compounds are
20% and 10%, respectively, of the corresponding DWELs. LTHAs are not derived for
compounds which are potentially carcinogenic for humans.
Maximum Contaminant Levels (MCLs) are drinking water standards promulgated by the EPA.
They represent levels of substances in drinking water that EPA deems protective of public health
over a lifetime (70 years) at an adult exposure rate of 2 liters of water per day. They differ from
other protective comparison values in that they are legally-enforceable and take into account the
availability and economics of water treatment technology.
Maximum Contaminant Level Action (MCLA) are action levels for drinking water set by
EPA under Superfund. When the relevant action level is exceeded, a regulatory response is
triggered.
When screening individual chemical substances, ATSDR staff compare the highest single
concentration of a chemical detected at the site with the appropriate comparison value available
for the most sensitive of the potentially exposed individuals (usually children). Typically the
cancer risk evaluation guide (CREG) or chronic environmental media evaluation guide (cEMEG)
is used. This "worst-case" approach introduces a high degree of conservatism into the analysis
and often results in the selection of many chemical substances for further public health
evaluation that will not, upon closer scrutiny, be judged to pose any hazard to human health.
However, in the interest of public health, it is more prudent to use an environmental screen that
identifies many chemicals for further evaluation that may be determined later to be harmless, as
opposed to one that may overlook even a single potential hazard to public health. The reader
should keep in mind the conservativeness of this approach when interpreting A TSDR' s analysis
of the potential health implications of site-specific exposures.
The most conservative ATSDR comparison value, the CREG, deserves special mention. The
CREG is a media-specific contaminant concentration derived from the chronic (essentially,
18
lifetime) dose of that substance which, according to an EPA estimate, corresponds to a 1-in-•
1,000,000 cancer risk level. This does not mean that exposures equivalent to the CREG actually
are expected to cause I excess cancer case in 1,000,000 people exposed over a lifetime. Nor does
it mean that every person in that exposed population has a l-in-1,000,000 risk (i.e., lxl0·6) of
developing cancer from the specified exposure. Although commonly misinterpreted in precisely
this way, cancer risk assessment methodology can only provide conservative estimates of
population risk which do not, in fact, apply to any particular individual. Even for populations,
cancer risk estimates do not necessarily constitute realistic predictions of the risk. As EPA states
in its Guidelines for carcinogen Risk Assessment, "the true value of the risk is unknown and may
be as low as zero" [51 Federal Register33997].
Unlike non-cancer comparison values which correspond to safe levels that include specified
margins of safety, ATSDR CREGs (and the risk estimates on which they are based) correspond
to purely hypothetical (and unmeasurable) 1-in-a-million cancer risk levels that include
unspecified margins of safety (i.e., relative to the lowest known cancer effect levels) which often
range from thousands to millions or more. In the U.S., these hypothetical risk levels are based on
the zero-threshold assumption according to which any non-zero dose of a carcinogen must be
associated with some finite increment of risk, however small. Using linear models based on this
assumption, it is actually possible to quantify undetectable/non-existent cancer risks that are
(hypothetically) associated with even immeasurably small doses. EPA uses such risk estimates
as regulatory tools in, for example, the ranking of contaminated sites for cleanup. ATSDR uses
them as screening values. However, once ATSDR has screened a substance and selected it for
further evaluation, the CREG, like all other screening values, becomes irrelevant in subsequent •
stages of analysis. Further evaluation of the public health implications of site-specific exposures
must, necessarily, be based on the best medical and toxicologic information available [ATSDR
1992],
• 19
APPENDIX B
•
•
•
•
•
TABLE 1
August 1997 PA/SI Surface Water Pathway Sampling Locations
Sample ID
SS-07-SW/SD
SS-08-SW/SD
SS-09-SW/SD
SS-10-SW/SD
SS-110-SW
SS-11-SL
SS-13-SL
SS-16-SW/SD
SS-116-SW/SD
SS-17-SW/SD
Sample Location
Surface water/sediment samples collected
from the unnamed tributary to the Catawba
River, approximately 100 feet below
Probable Point of Entry 4 (PPE4).
Surface water/sediment samples collected
from a pond located ½ mile south of the
lagoon area. Samples considered background
pond samples for sampling event.
Surface water/sediment samples collected
from Norwood Creek, about 1.3 miles east of
the site. Utilized as background surface water
and sediment samples for sampling event.
Surface water/sediment samples collected
from pond southeast of the lagoon area, just
below PPE3.
Duplicate surface water sample for
SS-10-SW .
Soil sample collected in the drainage ditch at
the southeast corner of the site. (Surface
water runoff from the source areas to the
southwest, south, and southeast are
intercepted by a drainage ditch on the north
side of Lauren Dri"._e.)
Soil sample collected in the drainage ditch,
southwest of the lagoon area, in an area that
appears to be a crest for dividing the ditch
flow to the east and west, for the purpose of a
background ditch sample.
Surface water and sediments samples
collected in intermittent stream #1, about 40
feet topographically up gradient of the
confluence with intermittent stream #2.
Surface water and sediments samples
collected in intermittent stream #2 as
background samples for intermittent stream
#1. Samples about 40 feet topographically up
gradient of the confluence with intermittent
stream #1.
Surface water sample collected downstream
of the pond dam below PPEI. Concurrently,
sediment sample collected near the head of
the same pond .
21
Comment,;
Sediment sample was a light brown silty sand
with little organic content.
Runoff from pond enters intermittent stream
#5, topographically up gradient of PPE4.
Sediment sample consisted of gray, silty sand
with light to moderate organic matter.
Sediment sample consisted of medium brown
fine silt
Sediment sample was a olive gray silt with
sand, containing organic matter.
Soil sample was a reddish brown loamy clay,
collected at a depth of 2 inches.
Soil sample was a brown, organic, clayey
sand, collected at a depth of 3 to 6 inches.
Sediment sample was a gray fine silt, organic
rich, with a slight hydrogen sulfide odor.
Sediment sample was a gray fin~ silt with a
small amount of sand, and presented a
hydrogen sulfide odor.
Sediment sample was a gray fine silt with
little sand.
TABLE2
December 1999 ESI Surface Water Pathway Sampling Locations
Sample ID
SST-017-SL
SST-018-SL
SST-019-SW/SD
SST-020-SW/SD
SST-021-SW/SD
SST-022-SW/SD
SST-023-SW/SD
SST-024-SW/SD
Sample Description/Location
Soil sample collected from drainage ditch around southeast
corner of the site showing attribution from the lagoon area.
Soil sample collected from drainage ditch farther east of
SST-017-SL showing attribution from the property east of
site.
Swface water/sediment samples collected at PPE3 or the
discharge location from the drainage ditch into the pond just
below PPE3.
Surface water/sediment samples collected from the pond
below PPE3.
Surface water/sediment samples collected from a pond
located ½ mile south of the lagoon area.
Surface water and sediments samples collected in
intennittent stream #5, topographically up gradient of PPE4
or the confluence for the unnamed perennial tributary formed
by intermittent streams #4 and #5.
Surface water and sediments samples collected in
intermittent stream #4, topographicalJy up gradient of PPE4
or the confluence for the unnamed perennial tributary formed
by intennittent streams #4 and #5.
Surface water and sediments samples collected in the
unnamed tributary just below PPE4.
22
Comments
Samples used as background
samples for sampling event.
•
•
•
•
ead'
•.1 anese
;,hckel
anadium
PAHs
thene
Anthracene
aenzo a anthraceoe
Benzo a) ene
Bemo b fluoran\hene
Beru:o( .h.i)pe er.e'
Benzo k fluoranlhene
arbazole
Ch ene
Dibenz a.h anthracene
Dibenzoturan
Fluoranthene
hro<eoo
lndeno 1,2,3-cd rene
Phenanthrene•
Pyrena voes
enzaldeh e
o,meth hthalate voes
e1one
oluene
• Summary of Detected Chemical Concentrations found in "Soil/Sediment" Samples collected in 1997 and 1999
3.5-74
10--37
3.200-37,000
1.6--22
25 •. 500
0.92 •. 21
27 .• 85 , __
0.13.J
0.082.J, 0.25.J
0.43J,0.83
0.4SJ.0.73
0.66. 0.96
0.17J,0.28J
0.48J, 0.84
0.099J, 0.27J
0.SIJ, 0.92
0.088J
0.068J
0.81, 1.6
0.12J
0.21J, 0.32J
1.2
1 •. 6
0.052J. 0.44J
"
74.1
21.9
23.7
16,675
12.2
188
8.3
48.7
0.13
0.166
0.63
0.59
0.81
0.23
0.66
0.185
0.72
0.088
0.068
1.21
0.12
0.27
1.2
1.
0.25
.4
0.161
16
24
17.500
12
180
' 45,5
0.13
0.166
0.63
0.59
0.81
023
0.66
0.185
0.72
0.088
0.068
1.21
0.12
0.27
1.2
0.25
0.118
16/17
~8
&8
~17
17/17
&8
&8
1/8
V8
V8
V vs
218
V8 VO
218
1/8
"' VO
1/8
VO
118
W17
1 0,
"10,000
1.000,000
300.1100
300,000
1.000,000
1
200
30.000
500.000
20.000
20,000
100.000
1,000,000 RMEG
29,000 RBC
440,000 RBC
40,000 RMEG
1 0,(X)O RM EG
5,100 RSC
40,000 AMEG
200,000 RMEG
2,900 ABC
30,000 AMEG
30,000 RMEG
70,000 RMEG
200,000 RMEG
1
80,000 RMEG
3,100 ABC
47,000 ABC
400 PRG
3,000 RMEG
1,000 AMEG
550 ABC
3,000 RMEG
20,000 AMEG
310 ABC
2.000 AMEG
2.000 RMEG
5,000 AMEG
20.000 RMEG
1'
0.87 ABC
~"tf0.1 CAEGn;:.
~':I: 0:87 RBC;fg:;i,
8.7 ABC
32 ABC
87 ABC
~«;0.087 RB !L'l:!11
0.87 ABC
200.
2'
200,
No
No
No
No
No
No
y~
y~
NA
No
No
No
y~
No
No
No
No
NA
No
No
0 0.002 --0.44
1 --o.
A chemical is selected for further public health ev.tluacion if ehe maximum detected chemical level exceeds .tt Jeasc one of ies cotr,P.trison values. Shading
indicates the comparison values that are exceeded.
CREG -S,G
RXEG
J
Cancer Risk Evaluation Guide
Environmental Hedi.a Evaluation Guide
Preliminary Remediation Gaal (Note, PRG values derived from equations documented in following reference, EP1' 'legion IX Preliminary
Re::iediation Go.J:ls. United Scates £nvironr:,encal Proceccion Agency, Region 9 Office: 15 Hawthorne sc., San Fr;u,.:i-.co. Calif., 94105
(Send PRG-rel.,,Ced comrnents and questions to smucker.scani!lepa..gov). Available on EPA Region IX's Internet website,
htep: / /..,,.,-.,. epa. gov/region09/waste/sfund/prg/index. htm, JJ&ckgxoun(I Information -[PDI'] J
Risk Based Concentration (Note, RBC values derived from BqtJations documented in following reference: EPA Region III Risk-Based
Concentration Table. United States Enviro/llltelltal Protection Agency, Region III, 841 Chestnut Street, Philadelphia, PA. 1911:17. Available on
EPA Region III's Internet ""'bsice, http://......,._epa.gov/reg3hwmdlrisk/risJo'/lenu.htm, ••c:kgroun(I Information -[PDl'l/
Reference Dose Media Evaluation Guide
&otimated Value
None Av11.ilable '" pp,, parts per m1llion
'All chemical detects of chromium a.re considered to Chromium III {i.e., Chromium, Trivalent}, predominant chemical series, inste"d of Chromium VI Ii. e., Chromium,
Hexavalent/: therefore, the comparison values are reflective of Chromium 111:
'The liBted Lead compar1son value for industrial exposures is EPA Region IX's Lead PRG tor industrial activities. Also, the listed Lead comparison values tor both
res.idenei11l and industri.,1 exposures are based on EPA models /IEVBK 1994 and TRW 1996}.
'senzofg,h,iJperylene is not classifiable 11s co ht.U'l>all carcin0genicity, Classification D, {HSDB 2002, IRIS 2002] and the detected levels of 0.17 and 0.25 ppm is tar
below the non-carcinogenic comparison values for three other PAHs listed above fi.e., Anthracene, Dibenzo(a,h)a.nthracene, and Pyrene); therefore, it is preswned
Chat this chemical should not be selected for further public heal ch ev111uat1on.
'Phenanthrene is not classifiable .ts co human carcin.:,gen1city, Classificacion D. (HSDB 2002. IRIS 2002] and the detected level of l 2 ppm is far belo...-the non-
carcinogenic comparison values £or three ocher PAHs listed above (i.e., Anthracene, Dibenzo(a,h}anthracene, and Pyrene); therefore, J.t is presumed that this
chemical should not be selected for further public h...,lth evaluation.
'values for adult RBCs are derived fror., Region III RBC equacio.ns, ..-he.re the exposure factors for an average hY.1:>0thetical child are replaced with the exposure
factors for an average hypothetical adult (i.e., body weight eqvals 70 kilograms, so11 ingesUon rate equals 100 milligrams per day, and exposure duration equals
JO yearsJ.
23
Barium
Cadmium
Chromium
Cobalt
lron1
Man anese1
Nickel
Zinc
voes
Acetone
Toluene
Notes:
TABLE 4
Summary of Detected Chemical Concentrations found in Surface Water Samples collected in 1997 and 1999
•
14--210
1 --1.2
1 --10
4.B--14
740--7,000
1.6--16
9.4 --1,300
4.3--11
85--220
a --32
0.4 •• 0.6
A chemical is
selected for
CREG
EMEG
LTHA
MCL
REC
RMEG
ppb
1,900
8.8
97.9
1.1
5.5
9.4
3,713
7.13
330
7.65
153
17.1
0.53
1,900 1/6
4.8 3/6
100 7/14
1.1 2/6
5.5 2/14
9.4 2/6
3,400 3/6
4.1 3/14
70 13114
7.65 2/6
153 2/6
14.5 10/14
0.6 3/14 30,000 8.000
Cancer Risk Evaluation Guide
Environmental Media Evaluation Guide
Drinking Water Lifetime Health Advisory
Maximum Contaminant Level
10,000
70,000
700
20,000 37,000 ABC
wm.1;r~10 EMEGh!,;i
2,000 AMEG
7 EMEG
100 LTHA
730 ABC
22,000 ABC
2,000 RMEG
700 RMEG
3,000 10,000 EMEG
20,000 10,000 RMEG
200 750 ABC
16,000 ABC No _,,m EMEG;;"t:E; ~0:02 GREG~: 50 Yes
700 RMEG 2,000 No
2 EMEG 5 No
100 No
310 ABC No
9,400 ABC Yes
Yes
tl/Jiililsoo F.l)ieGW, ltlBU:tTh.~!,if Yes
200 AMEG No
3,000 EMEG 5,000 No
3,000 RMEG No
270 RB 1,000 No
Risk Based Concentration (Note, RBC values derived from equations documented in following reference.-EPA Region III Risk-
Based Concentration Table. United States Environmental Protection Agency, Region III, 841 Chestnut Street, Philadelphia, PA,
19107. Available-on EPA Region III's Internet website, http://www.epa.gov/reg3hMnd/risklriskmenu.htm, Back~roun4 Informa.tion
[PDF] J
Reference Dose Media Evaluation Guide
parts per billion
1 Listed value in "EPA MCL" column is a Secondary MaximWll conta111inant Level (SMCLJ tor drinking water as set by EPA. SMCLs are unenforceable federal
guidelines regarding taste, odor, color, and other non-aesthetic effects of drinking water. EPA recommends them to States as reasonable goals, but
federal law does not require water supply systems to comply with them. States may, however, adopt their own enforceable regulations governing these
concerns.
2Listed value in "EPA MCL" column is a Maximum Contaminant Level Action (MCLA) tor drinking water as set by EPA under Superfund. If the relevant
action level is exceeded, a regulatory response is triggered .
•
Arsenic
Barium
Cadmium
Chromium
Cobalt
Iron
Lead
Man anese
Nickel
Zinc
voes
cetone
oluene
Notes:
•
TABLE 5
Estimated Bio-Accumulation in Fish Tissue
1,900 1,900 1,900 .1/6 19,000 19,000 19,000
3.6 --18 8.8 4.8 3/6 1,008 --5,040 2,464 1,344
14--210 97.9 100 7114 56 --840 392 400
1 --1.2 1.1 1.1 2/6 200 --240 220 220
1 --10 5.5 5.5 2/14 200 --2,000 1,100 1,100
4.8--14 9.4 9.4 2/6 1,440 --4,200 2,820 2,820
740 --7,000 3,713 3,400 316 148,000 --1,400,000 742,600 680,000
1.6 --16 7.13 4.1 3/14 480 --4,800 2,139 1,230
9.4 --1,300 330 70 13/14 3,760 --520,000 132,000 28,000
4.3 --11 7.65 7.65 2/6 430 --1,100 765 765
85 --220 153 153 2/6 85,000 --220,000 153,000 153,000
8--32 17.1 14.5 10114 3.12--12.48 7 6
0.4 --0.6 0.53 0.6 3114 26.4 .. 39.6 35 40
The following equation was used to estimate the tissue concentrations of edible fish for the chemicals found in the surface
features located near the Sigmon's Septic Tank Service Facility.
where,
Cnah = Cw X BAF
Clish c.
BAF
fish concentration (µg/kg)
water concentration (µg/L)
bio-accumulation factor (Ukg)
10
280
4
200
200
300
200
300
400
100
1,000
0.39
66
The BAF was used and that the measured water concentrations were assumed to be total water concentrations, yielding an overly
conservative estimate of the edible fish tissue concentrations.
unils:
µg/kg
µg/L
Ukg
microgram per kilogram
microgram per liter, which is equivalent to parts per billion (i.e., ppb)
liter per kilogram
25
TABLE 6
Biota Comp_;:irison Values for Sigmon's Septic Tank Service Facility
0.21 --1 0.51 0.28 0.76 5
0.012--0.17 0.081 0.083 0.032--0.47 0.22 0.23 70
0.041 --0.05 0.046 0.046 0.11 ··0.14 0.12 0.12 0.2 0.041 -· 0.41 0.23 0.23 0.11 --1.1 0.62 0.62 1,500
0.3 •. 0.87 0.58 0.58 0.81--2.4 1.6
31 --290 154 141 83--788 418
0.1 --1 0.44 0.25 0.3--2.7 1.2
0.78 .• 108 27 5.8 2.1 ··293 74 Man anese 16
No
No
No
No
Yes
NA
Yes 0.09 .• 0.23 0.16 0.16 0.24 •• 0.62 0.43 Nickel 0.43 20 No
No 18--46 32 32 48--124 86 Zinc 86 300 300 300 voes
Acetone
Toluene
Notes:
0.082J, 0.25J 0.1660 0.1660 2/8 0.0038 0.43J, 0.83 0.6300 0.6300 2/8 0.02
0.0032
0.022 800
2,000
20
300
200
No
No
A chemical is selected for further public health evaluation it the estimated dose at the maximum detected chemical level exceeds either one of ATSDR's Oral MRLs
of EPA's RfDs. Shading indicates the health guidelines that are exceeded.
MRL
RfD
NA
ug/kg/day
Minimum Risk Level
Reference Dose
None Available
microgram per kilogram per day
EThe EPA Superfund Health Risk Technical Support Center, part of the EPA National Center for Environmental Assessment in Cincinnati, develops provisional R[Ds
and CPSs on request for chemicals not in IRIS or HEAST. These provisional values are superscripted •E• {i.e., EPA-NCEA provisional) in the table. It is
possible they may be obsolete. If one of the "E" constants is important to a Superfund Risk Assessment, consider requesting, through a Regional Risk Assessor,
a new provisional value {EPA III 2001].
•
Estimated doses used the following assumptions:
1/
2/
The average adult weighs 70 kg (i.e., 150 lbs.) and consumes 14.5 grams of sport fish (i.e., fish only caught via recreational activities) per
day [West et al 1989, West et al 1993].
The average child weighs 10 kg (i.e., 20 lbs.} and consumes 5.63 grams of sport fish (i.e., fish only caught via recreational activities) per
day [~lest et al 19891.
•
Surface Water Health Consultation Sigmon's Septic Tank Service Facility
APPENDIX C
•
•
0
•
•
Figure 1
Site Map for 1999 Expanded Site Inspection
• • PW33
• MW1A
({~PW&
PW32 • •
D
pond
• Sigmon Environmental
Services Office
storage 0o
tanks C
lagoons
• -·x
~ I I 4 I I
x I I
I • :i( PWS
I
'I.
I
'){
I
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waste pile I
• )!
D CJ
ape~ pits I drainage.ditch
'X-'1<-'l<-X-1'--x-x -x ->< -i< --·-·-·-·-· --· ·-·---·-·
.. PW3 PW2 ·-
Source: NCDEHR (2000) Site
Lauren Drive • •
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joate: November 1999
Name: Sigmon's Septic Tanlc Service
0
Drawn By:
NCD 062 555 792
Figure 2
Surface Water Sampling Locations for 1997 Preliminary Assessment/ Site Inspection
Courtesy of
North Carolina
Division of
Title, Probable Points of Entry, Ponds, Intermittent Streams, and
1997 PA/SI Sampling Locations
Waste Management Scale: 1 11 = 850'
Superfund Section
Date, Drawn By,
(NC DENR 1998) Site Name, Sigmon's Septic Tank Service NCD 062 555 792
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Figure 3
Surface Water Sampling Locations for 1999 Expanded Site Inspection
Courtesy of
North Carolina
Division of
Tit 1 e : Probable Points of Entry, Ponds, Intermittent Streams, and
1999 ESI Sampling Locations
Waste Management Scale: 1 11 = 850'
Superfund Section
Date: Drawn By:
(NC DENR 2000) Site Name: Sigrnon's Septic Tank Service NCO 062 555 792
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Health Consultation
Review of Groundwater Data
SIGMON'S SEPTIC TANK SERVICE FACILITY
(a/k/a SIGMON'S SEPTIC TANK SERVICE)
L ..
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
EPA FACILITY ID: NCD062555792
MARCH 29, 2002
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Atlanta, Georgia 30333
APR - 4
Health Consultation: A Note of Explanation
An A TSDR health consultation is a verbal or written response from ATSDR to a specific request
for information about health risks related to a specific site, a chemical release, or the presence of
hazardous material. In order to prevent or mitigate exposures, a consultation may lead to
specific actions, such as restricting use of or replacing water supplies; intensifying
environmental sampling; restricting site access; or removing the contaminated material.
In addition, consultations may recommend additional public health actions, such as conducting
health surveillance activities to evaluate exposure or trends in adverse health outcomes;
conducting biological indicators of exposure studies to assess exposure; and providing health
education for health care providers and community members. This concludes the health
consultation process for this site, unless additional information is obtained by A TSDR which, in
the Agency's opinion, indicates a need to revise or append the conclusions previously issued.
You May Contact ATSDR TOLL FREE at
l-888-42A TSDR
or
Visit our Home Page at: http://www.atsdr.cdc.gov
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HEALTH CONSULTATION
Review of Groundwater Data
SIGMON' S SEPTIC TANK SERVICE FACILITY
(a/k/a SIGMON'S SEPTIC TANK SERVICE)
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA
EPA FACILITY ID: NCD062555792
Prepared by:
Exposure Investigation and Consultation Branch
Di vision of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
• Background and Statement of Issues
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On June 27, 2001, the Agency for Toxic Substances and Disease Registry (ATSDR) received a
request from the Environmental Protection Agency (EPA) to determine the public health impact
the Sigmon's Septic Tank Service Facility, septage removal business, has on private wells
located near the facility [ATSDR 2001a]. ATSDR is also reviewing the migration of chemical
constituents to nearby surface water bodies (i.e., streams, creeks, ponds, etc.) and their potential
impact on public health through recreational fishing. That evaluation will be released in a
separate health consultation.
The Sigmon's Septic Tank Service Facility (CERCLIS No.: NCD062555792) is located at 1268
Eufola Road, approximately five miles southwest of Statesville, Iredell County, North Carolina
[NC DENR 1998, NC DENR 2000} The facility is active under the current name Sigmon's
Environmental Services. Septic wastes are temporarily stored in four cylindrical tanks on the
property, and the sludges are periodically removed and transported to a wastewater treatment
plant for disposal. The business employs five workers. The work area includes the area
surrounding the storage tanks (Figure 2). The owner of the business lives on the property.
Drinking water for the owner's home and the business office is obtained from a private water
well located on the property (Figures l and 2). Public access is not restricted on the south side of
the property (i.e., former lagoon area/waste pile), and unauthorized persons have been reported to
enter the property with recreational vehicles through breaks in the fence .
The site has been listed under several names including: Sigmon's Septic Tank Service, AAA
Enterprises, and Sigmon Environmental Services (current name). Services provided by the
business owners have included the pumping and removal of septic tank wastes and heavy sludges
for various customers (e.g., residential, commercial, and industrial), installation and repair of
septic tanks, and a variety of other waste removal services to various industries. The
groundwater medium has been investigated for many years and the residents are well aware of
the groundwater contamination resulting from activities at the Sigmon' s Septic Tank Service
Facility [NC DENR 1998, NC DENR 2000]. Below is a chronological list summarizing the
events that have occurred at the Sigmon' s Septic Tank Service Facility:
Historical Events at Sigmon's Septic Tank Service Facility
Time Period
1970-1978
1973-1974
1978-1992
Event Summary
Wastewaters from the Sigmon's Septic Tank Service Facility are originally discharged to the
City of Statesville wastewater treatment plant.
Sludges from the Sigmon's Septic Tank Service Facility are land applied to area farmlands.
Sigmon's Septic Tank Service begins disposing of septic wastes within ten on-site lagoons.
Within time period, the North Carolina Department of Natural Resources and Community
Development-Division of Environmental Management (DEM) collected groundwater samples
from on-site monitoring wells and from nearby private water wells. Analysis revealed elevated
levels of metallic and organic chemicals .
I
Historical Events at Sigmon's Septic Tank Service Facility
Time Period
1992
1992 -1995
1995
Dec. 1995
Dec. 1996
Jan. 1997
Apr. 1997
Aug. 1997
Dec. 1999
Event Summary
DEM and the North Carolina Hazardous Waste Section conduct a site investigation and
sampling trip to detennine if the wastes in the on-site lagoons are hazardous. Since the
chemical constituents of the on-site lagoolls did not meet the definition of a hazardous waste,
the North Carolina Hazardous Waste Section decides the site does not fall under its jurisdiction
and refers it to the North Carolina Solid Waste Section for further evaluation.
On-site lagoons are non-operational.
DEM requires the on-site·Iagoons to be closed. Lagoon sludges are excavated and piled in
lagoon area.
DEM refers site to th~ North Carolina Superfund Section regarding removal options of the piled
sludge in lagoon area.
North Carolina Superfund Section adds the site to the CERCLIS database as one for further
investigation.
North Carolina Superfund Section refers the site to the EPA Emergency Response and Removal
Branch for removal evaluation.
EPA concludes that the site does not meet their criteria for removal eligibility.
North Carolina Supetfund Section initiates its investigation of the Sigmon site by conducting
sampling in a combined Preliminary Assessment/Site Inspection (P NS!). Collected samples
from the waste pile, open pits; former lagoon area, storage tank area, sutface water pathways,
on-site/off-site monitoring wells, and nearby private wells.
North Carolina Superfund Section conducts additional sampling at the site through an Expanded
Site Inspection (ES!). Again, collected samples from the waste pile, former lagoon area,
surface water pathways, an on-site monitoring well, and nearby private wells.
The groundwater pathway appears-to be of great concern to nearby private well users. Within
one-quarter mile of the Sigmon property, 14 people have some degree of chemical contamination
in their well water. Several residents have been advised by the North Carolina Occupational and
Environmental Epidemiology Section that water from their private wells should not be used for
drinking purposes [NC DENR 1998].
Large amounts of waste still remain on site, which the North Carolina Superfund Section
believes is the source of the contamination. They have recommended to EPA that a non-critical
removal be conducted to address the remaining source areas al the site. This would result in
further mitigating any potential chemical releases to the soil, groundwater, and surface water
pathways [NC DENR 2000].
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Discussion
A TSDR reviewed analytical results of collected groundwater samples to determine if chemical
releases to the area's groundwater may be impacting the public health of nearby private well
users [NC DENR 1998, NC DENR 2000].
Environmental Monitoring Data
In September 1987, four on-site monitoring wells (MWl, MW2, MW3, and MW4) were
installed around the lagoon area at depths of 34 to 39 feet. Figures l and 2 give an aerial
perspective illustrating the location of the on-site monitoring wells (refer to label MWlA in
Figures l and 2) in respect to the source areas, nearby private wells, and other sampling locations
(i.e., an off-site monitoring well). Figure 3 gives a more detailed areal perspective of the on-site
monitoring wells in proximity to the closed lagoons.
Between 1987 and 1999, 12 samples were collected from the on-site monitoring wells and
subsequently analyzed for chlorides, nitrates, sulfates, metals, volatile organic compounds
(VOCs), and semi-volatile organic compounds (SVOCs). Table l (see Appendix B) summarizes
these analytical results and compares them to drinking water comparison values (CVs, see
Appendix A), assuming both short-term (i.e., acute or intermediate) and long-term (i.e., chronic)
exposures .
Data from the monitoring wells were not used to determine exposure levels since the most likely
points of exposures are private wells. Monitoring well data was reviewed to determine which of
the chemicals from the site could potentially impact private wells. Of the 40 chemicals detected
in on-site monitoring wells, only 12 (30 percent) were detected at levels above drinking water
CVs. Six of the twelve chemicals (i.e., aluminum, arsenic, barium, sodium, benzene, and vinyl
chloride) were not detected in private wells at levels above drinking water CVs. Therefore, these
six chemicals will not be evaluated any further in this health consultation.
Off-site Monitoring Well
During the August 1997 PNSI, a groundwater sample was collected from an off-site monitoring
well (see Figure I), located approximately 100 feet southeast of the closed lagoons. Chemical
analysis of the collected groundwater sample showed no chemical detects above their respective
detection limits except for acetone (31 parts per billion). However, that reading was thought lo
reflect lab contamination and was below drinking water CVs (refer to Table 2 in Appendix B).
As long as several source areas (i.e., closed lagoons, waste piles, and open pits) remain at the
site, routine collection and analysis of groundwater samples is advisable.
3
Private Wells
Chemical analyses of collected samples from the on-site monitoring wells did indicate that the
closed lagoons and the waste piles have been, and may still be, sources of contaminants that
leach into the area's groundwater. These contaminants may subsequently migrate into nearby
private wells. Such migration may account for contamination found in at least two private wells.
Samples collected from the two private wells showed chemical detects of mercury, nitrates, and
VOCs, that were also detected in the on-site monitoring wells. For these two private wells,
chemical constituents were generally detected at higher concentrations than in other nearby
private wells. Some of the chemical levels detected in the two private wells also exceeded
drinking water CVs. Because source areas still remain at the site and because it is likely that they
may have impacted at least two private wells, consideration should be given to removing these
source areas from the site to prevent or mitigate any potential migration of chemicals into nearby
private wells.
Between 1991 and 1999, groundwater samples were collected from 11 nearby privates wells,
with one well being abandoned due to a hazardous waste spill unrelated to the site.
Approximately 36 samples were collected and subsequently analyzed for nitrates, sulfates,
metals, VOCs, and SVOCs. Tables 3 through 13 (see Appendix B) summarize the analytical
results and compares them to drinking water CV s. The analytical results for each well are
summarized in the following paragraphs.
• Private Well PW2
Private Well PW2 (see Figures 1 and 2) is topographically down gradient of the
Sigmon source areas (i.e., 400 feet southwest of the lagoon area) and serves at
least one person. The drilled depth is unknown. Twenty-one of the 23 detected
chemicals were also detected on-site (most notably mercury, nitrates, and VOCs).
Thus, Pri vale Well PW2 is probably being impacted by the source areas located at
the site.
Of the 23 chemicals detected in samples collected from the Private Well PW2,
maximum detected concentrations for six chemicals (i.e., nitrates, iron,
manganese, mercury, 1,4--dichlorobenzene, and 1,2-dichloroethane) exceeded
drinking water CVs (see Table 3).
• Private Wells PWIA PWlR PWlS
In an area southeast of the site, a relatively large parcel of property contains a
private residence, a business, and four rental houses. Three private wells are also
located on the property approximately 1,000 feet east of the lagoon area. One of
the private wells (PW JR) provides water for the residence and business. The
other two private wells furnish water for the four rental houses, and water samples
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were collected from one of those wells (PWlS). The private wells furnishing
water for the rental houses are approximately 60 feet deep. The owner of the
property also installed two monitoring wells, located approximately 100 to 150
feet southeast of the lagoon area. As previously mentioned, the monitoring well
approximately 100 feet southeast of the site was sampled during the August 1997
PA/SI. Another well (PWIA) on the property, approximately 200 feet east of the
lagoon area, was abandoned in 1994 because a tenant of a house closest to the
well reportedly contaminated it with gasoline.
Of the 12 chemicals detected in samples collected from Private Wells PWlA,
PWlR, and PWIS (see Tables 4 through 6), the detected levels of only two
chemicals (i.e., iron and manganese) measured during a 1992 sampling event from
the abandoned well (PWlA) exceeded drinking water CVs (see Table 4). Even
though the levels of iron and manganese exceeded drinking water CVs, it is of no
public health concern now because the well in question is abandoned and water
from that well is not being used for either drinking or non-drinking purposes that
could lead to exposure [NC DENR 1998, NC DENR 2000).
Private Well PW33
Private Well PW33 is located approximately 800 feet northwest of the lagoon area
and serves at least two people (see Figures 1 and 2). The bored well is
approximately 56 to 62 feet deep. Of the ten chemicals detected in samples
collected from the well, only the maximum detected concentration of lead
exceeded its respective drinking water CV (see Table 7).
Private Well PW5
Of the five chemicals detected in a sample collected from Private Well PW5 (east
of the site; see Figure 2), drinking water CVs were available for only four.
However, these four chemicals were not selected for further public health
evaluation because none of the detected levels exceeded their respective drinking
water CVs (see Table 8).
Private Well PW3
Private Well PW3 (see Figures I and 2) is topographically down gradient of the
Sigmon source areas (i.e., 450 feet southwest of the lagoon area) and serves at
least one person. The bored well is approximately 27 feet deep. Sixteen of the 19
chemicals detected from samples were also detected on-site (most notably
mercury, nitrates, and VOCs). Thus, Private Well PW3 is probably another well
that is being impacted by the source areas located at the site .
5
Of the 19 chemicals detected in samples collected from Private Well PW3,
maximum detected concentrations for seven chemicals (i.e., nitrates, manganese,
mercury, bromodichloromethane, chloroform, dibromochloromethane,
1,4-dichlorobenzene) exceeded drinking water CVs (see Table 9).
• Private Well PW32
A private well is located at the facility that is used for drinking purposes. The
well is located approximately 1,200 feet north of the lagoon area and serves at
least two people (see Figure 1). Of the two chemicals detected in the well, none
of the detected levels exceeded any available drinking water CVs (see Table 10).
• Private Well PW4
Private Well PW4 is located approximately 1,100 feet northeast of the lagoon area
and serves at least one person (see Figure 1 ). The bored well is approximately 50
feet deep. The sample collected during the 1997 P NSI was intended to be used as
a background sample.
Of the nine chemicals detected in samples collected from the well, maximum
detected concentrations for two chemicals (i.e., lead and 1,4-dichlorobenzene)
exceeded drinking water CVs (see Table 11).
The maximum detectable level of 1,4-dichlorobenzene was measured in the well
during the 1997 P NSI. The validity of this measurement is in doubt because the
level via the extractable method was used, while the more reliable purgeable
method did not record any VOC levels in the well for this chemical or any other
volatile chemicals at a detection limit of 5 ppb.
• Private Well PW34
Private Well PW34 is located approximately 600 feet east of the lagoon area and
serves at least three people (see Figure 1). The well is 363 feet deep. Of the two
chemicals detected in a sample collected from the well, none of the detected levels
exceeded any available drinking water CVs (see Table 12).
• Private Well PW6
Private Well PW6 is located north of the site and was used as the background well
for the 1999 ESI (see Figure 2). Of the six chemicals detected in a sample
collected from the well, only five had available drinking water CVs. These five
chemicals were not selected for further public health evaluation because none of
the detected levels exceeded their respective drinking water CVs (see Table 13).
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Of the samples collected from l l nearby private wells surrounding the site, ten chemicals (i.e.,
Nitrates; Lead; Mercury; Iron; Manganese; 1,4-Dichlorobenzene; l ,2-Dichloroethane;
Bromodichloromethane; Chloroform; and Dibromochloromethane) were selected for further
public health evaluation because their maximum detect levels exceeded drinking water CVs (see
Table 14).
Three additional substances (i.e., calcium; magnesium; potassium) were also selectively screened
for further public health evaluation because there are no available drinking water CVs for these
elements (see Table 14). All three of these substances are essential elements required for normal
human growth and maintenance of health. Calcium is required for the development of strong
bones, magnesium is an essential cofactor of many enzymes, and potassium is important in the
transmission of nerve impulses.
The estimated maximum daily intake rates of these elements for an adult and a child who
consume water containing the maximum chemical levels found in the private wells sampled near
the Sigmon's Septic Tank Service Facility, are listed below. These estimated intake rates are
compared to the elements' Recommended Daily Allowance (RDA) Ranges that include children
and adults of various age groups. The estimated intake rates are too low to even meet the
minimal physiological requirements as set by the RD As. Therefore, these three elements (i.e.,
calcium, magnesium, and potassium) will not be evaluated any further in this health consultation.
Exposure Pathways
Element
Calcium
Magnesium
Potassium
RDA Comparison·
Estimated Daily Intake Rate
(mg/day)
Adult1 Child2
190 95
24 12
14 7
RDA Range
(mg/day
800-1,200
150-350
1,600 -3,500
1 Assuming the average adult weighs 70 kg (i.e., 150 lbs.) and
consumes 2 titers of water per day.
2 Assuming the average child weighs 10 kg (i.e., 20 lbs.) and
consumes 1 liter of water per day.
Chronic or long-term exposure to chemicals in the groundwater can occur via ingestion,
inhalation (i.e., VOCs), and dermal contact, when groundwater is used for drinking, showering,
bathing, and other household purposes. Studies indicate that significant exposures to VOCs can
occur during these activities as the chemicals volatilize, and are then subsequently inhaled and/or
absorbed through the skin. These exposures to VOCs may equal or exceed those from ingestion,
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usually, by no more than a factor of 2 [Jo et al 1988, Kerger & Paustenbach 2000, Kezic et al
1997, Mattie et al 1994, EPA 1999].
For the purposes of this health consultation, the primary route of human exposure is considered
to be ingestion. Inhalation exposure was determined to have no public health implications
because of the following: (1) VOCs were estimated to be released into the air at very low levels
(i.e., 0.0024 parts per miHion for 1,2-dichlorobenzene, 0.0022 parts per million for
1,4-dichlorobenzene, 0.0001 parts per million for 1,1-dichloroethane, etc.) during showering and
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other uses [Andelman 1990], (2) the estimated VOC levels in air (i.e., a conservative
approximation assuming the worst case scenario) were well below CVs for inhalation exposures
that considered both short-term and long-term exposures, (3) a dermal study indicated that 2% to
5% of organic chemicals (i.e., non-polar compounds) in an aqueous matrix are absorbed through
the skin during a 30-minute period [Webster et al 1987]; therefore, the absorption of organic
chemicals through dermal exposure from showering under such conditions (i.e., low-level water
concentrations) is also considered to be negligible, and (4) the detected metals in water will
neither volatilize into the air nor be absorbed through the skin because the detected metals are
dissolved in solution and not so readily released.
Public Health Implications
Based on ATSDR's review of the groundwater sampling and analysis data, the following
chemicals were selected for further public health evaluation: nitrates; lead; mercury; iron;
manganese; 1,4-dichlorobenzene; 1,2-dichloroethane; bromodichloromethane; chloroform; and
dibromochloromethane. With the exception of nitrates, these chemicals were classified as metals
(i.e., lead, mercury, iron, manganese) or VOCs (i.e.; 1,4-dichlorobenzene; 1,2-dichloroethane;
bromodichloromethane; chloroform; dibromochloromethane ).
Nitrates
The toxicity of nitrates is due to its conversion to nitrites by bacteria in the gastrointestinal tract
(i.e., intestines). Infants are especially susceptible to methemoglobinemia because the higher pH
of their gastric juice is more compatible with the growth of nitrate-reducing bacteria in the gut.
Older children, with their more acidic gastric juices, are much less susceptible [Craun et. al.
1981]. Nitrite oxidizes the Fe(+2) of iron in hemoglobin to the Fe(+3) state. The resulting
compound (methemoglobin) does not bind oxygen, so that the blood cannot transport as much
oxygen from the lungs to the tissues. Infants arc the particularly scnsiti veto nitrate/nitrite
toxicity. The characteristic blueness (cyanosis) of lips and mucous membranes, which generally
precedes the adverse symptoms of methemoglobinemia, can be produced by methemoglobin
levels as low as 10%. Methemoglobin levels under 30% produce minimal symptoms (fatigue,
lightheadedness, headache) in healthy children and adults, while levels between 30% and 50%
cause moderate depression of the cardiovascular and central nervous systems (weakness,
headache, rapid breathing and heartbeat, mild shortness of breath). Levels between 50% and
70% cause severe symptoms (stupor, slow and abnormal heartbeat, respiratory depression,
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convulsions), and levels above 70% are usually fatal [Ellenhorn, et. al., 1988]. Any levels of
methemoglobin that might be associated with the maximum detected nitrate levels in water from
private wells at this site are likely to be less than 2%. (See discussion below.)
EPA has developed a chronic oral reference dose for the ingestion of nitrates based on the early
clinical signs of methemoglobinemia (cyanosis) in infants ingesting water containing varying
concentrations of nitrate-nitrogen. That RID is set equivalent to the observed NOAEL (i.e., No
Observed Adverse Effect Level) of 1,600 µg nitrate-nitrogen/kg/day which is the dose that would
be received by a 0-3 month old infant weighing approximately 8.8 pounds (4 kg) and drinking
0.64 liters/day of water (as formula) containing 10,000 ug/L nitrate-nitrogen.
One primary source of organic nitrates is human sewage, which is the type of business conducted
at the site (i.e., removal and handling of septic wastes). Due to their high solubility and weak
retention by soil, nitrates and nitrites are very mobile in soil and have a high potential to migrate
to groundwater. Most nitrogenous materials in natural waters tend to be converted to nitrate, so
all sources of combined nitrogen, particularly organic nitrogen and ammonia, should be
considered as potential nitrate sources. Because it does not volatilize, nitrate/nitrite is likely to
remain in water until consumed by plants or other organisms. Ammonium nitrate will be taken
up by bacteria. Nitrate is more persistent in water than the ammonium ion. Nitrate degradation is
fastest in anaerobic conditions.
Nitrate was detected at levels above drinking water CVs in two private wells, Private Wells PW2
and PW3, near the site. The estimated daily dose of nitrate from water containing 23,350 ppb
(maximum nitrate detection in Private Well PW2) would be 667 µg/kg/day for a 70 kg (i.e., 150
pounds) adult ingesting two liters of water per day; 2,335 µg/kg/day for a 10 kg (i.e., 20 pounds)
child ingesting one liter of water per day; and 3,736 µg/kg/day for a 4 kg (i.e., 8 pounds) infant
ingesting 0.64 liters of water (as formula) per day. Although the estimated daily dose for a child
is slightly higher than the RID, non-cancerous health effects are not expected in adults or
children older than six months at these dose levels. Although it is not recommended that infants
1-3 months of age be chronically exposed to levels of nitrates that exceed EPA' s RID (in this
case, by a factor of 2.3), adverse effects would not be likely to occur in them, either. In one
study, oral doses of nitrate ranging from 100 µg/kg/day to 15,500 µg/kg/day in 111 infants less
than six months old was associated with methemoglobin levels as high as 5.3% (mean 1.6%),
but none of the children had the typical symptoms of methemoglobinemia [Winton, et. al., 1971].
In another study, mean methemoglobin levels were only 1.3% in infants aged 1-3 months who
received waler containing l l,000-23,000 µg nitrate-nitrogen/L [Simon et al., 1964]. No clinical
signs of methemoglobinemia were detected in any of these infants, either. Low levels of
methemoglobin (0.5 to 2.0%) occur normally and, due to the large excess capacity of blood to
carry oxygen, levels of methemoglobin up to 10% are seldom associated with any clinically
significant signs such as cyanosis (IRIS 2001). Most cases of infant methemoglobinemia are
associated with exposure to nitrate in drinking water used to prepare infants' formula at levels
>20,000 ppb of nitrate-nitrogen. However, cases have been reported at levels of 11,000-20,000
ppb nitrate-nitrogen, especially when associated with concomitant exposure to bacteriologically
9
contaminated water or excess intake of nitrate from other sources. Therefore, if other sources of
drinking water are available, well water from Private Well PW2, and possibly Private Well PW3,
should not be used for making infant formula.
On July 11, 2001, an ATSDR regional representative learned that a six-month-old baby lived in a·
home located on the same street as Private Wells PW2 and PW3, probably impacted by the
source areas located on site [ATSDR 2001c]. During the 1997 PNSI, the well for this home was
not tested because there was no response to NC DENR messages left at the door. However, the
ATSDR regional representative learned from one of the occupants that they used bottle water for
both cooking and drinking. The same ATSDR regional representative later learned that the water
supplied to the home is from Private Well PWlR [ATSDR 200le]. Past sampling (i.e., 1997
PNSI) has indicated that no chemicals from the site have impacted Private Well PWlR.
Initially, EPA planned to sample the well supplying water to the home in question during
November 2001; however, upon learning that the well water originated from Private Well
PWlR, they concluded there was no immediate need to resample the well because it was not
contaminated [ATSDR 2001d, ATSDR 200le]. (Note, detected nitrate levels in Private Well
PWlR were no higher than 1,400 ppb as of August 1997.) Even though the water from Private
Well PWlR is probably safe for an infant to consume, ATSDR recommends that EPA
periodically collect and analyze groundwater samples, especially for nitrates, for households with
infants and small children until the sources areas are removed from the site.
Metals
Lead, mercury, and two nutrient metals, iron and manganese, were detected in several private
wells near the site. The public health implications of these metals are discussed below.
Lead
The EPA Office of Drinking Water has established 15 ppb as an action level for lead in drinking
water [EPA 1991]. For children and adults drinking water with lead levels at 1-14 ppb, no action
is necessary; however, children and pregnant females, should stop drinking the water if it
contains lead levels at 15 ppb or greater. Furthermore, one may want to consider not using the
water for cooking, especially if children and pregnant females reside in the household. Adults
drinking water with lead levels of 15 to 50 ppb should try to reduce their consumption, and water
containing lead levels at 50 ppb or greater should not be used for either drinking or cooking.
Lead was detected in five private wells near the Sigmon's Septic Tank Service Facility; however,
only two wells (Private Wells PW33 and PW4) contained lead levels (17 ppb and 28 ppb
respectively) that exceeded EPA's Lead Action Level of 15 ppb. EPA's Lead Action Level of
15 ppb was exceeded only once in each well between 1994 and 1999. Intermittent exposures of
this type (i.e., limited and infrequent excursions above the action level of 15 ppb) over an
extended period of time (e.g., more than a year) are not likely to be associated with any adverse
health effects. As estimated by EPA' s Integrated Exposure Uptake Biokinetic Model for Lead in
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Children (IEUBK), a blood lead level increase of 2 µg/dL is expected in children drinking water
containing the maximum lead level (28 ppb) found in the Private Well PW4 [EPA 2001].
Inasmuch as average blood lead levels in the U.S. (i.e., levels not associated with toxicity) fell by
five times that amount (from 12.8 to 2.8 µg/dL) in the 1980s (i.e., between NHANES II and ID),
an increase of 2 µg/dL is not likely to be of any toxicological significance. However, since it is
the total blood lead level, and not some increment, that is associated with health risks, concerned
residents should ask their local physicians to determine their blood lead levels.
The health effects of lead are not immediately apparent. Once in the blood, lead is distributed to
the soft tissue (kidneys, bone marrow, liver, and brain) and mineralizing tissue (bones and teeth).
Bones and teeth contain about 95% of the total body burden of lead [ATSDR 1999b]. It is the
level of lead in the blood that is related to the risk of adverse health effects, and the small
amounts of lead that are released from the bones over time contribute to those blood levels.
Thus, cumulative, low-level exposures, as well as higher acute exposures, can be of potential
health concern, especially in pregnant women. However, CDC's current limit of 10 ug/dL is
designed to be protective of the public's health and does not constitute an established level of
toxicity. Exposure to very high levels of lead can cause anemia and encephalopathy (80-100
µg/dL), kidney damage in adults (40 -100 µg/dL) and children (35 -50 µg/dL), and increased
blood pressure in adult males (30 µg/dL) [Goyer 1996, Table 23-5, pg 705]. Acute effects of
exposure to high lead levels are nausea, vomiting, and headache. High levels of blood lead (40
µg/dL) may affect sperm or damage other parts of the male reproductive system making it
difficult for a couple to have children [ATSDR 1999b].
Certain subgroups of the population may be more susceptible to the harmful effects of lead
exposure: preschool age children ( < 6 years old), pregnant women and their fetuses, and the
elderly. Other susceptible people may include those with genetic diseases affecting heme
synthesis (a component of the blood), nutritional deficiencies (especially iron and calcium), and
neurological or kidney dysfunctions. Smoking cigarettes and drinking alcohol also may increase
the risk of noncancerous health effects to lead exposure [ATSDR 1999b].
EPA has concluded that the human data are inadequate to determine if lead exposure could cause
cancerous health effects in people. However, based on sufficient evidence in animals and
inadequate evidence in humans, EPA has classified lead as a probable (B2) human carcinogen.
A simple medical test is available for screening blood lead levels. People who are concerned
about their exposure lo lead should sec their doctor for more information. In addition, there arc a
number of short-term remedies that you can take to reduce the lead concentrations in your
drinking water and, thus, your exposure to lead.
If the source of lead is the plumbing, let the water run from the tap for from 30 seconds
to two minutes before using it for drinking and cooking. The longer water stays in water
pipes, the more lead may have dissolved out of the lead pipes. Water that has been in the
pipes for more than four hours should be flushed for three to five minutes, for example,
11
first thing in the morning and when you arrive home in the evening. A good indication of
when to stop flushing the cold water tap is when the water becomes noticeably colder.
Use cold water for cooking or making infant formula because water from the hot water
tap tends to dissolve lead more quickly, which will cause lead concentrations to be higher
in hot water.
If the source of lead is the groundwater and your tap water contains lead in excess of 15
ppb even after flushing, then you may want to consider using bottled water instead of tap
water for drinking or cooking purposes. Alternatively, you may choose to use a water
purification system. Purification systems range in size and cost from the water pitcher
filtration systems to purification systems for the entire household.
Mercury
•
Mercury was selected for further analysis because the average (2.8 ppb) and maximum (7 ppb)
levels detected in drinking water wells at the Sigmon site exceeded the MCL of 2 ppb (Table 14),
but only marginally so, relative to built-in margins of safety. (The RID for mercuric chloride
contains an uncertainty factor of 1000.) ATSDR currently has no comparison values specific for
inorganic mercury. However, concentrations of mercury in groundwater at the Sigmon site did
not exceed ATSDR's CVs for either chronic or intermediate duration exposure to mercury
chloride via the oral route in adults. More importantly, the dose (0.2 µg/kg/day) that would
result if a 70-kg adult (i.e., 150 pound adult) consumed 2 liters of water per day containing the
maximum level of mercury (7 ppb) detected near the Sigmon's Septic Tank Facility is at least •
1000 times lower than the lowest known LOAELs for inorganic mercury (the predominant form
in water) in humans or animals exposed via the oral route [ATSDR 1997, Table 2-2). This
maximum estimated dose is also below all known LOAELs for organic mercury in humans or
animals exposed via the oral route. Therefore, none of the levels of mercury detected in
groundwater at the Sigmon site would be expected to produce adverse health effects of any kind
in exposed residents.
Nutrient Metals: Iron & Manganese
The Environmental Protection Agency (EPA) has established non-enforceable Secondary
Drinking Water Guidelines (SDWGs) to maintain the aesthetic quality of water, including its
taste and odor. EPA's SDWGs for iron and manganese are 300 and 50 ppb, respectively. At
c;unccntrations above the SDWGs, iron and manganese may cause undesirable tastes, deposit on
foods during cooking, and leave reddish-brown (iron) or brownish-black (manganese) stains on
plumbing fixtures and laundry. The concentrations of iron and manganese in some of the
residential wells surrounding the Sigmon's Septic Tank Facility were above these non-health-
based standards.
The water samples collected from nearby private wells surrounding the site contained from 14 to
5,500 ppb iron. Water containing about 300 ppb of iron or more may not taste very good, but
12 •
•
•
even at 5,500 ppb iron, no adverse health effects would be expected. Iron is among the most
abundant elements prese!]t naturally in the Earth's crust, and there is very little risk of toxicity
from iron in natural foods and water. This is because (1) iron is an essential element in the
human diet and (2) the body has a number of mechanisms specifically designed to maintain a
·relatively constant blood level in the face of wide variations in dietary intake [Goyer, 1996, pp
715-16]. The recommended daily allowance of iron for adult males and females of reproductive
age is 10 and 18 mg, respectively. (As noted previously, the secondary MCL of 0.3 mg/Lis
based on taste and appearance, and not on any potential for adverse health effects.) The long-
term toxic levels of dietary iron seen in most monogastric animals (i.e., those with a single
stomach) are generally 340 to 1,700 times greater than the nutritional requirement for humans
[NRC 1980, pp 309-12,and Table V-12 on page 320]. By comparison, for women of
reproductive age whose iron requirements are met entirely by food alone, and who additionally
consume 2Uday of well water containing 5,500 ppb iron, the total daily dietary intake of iron
would be little more than twice the nutritional requirement. Thus, while iron toxicity is a
possibility under certain circumstances, drinking water is seldom the source of toxic exposures.
Manganese (Mn) is another nutrient metal with very limited toxic potential via the oral route. .
(Adverse effects in humans resulting from manganese exposure are associated primarily with
inhalation exposure in occupational settings such as mining.) The levels of manganese in private
wells in the vicinity of the site ranged from 4.2 to 830 ppb. Assuming consumption of 2Uday for
adults and lllday for children, the highest concentration of manganese detected in wells around
the site (830 ppb) would correspond to a daily intake of only _1.66 mg Mn/day for adults and half
that for a small child. These amounts are of little consequence when compared to safe normal
dietary exposures. The World Health Organization (WHO) estimates that the average daily
intake of Mn ranges from 2 to 8.8 mg Mn and that 8-9 mg/day is perfectly safe. A normal diet,
especially a vegetarian diet, may contain well over 10 mg Mn/day or 0.14 mg Mn/kg/day for a 70
kg adult [NRC 1980]. The maximum concentration detected does exceed the secondary MCL of
50 ppb, but this MCL, like the one for iron, is based solely on aesthetic considerations. (At
concentrations over 2,000 ppb, Mn precipitates upon oxidation and causes undesirable tastes,
deposits on foods during cooking, and leaves black stains on plumbing fixtures and laundry.)
Therefore, the Mn levels detected in private wells around the site are expected to have no public
health implications.
voes
Based on the: pri vale well sampling data, the concentrations for none of the detected VOCs
exceeded EPA's MCLs or any CVs for non-cancer effects. The maximum concentrations of five
VOCs ( bromodichloromethane, chloroform, dibromochloromethane, 1,4-dichlorobenzene, and
1,2-dichloroethane) did exceed their respective cancer-based CVs for drinking water. These CVs
were based on studies in which laboratory animals were force-fed very high, single, daily doses
of the substance in oil over most of the animals' lifetimes, an experimental practice that
maximizes the instantaneous assault on the animals' defense systems and increases the likelihood
that toxic effects will be produced. However, humans are exposed to chloroform and other
13
chlorination by-products in drinking water (not in gavage oil) and substances like chloroform and
dibromochloromethane do not cause cancer in laboratory animals when they are administered in
drinking water. This is probably because (a) the substances are less soluble in water than in oil
and (b) the total daily dose in humans is spread out over the entire day so that each individual
dose is much smaller (and, therefore, more easily detoxified) than the single daily dose
administered to laboratory animals. Therefore, ATSDR considers that neither cancer nor non-
cancer effects would be expected to occur as a result of site-specific exposures to VOCs in
drinking water at the Sigmon site, even with a lifetime of exposure.
Assessment Limitations
The following issues should be noted regarding the groundwater contamination found near the
Sigmon's Septic Tank Service Facility:
• Unknown aquifer conditions -ATSDR was not provided enough information to identify
the site groundwater flow direction and groundwater level fluctuations with seasonal
variations. Knowing the site groundwater flow direction would give better insight to
which private wells are actually being impacted by the source areas located at the site.
Furthermore, the groundwater plume has not been properly delineated to determine where
the minimum and maximum concentration levels are located within the area's
groundwater.
• Unknown lead sources -Lead was detected in five private wells near the Sigmon's Septic
Tank Service Facility; however, only two wells (Private Wells PW33 and PW4)
contained lead levels (17 ppb and 28 ppb respectively) above EPA's Lead Action Level of 15 ppb. Both of these wells are topographically up gradient (i.e., "uphill") of the
source areas located at the site. Also, at the time these lead levels were detected (i.e.,
1997 PA/SI), they were higher than the lead level (12 ppb) detected in on-site monitoring
well MW I A. Therefore, even though lead is a site contaminant, it is probable that other
attributable sources, such as plumbing (lead piping, lead-based solder, and water faucets
containing lead), were responsible for. the high measurements. These varied results could
also indicate the possibility of discrepancies in sampling location (i.e., indoor or outdoor
tap sample collection) or faucet run-time.
• Unknown well construction quality-Because the Sigmon's Septic Tank Service Facility
is located in a rural area, it was difficult to determine when some ol' these pri vatc wcllo
were constructed. Becaus_e the construction details were not provided, it was also hard to
verify the wells' integrity. (Note that contaminants may enter poorly constructed wells
more easily than wells of good quality.)
• Differences in well sampling plans -Of the 11 private wells sampled between 1991
through 1999, there was no consistency in the number of samples collected from each
well, ranging from one sample per well to ten samples per well. In addition, each
14
•
•
•
•
•
•
sampling event (e.g., 1997 PNSI, 1999 ESI, etc.) did not sample all of the same wells,
sometimes even changing the well used to measure background levels. For both the 1997
PNSI and 1999 ESI, the chemical analysis methods seem to be the same, analyzing for
metals, SVOCs, and VOCs; however, it is unknown which methods were used for
analysis of the other samples collected before the 1997 PNSI. Inconsistencies such as
these can be alleviated if a uniform sampling plan is adhered to, one in which the same
set of wells and the same methods of chemical analysis are employed for each sampling
event.
Unknown origin of chlorination by-products -Three VOCs (i.e., the trihalomethanes
bromodichloromethane, chlorodibromomethane, and chloroform) detected in the Private
Well PW3 (note, only chloroform was detected in Private Well PW4) are common by-
products of the chlorination cif drinking water. None of these chemicals were detected in
the on-site monitoring wells. While chlorination of the well water would be a plausible
source of the observed trihalomethanes, it is unknown whether an alternative method (or
no method at all) was used to purify the well water. It is also possible that the
trihalomethanes leached from septic tank leaching fields. Chlorination is an effective
means of treating drinking water for microbial agents (e.g., coliform, cryptosporidium,
giardia lambia, etc.); however, guidelines are set to ensure that the chlorination of non-
municipal water sources is done correctly. Therefore, it may be wise to contact your
county health department to determine if the proper guidelines for ehlorinating such water
sources are being followed .
• Unknown presence of microbial agents -Drinking water quality can also be affected by
the presence of microbial agents. Unpleasant taste, odor, and color of water are not only
caused by elevated levels of metals such as iron and manganese, but by some types of
bacteria as well. Due to the type of business conducted at the Sigmon's Septic Tank
Service Facility, there may be microbial agents migrating from the source areas located at
the site. ATSDR contacted the Iredell County Health Department and was informed by a
representative that none of the private wells near the Sigmon's Septic Tank Facility have
been sampled/analyzed for fecal and total coliform counts. The representative stated that
the Iredell County Health Department would provide such an analysis upon the request of
any concerned well owner who feels their well has been contaminated by microbial
agents.
ATSDR's Child Health Initiative
As part of ATSDR's Child Health Initiative, ATSDR considers children in the evaluation for all
environmental exposures and uses health guidelines that are protective for children. When
evaluating any potential health effects via ingestion, children are considered a special population
because their lower body weight causes an increased body burden (i.e., higher exposure doses),
which can make them more susceptible to adverse health effects via chemical exposure. Average
15
body weight differences, as well as average differences in child-specific intake rates for various
environmental media, are taken into account by ATSDR's child Environmental Media
Evaluation Guides (EMEGs).
The maximum levels of nitrate detected (23,350 ppb) could pose an increased risk of higher
methemoglobin levels to very young infants (less than six months of age) drinking formula
prepared with private well water. However, the information available to ATSDR suggests that
no infants lived in the homes serviced by the wells containing high levels of nitrate.
Nevertheless, as a matter of prudent public health policy, ATSDR recommends that households
with infants and small children, have their well water tested periodically to assure that the
concentrations of nitrates and lead are within safe drinking water standards.
Conclusions
1. At the concentrations detected between 1991 and 1999, the chemicals identified in the
following private wells surrounding the Sigmon's Septic Tank Service Facility, pose no
apparent public health hazard to area residents using these wells: Private Wells PWIA,
PWIR, PWIS, PW5, PW6, PW32, and PW34.
2. Private Wells PW2 and PW3 showed nitrate levels greater than 10,000 ppb. This could
pose an increased risk of higher methemoglobin levels in very young infants (0 to 6
months) drinking formula prepared with water from these wells.
3. Private Wells PW33 and PW4 contained lead levels that exceeded EPA's Lead Action
Level of 15 ppb at least once in each well between 1994 and 1999. Intermittently
elevated exposures of this type (i.e., limited and infrequent excursions above the lead
action level) over an extended period of time are not likely to produce adverse health
effects.
4. ATSDR identified several limitations in the site investigations regarding groundwater
contamination found near the Sigmon's Septic Tank Service Facility: I) Unknown
Aquifer Conditions, 2) Unknown Lead Sources, 3) Unknown Well Construction Quality,
4) Differences in Well Sampling Plans, 5) Unknown Origin of Chlorination By-products,
and 6) Unknown Presence of Microbial Agents. Based on the information provided,
ATSDR concluded the site currently pose no apparent public health hazard to area
residents; however, it is uncertain of what impact these limitations may impose in the
future regarding long term exposure to residential well water near the site.
16
•
•
•
• Recommendations:
•
•
l. Give consideration to removing the source areas from the Sigmon's Septic Tank Service
Facility so as to prevent or mitigate any potential migration of chemicals into nearby
private wells.
2. Continue to routinely collect and analyze groundwater samples from both the monitoring
wells and nearby privates wells surrounding the site until these source areas are removed.
3. Periodically test well water, especially for nitrates and lead, for households with infants
and small children until the source areas at the Sigmon's Septic Tank Service Facility are
removed.
4. Do not use well water from Private Wells PW2 and PW3 to prepare infant formula until it
is confirmed that the nitrate levels are below 10,000 ppb. And, continue monitoring to
assure that nitrate levels do not exceed 10,000 ppb in the future.
5. Inform the residents living near the Sigmon's Septic Tank Service Facility that the Iredell
County Health Department would provide an analysis of fecal and total coliform counts
upon the request of any concerned well owner who feels their well has been contaminated
by microbial agents .
6. Collect the hydro-geological information required to identify the direction of groundwater
flow near the site and groundwater level fluctuations with seasonal variations. Knowing
the direction of groundwater flow would give better insight into which private wells are
actually being impacted by the source areas located at the site .
17
• Prepared by
•
•
Environmental Health Scientist
Toxicologist
Writer/Editor
Reviewed by
Chief
Chief,
Health Consultation Section
Regional Representative,
Region IV
David S. Sutton, PhD
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Frank C. Schnell, PhD, DABT
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Kathryn D. Harmsen, MPH
Office of Policy and External Affairs
Agency for Toxic Substances and Disease Registry
John E. Abraham, PhD, MPH
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Susan Moore, MS
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Benjamin Moore
Office of Regional Operations
Agency for Toxic Substances and Disease Registry
18
•
•
References
'Andelman JB. 1990. Total Exposure to Volatile Organic Compounds in Potable
Water (in textbook entitled "Significance and Treatment of Volatile Organic
Compounds in Water Supplies"). Lewis Publishers. Chelsea, MI. 485-504.
*Andres P. 1984. lgA-lgG Disease in the Intestine of Brown Norway Rats
Ingesting Mercuric Chloride. Clin. lmmunol. lmmunopathol. 30: 488-494.
Agency for Toxic Substances and Disease Registry. December 1989.
Toxicological Profile for Bromodichloromethane. US DHHS, Public Health
Service; Atlanta, GA.
Agency for Toxic Substances and Disease Registry. December 1990.
Toxicological Profile for Chlorodibromomethane. US DHHS, Public Health
Service; Atlanta, GA.
Agency for Toxic Substances and Disease Registry. September 1997.
Toxicological Profile for Chloroform (Update). US DHHS, Public Health
Service; Atlanta, GA .
Agency for Toxic Substances and Disease Registry. December 1998.
Toxicological Profile for l,4-Dichlorobenzene (Update). US DHHS, Public
Health Service; Atlanta, GA.
* Agency for Toxic Substances and Disease Registry. March 1999a.
Toxicological Profile for Mercury (Update). US DHHS, Public Health Service;
Atlanta, GA.
* Agency for Toxic Substances and Disease Registry. July 1999b. Toxicological
Profile for Lead (Update). US DHHS, Public Health Service; Atlanta, GA.
Agency for Toxic Substances and Disease Registry. August 1999c.
Toxicological Profile for 1,2-Dichloroethane (Draft Update-Public Comment).
US DHHS, Public Health Service; Atlanta, GA.
Agency for Toxic Substances and Disease Registry. September 2000.
Toxicological Profile for Manganese (Update). US DHHS, Public Health Service;
Atlanta, GA.
'Cited in text
19
*ATSDR Electronic Mail, To: Susan Moore, Section Chief, Consultations
Section, Exposure Investigations and Consultations Branch, Division of Health
Assessment and Consultation, ATSDR, Atlanta, GA, From: Benjamin Moore,
Office of Regional Operations, ATSDR, Region 4, Atlanta, GA, Date: June 27,
2001a.
Agency for Toxic Substances and Disease Registry. "Drinking Water Comparison
Value Table." US DHHS, Public Health Service; Atlanta, GA. June 30, 2001b.
* Agency for Toxic Substances and Disease Registry. ATSDR Record of Activity.
Site Visit Report. Sigmon's Septic Tank Service (CERCLIS No.:
NCD062555792), Statesville, Iredell County, North Carolina. Date: July 11,
2001c.
*Agency for Toxic Substances and Disease Registry. ATSDR Record of Activity.
Site Visit Report. Sigmon' s Septic Tank Service (CERCLIS No.:
NCD062555792), Statesville, Iredell County, North Carolina. Date: September
26, 2001d.
*ATSDR Electronic Mail, To: Benjamin Moore, Office of Regional Operations,
ATSDR, Region 4, Atlanta, GA, From: Giezelle Bennett, EPA, Region 4,
Atlanta, GA, Date: November 19, 200le.
*Bemaudin JF, Drue! E, Druet P, and Masse R. 1981. Inhalation or Ingestion of
Organic or Inorganic Mercurials Produces Auto-Immune Disease in Rats. Clin.
Irnmunol. Immunopathol. 20: 129-135.
*Craun, GF, DG Greathouse and DH Gunderson. 1981. Methemoglobin levels in
young children consuming high nitrate well water in the United States. Int. J.
Epidemiol. 10(4): 309-317.
*Druet P, Druet E, Potdevin F, and Sapin C. 1978. Immune Type
Glomerulonephritis Induced by HgCl2 in the Brown Norway Rat. Ann. Irnmunol.
129C: 777-792.
*Ellcnhorn MJ and Barccloux DG. 1988. Medical Toxicology: Diagnosis and
treatment of human poisoning. Elsevier Science Publishing Company, Inc., New
York, NY, pg. 849
Environmental Protection Agency. Guidelines for Carcinogenic Risk Assessment.
Fed. Reg., 51: 33997-33998, September 24, 1986.
*EPA. 1991. U.S. Environmental Protection Agency. National Primary Drinking
Water Regulations. Code of Federal Regulations.
20
•
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•
•
Environmental Protection Agency. October 1996. Drinking water regulations and
health advisories. Office of Water. EPA 822-B-96-002.
Environmental Protection Agency. May 5, 1998a. URL:
http://www.epa.gov/i1is/subst/0076.htm "Safe Drinking Water Fact Sheet for
Nitrate."
Environmental Protection Agency. December 16, 1998b. National Primary
Drinking Water Regulations: Disinfectants and Disinfection By Products; Final
Rule. Federal Register: Vol. 63, No. 241, pp 69389-69476.
*Environmental Protection Agency. 1999. "Risk Assessment Guidelines for
Dermal Assessment." Washington, DC.
*Environmental Protection Agency. 2001. URL:
http://www.epa.gov/superfund/programs/lead/ieubk.htm "The IEUBK."
Environmental Protection Agency, Region Ill Office. "Risk-Based Concentration
Table." Philadelphia, Pennsylvania. May 8, 200 I.
*Goyer, Robert A. Toxic Effects of Metals. Chap. 23 of Casarett and Doull's
TOXICOLOGY: The basic Science of Poisons. McGraw-Hill, New York, N.Y.,
1996, pp 691-736.
*Integrated Risk Information System. U.S. Environmental Protection Agency,
Office of Health and Environmental Assessment, Environmental Criteria and
Assessment Office, Cincinnati, OH.
*Jo WK, Weisel CP, Lioy PJ. 1988. "Routes of Chloroform Exposure and Body
Burden from Showering with Chlorinated Tap Water." Risk Anal. 10:575-580.
*Kerger Band Paustenbach D. 2000. "Exposure to 1,1,1-TCE Vapors in a Home
Due to Contaminated Groundwater." Risk Anal. in press.
*Kezic S, Mahieu K, Monster AC, de Wolff FA. 1997. "Dermal Absorption of
Vaporous and Liquid 2-Mcthoxycthanol and 2-Ethoxycthanol in Volunteers."
Occup. Environ. Med. 54:38-43.
*Mattie DR, Bates GD (Jr.), Jepson GW, Fisher JW, McDougal JN. 1994.
"Determination of Skin-Air Partition Coefficients for Volatile Chemicals:
Experimental Method and Applications." Fundam. Appl. Toxicol. 22:51.
21
*North Carolina Department of Environment and Natural Resources-Division of
Waste Management-Superfund Section. Combined Preliminary Assessment/Site
Inspection Report. Sigmon's Septic Tank Service (CERCLIS No.:
NCD062555792), Statesville, Iredell County, North Carolina, Reference No.
06611. September 1998.
*North Carolina Department of Environment and Natural Resources-Division of
Waste Management-Superfund Section. Expanded Site Inspection Report.
Sigmon's Septic Tank Service (CERCLIS No.: NCD062555792), Statesville,
Iredell County, North Carolina, Reference No. 0406611. March 2000.
*National Research Council, Safe Drinking Water Committee, National Academy
Press, Washington, D.C. Drinking Water and Health. Volume 3. 1980.
*National Toxicology Program. 1993. "Toxicology and Carcinogenesis Studies
of Mercuric Chloride (CAS No. 7487-94-7) in F344/N Rats and B6C3Fl Mice
(gavage studies)." U.S. Department of Health and Human Services, Public Health
Service, National Institutes of Health, Research Triangle Park, North Carolina.
NTP TR 408, NIH Publication No. 91-3139.
Public Health Assessment Guidance Manual. US DHHS, Public Health Service;
Atlanta, GA. March, 1992.
Salvato JA. 1992. Environmental Engineering and Sanitation. 4th edition. Chapter
3: Water Supply.
*Simon CH, Manzke HK and GM. 1964. "Occurrence, Pathogenesis, and
Possible Prophylaxis of Nitrite Induced Methemoglobinemia. Zeitschr.
Kinderheilk. 91:124-138. (German)
*Webster RC, Mobayen M, Maibach HI. 1987. "In Vivo and In Vitro Absorption
and Binding to Powdered Stratum Comeum _as Methods to Evaluate Skin
Absorption of Environmental Chemical Contaminants from Ground and Surface
Water." J. Toxicol. Eviron. Health 21:367-374.
22
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APPENDIX A
COMPARISON VALVES
ATSDR comparison values (CVs) are media-specific concentrations that are considered to be
"safe" under default conditions of exposure. They are used as screening values in selecting site-
specific chemicals for further evaluation of their public health implications. Generally, a
chemical is selected for further public health evaluation because its maximum concentration in
air, water, or soil at the site exceeds at least one of ATSDR's CVs. This approach is conservative
by design. ATSDR may also select detected chemical substances for further public health
evaluation and discussion because ATSDR has no CVs or because the community has ex.pressed
special concern about the substance, whether it exceeds CVs or not.
It cannot be emphasized strongly enough that CVs are not thresholds of toxicity. While
concentrations at or below the relevant CV are generally considered to be safe, it does not
automatically follow that any environmental concentration that exceeds a CV would be expected
to produce adverse health effects. In fact, the whole purpose behind highly conservative, health-
based standards and guidelines is to enable health professionals to recognize and resolve
potential public health problems before they become actual health hazards. For that reason,
ATSDR's CVs are typically designed to be I to 3 orders of magnitude lower (i.e., 10 to 1,000
times lower) than the corresponding no-effect levels or lowest-effect levels on which they are
based. The probability that adverse health outcomes will actually occur depends, not on
environmental concentrations alone, but on several additional factors, including site-specific
conditions of exposure, and individual lifestyle and genetic factors that affect the route,
magnitude, and duration of actual exposures.
Listed below are the abbreviations for selected CVs and units of measure used within this
document. Following this list of abbreviations are more complete descriptions of the various
comparison values used within this document, as well as a brief discussion on one of ATSDR's
most conservative CVs.
CREG = Cancer Risk Evaluation Guide
EMEG = Environmental Media Evaluation Guide
LTHA = Drinking Water Lifetime Health Advisory
MCL = Maximum Contaminant Level
MCLA = Maximum Contaminant Level Action.
MRL = Minimal Risk Level
RBC = Risk-Based Concentration
RID = Reference Dose
RMEG = Reference Dose Media Evaluation Guide
23
Units of Measure:
ppm = Parts Per Million [e.g., mg/L (water), mg/kg (soil)]
ppb = Parts Per Billion [e.g., µ.g/L ,(water), µ.g/kg (soil)]
kg = kilogram (1,000 grams)
mg = milligram (0.001 gram)
µ.g = microgram (0.000001 gram)
L = liter (1000 mL or 1.057 quarts of liquid, or 0.001 m3 of air)
m3 = cubic meter (a volume of air equal to 1,000 liters)
Cancer Risk Evaluation Guides (CREGs) are derived by ATSDR. They are estimated
chemical concentrations theoretically expected to cause no more than one excess cancer in a
million people exposed over a lifetime. CREGs are derived from EPA's cancer slope factors and
therefore reflect estimates of risk based on the assumption of zero threshold and lifetime
exposure. Such estimates are necessarily hypothetical for, as stated in EPA's 1986 Guidelines
for Carcinogenic Risk Assessment, "the true value of the risk is unknown and may be as low as
zero."
Drinking Water Equivalent Levels (DWELs) are lifetime exposure levels specific for drinking
water (assuming that all exposure is from that medium) at which adverse, noncarcinogenic health
effects would not be expected to occur. They are derived from EPAs RIDs by factoring in
default ingestion rates and body weights to convert the RID dose to an equivalent concentration
in drinking water.
•
Minimal Risk Levels (MRLs) are ATSDR's estimates of daily human exposure to a chemical •
that are unlikely to be associated with any appreciable risk of deleterious noncancer effects over a
specified duration of exposure. MRLs are calculated using data from human and animal studies
and are reported for acute G; 14 days), intermediate (15-364 days), and chronic~ 365 days)
exposures. MRLs for oral exposure (i.e., ingestion) are doses and are typically expressed in
mg/kg/day. Inhalation MRLs are concentrations and are typically expressed in either parts per
billion (ppb) or ug/m3• The latter are identical to ATSDR's EMEGs for airborne contaminants.
ATSDR's MRLs are published in ATSDR Toxicological Profiles for specific chemicals.
Environmental Media Evaluation Guides (EMEGs) are media-specific concentrations that are
calculated from A TSDR's Minimal Risk Levels by factoring in default body weights and
ingestion rates. Different EMEGs are calculated for adults and children, as well as for acute G:;14
days), intermediate (15-364 days), and chronic (;,365 days) exposures.
EPA's Reference Dose (RID) is an estimate of the daily exposure to a contaminant unlikely to
cause any non-carcinogenic adverse health effects over a lifetime of chronic exposure. Like
ATSDR's MRL, EPA's RID is a dose and is typically expressed in mg/kg/day.
Reference Dose Media Evaluation Guide (RMEG) is the concentration of a contaminant in air,
water, or soil that ATSDR derives from EPA's RID for that contaminant by factoring in default
24 •
• values for body weight and intake rate. RMEGs are calculated for adults and children. RMEGs
are analogous to ATSDR's EMEGs.
Risk-Based Concentrations (RBCs) are media-specific values derived by the Region III Office
of the Environmental Protection Agency from EPA' s RfDs, RfCs, or cancer slope factors, by
factoring in default values for body weight, exposure duration, and ingestion/inhalation rates.
These values represent levels of chemicals in air, water, soil, and fish that are considered safe
over a lifetime of exposure. RBCs are calculated for adults and children. RBCs for
noncarcinogens and carcinogens are analogous to ATSDR's EMEGs and CREGs, respectively.
Lifetime Health Advisories (LTHAs) are calculated from the DWEL (Drinking Water
Equivalent Level) and represent the concentration of a substance in drinking water estimated to
have negligible deleterious effects in humans over a lifetime of 70 years, assuming 2 IJday water
consumption for a 70-kg adult, and taking into account other sources of exposure. In the absence
of chemical-specific data, LTHAs for noncarcinogenic organic and inorganic compounds are
20% and 10%, respectively, of the corresponding DWELs. LTHAs are not derived for
compounds which are potentially carcinogenic for humans.
Maximum Contaminant Levels (MCLs) are drinking water standards promulgated by the EPA.
They represent levels of substances in drinking water that EPA deems protective of public health
over a lifetime (70 years) at an adult exposure rate of 2 liters of water per day. They differ from
other protective comparison values in that they are legally-enforceable and take into account the
• availability and economics of water treatment technology.
•
Maximum Contaminant Level Action (MCLA) are action levels for drinking water set by
EPA under Superfund. When the relevant action level is exceeded, a regulatory response is
triggered.
When screening individual chemical substances, ATSDR staff compare the highest single
concentration of a chemical detected at the site with the lowest comparison value available for
the most sensitive of the potentially exposed individuals (usually children). Typically the cancer
risk evaluation guide (CREG) or chronic environmental media evaluation guide (cEMEG) is
used. This "worst-case" approach introduces a high degree of conservatism into the analysis and
often results in the selection of many chemical substances for further public health evaluation
that will not, upon closer scrutiny, be judged to pose any hazard to human health. However, in
the interest of public health, it is more prudent to use an environmental screen that identifies
many chemicals for further evaluation that may be determined later to be "harmless," as opposed
to one that may overlook even a single potential hazard to public health. The reader should keep
in mind the conservativeness of this approach when interpreting ATSDR's analysis of the
potential health implications of site-specific exposures.
As ATSDR's most conservative comparison value, the CREG, deserves special mention.
ATSDR's CREG is a media-specific contaminant concentration derived from the chronic
25
(essentially, lifetime) dose of that substance which, according to an EPA estimate, corresponds to •
a l-in-1,000,000 cancer risk level. Note, this does not mean that exposures equivalent to the
CREG actually are expected to cause l excess cancer case in 1,000,000 people exposed over a
lifetime. Nor does it mean that every person in that exposed population has a l-in-1,000,000 risk
(i.e., lxl0·6) of developing cancer from the specified exposure. Although commonly
misinterpreted in precisely this way, cancer risk assessment methodology can only provide
conservative estimates of population risk which do not, in fact, apply to any particular individual.
Even for populations, cancer risk estimates do not necessarily constitute realistic predictions of
the risk. As EPA stated in its Guidelines for carcinogen Risk Assessment, "the true value of the
risk is unknown and may be as low as zero" [EPA 1986].
Unlike non-cancer comparison values which correspond to "safe" levels that include specified
margins of safety, A TSDR' s CREGs (and the risk estimates on which they are based) correspond
to purely hypothetical (and unmeasurable) 1-in-a-million cancer risk levels that include
unspecified margins of safety (i.e., relative to the lowest known cancer effect levels) which often
range from thousands to millions or more. In the U.S., these hypothetical risk levels are based on
the zero-threshold assumption according to which any non-zero dose of a carcinogen must be
associated with some finite increment of risk, however small. Using linear models based on this
assumption, it is actually possible to "quantify" undetectable/non-existent cancer risks that are
(hypothetically) associated with even immeasurably small doses. EPA uses such risk estimates
as regulatory tools in, for example, the ranking of contaminated sites for cleanup. A TSDR uses
them as screening values. However, once ATSDR has screened a substance and selected it for
further evaluation, the CREG, like all other screening values, becomes irrelevant in subsequent •
stages of analysis. Further evaluation of the public health implications of site-specific exposures
must, necessarily, be based on the best medical and toxicologic information available [PHAGM
1992].
References
"Public health Assessment Guidance Manual. U.S. Department _of Health and
Human Servictcs, Public Health Service, Agency for Toxic Substances and
Disease Registry, Atlanta, GA 30333, March 1992.
"Environmental Protection Agency. Guidelines for Carcinogenic Risk
Assessment. Fed. Reg., 51: 33997-33998, September 24, 1986.
Williams, Gary M., and Weisburger, John H. 1991. "Chemical Carcinogenesis".
Chapter 5 in: Casarett and Doull's TOXICOLOGY: The Basic Science of
Poisons. (Mary O Amdur, John Doull, and Curtis Klaassen, Editors.) Pergamon
Press pp 127-200. [See section entitled "Quantitative Aspects of Carcinogenesis,"
ppl52-155.
"Cited in Appendix
26 _ •
• APPENDIX B
•
Nitrates
Sulfates
METALS
Aluminum
Arsenic
Barium
Calcium
Chromium
Cobalt
Cop er2
lron1
Lead
Ma nesium
Manganese1
Mercu
Nickel
Potassium
Sodium3
inc
•
ORGANIC COMPOUNDS
cetone
Benzene
n-Bu benzene
Chlorobenzene
Chloroethane
2-Chlorotoluene
1,2-Dichlorobenzene
1,3-Dichlorobenzene
1.4-0ichlorobenzene
1, 1-Dichloroethane
roethene CE
rimeth !benzene
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found In On-Site Groundwater Monitoring Wells between 1987 -1999)
70-· 54,000 23,914 7,300 60,000 AMEG l!!!li20'000 F.!MEG;~~
8,000 --11,000 9,333 9,000 250,000
12,000 --120,000 64,667 62,000
4.2 4.2 4.2 200 50 10 EMEG ~--ru~wa EMEGW..'Q; i11'.~0;02 CREGwtlf 50
590 --6,600
29.000 .• 50,000
20 •• 86
39
17 •• 82
100 •• 87,000
12 --210
13,C00 --64,000
430 •• 27,000
0.2 •• 670
73
5,600 •• 24,000
3,700 •• 57,000
42--400
29 •• 76
2 •• 3
1.6
0.81 --72
2
0.28 ·-13
0.38--1
3 -11
0.28--5
0.51 --3
0.2-4
3.1
3 ·-5
2
0.25
1
2,051
37,333
59
39
39.25
21,886
95
34,000
13,014
119
73
14,650
34,033
164
52.5
2.43
1.6
29.33
2
6.37
0.69
6.78
1.76
1.95
2.1·
1·
3.1
4
2·
0.25
1
2
3.53'
710
33,000
65
39
29
10,050
75
29,500
15,500
6.3
73
14,500
37,000
107
52.5
2.3
1.6
22.25
2
6.1
0.69
6.1
2.15
2.1·
3.1
4
2·
0.25
1
2
3_05•
40,000
7,000
2,000
30,000
7,000
10,000
70,000
10,000
10,000
10,000 10,000
2,000
500 700
8,000 700
2,000
7,000
28
100 LTHA
730 ABC 310 ABC
1,500 ABC 630 ABC
700 RMEG 200 RMEG
3,000 10,000 EMEG 3,000 EMEG
20,000 10,000 AMEG 3,000 AMEG
4,000
4,000
3,000
200
200
11 ABC
240 ABC
700 AMEG
8,600 ABC
700 AMEG
3,000 RMEG
600 LTHA
75 LTHA
4 ABC
89 ABC
200 AMEG
3,400 ABC
200 RMEG
900 AMEG
800 ABC 300 ABC
61 ABC 22 ABC
4,000 AMEG 1,000 AMEG
2,000 EMEG 600 EMEG
140 ABC 50 ABC
700 AMEG 200 AMEG
20,000 RMEG 6,000 AMEG
750 ABC 270 ABC
37 ABC 13 ABC
120 ABC 44 ABC
36 RSC
5CAEG
1.6 ABC
~lmOFl EMEG~ ~0;2 EMEG~'li ~o:oa GREG~
2,000 10,000 LTHA 4,500 ABC
100
iill!lllllill!l20'000
5,000
5
100
1,000
5
2
10,000
•
TABLE 1
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found In On-Site Groundwater Monitoring Wells between 1987 -1999)
EMEG
LTW.
MCL
REC
RMEG
NA
ppb
cancer Risk Evaluation Guide
Environmental Media Evaluation Guide
Drinking Water Lifetime Health Advisory
Maximum Contaminant Level
Risk Based Concentration (Note, RBC values derived from equations documented in following reference:
Region III Risk-Based Concentration Table. United States Environmental Protection Agency, Region III,
Chestnut Street, Philadelphia, PA, 19107. Available on EPA Region III's Internet website,
http://www.epa.gov/reg3hwmd/risklriskmenu.htm, Background.Information -[PDFJ)
Reference Dose Media Evaluation Guide
None Available
parts per billion
*Average and Median concentrations may be different than displayed in table since some detections were below the quantitation
limi:: for the analyzed chemical (i.e., no value given in inspection/sampling report).
EPA
841
1 Lis,:ed value in ff EPA MCLN column is a Secondary Maximum Contaminant Level (SMCL) for drinking water as set by EPA. SMCLs are
unenforceable federal guidelines regarding taste, odOr, color, and other non-aesthetic effects of drinking water. EPA recommends
then-. to States as reasonable goals, but federal law does not require water supply systems to comply with them. States may,
howe·.·er, adopt their own enforceable regulations governing these concerns.
2 Lis::ed value in "EPA MCLff column is a Maximum Contaminant Level Action (MCLA) for drinking water as set by EPA under Superfund.
If the relevant action level is exceeded, a regulatory response is triggered.
3Lisced value in -EPA MCLff column is a Drinking Water Equivalent Level (DWEL}. The drinking water standard is based on EPA's oral
RfD ~nd represent corresponding concentrations of a substance in drinking water that are estimated to have negligible deleterious
effects in hwnans at an intake rate of 2 L/day, assuming that drinking water is the sole source of exposure; however, the listed
standard for Sodium is only to be used as a guideline, similar to the Secondary Maximum Contaminant Levels.
5Lisced comparison values for inorganic mercury, except for EPA's MCL, are based on studies of animals administered high doses of
merc~ric chloride [ATSDR 1999a, NTP 1993, Druet et al. 1978, Bernaudin et al. 1981, Andres 1984].
• •
• ftsLE 2
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found in Off-Site Groundwater Monitoring Well during 1997)
EMEG
LTHI,
MCL
RBC
RMEG
NA
ppb
31 31
Evaluation Guide
Environmental Media Evaluation Guide
Drinking Water Lifetime Health Advisory
Maximum Contaminant Level
10,000 RMEG
Risk Based Concentration (Note, RBC values derived from equations documented in following reference: EPA
Region III Risk-Based Concentration Table. United States Environmental Protection Agency, Region III, 841
Chestnut Street, Philadelphia, PA, 19107. Available on EPA Region III's Internet website,
http://www.epa.gov/regJhwmd/risklriskmenu.htm, Background Information -[PDF])
Reference Dose Media Evaluation Guide
None Available
parts per billion
30
Calcium
Cobalt
Co ,'
lron1
Lead"
Ma nesium
Man anese1
Mercu
Nickel
Potassn.Jm
Sodlum3
Zirtc
ORGANIC COMPOUNDS
Acetone
1,2-Dichlorobenzene
1,4-Dichlorobenzene
1, 1-0ichloroethane
1,2-Dich!oroethane
is-1,2-Dichloroethene
etrachloroethene PCE
richloroethene CE
X enes
Notes,
•
TABLE 3
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found In Private Well PW2 between 1991 -1999)
;:'<~~
. AdUlt,/llif •. Chlld
140 .• 400 282 270 2,000 RMEG 700 RMEG 2,000 NO 21,000--95,000 58,000 58,CXX) NA
2.4 •• 2.6 2.5 25 730 ABC 310 ABC NO
14--39 28.67 33 1,500 ABC 630 ABC 1,300 NO
80--5,500 1,900 120 22,000 ABC 9,400 ABC ~~300 YES
3--4,4 3.7 3.7 15 NO 4,500-12,000 8,833 10.000 NA
66 --260 161.2 140 2,000 AMEG 500 RMEG ~~HE~5 YES
U--7 1.9 1.3 70 20 10 AMEG B~~3 BME"Gfilg 'la!--YES 2.3--4.2 3.25 3.25 700 AMEG 200 RMEG NO
2.800--7,000 4.833 4,700 NA
5.300 --15,000 10,150 10,150 20,000 NO
28 •• 2,500 853.00 31.CXJ 10,000 3,000 2,000 EMEG 500 EMEG 5,000 NO
99 99 99 70,000 20,000 10,000 AMEG 3,000 AMEG NO
03 0.3' 0.3' 3000 RMEG 900 AMEG 600 NO
0.27--1.5 0.73" 0.6' 10000 4,000 75 LTHA ~..llt0.47 ABC~ 75 YES
0.5--1.5 0.83' o.s· BOO ABC 300 ABC NO
0.53 0.53 0.53 7,000 2,000 10 ABC 3.6 ABC ~~.:10.'4 GREG~ 5 YES
0.8--3.5 2.2· 2' 40,CXXJ 10,000 10,CXXJ 3,000 61 ABC 22 ABC 70 NO
0.29 -0.53 0.41' 0.41' 2,000 500 400 AMEG 100 AMEG 1.1 ABC 5 NO
0.35 -0.89 0.62' 0.62' 7,000 2,000 37 ABC 13 ABC 1.6 ABC 5 NO
5.1 5,1· 5.1° 7,000 2,000 10,000 LTHA 4,500 ABC 10, NO
A chemical is selected tor further public health evaluation if the maximum detected chemical level exceeds at lease one of its comparison
vc,lues. Shading indicates the comparison values chat are exceeded.
Cancer Risk Evaluation Guide
Environmental Media Evaluotion Guide
Drinking Water Lifetime Health Advisory
Maximum Contominant L,evel
CF-EG
EXF:G
l,1,:.:_:i.
Mc:..
REC Risk Based Concentration
Risk-Btlsed Concentration
Philadelphia, PA, 19107.
Backar01lll4 Info:rn.a.t.ion -
(Note, RSC values derived from equations documented in following reference.-EPA Region III
Table. United States Environmental Protection Agency, Region III, 841 Chestnut Street,
Available on EPA Region III's Internet website, http://www.epa.9ovlregJhwrrd/risk/riskmenu.htm,
[PDF]}
Reference Dose Media Evctluation Guide
None Available
parts per billion
'Average and Median concentrations may be different than displayed in table since some detections were below the quantitation limit tor the
a.-:,.;-lyzed chemical (i.e., no value given in inspection/sampling report}.
1 L.isted value in 'EPA HCl," column is a Secondary Maximum Contaminant Level (SMCL} for drinking water as set by EPA. SMCLs are unenforceable
fe::faral guidelines regarding taste, odor, color, <'Uld other non-aesthetic effects of drinking water. EPA recom-nends them to States os reasonable
gc<Jls, but federal law does not require water supply systems co comply with them. Scates may, however, adopt their own enforceable regulations
gc·,erning these concerns.
2L~sted value in •ePA MCL" col= is a Ma,dmum Contaminant Level Action (MCLA) for drinking water as set by EPA under Superfund. It the
rE•levant action level is excee_ded, a regulatory response is triggered.
'Listed value in "EPA MCL" col= is a Drinking Water Equivalent Level (WEL). The drinking water standard is based on EPA'S oral RfD and
represent corresponding concentrations of a substance in drinking water that are estimated to have negligible deleterious effects in humans at
a:: ~ntake rate of 2 L/day, assu.'ll:lng that drinking water is the sole source of exposure: however, the listed standard tor Sodium is only to be
W!'ed as a guideline, similar to the Secondary Maximum Contaminant Levels.
5 Listed compdrison values for inorganic mercury, except for EPA• s MCL, are based on studies of animals administered high doses of mercuric
ci":J.oride {ATSDR 1999a, NTP 1993, Dn.et et al. 1978, Bernaudin et al. 1981, Andres 1984] .
• •
•
Barium
Co per2
lron1
Man anese'
Mercury
otes:
TA~4
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found In Private Well PW1A between 1992 --1995)
1,400 1,400
6,000 6,000
70 70
60 60
4,430 4,430
830 830
1,400
6,000
70
60
4,430
830
70 20
60,000 RMEG
2,000 RMEG 700 RMEG
1,500 RBC 630 RBC
22,000 RBC 9,400 RBC
2,000 RMEG ,i;;,.wsoo RMEG~
10 RMEG 3 RMEG
•
A chemical is selected for further public health evaluation if the maximum detected chemical level exceeds at least one of its comparison
values. Shading indicates the COJ!lparison values that are exceeded.
CREG Cancer Risk Evaluation Guide
EMEG Environmental Media Evaluation Guide
LTHA Drinking water Lifetime Health Advisory
NO
NO
ND
YES
YES
NO
MCL
RBC
Maximum contaminant Level
Risk Based Concentration
Risk-Based concentration
Philadelphia, PA, 19107.
Background ~nformation -
(Note, RBC values derived from equations documented in following reference: EPA Region III
Table. united States Environmental Protection Agency, Region III, 841 Chestnut Street,
Available on EPA Region III's Internet website, http://www.epa.gov/reg3hw-mdlrisk/risk1nenu.hcm,
(PDP})
Reference Dose Media Evaluation Guide
None Available
2000 500 RMEG
NA
ppb parts per billion
J Listed value in "EPA MCL' column is a Secondary Maximum contaminant Level (SMCLJ for drinking water as set by EPA, SMCLs t1re unenforceable
federal guidelines regarding taste, odor, color, t1nd other non-aesthetic effects of drinking water. EPA recommends them to States as reasonable
goals, but federal law does not require water supply syst'ems to comply with them. States may, however, adopt their own enforceable regulations
governing these concerns.
2Listed value in "EPA MCL' column is a Maximum contaminant Level Action (MCLA} for drinking water as set by EPA under Superfund. If the relevant
action level is exceeded, a regulatory response is triggered.
5Listed comparison values for inorganic mercury, ex~ept for EPA's MCL, are based on studies of animals administered high doses of mercuric
chloride [ATSDR 1999a, NTP 1993, Druet et al. 1978, Bernaudin et al. 1981, Andres 1984].
32
otes:
•
TABLE 5
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found in Private Well PW1R between 1995-1999)
1,400
38 38 38
8.6 8.6 8.6
1,600 1,600 1,600
1,800 1,800 1,800
820 820 820 10,000 3,000
60,000 RMEG
1,500 RBC 630 ABC
10,000 EMEG 3,000 EMEG
1,300
15
5,000
NO
NO
NA
NA
NO
A chemical is selected for further public health evaluation if the maximum detected chemical level exceeds at least one of its comparison
values.
CREG
EMEG
LTHA
MCL
RBC
RMEG
NA
ppb
Shading indicates the comparison values that are exceeded.
Cancer Risk Evaluation Guide
Environmental Media Evaluation Guide
Drinking Water Lifetime Health Advisory
Maximum Contaminant Level
Risk Based Concentration (Note, RBC values derived from equations documented in following reference: EPA Region III
Risk-Based Concentration Table. United States Environmental Protection Agency, Region III, 841 Chestnut Street,
Philadelphia, PA, 19107. Available on EPA Region III• s Internet website, http: //www.epa.gov/reg3hwmd/risk/riskmenu .htm,
8ac::kground Zn!ormatioZI. -[PDF]}
Reference Dose Media Evaluation Guide
None Available
parts per billion
2000
1 Listed value in "EPA MCL" column is a Secondary Maximum Contaminant Level (SMCL) for drinking water as set by EPA. SMCLs are unenforceable
federal guidelines regarding caste, odor, color, and other non-aesthetic effects of drinking water. EPA recommends them co States as reasonable
goals, but federal law does not require water supply systems to CO!llply with them. States may, however, adopt their own enforceable regulations
governing these concerns.
1Listed value in 'EPA MCL" column is a Maximum Contaminant Level Action (MCLA) f_or drinking water as set by EPA under superfund. If the relevant
action level is exceeded, a regulatory response is triggered .
• •
•
Drinking Water Comparison Values,Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found In Private Well PW1S during 1997)
70,000
--. ~· __ ,--.•··.,,~:,,.(f~a385id8.y&) -_ =k:~~-• ~N6rf.cilrcl . ·enic1$P~ili !liit¥,)gelilc~_
10,000 RMEG 3,000 RMEG
A chemical further public health evaluation if the m.aximum detected chemical level exceeds at least one of its comparison
values. Shading indicates the comparison values that are exceeded.
CREG Cancer Risk Evaluation Guide
EM£G Environmental Media Evaluation Guide
LTHA Drinking Water Lifetime Health Advisory
MCL
RBC
RMEG
NA
ppb
Maximum Contaminant Level
Risk Based Concentration (Note, RBC values derived from equations documented in following reference: EPA Region III
Risk-Based Concentration Table. United States Environmental Protection Agency, Region III, 841 Chestnut Street,
Philadelphia, PA, 19107, Available on EPA Region III's Internet website, http://www.epa.gov/reg3hwmd/risk/riskmenu.htm,
Backgrowid Information -{PDl"l)
Reference Dose Media Evaluation Guide
None Available
parts per billion
34
Co er1
lron1
lead
Man anese1
Potassium
ORGANIC COMPOUNDS
Acetone
otes:
•
TABLE 7
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found In Private Well PW33 between 1994 --1999)
60,000 RMEG 20,000 RMEG
200 --1,700 950 950 20,000 37,000 ABC 16,000 ABC 32 32 32 2,000 RMEG 700 RMEG
49 49 49 1,500 ABC 630 ABC
270 270 270 22,000 ABC 9,400 ABC
4.6 •• 17 10.8 10.8
7 7 7 2,000 RMEG 500 AMEG
1,900 1,900 1,900
80-200 140 140 10,000 3,000 10,000 EMEG 3,000 EMEG
24 24 24 70,000 20,000 10,000 RMEG 3,000 RMEG
2,000
1,300
300
~~~15
50
5,000
A chemical is selecLed for further public health evaluation if t::he maximum detected chemical level exceeds at least one of its comparison
values. Shading indica~es the comparison values that are exceeded.
CREG Cancer Risk Evaluation Guide
EMEG Environmental Media Evaluation Guide 2000 500
Drinking Water Lifetime Health Advisory
Maximum Contaminant Level
NO
NO
NO
NO
YES
NO
NA
NO
NO
LTHA
MCL
RBC Risk Based Concentration (Note, RBC values derived from equations documented in following reference, EPA Region III
Risk-Based Concentration Table. United States Environmental Protection Agency, Region III, 841 Chestnut Street,
Philadelphia, PA, 19107. Available on EPA Region III's Internet website, http,/lwww.epa.gov/reg3hwmdlrisk/riskmenu.htm,
BaCkljl'Tound. IQf0nution -(PDF])
RMEG
NA
ppb
Reference Dose Media Evaluation Guide
None Available
parts per billion
l Listed ·,alue in '£PA MCL' column is a Secondary Maximum Contaminant Level (SMCLJ for drinking water as set by EPA. SMCLs are unenforceable
federal guidelines regarding taste, odor, color, and other non-aesthetic effects of drinking water. EPA recommends them to States as reasonable
goals, but federal law does not require w<1ter supply systems to comply with them. States may, however, adopt their own enforceable regulations
governing these concerns.
:Listed value in 'EPA MCL' column is a Maximum Cont=inant Level Action (MCLA) for drinking water as set by EPA under Superfund. If the relevant
action level is exceeded, a regulatory response is triggered.
• •
•
Man anese1
Potassium
inc
ORGANIC COMPOUNDS
cetone
ates,
TA~8
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found In Private Well PW5 during 1999)
16 16
21 21
1,300 1,300
110 110
5 5
A chemi-:-al is selected for
1,300
110
5
10,000
70,000
3,000
20,000
2,000 RMEG
2,000 RMEG
10,000 EMEG
10,000 RMEG
700 AMEG 2,000
500 RMEG 50
3,000 EMEG 5,000
3,000 RMEG
further public health evaluation if the maximum detected chemical level exceeds at least one of its comparison
NO
NO
NA
NO
NO
values.
CREG
EMEG
LTHA
MCL
Shading indicates the cOJ11parison values that are exceeded.
RBC
RMEG
NA
ppb
Cancer Risk Evaluation Guide
Environmental Media Evaluation Guide
Drinking Water Lifetime Health Advisory
Maximum Contaminant Level
Risk Based Concentration (Note, RBC values derived from equations documented in following reference: EPA Region III
Risk-Based Concentration Table. United States Environmental Protection Agency, Region III, 841 Chestnut Street,
Philadelphia, PA, 19107. Available on EPA Region III's Internet website, ~ttp://www.epa.gov/reg3hwmd/risk/risJanenu.htm,
Background Information -[FDFlJ
Reference f!Ose Media Evaluation Guide
None Available
parts per billion 2000 500
1 Listed •;alue in "EPA MCL' column is a secondary Maximum Contaminant Level (SMCL} for drinking water as set by EPA. SMCLs tire unenforceable
federal guidelines regarding taste, odor, color, and other non-aesthetic effects of drinking water. EPA recommends them to States as reasonable
goals, hut federal law does not require water supply systems to comply with them. States may, however, adopt their own enforceable regulations
governing these concerns.
36
ORGANIC COMPOUNDS
Acetone
Benzene
Bromodichloromethane'
hlorobenzene
Chloroform•
Dibromochloromethane4
1,4-0ichlorobenzene
1, 1-Dichloroethane
is-1,2-Dichloroethena
richloroethene CE
X lanes
otes,
•
TABLE 9
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found in Private Well PW3 between 1992 -1999)
60,000 RMEG 20,000 RMEG
83 .. 90 86.5 86.5 2,000 RMEG 700 RMEG
1.2 1.2 1.2 730 RBC 310 RBC
14 14 14 22,000 RBC 9,400 RBC
3,800 3,600 3,800
50 ·• 100 75 75 2,000 AMEG 500 AMEG
2.5--5.8 4.24 4.6 70 20 10 RMEG ;ill-'13 RMEGl1!J
2,400 2,400 2,400
108 108 108 70,000 20,000 10,000 RMEG 3,000 RMEG
0.4 0.4 0.4 11 ABC 4 ABC 0.6
3 3 3 1,000 400 700 EMEG 200 EMEG -.ro;s
0.4 0.4• 0.4* 10,000 4,000 700 RMEG 200 RMEG
0.6--39 19.8 19.8 10,000 3,000 4,000 1,000 2,000 EMEG 500 EMEG -6 1 1 1,000 400 1,000 EMEG 300 EMEG -0:4 0.53··2 'J.93 0.8 10,000 4,000 75 LTHA ~~0~41
0.4 •• 0.8 0.63· 0.63* 800 RBC 300 RBC
0.43 •• 0.81 0.63 0.64 40,000 10,000 10,000 3,000 61 ABC 22 ABC
0.27 0.27" 0.21· 7,000 2,000 37 ABC 13 ABC 1.6
0.5--2 1_23• 1.2· 7,000 2,000 10,000 LTHA 4,500 RBC
2,000
300
~tril£~il~gg~sci
i'!l:lml;l!ilill/l!'l!
CAEG 5
CREG~ 80
100
CAEG~ 80
CBEGt~ 80
ABC~ 75
70
RBC 5
10,000
A chemical is selected for further public health evaluation if the maximum detected chemical level exceeds at least one of its comparison
values. Shading indicates the comparison values that are exceeded.
CREG Cancer Risk Evaluation Guide
EMEG Environmental Media Evaluation Guide
LTHA Drinking Water Lifetime Health Advisory
MCL Maximum Contaminant Level
NO
NO
NO
NA
YES
YES
NA
NO
NO
YES
NO
YES
YES
YES
NO
NO
NO
NO
RBC Risk Based Concentrtttion (Note, RBC values derived from equtttions documented in following reference; EPA Region III
Risk-Based Concentrtttion Table. united States Environmental Protection Agency, Region III, 841 Chestnut Street,
Philadelphia, PA, 19107. Available on EPA Region III's Internet website, http,//"""1k/.epa.govlreg3hwmdlrisklriskmenu.htm,
Backfll:'ound Info:c-mation -[i'DI'])
RM£G Reference Dose Meditt Evaluation Guide
NA None Avtiilable
ppb parts per billion
~Averag1c and Median concentrations may be different than displtiyed in table since some detections were below the quantittttion limit for the
analyze,:, chemical (i.e., no value given in inspection/sampling report}.
1 Listed value in· 'EPA MCL" colwnn is a Secondary Maximum Contaminant Level (SM.CL) for drinking water as set by EPA. SMCLs are unenforceable
federal ;,uidelines regarding taste, odor, color, and other non-aesthetic effects of drinking water. EPA recommends them to States as reasonable
goals, b~t federal law does not require water supply systems to comply with them. States may, however, adopt their own enforceable regulations
governing these concerns.
1 Listed value in 'EPA MCL' column is a proposed MCL under the 1994 proposed rule for disinfection by products rule; the current MCL for most
trihalcir.ethanes is 100 ppb under the 1996 Drinking Water Advisory Report.
sListed comparison values for inorganic mercury, except for EPA's MCL, are based on studies of animals administered high doses of mercuric
chloride {ATSDR 1999a, NTF 1993, Druet et al. 1978, Bernaudin et al. 1981, Andres 1984] .
• •
•
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found In Private Well PW32 during 1997)
7,000 2,000
10,000 RMEG
2,000 EMEG
•
5 GREG 5
A chemical is selected for further public health evaluation if the maximum detected chemical level exceeds at least one of its comparison
values. Shading indicates the comparison values that are exceeded.
CREG Cancer Risk Evaluation Guide
EMEG Environmental Media evaluation Guide
LTHA Drinking Water Lifetime Health Advisory
MCL Milximum Contaminant Level
RBC
RMEG
NA
ppb
Risk Based Concentration
Risk-Based Concentration
Philadelphia, PA, 19107.
Backgro~ Infoniatioa -
(Note, RBC values derived from equations documented in following reference: EPA Region III
Table. United States Environmental Protection Agency, Region III, 841 Chestnut Street,
Available on EPA Region III's Internet website, http://"IWW.epa.gov/reg3hwmd/risklriskroenu.htm,
[l'DP])
Reference Dose Media Evaluation Guide
None Available
parts per billion
38
Man anese1
Potassium
ORGANIC COMPOUNDS
cetone
Chloroform'
1,2·Dich1oroben2:ene
1,4-0ichlorobenzene
otes:
•
TABLE11
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found in Private Well PW4 between 1995--1999)
31 31 31
2 .. 28 15 15
15 15 15
1,800 1,800 1,800
233 233 233
0.78 0.78* 0.78* 10,000 3,000
48 48 48
44 44 44
70,000 20,000
4,000 1,000
10,000 4,000
2,000 RMEG
2,000 RMEG
10,000 AMEG
400 EMEG
3,000 RMEG
75 LTHA
20,000 RMEG
700 RMEG
500 RMEG
3,000 RMEG
100 EMEG
900 RMEG
6 GREG
2,000
~1'5
50
80
600
75
NO
YES
NO
NA
NO
NO
NO
YES
A chemical is selected for further public health evaluation if ,he maximum detected chemical level exceeds at lease one of its comparison values.
CREG
EMEG
LTHA
MCL
REC
RMEG
NA
ppb
Shading indicaces the comparison values that are exceeded.
Cancer Risk Evaluation Guide
Environmental Media Evaluation Guide
Drinking Water Lifetime Health Advisory
Maximum Contaminant Level
2000 500
Risk Based Concentration {Note, RBC values derived from equations documented in following reference: EPA Region III
Risk-Based Concentration Table. United States Environmental Protection Agency, Region III, 841 Chestnut Street,
Philadelphia, PA, 19107. Available on EPA Region III's Internet: website, htt:p://1'1',,olW.epa.gov/regJhwmdlrisklriskmenu.htm,
Backg-round Iz:i.foniation -[PDI'])
Reference Dose Media Evaluation Guide
None Available
parts per billion
"Average and Median concentrations may be different than displayed in table since some detections were below the quantitation limit for the
analyzed chemical (i.e., no value given in inspection/sampling report},
J Listed ·,ralue in 'EPA MCL' collllll/'l is a secondary Maximum Contaminant Level (SMCL) for drinking water as set by EPA. SMCLs are unenforceable
federal guidelines rP.garding taste, odor, color, and ocher non-aesthetic effects of drinking water. EPA reco=ends them to States as reasonable
goals, but federal law does not require water supply systems to comply with them. States may, however, adopt their own enforceable regulations
governing these conctrns.
2 Listed value in "EPA MCL" cOllllll/'l is a Maximum Contaminant Level Action (MCLA) for drinking water as set by EPA under Superfund. If the relevant
action level is exceeded, a regulatory response is triggered.
f Listed value in 'EPA MCL' collllll/'l is a proposed MCL under the 1994 proposed rule for disinfection by products rule; the current MCL for most
trihalomethanes is 100 ppb under the 1996 Drinking Water Advisory Report,
• •
• •
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found In Private Well PW34 during 1997)
A chemical
values.
CREG
EMEG
LTHA
MCL
RBC
RMEG
NA
ppb
500 RMEG
3,000 RMEG
further public health evaluation if the maximum detected chemical level exceeds at least one of its comparison
indicates the comparison values that are exceeded.
Cancer Risk Evaluation Guide
Environmental Media Evaluation Guide
Drinking Water Lifetime Health Advisory
Maximum Contaminant Level
NO
Risk Based Concentration (Not:e, RBC values derived from equations doCW!lented in following reference: EPA Region III
Risk-Based Concentration Table. united States Environmental Protection Agency, Region III, 841 Chestnut Street,
Philadelphia, PA, 19107. Available on EPA Region III' s Inter11et website, http: I /WWW. epa. gov/regJhwmd/risk/riskmenu .htm,
Background. IQf0rmati0n -[PDP])
Reference Dose Media Evaluation Guide
None Available
parts per billion
i Listed -.-alue in 'EPA MCL• column is a secondary Maximum contaminant Level (SMCL) for drinking water as set by EPA. SMCLs are unenforceable
federal guidelines regarding caste, odor, color, and other non-aesthetic effects of drinking water. EPA recommends them to States as reasonable
goals, b..;t federal law does not require water supply systems co comply with them. States may, however, adopt their own enforceable regulations
governir.g these concerns.
40
Barium
Copper2
Lead2
Man anese1
Potassium
'"" otes:
•
TABLE13
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Detected Chemical Concentrations found in Private Well PW6 during 1999)
22 22 22 2,000 RMEG 700 RMEG 2,000 NO
30 30 30 1,500 ABC 630 ABC 1,300 NO
3.4 3.4 3.4 15 NO
4.2 4.2 4.2 2,000 RMEG 500 RMEG 50 NO 1,500 1,500 1,500 NA
560 560 560 10,000 3,000 10,000 EMEG 3,000 EMEG 5,000 NO
A chemi•::-al is selected for further public heal t:h evaluation if the maximum detected chemical level exceeds at least one of its cOJ11parison values.
CREG
EMEG
LTHA
MCL
RBC
RMEG
NA
ppb
Shading indicates the comparison values that are exceeded.
Cancer Risk Evaluation Guide
Environmental Media Evaluation Guide
Drinking Water Lifetime Health Advisory
Maximum Contaminant Level
Risk Based Concentration (Note, REC values derived from equations do,;:,umented in following reference: EPA Region III
Risk-Based Concentration Table. United States Environmental Protection Agency, Region III, 841 Chestnut Street,
Philadelphia, PA, 19107. Available on EPA Region III's Internet website, http://www.epa.gov/reg3hwmdlrisklriskmenu.htm,
Backgr01Ul4 Information -[PDF])
Reference Dose Media EValuation Guide
None Available
parts per billion 2000 500
i Listed ·1alue in "EPA MCL" column is a secondary Maximum Contaminant Level (SMCL) for drinking water as set by EPA. SMCLs are unenforceable
federal guidelines rt1garding taste, odor, color, and other non-aesthetic effects of drinking water. EPA recommends them to States as reasonable
goals, but federal law does not require water supply systems to comply with them. States may, however, adopt their own enforceable regulations
governiag these concerns.
1Listed ·1alue in "EPA MCL" column is a Maximum Contaminant Level Action (MCLAJ for drinking water as set by EPA under Superfund. If the relevant
action level is exceeded, a regulatory response is triggered.
• •
••
um1mim
Barium
alcium
obaJt
Iron
~
"
Ma neslum
an anese
Merc:ur
ickel
Potassium
odium
"' RGAN1C COMPOUNDS
Benzene
Bromodichloromethane
hlo,obenzene
hloro!orm
Oibromochlowmethane
1,2•Dichlorobenzene
1,4-Dichlorobenzene
1, l •Dichloroelhane
1.2-0ichloroethane
s-1 .2-0ichloroelhene
Meth ene Chlolide
etrachlOfoelhene PCE
richloroethene CE .,,.,
Noc es,
Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Summary ol Detected Chemical Concentrations found In all Private Wells between 1991 -1999)
-.. ~-.. .da)"5} ,-,,
c-,,~~;N en1ci;.;,.~:-:
m-~..;M ~~ hlld\;:;,I.,,?.'!!.:
60,000 AMEG s,,;20·000 RMEG-m
200 .• 1,700 950 70,000 20,000 37,000 ABC 16,000 RSC
15-400 16' 2,000 AMEG 700 AMEG
21.000 •• 95.000 58,000 "· 1.2 •· 2 6 2.1 2.4 730 ABC 310 ABC
14 -60 37.6 38 1.500 RSC 630 RSC
14 •• 5.500 1.736 195 22.000 RSC 9,400 RSC
2 .. 26 89 4.5
1.600--12,000 6,983 7.250
4.2 --830 153.\ 76 2,000 RMEG ~:@;/500 RMEG<re
1 --7 2.8 70 20 10 AMEG ,;:a:-'fi'ltil'3 RMEG~
2.3 •• 4.2 3.25 700 AMEG 200 RMEG
1,300 .• 7,000 2,990 2000 500
5,300-15.000 10,150 10,1
26 •• 2,500 541 10,000 3,000 10,000 EMEG 3,000 EMEG
5 •• 233 71.9 47.5 70,000 20,000 10,000 RMEG 3.000 RMEG
0.4 0.4 0.4 11 RBC 4 RBC 0.6 CREG
3 3.0 3 1,000 400 700 EMEG 200 EMEG 'e!!flrri!0.6 CREG:t:'<l
0.4 0.4 0 10.000 4,000 700 RMEG 200 RMEG
0.6-39 13.46' 0.78' 10,000 3,000 4,000 1,000 400 EMEG 100 EMEG i:<1~6 CAEGilll
1 1 1,000 400 1,000 EMEG 300 EMEG ~~0.4 OREG~
0.3 •• 48 24• 24· 3,000 RMEG 900 AMEG
0.27 •• 44 3.91' o.n· 10,000 4,000 75 LTHA tlti',.t<"Q.47 RBC:':of'A.l
0.4 ·• 1.5 0.7· 0.6" eoo RSC 300 ABC
0.53 0.53 0.53 7,000 2,000 10 RBC 3.6 ABC ~<'gQ,4 RE iilli\
0.43--35 1.3" 0.8" 40,000 10,000 10,000 3,000 61 ABC 22 ABC
2 2 2 7,000 2,000 2,000 EMEG 600 EMEG 5 CREG
0.29-0.53 0.41' 0.41" 2.000 500 400 AMEG 100 AMEG 1.1 RBC
0.27-0.89 0.5' 0.35" 7.000 2,000 37 RBC 13 ABC 1.6 ABC
2.2' 1.6" 7,000 2.000 10.000 LTHA 4.500 ABC
NO
NO
NA
NO
NO
YES
YES
NA
YES
YES
NO
NA
NO
NO
NO
NO
8 YES
1 NO
8 YES
YES
60 NO
YES
NO
YES
NO
NO
NO
NO
10 . NO 0.5-5.1
A c,hemic,.l is salec,ted tor further public health evaluation if the IMXimw,, detec,ted chemical level exceeds at lease one of its corrvarison
values. Sh.5ding indicates the coo;p,,rison valtJes that are exceeded.
Cancer Risk Evaluation Guide
£nviro=ental Media Evaluation Guide
Drinking water Lifetime Health Advisory
Maximw,, Cont1troi.nant Level
Risk &lsed Concentration (Note, RSC values derived from equations doc,w0ented in follo..,.ing reference: EPA Region III
Risk-Based Conc,entration Table. United Scates Environmental Protection Agency, Region III. 841 Chestnut Street.
PhiJade!ph1a, PA, 19107. Available on EPA Region III's Internet website,
http: I I""""-epa. govlreg3hwmdlrisk/d.skrdenu. hem, Bac:111:ground tnfo:nn&tiott -IPPl'l J
RMro Reference Dose Media Evaluation Guide
NA None Available
ppb parts per billion
'Average .snd Medi.an conc,entrations may be different than displayed in t"ble since some decec,tions ..,e,-e below che quancit.,tion limit tor the
"nalyzed chet11ical (i.e .• no value give."'! in inspec,tion/sampling ,-ep0rtJ.
: Listed value in •EPA MCL• column is a Seconda,-y Maximum contaminant Level {SMCLJ for drinking ..... te!" as set by EPA. SMCLs a,-e unenforceable
federal guidelines regarding taste, odor, color, .,_,,d other non-aes:hetic, effects of drinking water. EPA reconnends them to States as
reasonable go.,ls, but federal law does not require water supply systems to comply with them. States may, however, adopt their o""' entorc,eable
,-egulations governing these conc,erns.
2Listed v"lue in "EPA MCL" c,olumn i.s "Maximum Contaminant Level Ac,t!on (MCUJ for drinking water as sec by EPA under Superfund, If the
relevant ac,tion level is l!XCeeded, e regul,.co,-y response Is triggered.
'Listed v"lue in "EPA MCL" column is a Drinking Water Equivalent Level /Dl'mL,/. The drinking "'ater .standard is based on EPA's oral RfD and
represent corresponding concentrations of " substance in drinking Wilter chat are estimated to have negligible deleterious effects in h'1.":18ns at
"" i.ncake rate of 2 Llday, assw,,ing that drinking ""'ter is the sole source of exposu,-e; however, the listed standard for sodiw,, is only eo be
used as" guideline. sir.iilar to the Secondary 1".axictL'II Contaminant Levels.
'Listed value .in "EPA MCL" column ls a prop0sed MCL under the 1994 proposed rule tor dis.infection by products rule; the c,ui-rent MCL fo,-most
trlhal=eth.)nes is 100 PJ)b wider the 1996 Drinking ware,-Advisory Repcrt.
'Listed comparison values for inorganic, mercury, except tor EPA's MCL, are based on studies of animals admi.nistered high doses of merc,uric,
chloride fATSDR 1999a, NTP 1993, Druer ec al. 1978, Bemaudin et al. 1981, Andres 1984].
42
e
• APPENDIX C
•
•
•
•
•
Figure 1
Groundwater Sampling Locations for 1997 Preliminary Assessment / Site Inspection
Scale: 1" = 370' Date: September
1998
Drawn By:
Source: NCDENR/1998) Site Name: Sigmon' s Septic Tank Service NCD 062 555 792
Figure 2
Groundwater Sampling Locations for 1999 Expanded Site Inspection
• • PW33
. .
MW1A
(
f~PW&
I PW32
0 pond
I
Sigmon Environmental
Services Office
storage CJ
tanks C C
lagoons
0 ~
waste pile I
:IC • □
ope! pits I
~ · v ., drainage.ditch
CJ
A-1<-'K-X-~-><.-)( -x -)(, _,_ -·-·-·-· --·=-= .. -·---·-· PPE#1
CJ
DpWJ PW2 ·-Lauren Drive
D.nd
-·
/□ate: November 1999 Drawn By:
Source: NCDENR (2000) Site Name: Sigmon's Septic Tanlc Service NCD 062 555
•
•
• 792
"
•
•
Figure 3
On-site Monitoring Well Locations in Retrospect to the Fonner Lagoons
MW10
MW20
MW40
Scale: 1 11 = 65' Date: September
1998
Shed
0
MW40
Drawn By:
Source: NCDENR/1998) Site Name, Sig1110n' a Septic Ta'11k Sewice NCO 062 555 792