Supplemental Expert Report of Lisa J.N. Bradley, Ph.D.

SUPPLEMENTAL REPORT
LISA JN BRADLEY, PH.D., DABT
by Haley & Aldrich, Inc.
Boston, Massachusetts
for Duke Energy
Charlotte, North Carolina
File No. 43518-002

Supplemental Report
Lisa A Bradley, Ph.D., DAB
Table of Contents
Page
1.
Purpose of the Supplemental Report
1
2.
Hexavalent Chromium
1
3.
The Regulatory Risk Range
2
4.
Background Cancer Risk in the U.S.
3
5.
Use of Regulatory Risk Targets in North Carolina and the Do Not Drink
Letters
3
6.
Hinkley, CA
5
7.
References
6
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Supplemental Report
Lisa A Bradley, Ph.D., DAB
1. Purpose of the Supplemental Report
I am providing this Supplement to my Expert Reports of June 2016 (Bradley, 2016a) and August 2016
(Bradley, 2016b) to address specific topics covered in the deposition of Dr. Kenneth Rudo of the North
Carolina Department of Health and Human Services (DHHS) on July 11, 2016 and continued on October
14, 2016.
2. Hexavalent Chromium
A detailed evaluation of the toxicity of hexavalent chromium in drinking water, the studies used by
regulatory agencies in 2010 to develop draft or final toxicity values for their regulatory programs, and
the subsequent detailed research into the mode of action of the carcinogenicity and toxicity of
hexavalent chromium was provided in my expert report of August 2016 (Bradley, 2016b).
The National Toxicology Program (NTP) study of hexavalent chromium in drinking water in rats and mice
(NTP, 2007, 2008) used a study design where the lowest drinking water concentration of 5 mg/L used in
the study is 50- old higher than the current federal drinking water standard for total chromium of
100 ug/L (USEPA, 2012), and 500- old higher than the North Carolina 2L groundwater standard for total
chromium of 10 ug/L (NCAC, 2013). The challenge this presents regulators and toxicologists is
extrapolating from the very high drinking water concentrations used in the study to the low,
environmentally relevant concentrations of hexavalent chromium in groundwater and drinking water.
These concentrations have been demonstrated to average 0.58 ug/L and to range from 0.015 ug/L to
97.38 ug/L (USEPA, 2015a,b) in public drinking water supplies across the U.S.
The regulators at the U.S. Environmental Protection Agency (USEPA) (USEPA, 2010), the California
Environmental Protection Agency (CaIEPA) Office of Environmental Health Hazard Assessment (OEHHA)
(CaIEPA, 2011), and the New Jersey Department of Environmental Protection (NJDEP) (NJDEP, 2009)
used the NTP study results and a very conservative model of toxicity value generation for potential
carcinogenic effects to derive a toxicity value (called a cancer slope factor or CSF) for hexavalent
chromium of 0.5 (mg/kg-day)-1.
Each agency used its default exposure factors and calculation methods to develop a screening level for
hexavalent chromium in drinking water, each using a target risk level of one in one million, or 1x10-6, or
1E-06. The CaIEPA Public Health Goal (PHG) is 0.02 ug/L (CaIEPA, 2011). The USEPA Risk -Based
Screening Level (RSL) for tap water is 0.035 ug/L (USEPA, 2016a). The NC DHHS used the same CSF to
derive a Health Screening Level (HSL) for hexavalent chromium of 0.07 ug/L (NC DHHS, 2015). (An
independent expert peer review panel met in May 2011 to review the USEPA draft assessment for
hexavalent chromium. In their final report, the peer review panel urged USEPA to consider the results of
research that would soon be completed and peer -reviewed that could provide relevant scientific
information that may inform the findings of the assessment. Based on the advice of the peer review
panel, USEPA has agreed to review original primary research related to the health effects of hexavalent
chromium that has been published since the release of the draft assessment for external peer review
and will incorporate the findings as appropriate into its hexavalent chromium assessment.)
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Each of these screening levels for hexavalent chromium in drinking water is between 70,000 and
250,000-fold lower than the lowest drinking water concentration of 5 mg/L used in the NTP study. This
extrapolation assumes that the mechanisms of toxicity that function at the high doses also function at
very low doses.
Aspirin can provide a simple real -world example of this concept. Aspirin is a safe and effective
medication. It is present in many homes and used by many Americans. "Low dose" aspirin is used by
many adults on a daily basis to serve as a blood thinner to prevent strokes and heart attacks. Two
aspirin every four hours can be taken to address headaches or muscle aches. However, it would be fatal
if someone were to ingest a single bottle of 100-count full-strength aspirin. Thus, while there are many
benefits to aspirin use, as noted in many toxicology texts, "it is the dose that makes the poison." In this
case, if the studies on the toxicity of aspirin has only used the equivalent of a full bottle of 100-count
aspirin as the lowest dose in an experiment, aspirin would not be on the market today. The type of
toxicity that aspirin exerts at the high dose (a full bottle) is not the same as its effects at much lower
doses. And here, that high dose is only 50-100-fold higher that what we take normally today as
medication.
For hexavalent chromium, the USEPA, CaIEPA, and NJDEP are extrapolating over 70,000 to 250,000 fold
below the experimental dose level. The recent studies into the Mode of Action (MOA) for the toxicity of
hexavalent chromium have demonstrated that indeed, the toxicity at low doses is very different than at
the high doses used in the NTP experiments (see Thompson, et al., 2014 for a summary of the body of
work and its application to risk assessment). These MOA studies have shown that there is a threshold of
hexavalent chromium in drinking water below which adverse effects are not seen in animal models.
Two regulatory agencies have reviewed these studies and have developed a toxicity value called a
reference dose or RfD, that results in a screening level for hexavalent chromium in drinking water of 100
ug/L. These are the Texas Commission on Environmental Quality (TCEQ, 2015) and Health Canada
(2015). The fact that this screening level is the same as the U.S. federal drinking water standard for total
chromium is coincidental. It is also reassuring, since that has been the regulation that has been in effect
nationally and in many state programs.
One should not dismiss out of hand, as Dr. Rudo has done, either the authors or the peer -reviewed
research conducted on the MOA of hexavalent chromium, nor should one dismiss out of hand the
regulatory agencies that have taken careful consideration of this research and used it to develop toxicity
values and screening levels for drinking water.
3. The Regulatory Risk Range
It is important to reiterate the concept of the regulatory risk range. For constituents classified as
potential carcinogens, the predicted level of exposure to a constituent is multiplied by a toxicity value
developed by USEPA that is used to predict the chance of cancer occurring as a result of the exposure,
and the result is referred to as the cancer risk (USEPA, 2016b). USEPA defines a target risk range for
potential carcinogens of one in one million (1 in 1,000,000 or 1x10-6) to one in ten thousand (1 in 10,000
or 1x10-4). Thus, the USEPA target risk range is between one in one million and one in ten thousand
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chance of developing cancer as the result of a specific exposure. A risk that falls within that range (1 in
10,000 to 1 in 1,000,000) or below that range is considered acceptable.
The target risk range is based on USEPA guidance. Specifically, USEPA provides the following guidance
(USEPA, 1991):
"Where the cumulative carcinogenic site risk to an individual based on reasonable maximum
exposure for both current and future land use is less than 10-4, and the non -carcinogenic hazard
quotient is less than 1, action generally is not warranted unless there are adverse environmental
[i.e., non human -health] impacts."
"The upper boundary of the risk range is not a discrete line at 1 x 10-4, although EPA generally
uses 1 x 10-4 in making risk management decisions. A specific risk estimate around 10-4 may be
considered acceptable if justified based on site -specific conditions."
4. Background Cancer Risk in the U.S.
To understand the USEPA target risk range in context, it is important to recognize that the background
cancer risk in the United States is generally 1 in 2 for men (0.5 or 5 x 10-1) and 1 in 3 for women (0.33 or
3.3 x 10-1) based on statistics published annually by the American Cancer Society (ACS, 2016). Thus the
USEPA regulatory target risk range is four to six orders of magnitude lower than the background cancer
rates in the U.S. This is illustrated graphically in Figure 6 in Bradley (2016a and b). The background
cancer rate in the U.S. is shown on the left-hand side of the arrow, with risk levels decreasing towards
the right. The USEPA target risk range is shown on the right-hand side of the risk arrow. The other risks
illustrated on the arrow are the risk of fatalities based on measurements for the U.S. population. Risks
of occurrence of these outcomes would be higher (i.e., those risks would move to the left on the risk
arrow); for example, the risk over a lifetime of being hit by lightning is 10 times higher than the risk of
dying from a lightning strike(http://www.lightningsafety.noaa.gov/medical.htm.) Thus, the target risk
range USEPA uses for regulatory decision making is lower than a person's chances of being struck by
lightning.
S. Use of Regulatory Risk Targets in North Carolina and the Do Not Drink
Letters
The NC 2L groundwater standards are regulatory levels applied to groundwater to determine the need
for remediation (NCAC, 2013). These are not the same as the drinking water standards used for public
drinking water sources. Dr. Rudo testified that the Do Not Drink (DND, for the purposes of this report)
form format has used the federal drinking water standards as the criteria for issuing advisories not to
drink private well water. The DND format was changed for the CAMA evaluations, however, to refer to
the 2L standards (including IMACs — Interim Maximum Allowable Concentrations) and HSLs.
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The NC 2L groundwater standards use a target risk level for carcinogens of one in one million. NC DHHS
is not bound by this target, as evidenced by the fact that Dr. Rudo initially suggested an HSL for
hexavalent chromium of 0.2 ug/L, based on the CalEPA PHG and a target risk level of 1 in 100 thousand.
He testified in his deposition that he considered 0.2 ug/L of hexavalent chromium to be a health -
protective value.
Similarly, for Dr. Rudo's initial evaluations of vanadium, he proposed a screening level of 18 ug/L. He
also indicated that this was a health -protective value, although the IMAC for vanadium is 0.3 ug/L. (See
the full discussion of vanadium in Bradley, 2016b.)
The North Carolina Coal Ash Management Act (CAMA) (2014) does say to use the NC 2L standards to
determine if an alternate water supply should be provided to well owners where it has been
demonstrated that the groundwater is impacted above the 2L standards as a result of a release from an
ash pond:
"If the sampling and water quality analysis indicates that water from a drinking water supply
well exceeds groundwater quality standards for constituents associated with the presence of
the impoundment, the owner shall replace the contaminated drinking water supply well with an
alternate supply of potable drinking water and an alternate supply of water that is safe for other
household uses. The alternate supply of potable drinking water shall be supplied within 24 hours
of the Department's determination that there is an exceedance of groundwater quality
standards attributable to constituents associated with the presence of the impoundment. The
alternate supply of water that is safe for other household uses shall be supplied within 30 days
of the Department's determination that there is an exceedance of groundwater quality
standards attributable to constituents associated with the presence of the impoundment."
CAMA, § 130A-309.209(c).
Thus, the 2L standards are required to be applied to determine if an alternate water supply is to be
provided to a well owner, where the groundwater impacts are demonstrated to be from a coal ash
impoundment. CAMA does not require that the 2L standards are to be used as the benchmark to
determine if DND letters should be sent to the well owner.
In Dr. Rudo's deposition, he testified that the change of the DND form format to use 2L standards rather
than drinking water standards was a decision made by the DHHS. It is unclear why the DHHS would
make this decision, and why the DND letters would be sent to well -owners when the concentrations
were below screening levels that Dr. Rudo has said would be safe. While the use of the 2L standards for
screening under CAMA is a requirement, there is no such requirement for the issuance of DND letters.
It is also unclear why the DHHS decided to use the 2L standards instead of the federal drinking water
standards that they normally use to issue the DND letters. Finally, it is unclear why the DHHS drew such
a bright line for communicating the DND letters for hexavalent chromium and vanadium, when Dr. Rudo
initially had proposed higher screening levels and felt that they were health protective. This bright line
has induced unnecessary fear and concern on the part of the public, that could have been avoided.
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As toxicologists, we understand that the methods used in regulatory toxicology to derive the toxicity
values used in risk calculations are mathematical models (some simple, some complex) that are
necessarily conservative in that they are more likely to overestimate than underestimate risk. The
screening levels based on these conservative toxicity values can be used to say with assurance that no
adverse effects will occur from exposures to lower concentrations, but the converse is not true —
exposure to higher concentrations does not mean that adverse effects will occur, only that additional
evaluation is needed. This acknowledgement of the (overly) conservative nature of the groundwater
screening levels has been missing from the public discourse.
6. Hinkley, CA
The concentrations of hexavalent chromium in the water supply wells included in the CAMA-directed
sampling program ranged from not detected to 21.2 ug/L. This is within the range of hexavalent
chromium concentrations identified in U.S. public drinking water supplies (USEPA, 2015a,b). Only six (6)
detected results were above the 2L standard of 10 ug/L for total chromium. All results are below the
federal drinking water standard for total chromium of 100 ug/L, and all results are below the hexavalent
chromium -specific drinking water screening level of 100 ug/L based on TCEQ and Health Canada
evaluations.
The hexavalent chromium concentration range in the water supply wells sampled under CAMA is much
lower than the range of hexavalent chromium concentrations in the plume in Hinkley, CA, which was the
subject of the "Erin Brokovich" movie.
"Since 1988, PG&E and their contractors have been monitoring the levels of total chromium and
hexavalent chromium in the groundwater in the vicinity of the Hinkley site. According to the
quarterly groundwater investigations conducted since 1988, the level of hexavalent chromium
ranged from non -detect to 3.64 mg/L [3,640 ug/L], and the level of total chromium ranged from
non -detect to 5.8 mg/L." (ATSDR, 2000)
Thus, the concentrations of hexavalent chromium in the groundwater ranged up to 100-fold higher than
the concentrations in North Carolina.
The Desert Sierra Cancer Surveillance Program has been collecting information on cancer occurrence in
the Hinkley Census Tract in San Bernardino County, CA. The data have been collected from 1988
through 2011 (California Cancer Registry, 2011). The 2011 study concludes:
"These findings identify cancer occurrence in the Hinkley Census Tract that is slightly, but
not significantly below the number of new cases expected for an average risk population
having the same demographic characteristics as the Hinkley Census Tract population. Similar
to the previous two cancer assessments that evaluate cancer occurrence in 1988-1993 and
1988-1998 (1), these 1996-2008 preliminary findings do not identify a generalized cancer
excess in the Census Tract encompassing Hinkley, San Bernardino County."
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Thus, an excess number of cancer cases has not been identified in this population of approximately
4 million people (California Cancer Registry, 2011).
7. References
ACS. 2016. Cancer Facts & Figures 2016. American Cancer Society. Atlanta: American Cancer Society.
Available at:
http://www.cancer.org/research/cancerfactsstatistics/cancerfactsfigures20l6/
ATSDR. 2000. Public Health Assessment for Pacific Gas & Electric (a/k/a Hickley Site); Hinkley, San
Bernardino County, California; EPA Facility ID: Ca0000206656. December 4, 2000. Agency for
Toxic Substances and Disease Registry.
Bradley, L.J.N. 2016a. Expert Report, Lisa JN Bradley, Ph.D., DABT (Allen, Cliffside, and Mayo Sites). By
Haley & Aldrich, Inc., Boston, Massachusetts, for Duke Energy, Charlotte, North Carolina, File
No. 43518-001, June.
Bradley, L.J.N. 2016b. Expert Report, Lisa JN Bradley, Ph.D., DABT (Marshall, Belews Creek, and Roxboro
Sites). By Haley & Aldrich, Inc., Boston, Massachusetts, for Duke Energy, Charlotte, North
Carolina, File No. 43518-001, August.
CaIEPA. 2011. Public Health Goals for Chemicals in Drinking Water. Hexavalent Chromium (Cr VI).
Office of Environmental Health Hazard Assessment (OEHHA). California Environmental
Protection Agency. July. Available at: http://oehha.ca.gov/water/public-health-goals-phgs
California Cancer Registry. 2011. Preliminary Assessment of Cancer Occurrence in the Hinkley Census
Tract, 1996-2008. J.W. Morgan. Desert Sierra Cancer Surveillance Program. The Criterion,
March 2011. Available at:
http://www.waterboards.ca.gov/lahontan/water issues/proiects/pge/docs/hinkley/ccr 032011
CAMA. 2014. North Carolina Coal Ash Management Act. Senate Bill S729v7. Available at:
http://www.ncleg.net/Sessions/2013/Bills/Senate/PDF/S729v7.PDF
Health Canada. 2015. Chromium in Drinking Water. Document for Public Consultation. Available at:
http://www.healthycanadians.gc.ca/health-system-systeme-sante/consultations/chromium-
chrome/document-eng.php
NCAC. 2013. 15A NCAC 02L.0202. Groundwater Standard (2L), Classifications and Water Quality
Standards Applicable to Groundwaters of North Carolina. North Carolina Administrative
Code. April 1, 2013. Available at:
http://portal.ncdenr.org/c/document library/get file?uuid=laa3fa13-2cOf-45b7-ae96-
5427fb1d25b4&groupld=38364
NC DHHS. 2015. DHHS Screening Levels. Department of Health and Human Services, Division of Public
Health, Epidemiology Section, Occupational and Environmental Epidemiology Branch. April 24,
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2015. Available at:
http://Portal.ncdenr.org/c/document library/get file?p I id=1169848&folderld=24814087&na
me=DLFE-112704.PDF
NC General Assembly. 2016. House Bill 630. Coal Ash Management. Available at:
http://www.ncleg.net/Sessions/2015/Bills/House/PDF/H630v4.pdf
NJDEP. 2009. Derivation of an Ingestion -Based Soil Remediation Criterion for Cr+6 Based on the NTP
Chronic Bioassay Data for Sodium Dichromate Dihydrate. June. Available at:
http://www.state.nw.us/dep/dsr/chromium/soil-cleanup-derivation.pdf
NTP. 2007. Toxicity Studies of Sodium Dichromate Dihydrate (CAS No. 7789-12-0) Administered in
Drinking Water to Male and Female F344/N Rats and B6C3F1 Mice and Male BALB/c and am3-
057BL/6 Mice. National Toxicology Program. NTP TOX 072. Available:
http://ntp.niehs.nih.gov/ntp/htdocs/st rpts/tox072.pdf
NTP. 2008. NTP Technical Report on the Toxicology and Carcinogenesis Studies of Sodium Dichromate
Dihydrate (Cas No. 7789-12-0) in F344/N Rats and B6C3F1 Mice (Drinking Water Studies).
National Toxicology Program. NTP TR 546. Available at:
http://ntp.niehs.nih.gov/ntp/htdocs/It rpts/tr546.pdf
TCEQ. 2016. Proposed Development Support Document (DSD) Hexavalent Chromium Oral Reference
Dose. Texas Commission on Environmental Quality. June. Available at:
http://www.tceg.com/assets/public/implementation/tox/dsd/proposed/oune2016/hexchromor
al.
Thompson, C., Kirman, C., Proctor, D., et al. 2014. A chronic oral reference dose for hexavalent
chromium -induced intestinal cancer. J. Appl. Toxicol. 34, 525-536.
USEPA. 1991. Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions. OSWER
Directive #9355.0-30. April. U.S. Environmental Protection Agency. Available at:
http://www.epa.gov/oswer/riskassessment/baseline.htm [Note — USEPA is in the process of
updating its website, so old links no longer work, but pages are not redirected. This reference
can currently be found here:
http://www.Im.doe.gov/cercla/documents/rockvflats docs/SW/SW-A-005200.pdf]
USEPA. 2010. IRIS Toxicological Review of Hexavalent Chromium (2010 External Review Draft). U.S.
Environmental Protection Agency, Washington, DC, EPA/635/R-10/004A. September. Available
at: https://cfpub.epa.gov/ncea/iris drafts/recordisplay.cfm?deid=221433
USEPA. 2012. 2012 Edition of the Drinking Water Standards and Health Advisories. Office of Water,
U.S. Environmental Protection Agency, Washington, DC. Available at:
https://www.epa.gov/dwstandardsregulations/drinking-water-contaminant-human-health-
effects-information
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USEPA. 2015a. The Third Unregulated Contaminant Monitoring Rule (UCMR3): Data Summary. Last
updated January 2015. http://www.epa.gov/dwucmr/third-unregulated-contaminant-
monitoring-rule
USEPA. 2015b. The Third Unregulated Contaminant Monitoring Rule (UCMR3): Occurrence Data. Last
updated January 2015. http://www.epa.gov/dwucmr/third-unregulated-contaminant-
monitoring-rule
USEPA. 2016a. USEPA Regional Screening Levels. May 2016. U.S. Environmental Protection Agency.
Available at: http://www.epa.gov/risk/regional-screening-table
USEPA. 2016b. Integrated Risk Information System (IRIS). Environmental Criteria and Assessment
Office. U.S. Environmental Protection Agency, Cincinnati, OH. Available at:
http://cfpub.epa.gov/ncea/iris/index.cfm
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