DEQ-CFW_00069747

Environment International 60 (2013) 242-248
=i f, Contents lists available at ScienceDirect
• t
Environment International 4
journal homepage: www.elsevier.com/locate/envint
Fluorinated alternatives to long -chain perfluoroalkyl carboxylic acids ;CrossMark
(PFCAs), perfluoroalkane sulfonic acids (PFSAs) and their
potential precursors
Zhanyun Wang a, Ian T. Cousins I', Martin Scheringer',*, Konrad Hungerbuhler'
Institute (or Chemical and Bioengineering, ETH Zurich, Wolfgang-Pauli-Stracse 10, CH-8093 Zurich, Switzerland
" Department ol'Applied Environmental Science (ITM). Stockholm University. SE-10691 .Stockholm, Sweden
A R T I C L E I N F O
A B S T R A C T
Article history:
Since 2000 there has been an on -going industrial transition to replace long -chain perfluoroalkyl carboxylic acids
Received 30 May 2013
(PFCAs), perfluoroalkane sulfonic acids (P1:SAs) and their precursors. To date, information on these replacements
Accepted 27 August 2013
including their chemical identities, however, has not been published or made easily accessible to the public, ham -
Available online 26 October 2013
poring risk assessment and management of these chemicals. Here we review information on fluorinated alterna-
Kevwords:
lives in the public domain. We identify over 20 fluorinated substances that are applied in [i] fluoropolymer
Perfluorinated alkyl substances
manufacture, [iij surface treatment of textile, leather and carpets, [iiij surface treatment of food contact materials,
Perrluorinated carboxylic acids
[iv] metal plating, [v] fire -fighting foams, and [vij other commercial and consumer products. We summarize cur-
Pernuorinated sulfonic acids
rent knowledge on their environmental releases, persistence, and exposure of biota and humans. Based on the
Fluorinated alternatives
limited information available, it is unclear whether fluorinated alternatives are safe for humans and the environ-
ment. We identify three major data gaps that must be filled to perform meaningful risk assessments and recom-
mend generation ofthe missingdata through cooperation amongall stakeholders (industry, regulators, academic
scientists and the public).
V 2013 Elsevier Ltd. All righrs reserved.
1. Introduction
Since 2000 long -chain perfluoroalkyl carboxylic acids f PFCAs,
CnF2„ „ 1CCCH, n > 71, perfluoroalkane sulfonic acids [PFSAs,
C„Fz„ _,_ tS03H, n >_ 61 and their potential precursors (Buck et al.,
201 1 ), have attracted attention as global contaminants. Long -
chain PFCAs and PFSAs are problematic because they are highly
persistent (Fromel and Knepper, 2010; Parsons et al., 2008),
bioaccumulative (fonder et al., 2008) and have been detected ubiqui-
tously in the abiotic environment (Rayne and Forest, 2009), biota
(Giesy et al., 2001), food items (Clarke and Smith, 201 1) and humans
(Vestergren and Cousins, 2009). As a result perfluorooctane sulfonate
(PFOS) and related substances based on perfluorooctane suffonyl fluo-
ride (POST) were listed under Annex B (restriction of production and
use) of the Stockholm Convention in 2009. In 2012 Cll—Ct4 PFSAs
were identified as vPvB chemicals (very persistent and very
bioaccumulative), and were included in the Candidate List of Sub-
stances of Very High Concern under the European chemicals regulation,
REACH (ECHA, 2013a). In 2013, also perfluorooctanoic acid (PFOA) and
ammonium perfluorcoctanoate (APFO) were listed in the Candidate List
Of Substances of Very High Concern ECHA (2013a).
Corresponding author. Tel.: [phone].
E-mail address: martin.scheri ngerca'che m.et h z.c'h (M. Scheringer).
0160-4120'S - see Gout matter 0 2013 Elsevier Ltd. All rights reserve(].
hill): clx.doi.oig-10.1016)i.envinL2013.08.0:'1
Driven by concerns about their undesired impacts on humans and
the environment, there has been a trend among global producers to re-
place long -chain PFCAs, PFSAs and their potential precursors with their
shorter -chain homologues (Ritter, 2010) or other types of (non)fluori-
nated chemicals (UNEP, 2012) (these replacements are referred to as
alteniaHves in the following). These industry initiatives began in 2000
when 3M announced a global phase-otlt of its products based on C(;,
Ca and C70 chemistry and replaced them with products based on CI
chemistry such as perfluorobutane sulfonic acid (PFBS) (3M, 2000:
Ritter, 2010). In 2006, eight major producers of PFCAs, fluoropolymers
and fluorotelomer substances joined the US EPA 2010/15 PFOA Stew-
ardship Program (t1S EPA, 2006) to worl< towards the elimination of
long -chain PFCAs and their potential precursors by 2015.
Ill this study we address the question: are the fluorinated alterna-
tives to long -chain per- and polyfluoroalkyl products safe for humans
and the environment? Recent experience with replacements of other
chemicals has shown a "lock -in" problem, i.e. one chemical from a
group of structurally similar chemicals was removed from the market
and replaced by other chemicals from the same group, but the basic
problem was not really solved (Goldstein et al., 20t3; Strempel et al.,
2012). For example, polychlorinated biphenyls (PCBs) were replaced
by short -chain chlorinated paraffins, which are currently being evaluat-
ed under the Stockholm Convention.
To answer this question, information regarding alternatives (includ-
ingchemical structures, physicochemical properties, (bio)clegraclability,
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Z. Wang et al. / Environment International 60 (2013) 242-248
r
243
bioaccumuladon potential, (eco)toxicity, production and releases, and
environmental and human exposure) is needed. However, due to con-
cerns of business confidentiality, most of the information required to as-
sess the safety of alternatives has not been published or made easily
accessible to the public. This lack of data makes it unclear whether alter-
natives have been fully tested before they are commercialized. It also
inhibits scientists and civil society organizations, as an essential supple-
ment to regulators and industry, from proactively minimizing the risks
associated with alternatives by conducting monitoring activities and re-
search into the environmental fate and potential adverse effects of alter-
natives (Goldstein et al., 2013).
Here, we review information on fluorinated alternatives in the public
domain in two respects: (i) to identify which chemicals are (possibly)
applied in various industry branches or consumer products; and (ii) to
summarize current knowledge on their environmental releases, persis-
tence, and exposure of biota and humans. With the information provid-
ed, we aim to give an overview of the on -going transitions to fluorinated
alternatives and of the potential environmental and human exposure
to these chemicals. Due to space limitations, we do not address potential
adverse effects of these chemicals. Related information, however, can be
found in the following references: Asahi (2006), Borg and Hakansson
(2012), ECHA (2013b), EFSA (2010, 2011a, 2011b), Gordon (2011),
Hagenaars et al. (2011), Lau et al. (2007), Norgaard et al. (2010), and
Wang et al. (2013a). In addition, it should be noted that several types
of nonfluorinated substances are also available as alternatives (e.g.,
dendrimers, siloxanes and silicone polymers) (Poulsen et al., 2005;
UNEP, 2012), but may not perform as well as fluorinated substances,
particularly in situations where extremely low surface tension and/
or durable oil- and water -repellence is needed (Holt, 2011). For
information on nonfluorinated alternatives, we recommend readers
to consult other studies that specifically address these substances
(e.g., Ulaszewska et al., 2012; Wang et al., 2013b).
2. Production and use of fluorinated alternatives
Here, we summarize the publicly accessible information on the
production and use of fluorinated alternatives in different industrial
branches (for examples, see Fig. 1). Other fluorinated alternatives
might also be on the market: their identities, however, could not be
identified.
2.1. Fluoropolymer manufacture
Historically, almost all producers applied ammonium or sodi-
um perfluorooctanoate (APFO and NaPFO) as processing aids
in the (emulsion) polymerization of polytetrafluoroethylene (PTFE),
perfluorinated ethylene -propylene copolymer (FEP), perfluoroalkoxy
polymer (PFA) and certain fluoroelastomers: and applied ammoni-
um perfluorononanoate (APFN) in the emulsion polymerization of
polyvinylidene fluoride (PVDF) (PrevedOtlros et al., 2006). However,
during the recent transition, most of the producers have developed their
own alternatives. Known commercialized fluorinated alternatives are
functionalized perfluoropolyethers (PFPEs), including (i) ADONA from
3M/Dyneon (CF30CF2CF2CF20CHFCF2C00-NH4 , CAS No. 958445-44-
8) (Gordon, 2011); (ii) GenX from DuPont (CF3CF2CF2OCF(CF3)COO "
NH4, CAS No. 62037-80-3) (DuPont. 2010); (iii) cyclic or polymeric
functionalized PFPEs from Solvay for its PTFE and PVDF manufacture
(Marchionni et al., 2010: Pied et al., 2011: Spada and Kent, 2011)
(e.g., a complex process mixture, C3Ft;C10-ICF2CF(CF3)0Ind CF(CF3)Oj,,,-
CFZCOOH, n = 1-4, m = 0-2, with a molecular weight in the range of
500 to 650 Da has been registered at the European Food Safety Authority
(EFSA), CAS No. 329238-24-6 (EFSA, 2010)); (iv) C2F5OC2F4OCF2C00
NH,; (CAS No.908020-52-0) from Asahi (EFSA, 2011 a): and (v) another
functionalized PFPE from Chenguang in China (its structure and CAS No.
remains unrevealed) (Xie et al., 2010, 2011). In Europe, GenX has been
registered under REACH with a production volume of 10-100 tonnes
per year (ECHA, 2013b).
In addition, some producers, such as Daikin (Iwai. 2011), may have
used ammonium perfluorohexanoate (APFHx) as polymerization pro-
cessing aids (supported by higher levels of perfluorohexanoic acid
(PFHxA) in comparison to other PFCA homologues detected in water
samples from a fluoropolymer manufacturing site in France (Dauchy
et al., 2012) ). Finally, a Chinese producer may use 6:2 fluorotelomer car-
boxylic acid (62 FTCA, C6F13CH2COOH, CAS No. 53826-12-3) as an alter-
native processing aid replacing perfluorooctanoic acid (PFOA) (Xu et al.,
2011). No information is available on the processing aids currently used
by other fluoropolymer manufacturers.
2.2. Surface treatment of textile, leather and carpets
Side -chain fluorinated polymers, which comprise non -fluorinated
carbon backbones and side -chains containing a mixture of 6:2-14:2
fluorotelomer moieties (C„F2„ - iC2H4—, n = 6-14) or moieties de-
rived from POSF, were widely used in surface treatment products to im-
part water- and oil -resistance to textile, leather and carpets (Buck et al.,
2011). A current trend is to use shorter -chain homologues to replace
long -chain flurotelomer- or POSF-based derivatives on side -chains
(Ritter, 2010). Since 2003, 3M has commercialized a series of surface
treatment products such as Scotchguard PM-3622 (CAS No. 949581-
65-1), PM-490 (CAS No. 940891-99-6) and PM-930 (CAS No. 923298-
12-8) containing C4 (C4F9SO2—) side -chain fluorinated polymers de-
rived from perfluorobutane sulfonyl fluoride (PBSF) (Renner, 2006).
Fluorotelomer manufacturers have developed products based on highly
purified fluorotelomer raw materials (mostly 6:2, see examples on the
OECD Portal on Perfluorinated Chemicals (OECD, 2013)), including
copolymers derived from 6:2 fluorotelomers and organosiloxane
(Unidyne TG-5521 developed by Daikin and Dow -Corning (Doi,,
Corning, 2007)). Miteni has commercialized polyfluoroalkyl alcohols
(3:1 and 5:1 FTOHs, C„ F2n I ICH20H, n = 3, 5, CAS No. 375-01-9 and
423-46-1) that can be used as building blocks for side -chain fluorinated
polymers (Miteni, 2012) and Solvay has applied PFPEs such as
FluorolinkO as alternatives to side -chain fluorinated polymers for textile
surface treatment (Solvay, 2011).
Some producers in China and Italy have initiated the production of
perfluorohexane sulfonyl fluoride (PHxSF, CoF13SO2F)-based derivatives
as alternatives in surface treatment products (China MEP, 2012; Miteni,
2012), but these can degrade into perfluorohexane sulfonate (PFHxS) in
the environment (D'eon et al., 2006: Martin et al., 2006) and are thus
considered as long -chain PFSA precursors (Buck et al., 2011). In China,
it is estimated that in the next 5-10 years production of surface treat-
ment products containing PHxSF- or PBSF-derivatives will reach more
than 1000 tonnes per year (Huang et al., 2010).
2.3. Surface treatment of food contact materials -
After 3M ceased its production of POSF-based side -chain fluorinated
polymers (e.g., CAS No. 92265-81-1) and phosphate diesters (SAmPAP,
e.g., FC 807, CAS No. 30381-98-7) that were used in food contact materials
(3M. 2000). there is no evidence that PBSF-based derivatives are used as
alternatives. Fluorotelomer manufacturers have developed products
based on 6:2 fluorotelomers to replace their earlier products (both side -
chain fluorinated polymers and phosphate diesters (diPAPs)I that were
based on longer -chain fluorotelomer derivatives (Loi et al., 2013). For ex-
ample, since 2008, seven 6:2 fluorotelomer-based side -chain fluorinated
polymers have been registered in the Inventory of Effective Food Contact
Substance (FCS) Notifications of the United States Food and Drug Admin-
istration: they are CAS No. 1345817-52-8 by Asahi, CAS No. 1012783-70-
8,1158951-85-9, and 1206450-09-0 by Daikin, and CAS No.1071022-25-
7, 357624-15-8, and 1071022-26-8 by DuPont (t1S FDA, 2013a). In
addition, products based on PFPEs such as Solvera(W from Solvay (chemi-
cal structures are likely similar to HO(0)(OH)PO-(CH2CH20)„CH;,CF.,-
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244 Z. Wang et al. / Environment International 60 (2013) 242-248
Fluoropolymer manufacture Metal plating
ADONA (CAS No. 958445-44-8)
Fz Fz
F3CSO\F SC\F SO\HC\COO
z z F
GenX (CAS No. 62037-80-3)
Fz
F3CSC\C/O\CSCOO -
Fz
F3
Asahi's product (CAS No. 908020-52-0)
Fz Fz
F3C SC 1-,0 SC \C SO \C SCOO-
Fz F2
Solvay's product (CAS No. 329238-24-6)
F3 C F3
O` % CF V
CFC\
CIF6C3S FS\0 \O m FCOO
z
Fire fighting foams and miscellaneous
N(Et)4-PFBS (CAS No. 25628-08-4)
CzHs
F, Fz
C C ,--,
F3C/ \CS \503 t+\
Fz C2H5/ C2H5
6:2 FTSA (CAS No. 27619-97-2)
Fz Fz Fz Hz
F3 CSC\CSC\CSC\CSC\S03
Fz Fz Hz
F-53 (CAS No. 754925-54-7)
Fz Fz Fz Fz _
F3C'/C\C/C\CSC\0SC\C/S03
Fz Fz Fz
F-53B (CAS No. 73606-19-6)
Fz Fz Fz Fz
CIFZCSC\CSC\CSC\OSC\C/ S03
Fz Fz Fz
0
Fz 02 02 Fz Fz Fz II
F3C\CSC\CSS\NHS\CSC\CSCF3 F3CSC\CSC\C.�C\ IH
Fz Fz H Fz Fz Fz Fz
H3C ` CH, C3H6 OCH3
Fz Fz Fz Hz H Hz \ /
F3CSC\CSC\CSC\CSC\SSN\CSC\CSN\CHZCOO- I \OCH3
Fz Fz Hz Oz Hz Hz OCH3
Fig.1. Examples of fluorinated alternatives identified in different industry branches.
(OCF2)p- (OCF2CF2),- OCF2CH2-(OCHZCH2)„-OP(OH)(0)(OH) (Trier et al., and F-53B were used in 2009 in the metal plating industry (both deco-
201 1)) have been used as alternatives (Solvay, 2011). rative and hard metal plating) in China (Huang et al., 2010).
2.4. Metal (chromium) plating
Historically, salts of PFOS have been used as wetting agents and
mist -suppressing agents in decorative plating and non -decorative
hard plating. Recent technology development using chromium -Ill in-
stead of chromium -VI has made PFOS use in decorative chrome plating
obsolete. Chromium -Ill, however, cannot be used for hard chrome
plating (UNEP, 2012). In Europe, salts of 6:2 fluorotelomer sulfonic
acid (6:2 FTSA, C(;F73C2H4SO3H) are applied as alternatives to PFOS,
however, they can only partly be applied in decorative plating due to
slightly higher surface tension compared to PFOS (UNEP, 2012). In
addition, N(Et)4-PFBS (CAS No. 25628-08-4) is registered for metal
plating under REACH with a production volume of 1-10 tonnes per
annum (ECHA, 2013b). Also, a German producer reported a produc-
tion of 20-50 tonnes of PFBS-based ]C4F9SO2N(CH3)CH2CH2O]2P(0)OH
(CAS No. 120945-47-3) in 2003, which is used as defoamer in
the electroplating industry (OECD, 2005). In China, several producers
have used F-53 (salts of C(3F73OCF2CF2S03H, CAS No. 754925-54-7)
and F-53B (CI-C6F120CF2CF2SO3K, CAS No. 73606-19-6), likely derived
from fluorotelomer raw materials, since the late 1970s (Huang et al.,
2010; UNEP, 2012). it is estimated that about 20-30 tonnes of F-53
2.5. Fire -fighting foams
In the past, various PFCA-, PFSA-, and fluorotelomer-based derivatives
were added (i) as film formers in aqueous film forming foams (AFFFs)
and film forming fluoroproteins (FFFPs), (ii) as fuel repellents in
fluoroprotein foams (FPs), and (iii) as foam stabilizers in FFFPs and
alcohol -resistant aqueous film -forming foams (AR-AFFFs) (Backe et al.,
2013; Kleiner and Jho, 2009; Place and Field, 2012). In 2002 3M, which
was the only producer, ceased its global production of POSF-based
AFFFs (Place and Field, 2012); and thereafter has developed a fire sup-
pression agent based on a gaseous fluorinated ketone [CF3CF2C(0)
CF(CF3)2, CAS No. 756-13-8] (UNEP, 2012). Also, AFFFs based on pure
6:2 fluorotelomers are under development to replace the early genera-
tions that are based on a mixture of predominantly 6:2 and 8:2
fluorotelomers (Klein, 2012; Kleiner and Jho, 2009). For example,
DuPont commercialized Forafac& 1157 that is based on 6:2
fluorotelomer sulfonamide alkylbetaine 16:2 FTAB, C6F13C2H4S02
NHC3H6N-'(CH3)2CH2C00-] (Hagenaars et al., 2011; Moe et al.,
2012; Pabon and Corpart, 2002) and Forafac@ 1183 that is based
on 6:2 fluorotelomer sulfonamide aminoxide ]C6F13C2H4SO2NH
C.3Hc,N(0)(CH3)2, CAS No. 80475-32-7i (Jensen et al., 2008). In addi-
tion, a Chinese institute has developed an AFFF formulation based
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245
on a PFBS derivative [C4F9SO2NH(CH2)3NH(CH3)2-,] (Yang et al.,
2009; Zhao, 2012), its commercialization, however, is unclear.
2.6. Miscellaneous
In addition to those mentioned above, we have identified the fol-
lowing fluorinated alternatives and their potential uses: (i) The po-
tassium salt of PFBS (CAS No. 29420-49-3) is marketed as a flame
retardant for polycarbonate resins; 30-50 tonnes of it were pro-
duced in 2003 in Germany (Hubei Hengxin, 2013; Miteni, 2012;
Mitsubishi, 2013; OECD, 2005; Wuhan Chemical, 2013). (ii) The
imide salt of PFBS I(C4F9SO2)2NH, CAS No. 39847-39-71 is marketed
as a surfactant, acid catalyst, and as a raw material for ionic liquids
(Mitsubishi, 2013). (iii) A PFHxA-derivative [CF3(CF2)4CONH(CH2)3
Si(OCH3)3, CAS No. 154380-34-4] is marketed as a surface treatment
for glasses, natural stones, metals, wood, cellulose, cotton, leather and
ceramics (Miteni, 2012). (iv) In Europe, Dow Corning registered a copol-
ymer comprising 6:2 fluorotelomers and siloxane (C6F13CH2CH2
Si(OCH3)3, CAS No. 85857-16-5) under REACH; its intended use is
unknown (ECHA, 2013b). (v) Nanofilm spray products based on
polysiloxanes with 6:2 fluorotelomers in (some of) the side -chains are
marketed for coatings of nonabsorbing floor materials (Nergaard et al.,
2010). (vi) In the US DuPont produced CF2=CF-OCF2CF(CF3)CF2CF2
S02F (CAS No. 16090-14-5) in an amount larger than •11.4 tonnes in
2011 (US EPA, 2012), which is likely used as a monomer for a copolymer
used in polymer electrolyte fuel cells (Uematsu et al., 2006). (vii) In the
US DuPont produced CF30CF(CF3)COF (CAS No. 2927-83-5) in an
amount larger than 11.4 tonnes in 2011 (US EPA, 2012); and its use
remains unknown.
3. Environmental and human exposure to fluorinated alternatives
3.1. Environmental releases
Similarly to APFO and APFN, fluorinated alternatives applied as poly-
merization processing aids may enter the environment at manufactur-
ing sites where they are produced and used to produce fluoropolymers
as well as during use and disposal of fluoropolymer resins. For example,
ADONA was monitored between June 2008 and November 2009 in the
River Alz (Germany) downstream of wastewater effluent discharges
from 3M/Dyneon's factory and was detected in all samples (range
from 0.32 to 6.2 µg/1 (BaLtU. 2010a)). In addition, ADONA is emitted to
air through exhaust gases and then deposited to the ground nearby
3M/Dyneon's factory. The average deposition rate of ADONA to surface
soil near the plant between December 2009 and May 2010 is estimated
at 684 ng/(m2 d) (BaLfU, 2010b). GenX has also been detected in river
water downstream of effluent discharges from the DuPont factory in
North Carolina (USA) (Strynar et al., 2012). The discharge of PFHxA
from a fluoropolymer manufacturing plant in France to the receiving
river is estimated at 10 t/yr (Dauchy et al., 2012).
To date, there is no information on releases during use and disposal of
fluoropolymer resins that contain fluorinated alternatives; but residual
levels of some fluorinated alternatives in fluoropolymer resins are report-
ed. The residual levels of ADONA in the final sintered fluoropolymer ma-
terials and an unsintered fluoropolymer micropowder are <0.02 mg/kg
and 3.3 mg/kg, respectively (EFSA, 2011b); and GenX residuals in
fluoropolymer resins are below 0.2 mg/kg (DuPont, 2010).
For other fluorinated alternatives, no information regarding releases is
available. However, elevated levels of PFBS and/or perfluorobutanoic acid
(PFBA, an impurity in PBSF-based derivatives) in water samples from the
river Rhine watershed (Lange et al., 2007; M611er et al., 2010), German
coast (Ahrens et al., 20101), Tokyo Bay (Japan) (Ahrens et al., 2010b)
and Northwest Pacific Ocean (Cai et al., 2012) indicate an increasing use
and release of PBSF-based derivatives and other potential precursors.
3.2. Persistence
Extensive studies have suggested that 6:2 fluorotelomer-based (Lee
et al„ 2010: Liu et al., 2010a. 2010b; Moe et al., 2012; Wang et al.. 2011.
2012; Young and Mabury. 2010; Zhao et al., 2013) and PBSF-based alter-
natives (Benskin et al., 2012, 2013: D'eon et al., 2006; Martin et al.,
2006; Plumlee et al., 2009) can undergo similar degradation processes
(reaction with OH radicals, photolysis or biodegradation, etc.) as their
higher homologues and be transformed into corresponding short -
chain PFCAs and/or PFSAs (such as PFBS, PFBA or PFHxA) in the environ-
ment or biota. Similarly to 6:2 fluorotelomers, 3:1 and 5:1 FTOHs can
undergo reaction with OH radicals and form short -chain PFCA homo-
logues in air (Hurley et al., 2004; Sulbaek et al., 2006). These short -
chain PFCAs and PFSAs are as persistent in the environment as their
long -chain homologues.
For PFPE-based alternatives, information on degradability is scarce
and often incomplete. Available information shows that ADONA is not
readily biodegradable (Gordon, 2011), but starts to decompose ther-
mally at 125 °C with completion at 175 °C, leading to formation of vol-
atile substances (details on degradation products were not provided)
(EFSA, 2011 b). No hydrolysis and biodegradability of GenX was ob-
served in tests according to the OECD test guidelines 111 (tested at
pH = 4, 7,9 at 50 °C) and 301B (tested for up to 28 days), respectively
(ECHA, 2013b). In addition, an atmospheric degradation study of a non-
functionalized PFPE-based product, Galden® HT70 (consisting of
mainly CF30CF(CF3)CF2OCF2OCF3 with smaller amounts of CF30CF(CF3)
CF2OCF2OCF2OCF3 and longer -chain analogs) indicates that these PFPEs
degrade slowly in air with a lifetime greater than 46 years (through
reaction with Cl and OH radicals) and 800 years (through photolysis),
respectively (Young et al., 2006).
3.3. Exposure of biota and humans
The bioaccumulation potential, in terms of serum elimination half-
life, of PFBA, PFBS, PFHxA, PFHxS, PFOA and PFOS in humans and mam-
mals has been well studied (see Table 1). In general, PFBA, PFBS and
PFHxA, which can be used as alternatives to their higher homologues
in some cases or occur as undesired byproducts or degradation products
of PBSF- or 6:2 fluorotelomer-based alternatives, have shorter half-lives
in humans and biota than their longer -chain homologues (Borg and
Hakansson, 2012: Iwai, 2011; Wilhelm et al., 2010). In contrast, PFHxS
has similar or even longer serum half-lives than PFOS in all tested ani-
mals (except female rats) and in humans, which makes PFHxS inappro-
priate as an alternative to PFOS. For other fluorinated alternatives, only
two industry studies of GenX in rats and mice were found (reported to
the European Chemicals Agency (ECHA)) (ECHA, 2013b); and the data
reported are only sufficient to calculate an approximate range of the
serum elimination half-life of GenX in rats and mice, see Table 1.
Regarding the absolute exposure levels, a recent study on the tem-
poral trends of PFCAs and PFSAs in serum from primiparous women in
Sweden between 1996 and 2010 observed a marked increase of PFBS
and PFHxS over time (Glynn et al., 2012). Similar observations of an in-
creasing PFHxS exposure trend after 2006 in the US have also been re-
ported by Kato et al. (2011). For other fluorinated alternatives, no
temporal trend data are available.
4. Major data gaps and future perspective
There is some publicly accessible information on fluorinated
alternatives; it is. however, still heterogeneous among industrial
branches and not sufficient for conducting realistic risk assessments.
There are three major data gaps: (i) the identity of many alternatives
remains unknown, particularly in those industry branches or regions
that are less strictly regulated, whereas e.g. in Europe (EFSA, 2013)
and the US (US FDA, 2013b) food contact material producers are
obliged to submit specific safety data; (ii) for alternatives that have
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Table 1
Serum elimination half-lives of PFBS, PFHxS, PFOS, PFBA, PFHxA, PFOA, GenX, and ADONA in male (M) and female (F) rats, mice, monkeys and humans. In some cases, half-life is expressed
in the form of "arithmetic mean f standard deviation", while in other cases when the standard deviation is less than 15% of the arithmetic mean only the arithmetic mean is provided.
Notes on studies on rats, mice and monkeys provide information on dosing method (single oral dose or single intravenous (IV) dose) and dosage (in ppm: mgsubstance/kg bw). Notes on
studies on humans provide sample numbers (n) of humans involved. "-" means no data available.
PFAAs Rats Mice Monkeys Humans
11Q Notes tr;c Notes tirz Notes tt12 Notts 1i;2 Notes tr!, Notes I_ _ Notes
PFBS (F) 4 It IV 8 It Oral'
PFBS (M) 5 It 30 ppm 5 It 30 ppm --
PFHxS (F) 2 d IV - - 25 d
PFHxS (M) 29 d 10 ppm - - 31 d
PFOS (F)
62 d
Oral'
71 d
Oral"
38 d
PFOS (M)
38 d
2 ppm
41 d
15 ppm
43 d
PFBA (F)
1 h
IV`
2 h
Oral'
3 It
PFBA (M)
6 It
30 ppm
9 It
30 ppm
13 ± 5 h
PFHxA (F)
0.4 h
IV'
1.2 It
IV'
<72 h
PFHxA (M)
1 It
10 ppm
2.4 h
15 ppm
<72 In
PFOA (F)
2 It
IV'
-
-
17 d
PFOA (M)
6 d
20 ppm
-
-
19 d
PFOA (all)
-
-
-
-
-
PFOA (all)
-
-
-
-
-
PFOA (all)
-
-
-
-
-
PFOA (all)
-
-
-
-
-
- 83t421t IV 8+2h IV' 46d 11=1'
- 95{27h 10 ppin 15f 10 ppm 24}7d n=51'''
9h
Oral 27 d Oran 87 f 27 d IV' - - 12.8 r n = 2y
1 ppm 28 d
Oral' 30 d
1 ppm 36 d
Oral' 3 h
10 ppm 16 t
7h
Gastric' -
50 ppm -
not reported1' -
20 ppnt
141 ±
l0 ppnt -
30 d
Oral`'
1 10 d
IV' -
20 ppm
132 d
2 ppm -
Oral'
41 It
IV" -
30 ppm
4011
10 ppin -
2.411 IV, -
5.3 h 10 ppm -
33f7d Iv" -
21 f 10 d 10 ppm -
GenX (F) <12 It Oral" - - >12 h,<7 d Orals - - - - -
GenX (M) ,12 It 30 ppm - - > 12 h, <-7 d 3 ppm - - - -
ADONA (M) 44 h 5x oral'" - - - - - - - - -
0.6 yr
8.2f5.1yr
n=24`"
- 5.9 i 1 yi
n = 24,"
- 5.4f3.7yr
n=24"''
- 87t31h
n=2`"
- 68 f 35 It
n = 76''
- <28d
n=8",'
- 33 yr
n = 24.17
- 3.8f1.7yr
n=244
- 3.26 yr
n = 138'c t;
- 2.3 ,yr
n = 200's.is
2.9 yr
it = 643'4- „'
- 8.5 yr
n =
10291,1J.1
- 23 f 11 d
n= 3'''
Olken et al. (2009),20hengelis et al. (2009).'Sundso6m et al. (2012), "Oken et al. (2007), 30iang el it]. (2012), "Chang cf al. (200N),'Ohm01 i It al. (2001), "Iwai (201 1)_'Nik ,on et al. (2010). "Lau et al. (2007),
" oker and Gorman 12n0}), 128m1r et al. (20 VU), 13Hnrtell et it). (2010), 14Soals et ni. (2011), "ECHA (20131,1, oTFSA (201 1 b). _'These studies focal on samples from people who were occupationally exposed to
these substances and the levels in senun were high. "sl'hese studies fbetis nil samples fmrn people who Were exposed to PFOA mainly through highly contaminated drinking water.
been identified, information on their potential impacts on humans
and the environment is insufficient (e.g., knowledge on degradabili-
ty, bioaccumulation potential and (eco)toxicity of PFPEs is largely
missing.); (iii) for all fluorinated alternatives, the actual Volumes
that are produced, used and emitted remain unknown.
Furthermore, even those fluorinated alternatives that are considered
safe because of low acute toxicity and bioaccumulation according to
current regulations may still pose risks in the future. For example,
short -chain PFCA and PFSA homologues such as PFHxA and PFBS
are as persistent in the environment as the long -chain homologues.
Thus, the current increasing global production and use of these
chemicals and their potential precursors will lead to increasing
widespread environmental and human exposure that will last for
the foreseeable future. If, in the future, risks associated with short -
chain homologues are discovered and regulatory action needed, it
is important to be aware that it will take decades for global environ-
mental levels of these short -chain 11011101ogues to respond to any
emission reductions.
In order to prevent a "lock -in" problem in the field of fluorinated
alternatives, much effort is needed. Above all, communication among
stakeholders (manufacturers of fluorinated materials, industrial users
of these materials, regulators, scientists and the public) needs to be im-
proved and intensified. A transparent knowledge exchange among
stakeholders would enable: (i) developing accurate analytical techniques
for alternatives that can be used for further laboratory testing and field
monitoring of these chemicals (e.g. PFPEs (Di Lorenzo, 2012)); (ii) devel-
oping more sophisticated study designs and data analysis for environ-
mental fate, toxicity and bioaccumulation studies to facilitate up-to-
date regulatory decisions; and (iii) developing a new industrial ecology
where the latest scientific findings can be readily implemented in the
product design phase to develop materials with similar function, but
with negligible hazardous properties.
Acknowledgment
Funding by the Swiss Federal Office for the Environment (FOEN) is
gratefully acknowledged.
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