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Legacy and Emerging Perfluoroalkyl Substances Are Important Drinking Water Contaminants in the Cape Fear River Watershed of North Carolina


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Long-chain per- and polyfluoroalkyl substances (PFASs) are being replaced by short-chain PFASs and fluorinated alternatives. For ten legacy PFASs and seven recently discovered perfluoroalkyl ether carboxylic acids (PFECAs), we report (1) occurrence in the Cape Fear River (CFR) watershed, (2) fate in water treatment processes, and (3) adsorbability on powdered activated carbon (PAC). In the headwater region of the CFR basin, PFECAs were not detected in raw water of a drinking water treatment plant (DWTP), but concentrations of legacy PFASs were high. The US Environmental Protection Agency’s lifetime health advisory level (70 ng/L) for perfluorooctane sulfonic acid and perfluorooctanoic acid (PFOA) was exceeded on 57 of 127 sampling days. In raw water of a DWTP downstream of a PFAS manufacturer, the mean concentration of perfluoro-2-propoxypropanoic acid (PFPrOPrA), a replacement for PFOA, was 631 ng/L (n=37). Six other PFECAs were detected with three exhibiting chromatographic peak areas up to 15 times that of PFPrOPrA. At this DWTP, PFECA removal by coagulation, ozonation, biofiltration, and disinfection was negligible. PFAS adsorbability on PAC increased with increasing chain length. Replacing one CF2 group with an ether oxygen decreased PFAS affinity for PAC, while replacing additional CF2 groups did not lead to further affinity changes.
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Legacy and Emerging Peruoroalkyl Substances Are Important
Drinking Water Contaminants in the Cape Fear River Watershed of
North Carolina
Mei Sun,*
Elisa Arevalo,
Mark Strynar,
Andrew Lindstrom,
Michael Richardson,
Ben Kearns,
Adam Pickett,
Chris Smith,
and Detlef R. U. Knappe
Department of Civil and Environmental Engineering, University of North Carolina at Charlotte, Charlotte, North Carolina 28223,
United States
Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, North Carolina
27695, United States
National Exposure Research Laboratory, U.S. Environmental Protection Agency Research, Triangle Park, North Carolina 27711,
United States
Cape Fear Public Utility Authority, Wilmington, North Carolina 28403, United States
Town of Pittsboro, Pittsboro, North Carolina 27312, United States
Fayetteville Public Works Commission, Fayetteville, North Carolina 28301, United States
SSupporting Information
ABSTRACT: Long-chain per- and polyuoroalkyl substances
(PFASs) are being replaced by short-chain PFASs and
uorinated alternatives. For ten legacy PFASs and seven
recently discovered peruoroalkyl ether carboxylic acids
(PFECAs), we report (1) their occurrence in the Cape Fear
River (CFR) watershed, (2) their fate in water treatment
processes, and (3) their adsorbability on powdered activated
carbon (PAC). In the headwater region of the CFR basin,
PFECAs were not detected in raw water of a drinking water
treatment plant (DWTP), but concentrations of legacy PFASs
were high. The U.S. Environmental Protection Agencys
lifetime health advisory level (70 ng/L) for peruorooctane-
sulfonic acid and peruorooctanoic acid (PFOA) was exceeded on 57 of 127 sampling days. In raw water of a DWTP
downstream of a PFAS manufacturer, the mean concentration of peruoro-2-propoxypropanoic acid (PFPrOPrA), a replacement
for PFOA, was 631 ng/L (n= 37). Six other PFECAs were detected, with three exhibiting chromatographic peak areas up to 15
times that of PFPrOPrA. At this DWTP, PFECA removal by coagulation, ozonation, bioltration, and disinfection was negligible.
The adsorbability of PFASs on PAC increased with increasing chain length. Replacing one CF2group with an ether oxygen
decreased the anity of PFASs for PAC, while replacing additional CF2groups did not lead to further anity changes.
Per- and polyuoroalkyl substances (PFASs) are extensively
used in the production of plastics, water/stain repellents,
reghting foams, and food-contact paper coatings. The
widespread occurrence of PFASs in drinking water sources is
closely related to the presence of sources such as industrial
sites, military re training areas, civilian airports, and waste-
water treatment plants.
Until 2000, long-chain peruoroalkyl
sulfonic acids [CnF2n+1SO3H; n6 (PFSAs)] and peruoro-
alkyl carboxylic acids [CnF2n+1COOH; n7 (PFCAs)] were
predominantly used.
Accumulating evidence about the
ecological persistence and human health eects associated
with exposure to long-chain PFASs
has led to an increased
level of regulatory attention. Recently, the U.S. Environmental
Protection Agency (USEPA) established a lifetime health
advisory level (HAL) of 70 ng/L for the sum of
peruorooctanoic acid (PFOA) and peruorooctanesulfonic
acid (PFOS) concentrations in drinking water.
Over the past
decade, production of long-chain PFASs has declined in Europe
and North America, and manufacturers are moving toward
short-chain PFASs and uorinated alternatives.
uorinated alternatives were recently identied,
but others
remain unknown
because they are either proprietary or
manufacturing byproducts.
Received: October 13, 2016
Revised: November 8, 2016
Accepted: November 10, 2016
Published: November 10, 2016
© XXXX American Chemical Society ADOI: 10.1021/acs.estlett.6b00398
Environ. Sci. Technol. Lett. XXXX, XXX, XXXXXX
One group of uorinated alternatives, peruoroalkyl ether
carboxylic acids (PFECAs), was recently discovered in the Cape
Fear River (CFR) downstream of a PFAS manufacturing
Identied PFECAs included peruoro-2-methoxy-
acetic acid (PFMOAA), peruoro-3-methoxypropanoic acid
(PFMOPrA), peruoro-4-methoxybutanoic acid (PFMOBA),
peruoro-2-propoxypropanoic acid (PFPrOPrA), peruoro-
(3,5-dioxahexanoic) acid (PFO2HxA), peruoro(3,5,7-trioxa-
octanoic) acid (PFO3OA), and peruoro(3,5,7,9-tetraoxadeca-
noic) acid (PFO4DA) (Table S1 and Figure S1). The
ammonium salt of PFPrOPrA is a known PFOA alternative
that has been produced since 2010 with the trade name
GenX. To the best of our knowledge, the only other
published PFECA occurrence data are for PFPrOPrA in Europe
and China,
and no published data about the fate of PFECAs
during water treatment are available. Except for a few studies
(most by the manufacturer),
little is known about the
toxicity, pharmacokinetic behavior, or environmental fate and
transport of PFECAs.
The strong CF bond makes PFASs refractory to abiotic and
biotic degradation,
and most water treatment processes are
ineective for legacy PFAS removal.
Processes capable of
removing PFCAs and PFSAs include nanoltration,
ion exchange,
and activated carbon adsorp-
with activated carbon adsorption being the most
widely employed treatment option.
The objectives of this research were (1) to identify and
quantify the presence of legacy PFASs and emerging PFECAs
in drinking water sources, (2) to assess PFAS removal by
conventional and advanced processes in a full-scale drinking
water treatment plant (DWTP), and (3) to evaluate the
adsorbability of PFASs on powdered activated carbon (PAC).
Water Samples. Source water of three DWTPs treating
surface water in the CFR watershed was sampled between June
14 and December 2, 2013 (Figure S2). Samples were collected
from the raw water tap at each DWTP daily as either 8 h
composites (DWTP A, 127 samples) or 24 h composites
(DWTP B, 73 samples; DWTP C, 34 samples). Samples were
collected in 250 mL HDPE bottles and picked up (DWTPs A
and B) or shipped overnight (DWTP C) on a weekly basis. All
samples were stored at room temperature until they were
analyzed (within 1 week of receipt). PFAS losses during storage
were negligible on the basis of results of a 70 day holding study
at room temperature. On August 18, 2014, grab samples were
collected at DWTP C after each unit process in the treatment
train [raw water ozonation, coagulation/occulation/sedimen-
tation, settled water ozonation, biological activated carbon
(BAC) ltration, and disinfection by medium-pressure UV
lamps and free chlorine]. Operational conditions of DWTP C
on the sampling day are listed in Table S2. Samples were
collected in 1 L HDPE bottles and stored at room temperature
until they were analyzed. On the same day, grab samples of
CFR water were collected in six 20 L HDPE carboys at William
O. Huske Lock and Dam downstream of a PFAS manufacturing
site and stored at 4 °C until use in PAC adsorption experiments
(background water matrix characteristics listed in Table S3).
Adsorption Experiments. Adsorption of PFASs by PAC
was studied in batch reactors (amber glass bottles, 0.45 L of
CFR water). PFECA adsorption was studied at ambient
concentrations (1000 ng/L PFPrOPrA, chromatographic
peak areas of other PFECAs being approximately 10800%
of the PFPrOPrA area). Legacy PFASs were present at low
concentrations (<40 ng/L) and spiked into CFR water at
1000 ng/L each. Data from spiked and nonspiked experi-
ments showed that the added legacy PFASs and methanol (1
ppmv) from the primary stock solution did not aect native
PFECA removal. A thermally activated, wood-based PAC
(PicaHydro MP23, PICA USA, Columbus, OH; mean diameter
of 12 μm, BET surface area of 1460 m2/g)
proven to be
eective for PFAS removal in a prior study
was used at doses
of 30, 60, and 100 mg/L. These doses represent the upper
feasible end for drinking water treatment. Samples were taken
prior to and periodically after PAC addition for PFAS analysis.
PFAS losses in PAC-free blanks were negligible.
PFAS Analysis. Information about analytical standards and
liquid chromatographytandem mass spectrometry (LCMS/
MS) methods for PFAS quantication is provided in the
Supporting Information.
Occurrence of PFASs in Drinking Water Sources. Mean
PFAS concentrations in source water of three DWTPs treating
surface water from the CFR watershed are shown in Figure 1.
In communities A and B, only legacy PFASs were detected
(mean PFAS of 355 ng/L in community A and 62 ng/L in
community B). Detailed concentration data are shown in Table
S6 and Figure S3. In community A, PFCAs with four to eight
total carbons, peruorohexanesulfonic acid (PFHxS), and
PFOS were detected at mean concentrations above the
quantitation limits (QLs). During the 127 day sampling
campaign, the sum concentration of PFOA and PFOS exceeded
the USEPA HAL of 70 ng/L on 57 days. The mean sum
concentration of PFOA and PFOS over the entire study period
was 90 ng/L, with approximately equal contributions from
PFOS (44 ng/L) and PFOA (46 ng/L). Maximum PFOS and
PFOA concentrations were 346 and 137 ng/L, respectively.
Similar PFOS and PFOA concentrations were observed in the
same area in 2006,
suggesting that PFAS source(s) upstream
of community A have continued negative impacts on drinking
water quality. Also, our data show that legacy PFASs remain as
surface water contaminants of concern even though their
production was recently phased out in the United States. It is
important to note, however, that among the PFCAs that were
measured in both 2006 and 2013 (PFHxA to PFDA), the
PFCA speciation shifted from long-chain (8085%
CnF2n+1COOH; n=79) in 2006 to short-chain (76%
CnF2n+1COOH; n=56) in 2013. In contrast, the PFSA
speciation was dominated by PFOS in both 2006 and 2013.
Figure 1. Occurrence of PFASs at drinking water intakes in the CFR
watershed. Concentrations represent averages of samples collected
between June and December 2013. Individual samples with
concentrations below the quantitation limits (QLs) were considered
as 0 when calculating averages, and average concentrations below the
QLs were not plotted.
Environmental Science & Technology Letters Letter
DOI: 10.1021/acs.estlett.6b00398
Environ. Sci. Technol. Lett. XXXX, XXX, XXXXXX
Relating total PFAS concentration to average daily streamow
(Figure S4) illustrated a general trend of low PFAS
concentrations at high ow, and high concentrations at low
ow, consistent with the hypothesis of one or more upstream
point sources.
In community B, peruorobutanoic acid (PFBA) and
peruoropentanoic acid (PFPeA) were most frequently
detected with mean concentrations of 12 and 19 ng/L,
respectively. Mean PFOA and PFOS concentrations were
below the QLs, and the maximum sum concentration of PFOA
and PFOS was 59 ng/L. Lower PFAS concentrations in
community B relative to community A can be explained by the
absence of substantive PFAS sources between the two
communities, dilution by tributaries, and the buering eect
of Jordan Lake, a large reservoir located between communities
A and B.
In community C (downstream of a PFAS manufacturing
site), only mean concentrations of PFBA and PFPeA were
above the QLs. The relatively low concentrations of legacy
PFASs in the nished drinking water of community C are
consistent with results from the USEPAs third unregulated
contaminant monitoring rule for this DWTP.
However, high
concentrations of PFPrOPrA were detected (up to 4500 ng/
L). The average PFPrOPrA concentration (631 ng/L) was
approximately 8 times the average summed PFCA and PFSA
concentrations (79 ng/L). Other PFECAs had not yet been
identied at the time of analysis. Similar to communities A and
B, the highest PFAS concentrations for community C were also
observed at low ow (Figure S4). Stream ow data were used
in conjunction with PFPrOPrA concentration data to
determine PFPrOPrA mass uxes at the intake of DWTP C.
Daily PFPrOPrA mass uxes ranged from 0.6 to 24 kg/day with
a mean of 5.9 kg/day.
Fate of PFASs in Conventional and Advanced Water
Treatment Processes. To investigate whether PFASs can be
removed from impacted source water, samples from DWTP C
were collected at the intake and after each treatment step.
Results in Figure 2 suggest conventional and advanced
treatment processes (coagulation/occulation/sedimentation,
raw and settled water ozonation, BAC ltration, and
disinfection by medium-pressure UV lamps and free chlorine)
did not remove legacy PFASs, consistent with previous
The data further illustrate that no measurable
PFECA removal occurred in this DWTP. Concentrations of
may have increased after ozonation, possibly because of the
oxidation of precursor compounds.
Disinfection with
medium-pressure UV lamps and free chlorine (located between
the BAC euent and the nished water) may have decreased
concentrations of PFMOAA, PFMOPrA, PFMOBA, and
PFPrOPrA, but only to a limited extent. Small concentration
changes between treatment processes may also be related to
temporal changes in source water PFAS concentrations that
occurred in the time frame corresponding to the hydraulic
residence time of the DWTP.
Results in Figure 2 further illustrate that the PFAS signature
of the August 2014 samples was similar to the mean PFAS
signature observed during the 2013 sampling campaigns shown
in Figure 1; i.e., PFPrOPrA concentrations (400500 ng/L)
greatly exceeded legacy PFAS concentrations. Moreover, three
PFECAs (PFMOAA, PFO2HxA, and PFO3OA) exhibited peak
areas 2113 times greater than that of PFPrOPrA (Figure 2b).
The existence of high levels of emerging PFASs suggests a need
for their incorporation into routine monitoring.
Adsorption of PFASs by PAC. PAC can eectively remove
long-chain PFCAs and PFSAs, but its eectiveness decreases
with decreasing PFAS chain length.
It is unclear,
however, how the presence of ether group(s) in PFECAs
impacts adsorbability. After a contact time of 1 h, a PAC dose
of 100 mg/L achieved >80% removal of legacy PFCAs with
total carbon chain lengths of 7. At the same PAC dose,
removals were 95% for PFO4DA and 54% for PFO3OA, but
<40% for other PFECAs. Detailed removal percentage data as a
function of PAC contact time are shown in Figure S5. There
was no meaningful removal of PFMOBA or PFMOPrA, and the
variability shown in Figure S5 is most likely associated with
analytical variability. PFMOAA could not be quantied by the
analytical method used for these experiments; however, on the
basis of the observations that PFAS adsorption decreases with
decreasing carbon chain length and that PFECAs with one or
two more carbon atoms than PFMOAA (i.e., PFMOPrA and
PFMOBA) exhibited negligible removal (Figure 3), it is
expected that PFMOAA adsorption is also negligible under
the tested conditions.
To compare the anity of dierent PFASs for PAC, PFAS
removal percentages were plotted as a function of PFAS chain
length [the sum of carbon (including branched), ether oxygen,
and sulfur atoms] (Figure 3b). The adsorbability of both legacy
and emerging PFASs increased with increasing chain length.
PFSAs were more readily removed than PFCAs of matching
chain length, a result that agrees with those of previous
Figure 2. Fate of (a) legacy PFASs and PFPrOPrA and (b) PFECAs
through a full-scale water treatment plant. Because authentic standards
were not available for PFECAs other than PFPrOPrA, chromato-
graphic peak area counts are shown in panel b. PFPrOPrA data are
shown in both panels and highlighted with dashed ovals for reference.
Compounds with concentrations below the QLs were not plotted.
Environmental Science & Technology Letters Letter
DOI: 10.1021/acs.estlett.6b00398
Environ. Sci. Technol. Lett. XXXX, XXX, XXXXXX
PFECAs exhibited adsorbabilities lower than
those of PFCAs of the same chain length (e.g., PFMOBA <
PFHxA), suggesting that the replacement of a CF2group with
an ether oxygen atom decreases the anity of PFASs for PAC.
However, the replacement of additional CF2groups with ether
groups resulted in small or negligible anity changes among
the studied PFECAs (e.g., PFMOBA PFO2HxA, PFPrOPrA
~ PFO3OA). Alternatively, if only the number of peruorinated
carbons were considered as a basis of comparing adsorbability,
the interpretation would be dierent. In that case, with the
same number of peruorinated carbons, PFCAs have an anity
for PAC higher than that of monoether PFECAs (e.g., PFPeA >
PFMOBA) but an anity lower than that of multi-ether
PFECAs (e.g., PFPeA < PFO3OA).
To the best of our knowledge, this is the rst paper reporting
the behavior of recently identied PFECAs in water treatment
processes. We show that PFECAs dominated the PFAS
signature in a drinking water source downstream of a
uorochemical manufacturer and that PFECA removal by
many conventional and advanced treatment processes was
negligible. Our adsorption data further show that PFPrOPrA
(GenX) is less adsorbable than PFOA, which it is replacing.
Thus, PFPrOPrA presents a greater drinking water treatment
challenge than PFOA does. The detection of potentially high
levels of PFECAs, the continued presence of high levels of
legacy PFASs, and the diculty of eectively removing legacy
PFASs and PFECAs with many water treatment processes
suggest the need for broader discharge control and contaminant
SSupporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.estlett.6b00398.
Six tables, ve gures, information about PFASs,
analytical methods, and detailed results (PDF)
Corresponding Author
*E-mail: Phone: 704-687-1723.
Mei Sun: 0000-0001-5854-9862
The views expressed in this article are those of the authors and
do not necessarily represent the views or policies of the
The authors declare no competing nancial interest.
This research was supported by the National Science
Foundation (Grant 1550222), the Water Research Foundation
(Project 4344), and the North Carolina Urban Water
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Environmental Science & Technology Letters Letter
DOI: 10.1021/acs.estlett.6b00398
Environ. Sci. Technol. Lett. XXXX, XXX, XXXXXX
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Environmental Science & Technology Letters Letter
DOI: 10.1021/acs.estlett.6b00398
Environ. Sci. Technol. Lett. XXXX, XXX, XXXXXX
... This manufacturer is known to produce a variety of emerging PFEAs such as hexafluoropropylene oxide dimer acid (HFPO-DA, "GenX"). While GenX has been the major focus of the Cape Fear River PFEA contamination, many other structurally similar emerging PFAS have been detected within the river, often at substantially higher abundance (24,(47)(48)(49)(50). Furthermore, several PFEAs have recently been detected in the serum of (i) individuals with drinking water provided by the Cape Fear Public Utility Authority (12), (ii) Cape Fear River fish (51), and (iii) alligators living in the Cape Fear River basin and surrounding coastal waters (52). ...
... The second group of elucidated structures are perfluorinated ether sulfonic acids, a common contaminant in this region given the production of Nafion (24,48,49). Compounds 4 to 6 belong to the perfluoro(2-ethyoxyethane)sulfonic acid (PFEESA) homologous series. ...
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Because of environmental and health concerns, legacy per- and polyfluoroalkyl substances (PFAS) have been voluntarily phased out, and thousands of emerging PFAS introduced as replacements. Traditional analytical methods target a limited number of mainly legacy PFAS; therefore, many species are not routinely assessed in the environment. Nontargeted approaches using high-resolution mass spectrometry methods have therefore been used to detect and characterize unknown PFAS. However, their ability to elucidate chemical structures relies on generation of informative fragments, and many low concentration species are not fragmented in typical data-dependent acquisition approaches. Here, a data-independent method leveraging ion mobility spectrometry (IMS) and size-dependent fragmentation was developed and applied to characterize aquatic passive samplers deployed near a North Carolina fluorochemical manufacturer. From the study, 11 PFAS structures for various per- and polyfluorinated ether sulfonic acids and multiheaded perfluorinated ether acids were elucidated in addition to 36 known PFAS. Eight of these species were previously unreported in environmental media, and three suspected species were validated.
... Besides, 8:2 Cl-PFESA was also detected in about 50 % of the rivers in China with a concentration ranging from n.d. to 0.06 ng/L . Researchers pointed out that these alternatives were released into the environment primarily from electroplating processes (Ruan et al., 2015) and fluoropolymer resin manufacturing (DuPont, 2010;Heydebreck et al., 2015;Sun et al., 2016). However, limited research has been conducted to investigate the water-sediment partitioning behavior of GenX and Cl-PFESAs (such as F-53B), which determines their fate and transport in the environment. ...
... 30 In 2022, the US EPA revised to a decreased interim lifetime health advisory level of 0.004 ppt for PFOA, alongside the release of 10 ppt for GenX and 2000 ppt for PFBS. 10 Studies are continuing to provide more information on the concentration range of PFAS as drinking water sampling sites are expanded, and technological improvements have advanced detection capabilities and decreased limits of detection. For example, private drinking water wells in the Cape Fear River, NC, USA area measured up to 4000 ppt (4 ppb) GenX stemming from a PFAS manufacturing facility 6 and PFBS was detected at up to 0.3 ppb in public drinking water in Minnesota (USA). 41 Moreover, in a study completed by the United States Geological Services (USGS) sampling public and private drinking water, the hazard index of 1 for the sum of GenX, PFBS, PFNA, and PFHxS was exceeded in 4.6% of the samples. ...
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Several perfluoroalkyl and polyfluoroalkyl substances (PFASs) have been identified as chemicals of concern in the environment due to their persistence, global ubiquity, and classification as reproductive and developmental toxicants, endocrine disrupters, and possible carcinogens. Multiple PFASs are often found together in the environment due to product manufacturing methods and abiotic and biotic transformations. Treatment methods are needed to effectively sequester or destroy a variety of PFASs from groundwater, drinking water, and wastewater. This review presents a comprehensive summary of several categories of treatment approaches: (1) sorption using activated carbon, ion exchange, or other sorbents, (2) advanced oxidation processes, including electrochemical oxidation, photolysis, and photocatalysis, (3) advanced reduction processes using aqueous iodide or dithionite and sulfite, (4) thermal and nonthermal destruction, including incineration, sonochemical degradation, sub-or supercritical treatment, microwave-hydrothermal treatment, and high-voltage electric discharge, (5) microbial treatment, and (6) other treatment processes, including ozonation under alkaline conditions, permanganate oxidation, vitamin-B12 and Ti(III) citrate reductive defluorination, and ball milling. Discussion of each treatment technology, including background, mechanisms, advances, and effectiveness, will inform the development of cost-effective PFAS remediation strategies based on environmental parameters and applicable methodologies. Further optimization of current technologies to analyze and remove or destroy PFASs below regulatory guidelines is needed. Due to the stability of PFASs, a combination of multiple treatment technologies will likely be required to effectively address real-world complexities of PFAS mixtures and cocontaminants present in environmental matrices.
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Ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate, developed for use as a polymerization processing aid in the manufacture of fluoropolymers, was tested for its potential chronic toxicity and carcinogenicity in a 2-year oral dosing study in Sprague-Dawley rats. Male rats were given daily doses of either 0, 0.1, 1 or 50. mg/kg; females were given either 0, 1, 50 or 500. mg/kg. Body weights, food consumption and clinical signs were monitored daily; clinical pathology was conducted at designated intervals and animals were given a complete pathological evaluation after 12 months and 24 months of dosing. Normal survival was seen in all groups, no abnormal clinical signs were seen, and body weight gain was reduced only in female rats at 500. mg/kg. Both sexes at the high dose had mild decreases in red cell mass which were somewhat more pronounced in females. Clinical pathology indicative of liver injury was present in males that received 50. mg/kg and correlated with histomorphological liver changes that included both hypertrophic and degenerative/necrotic lesions. Similar histomorphological lesions were seen in the livers of females at 500. mg/kg. Previous shorter term toxicity studies have identified this chemical as a PPARα agonist and the finding of benign tumors of the liver, pancreas and/or testes in males at 50. mg/kg and females at 500. mg/kg is consistent with the rat response to peroxisome proliferators and is of questionable human relevance. Changes in the kidney, tongue, and stomach were observed only at the highest dose of 500. mg/kg in females. The no-observed-adverse-effect-level in this study lies between 1 and 50. mg/kg for males and between 50 and 500. mg/kg for females.
Drinking water contamination with poly-and perfluoroalkyl substances (PFASs) poses risks to the developmental, immune, metabolic, and endocrine health of consumers. We present a spatial analysis of 2013−2015 national drinking water PFAS concentrations from the U.S. Environmental Protection Agency's (US EPA) third Unregu-lated Contaminant Monitoring Rule (UCMR3) program. The number of industrial sites that manufacture or use these compounds, the number of military fire training areas, and the number of wastewater treatment plants are all significant predictors of PFAS detection frequencies and concentrations in public water supplies. Among samples with detectable PFAS levels, each additional military site within a watershed's eight-digit hydrologic unit is associated with a 20% increase in PFHxS, a 10% increase in both PFHpA and PFOA, and a 35% increase in PFOS. The number of civilian airports with personnel trained in the use of aqueous film-forming foams is significantly associated with the detection of PFASs above the minimal reporting level. We find drinking water supplies for 6 million U.S. residents exceed US EPA's lifetime health advisory (70 ng/L) for PFOS and PFOA. Lower analytical reporting limits and additional sampling of smaller utilities serving <10000 individuals and private wells would greatly assist in further identifying PFAS contamination sources.
The toxicological impact of traditional perfluoroalkyl chemicals has led to the elimination and restriction of these substances. However, many novel perfluoroalkyl alternatives remain unregulated and little is known about their potential effects on environmental and human health. Daily administration of two alternative perfluoroalkyl substances, HFPO2 and HFPO4 (1 mg kg−1 body weight), for 28 days resulted in hepatomegaly and hepatic histopathological injury in mice, particularly in the HFPO4 group. We generated and compared high-throughput RNA-sequencing data from hepatic tissues in control and treatment group mice to clarify the mechanism of HFPO2 and HFPO4 hepatotoxicity. We identified 146 (101 upregulated, 45 downregulated) and 1295 (716 upregulated, 579 downregulated) hepatic transcripts that exhibited statistically significant changes (fold change ≥2 or ≤0.5, false discovery rate < 0.05) after HFPO2 and HFPO4 treatment, respectively. Among them, 111 (82 upregulated, 29 downregulated) transcripts were changed in both groups, and lipid metabolism associated genes were dominant. Thus, similar to their popular predecessors, HFPO2 and HFPO4 exposure exerted hepatic effects, including hepatomegaly and injury, and altered lipid metabolism gene levels in the liver, though HFPO4 exerted greater hepatotoxicity than HFPO2. The unregulated use of these emerging perfluoroalkyl alternatives may affect environmental and human health, and their biological effects need further exploration. Copyright
The fluoropolymer manufacturing industry is moving to alternative polymerization processing aid technologies with more favorable toxicological and environmental profiles as part of a commitment to curtail the use of long-chain perfluoroalkyl acids (PFAAs). To facilitate the environmental product stewardship assessment and premanufacture notification (PMN) process for a candidate replacement chemical, we conducted acute and chronic aquatic toxicity tests to evaluate the toxicity of ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate (C6HF11O3.H3N) or the acid form of the substance to the cladoceran, Daphnia magna, the green alga, Pseudokirchneriella subcapitata, and a number of freshwater fish species including the rainbow trout, Oncorhynchus mykiss, In addition, testing with the common carp, Cyprinus carpio, was conducted to determine the bioconcentration potential of the acid form of the compound. Based on the relevant criteria in current regulatory frameworks, the results of the aquatic toxicity and bioconcentration studies indicate the substance is of low concern for aquatic hazard and bioconcentration in aquatic organisms. Evaluation of environmental monitoring data in conjunction with the predicted no effect concentration (PNEC) based on the available data suggest low risk to aquatic organisms.
Ammonium, 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate has been developed as a processing aid used in the manufacture of fluoropolymers. The absorption, distribution, elimination, and distribution (ADME) and kinetic behavior of this substance has been evaluated in rats, mice, and cynomolgus monkeys by oral and intravenous routes of exposure and studied in both plasma and urine. The test substance is rapidly and completely absorbed in both rats and mice and both in vivo and in vitro experiments indicate that it is not metabolized. The test substance is rapidly eliminated exclusively in the urine in both rats and mice, with rats eliminating it more quickly than mice (approximately 5h elimination half-life in rats, 20h half-life in mice). Pharmacokinetic analysis in monkeys, rats, and mice indicate rapid, biphasic elimination characterized by a very fast alpha phase and a slower beta phase. The beta phase does not contribute to potential accumulation after multiple dosing in rats or monkeys. Comparative pharmacokinetics in rats, mice, and monkeys indicates that the rat is more similar to the monkey and is therefore a more appropriate rodent model for pharmacokinetics in primates.
Due to the lack of analytical standards the application of surrogate parameters for organofluorine detection in the aquatic environment is a complementary approach to single compound target analysis of perfluoroalkyl and polyfluoroalkyl chemicals (PFASs). The recently developed method adsorbable organically bound fluorine (AOF) is based on adsorption of organofluorine chemicals to activated carbon followed by combustion ion chromatography. This AOF method was further simplified to enable measurement of larger series of environmental samples. The limit of quantification (LOQ) was 0.77 μg/L F. The modified protocol was applied to 22 samples from German rivers, a municipal wastewater treatment plant (WWTP) effluent, and four groundwater samples from a fire-fighting training site. The WWTP effluent (AOF = 1.98 μg/L F) and only three river water samples (AOF between 0.88 μg/L F and 1.47 μg/L F) exceeded the LOQ. The AOF levels in a PFASs plume at a heavily contaminated site were in the range of 162 ± 3 μg/L F to 782 ± 43 μg/L F. In addition to AOF 17 PFASs were analyzed by high performance liquid chromatography-tandem mass spectrometry. 32–51% of AOF in the contaminated groundwater samples were explained by individual PFASs wheras in the surface waters more than 95% remained unknown. Organofluorine of two fluorinated pesticides, one pesticide metabolite and three fluorinated pharmaceuticals was recovered as AOF by >50% from all four tested water matrices. It is suggested that in the diffusely contaminated water bodies such fluorinated chemicals and not monitored PFASs contribute significantly to AOF.
Recent scientific scrutiny and concerns over exposure, toxicity, and risk have led to international regulatory efforts resulting in the reduction or elimination of certain perfluorinated compounds from various products and waste streams. Some manufacturers have started producing shorter chain per- and polyfluorinated compounds to try to reduce the potential for bioaccumulation in humans and wildlife. Some of these new compounds contain central ether oxygens or other minor modifications of traditional perfluorinated structures. At present, there has been very limited information published on these "replacement chemistries" in the peer-reviewed literature. In this study we used a time-of-flight mass spectrometry detector (LC-ESI-TOFMS) to identify fluorinated compounds in natural waters collected from locations with historical perfluorinated compound contamination. Our workflow for discovery of chemicals included sequential sampling of surface water for identification of potential sources, nontargeted TOFMS analysis, molecular feature extraction (MFE) of samples, and evaluation of features unique to the sample with source inputs. Specifically, compounds were tentatively identified by (1) accurate mass determination of parent and/or related adducts and fragments from in-source collision-induced dissociation (CID), (2) in-depth evaluation of in-source adducts formed during analysis, and (3) confirmation with authentic standards when available. We observed groups of compounds in homologous series that differed by multiples of CF2 (m/z 49.9968) or CF2O (m/z 65.9917). Compounds in each series were chromatographically separated and had comparable fragments and adducts produced during analysis. We detected 12 novel perfluoroalkyl ether carboxylic and sulfonic acids in surface water in North Carolina, USA using this approach. A key piece of evidence was the discovery of accurate mass in-source n-mer formation (H(+) and Na(+)) differing by m/z 21.9819, corresponding to the mass difference between the protonated and sodiated dimers.
The production and use of long-chain perfluoroalkyl substances (PFASs) must comply with national and international regulations. Driven by increasingly stringent regulations, their production has been outsourced to less regulated countries in Asia. In addition, the fluoropolymer industry started to use fluorinated alternatives, such as 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)propanoic acid (HFPO-DA). Between August 2013 and September 2014, we investigated the occurrence and distribution of HFPO-DA and legacy PFASs in surface waters of the following river/estuary systems: the Elbe and Rhine Rivers in Germany, the Rhine-Meuse delta in the Netherlands, and the Xiaoqing River in China. Distinct differences were revealed among the study areas; notably: the Chinese samples were highly polluted by an industrial point source discharging mainly perfluorooctanoic acid (PFOA). This particular point source resulted in concentrations more than 6000 times higher than an industrial point source observed in the Scheur River, where HFPO-DA was the dominant compound with a concentration of 73.1 ng/L. Moreover, HFPO-DA was detected in all samples along the coastline of the North Sea, indicating that the compound may be transported from the Rhine-Meuse-delta into the German Bight via the water current. To the best of our knowledge, the fluorinated alternative, HFPO-DA, was detected for the first time in surface waters of Germany and China.
Historically, 3M aqueous film-forming foams (AFFFs) were released at U.S. military and civilian sites to extinguish hydrocarbon-based fuel fires. To date, only C4-C10 homologues of the perfluoroalkyl sulfonic acids (PFSAs) are documented in 3M AFFFs. Perfluoroethanesulfonate (PFEtS) and perfluoropropanesulfonate (PFPrS), two ultra-short-chain PFSAs, were discovered by liquid chromatography (LC) quadrupole time-of-flight mass spectrometry. Once they were identified, PFEtS and PFPrS were then quantified in five 3M AFFFs and in one groundwater sample from each of 11 U.S. military bases by LC tandem mass spectrometry. Concentrations of PFEtS and PFPrS in the five AFFFs ranged from 7 to 13 mg/L and from 120 to 270 mg/L, respectively. For the groundwater, PFEtS was quantified in 8 of the 11 samples (11-7500 ng/L) and PFPrS in all samples (19-63000 ng/L). The high water solubility, mobility, and detection frequency of these ultra-short-chain PFSAs indicate that groundwater contaminant plumes may be larger than previously believed, and their removal by conventional activated carbon will be challenging.