Fluorotelomer alcohol biodegradation-direct evidence that perfluorinated carbon chains breakdown

Comparative acute freshwater hazard assessment and preliminary PNEC development for eight fluorinated acids

Short-term 48, 72 and 96-h aquatic toxicity tests were conducted to evaluate the acute toxicity of eight fluorinated acids to the cladoceran, Daphnia magna, the green alga, Pseudokirchneriella subcapitata, and the rainbow trout, Oncorhynchus mykiss or the fathead minnow, Pimephales promelas. The eight fluorinated acids studied were tridecafluorohexyl ethanoic acid (6:2 FTCA), heptadecafluorooctyl ethanoic acid (8:2 FTCA), 2H-dodecafluoro-2-octenoic acid (6:2 FTUCA), 2H-hexadecafluoro-2-decenoic acid (8:2 FTUCA), 2H,2H,3H,3H-undecafluoro octanoic acid (5:3 acid), 2H,2H,3H,3H-pentadecafluoro decanoic acid (7:3 acid), n-perfluoropentanoic acid (PFPeA) and n-perfluorodecanoic acid (PFDA). The results of the acute toxicity tests conducted during this study suggest that the polyfluorinated acids, 8:2 FTCA, 8:2 FTUCA, 6:2 FTCA, 6:2 FTUCA, 7:3 acid and 5:3 acid, and the perfluorinated acids PFPeA and PFDA, are generally of low to medium concern based on evaluation of their acute freshwater toxicity (EC/LC50s typically between 1 and >100 mg L(-1)) using the USEPA TSCA aquatic toxicity evaluation paradigm. For the polyfluorinated acids, aquatic toxicity generally decreased as the number of fluorinated carbons decreased and as the overall carbon chain length decreased from 12 to 8. Acute aquatic toxicity of the 5 and 10 carbon perfluorocarboxylic acids (EC/LC50s between 10.6 and >100 mg L(-1)) was greater or similar to that of the 6-9 carbon perfluorocarboxylic acids (EC/LC50s>96.5 mg L(-1)). This study also provides the first report of the acute aquatic toxicity of the 5:3 acid (EC/LC50s of 22.5 to >103 mg L(-1)) which demonstrated less aquatic toxicity than the 7:3 acid (EC/LC50s of 0.4-32 mg L(-1)). The cladoceran, D. magna and the green alga, P. subcapitata had generally similar EC50 values for a given substance while fish were typically equally or less sensitive with the exception that PFPeA was most toxic to fish. Predicted no-effect concentrations (PNECs) were estimated using approaches consistent with REACH guidance and when compared with available environmental concentrations, these PNECs suggest that the fluorinated acids tested pose little risk for aquatic organisms.

Aerobic soil biodegradation of 8:2 fluorotelomer stearate monoester

A laboratory investigation on the biotransformation of 8:2 fluorotelomer stearate monoester (8:2 FTS) in aerobic soils was conducted by monitoring the loss of 8:2 FTS, production of 8:2 fluorotelomer alcohol (8:2 FTOH) and stearic acid, which would be released by cleavage of the ester linkage, and subsequent degradation products from FTOH for 80 d. Soil microcosms were extracted with ethyl acetate followed by two heated 90/10 v/v acetonitrile/200 mM NaOH extractions. 8:2 FTS was degraded with an observed half-life (t(1/2)) of 10.3 d. The rate of 8:2 FTS biotransformation substantially decreased after 20 d with 22% of 8:2 FTS still remaining on day 80. No biotransformation of 8:2 FTS occurred in autoclaved soil controls, which remained sterile with 102 ± 6% recovery, through day 20. 8:2 FTOH was generated with cleavage of the ester linkage of 8:2 FTS followed by a rapid decline (t(1/2) ~ 2 d) due to subsequent biodegradation. All the expected 8:2 FTOH degradation products were detected including 8:2 fluorotelomer unsaturated and saturated carboxylic acids, 7:2s FTOH, 7:3 acid, and three perfluoroalkyl carboxylic acids with the most prominent being perfluorooctanoic acid (PFOA). PFOA consistently increased over time reaching 1.7 ± 0.07 mol % by day 80. Although cleavage of the ester linkage was evidenced by 8:2 FTOH production, an associated trend in stearic acid concentrations was not clear because of complex fatty acid metabolism dynamics in soil. Further analysis of mass spectrometry fragmentation patterns and chromatography supported the conclusion that hydrolysis of the ester linkage is predominantly the first step in the degradation of 8:2 FTS with the ultimate formation of terminal products such as PFOA.

5:3 Polyfluorinated acid aerobic biotransformation in activated sludge via novel "one-carbon removal pathways"

The polyfluorinated carboxylic acids 5:3 acid (C(5)F(11)CH(2)CH(2)CO(2)H) and 7:3 acid (C(7)F(15)CH(2)CH(2)CO(2)H) are major products from 6:2 FTOH (C(6)F(13)CH(2)CH(2)OH) and 8:2 FTOH (C(8)F(17)CH(2)CH(2)OH) aerobic biotransformation, respectively. The 5:3 and 7:3 acids were dosed into domestic WWTP activated sludge for 90 d to determine their biodegradability. The 7:3 acid aerobic biodegradability was low, only 1.7 mol% conversion to perfluoroheptanoic acid (PFHpA), whereas no transformation was observed previously in soil. In stark contrast, 5:3 acid aerobic biodegradability was enhanced 10 times in activated sludge compared to soil. The 5:3 acid was not activated by acyl CoEnzyme A (CoA) synthetase, a key step required for further α- or ß-oxidation. Instead, 5:3 acid was directly converted to 4:3 acid (C(4)F(9)CH(2)CH(2)CO(2)H, 14.2 mol%) and 3:3 acid (C(3)F(7)CH(2)CH(2)CO(2)H, 0.9 mol%) via "one-carbon removal pathways". The 5:3 acid biotransformation also yielded perfluoropentanoic acid (PFPeA, 5.9 mol%) and perfluorobutanoic acid (PFBA, 0.8 mol%). This is the first report to identify key biotransformation intermediates which demonstrate novel one-carbon removal pathways with sequential removal of CF(2) groups. Identified biotransformation intermediates (10.2 mol% in sum) were 5:3 Uacid, α-OH 5:3 acid, 5:2 acid, and 5:2 Uacid. The 5:2 Uacid and 5:2 acid are novel intermediates identified for the first time which confirm the proposed pathways. In the biodegradation pathways, the genesis of the one carbon removal is CO(2) elimination from α-OH 5:3 acid. These results suggest that there are enzymatic mechanisms available in the environment that can lead to 6:2 FTOH and 5:3 acid mineralization. The dehydrogenation from 5:3 acid to 5:3 Uacid was the rate-limiting enzymatic step for 5:3 acid conversion to 4:3 acid.

Fate of a broad spectrum of perfluorinated compounds in soils and biota from Tierra del Fuego and Antarctica

In this study, the presence of 18 perfluorinated compounds was investigated in biota and environmental samples from the Antarctica and Tierra de Fuego, which were collected during a sampling campaign carried out along February and March 2010. 61 samples were analysed including fish, superficial soils, guano, algae, dung and tissues of Papua penguin by liquid chromatography coupled to tandem mass spectrometry. The concentrations of PFCs were ranging from 0.10 to 240 ng/g for most of the samples except for penguin dung, which presented levels between 95 and 603 ng/g for perfluorooctane sulfonate, and guano samples from Ushuaia, with concentration levels of 1190-2480 ng/g of perfluorohexanoic acid. PFCs acids presented, in general, the highest levels of concentration and perfluorooctanesulfonate was the most frequently found compound. The present study provides a significant amount of results, which globally supports the previous studies, related to the transport, deposition, biodegradation and bioaccumulation patterns of PFCs.

Wastewater treatment plants (WWTPs)-derived national discharge loads of perfluorinated compounds (PFCs)

The discharge of perfluorinated compounds (PFCs) was investigated for 15 wastewater treatment plants (WWTPs), comprising 25% of total domestic wastewater and 23% of total industrial wastewater produced in Korea. PFCs concentrations in influent, effluent, and sludge were greater in industrial wastewater than in the majority of domestic wastewater. Individual PFCs were found to have differing industrial sources, with perfluorocarboxylates used in fabric/textiles, paper-mill, and dyeing industries, and perfluoroalkylsulfonates occurring in oil/chemical and metal-plating/processing industries. Total WWTP-derived national discharge loads were calculated based on the average concentrations in effluents and the total volume of wastewaters produced in Korea. The average WWTP-derived national discharge loads of individual PFCs were 0.04-0.61 ton/year, with 63% of perfluorooctanoate being from domestic wastewater, and 75% of perfluorooctanesulfonate being from industrial wastewater. These estimates accounted for the majority of national emissions, based on measurements in major river mouths, indicating the major contribution of WWTPs to PFC occurrence in Korean aquatic environments. Both the per capita emission factor (μg/capita/day) for domestic discharge, and area-normalized national discharge loads (g/capita/km(2)/day) for all wastewaters were several factors lower in Korea than in Japan or Europe, which is consistent with the lower levels of human exposure to PFCs in Korea.

Perflurooctanoic acid induces developmental cardiotoxicity in chicken embryos and hatchlings

Perfluorooctanoic acid (PFOA) is a widespread environmental contaminant that is detectable in serum of the general U.S. population. PFOA is a known developmental toxicant that induces mortality in mammalian embryos and is thought to induce toxicity via interaction with the peroxisome proliferator activated receptor alpha (PPARα). As the cardiovascular system is crucial for embryonic survival, PFOA-induced effects on the heart may partially explain embryonic mortality. To assess impacts of PFOA exposure on the developing heart in an avian model, we used histopathology and immunohistochemical staining for myosin to assess morphological alterations in 19-day-old chicken embryo hearts after PFOA exposure. Additionally, echocardiography and cardiac myofibril ATPase activity assays were used to assess functional alterations in 1-day-old hatchling chickens following developmental PFOA exposure. Overall thinning and thinning of a dense layer of myosin in the right ventricular wall were observed in PFOA-exposed chicken embryo hearts. Alteration of multiple cardiac structural and functional parameters, including left ventricular wall thickness, left ventricular volume, heart rate, stroke volume, and ejection fraction were detected with echocardiography in the exposed hatchling chickens. Assessment of ATPase activity indicated that the ratio of cardiac myofibril calcium-independent ATPase activity to calcium-dependent ATPase activity was not affected, which suggests that developmental PFOA exposure may not affect cardiac energetics. In summary, structural and functional characteristics of the heart appear to be developmental targets of PFOA, possibly at the level of cardiomyocytes. Additional studies will investigate mechanisms of PFOA-induced developmental cardiotoxicity.

Prenatal perfluorooctanoic acid exposure in CD-1 mice: low-dose developmental effects and internal dosimetry

Perfluorooctanoic acid (PFOA) is an environmental contaminant that causes adverse developmental effects in laboratory animals. To investigate the low-dose effects of PFOA on offspring, timed-pregnant CD-1 mice were gavage dosed with PFOA for all or half of gestation. In the full-gestation study, mice were administered 0, 0.3, 1.0, and 3.0 mg PFOA/kg body weight (BW)/day from gestation days (GD) 1-17. In the late-gestation study, mice were administered 0, 0.01, 0.1, and 1.0 mg PFOA/kg BW/day from GD 10-17. Exposure to PFOA significantly (p < 0.05) increased offspring relative liver weights in all treatment groups in the full-gestation study and in the 1.0 mg PFOA/kg group in the late-gestation study. In both studies, the offspring of all PFOA-treated dams exhibited significantly stunted mammary epithelial growth as assessed by developmental scoring. At postnatal day 21, mammary glands from the 1.0 mg/kg GD 10-17 group had significantly less longitudinal epithelial growth and fewer terminal end buds compared with controls (p < 0.05). Evaluation of internal dosimetry in offspring revealed that PFOA concentrations remained elevated in liver and serum for up to 6 weeks and that brain concentrations were low and undetectable after 4 weeks. These data indicate that PFOA-induced effects on mammary tissue (1) occur at lower doses than effects on liver weight in CD-1 mice, an observation that may be strain specific, and (2) persist until 12 weeks of age following full-gestational exposure. Due to the low-dose sensitivity of mammary glands to PFOA in CD-1 mice, a no observable adverse effect level for mammary developmental delays was not identified in these studies.

Fluorinated alkyl compounds including long chain carboxylic acids in wild bird livers from Japan

A wide range of fluorinated alkyl compounds (FACs) has been reported in wildlife in various locations in the world. However, such information regarding Japanese wildlife is rarely found. In the present study, we investigated the occurrence of 21 FACs, including perfluorinated alkyl sulfonates (PFASs), perfluorinated carboxylates (PFCAs), and fluorotelomer acids, in the livers of 10 wild bird species from two regions in northern Japan. To avoid interferences, FACs were quantified by a recently developed method using acetonitrile and solid-phase extraction followed by an ion exchange HPLC column separation. Apart from perfluorooctane sulfonate (PFOS), which was found at the highest levels of all the compounds detected, several long chain perfluorinated carboxylates (PFCAs) from C8 to C16, particularly perfluorotetradecanoic acid (PFTeDA) and perfluorohexadecanoic acid (PFHxDA), were detected for the first time. Additionally, 7:3 FTCA, a fluorotelomer acid, was also detected in most swan livers from Miyagi prefecture and all the birds from Tochigi prefecture. However, none of the sulfonamides and unsaturated telomer acids were detected in any species. Swans seem to be the least exposed wild birds to FACs among the investigated birds, signifying that feeding habits may reflect FAC accumulation in wild birds. The highest total concentration of detected FACs was 405ngg(-1)wet wt., which was found in a Japanese sparrowhawk, indicating that the top predatory wild birds can accumulate several long chain carboxylic acids. However, the current FAC concentrations found in livers may suggest that these compounds alone would not cause a severe toxic effect in these species.

Long-chain perfluorinated chemicals in digested sewage sludges in Switzerland

This study focused on the occurrence of long-chain perfluorinated chemicals (PFCs) in anaerobically stabilized sewage sludges from 20 municipal WWTPs using current and historic samples to evaluate the levels of PFCs and to identify the relative importance of commercial and industrial sources. A quantitative analytical method was developed based on solvent extraction of the analytes and a LC-MS/MS system. For total perfluoralkyl carboxylates (PFCAs), the concentrations ranged from 14 to 50 μg/kg dry matter. Concentrations of perfluorooctane sulfonic acid (PFOS) ranged from 15 to 600 μg/kg dry matter. In three WWTPs, the PFOS levels were six to nine times higher than the average values measured in the other plants. These elevated PFOS concentrations did not correlate with higher levels of PFCAs, indicating specific additional local sources for PFOS at these WWTPs. Average concentrations in selected samples from the years 1993, 2002, and 2008 did not change significantly.

6:2 fluorotelomer sulfonate aerobic biotransformation in activated sludge of waste water treatment plants

The aerobic biotransformation of 6:2 FTS salt [F(CF2)6CH2CH2SO3- K+] was determined in closed bottles for 90d in diluted activated sludge from three waste water treatment plants (WWTPs) to compare its biotransformation potential with that of 6:2 FTOH [F(CF2)6CH2CH2OH]. The 6:2 FTS biotransformation was relatively slow, with 63.7% remaining at day 90 and all observed transformation products together accounting for 6.3% of the initial 6:2 FTS applied. The overall mass balance (6:2 FTS plus observed transformation products) at day 90 in live and sterile treatments averaged 70% and 94%, respectively. At day 90, the stable transformation products observed were 5:3 acid [F(CF2)5CH2CH2COOH, 0.12%], PFBA [F(CF2)3COOH, 0.14%], PFPeA [F(CF2)4COOH, 1.5%], and PFHxA [F(CF2)5COOH 1.1%]. In addition, 5:2 ketone [F(CF2)5C(O)CH3] and 5:2 sFTOH [F(CF2)5CH(OH)CH3] together accounted for 3.4% at day 90. The yield of all the stable transformation products noted above (2.9%) was 19 times lower than that of 6:2 FTOH in aerobic soil. Thus 6:2 FTS is not likely to be a major source of PFCAs and polyfluorinated acids in WWTPs. 6:2 FTOH, 6:2 FTA [F(CF2)6CH2COOH], and PFHpA [F(CF2)6COOH] were not observed during the 90-d incubation. 6:2 FTS primary biotransformation bypassed 6:2 FTOH to form 6:2 FTUA [F(CF2)5CF=CHCOOH], which was subsequently degraded via pathways similar to 6:2 FTOH biotransformation. A substantial fraction of initially dosed 6:2 FTS (24%) may be irreversibly bound to diluted activated sludge catalyzed by microbial enzymes. The relatively slow 6:2 FTS degradation in activated sludge may be due to microbial aerobic de-sulfonation of 6:2 FTS, required for 6:2 FTS further biotransformation, being a rate-limiting step in microorganisms of activated sludge in WWTPs.

Ecotoxicology of organofluorous compounds

Organofluorous compounds have been developed for myriad purposes in a variety of fields, including manufacturing, industry, agriculture, and medicine. The widespread use and application of these compounds has led to increasing concern about their potential ecological toxicity, particularly because of the stability of the C-F bond, which can result in chemical persistence in the environment. This chapter reviews the chemical properties and ecotoxicology of four groups of organofluorous compounds: fluorinated refrigerants and propellants, per- and polyfluorinated compounds (PFCs), fluorinated pesticides, and fluoroquinolone antibiotics. These groups vary in their environmental fate and partitioning, but each raises concern in terms of ecological risk on both the regional and global scale, particularly those compounds with long environmental half-lives. Further research on the occurrence and toxicities of many of these compounds is needed for a more comprehensive understanding of their ecological effects.

Biology of fluoro-organic compounds

Investigations on diverse aspects of fluoro-organic compounds have rapidly increased during the past decades. Because natural sources of fluoro-organic compounds are extremely rare, the industrial synthesis of fluorinated organic compounds and production of fluorinated natural product derivatives have greatly expanded in recent years because of their increasing importance in the agrochemical and pharmaceutical industries. Due to structural complexity or instability, synthetic modification is often not possible, and various biofluorination strategies have been developed in recent years for applications in the anti-cancer, anti-viral and anti-infection fields. Despite the industrial importance of fluorinated compounds, there have been serious concerns worldwide over the levels and synthetic routes of certain fluorinated organic compounds, in particular perfluorinated chemicals (PFCs). PFCs are emerging and recalcitrant pollutants which are widely distributed in the environment and have been detected in humans and wildlife globally. PFCs have been demonstrated to be potentially carcinogenic, adversely affect the neuroendocrine and immune systems, and produce neurotoxicity, heptatotoxicity and endocrine disrupting effects in vertebrate animals. Here, we provide an overview of recent advances in our understanding of the biology of various fluoro-organic compounds and perspectives for new enzymes and metabolic pathways for bioremediation of these chemicals.

Biotransformation of the 8:2 fluorotelomer acrylate in rainbow trout. 2. In vitro incubations with liver and stomach S9 fractions

The biotransformation of the 8:2 fluorotelomer acrylate (C(8) F(17) CH(2) CH(2) OC(O)CH = CH(2) , 8:2 fluorotelomer-based acrylate [FTAc]) was quantitatively investigated in cytosolic (S9) fractions isolated from rainbow trout stomach and liver. The in vitro studies presented in this manuscript compliment the whole body 8:2 FTAc dietary exposure study, presented as a companion paper. The S9 fractions were prepared in our laboratory, using fish that had previously been used as control animals in our in vivo study. Before 8:2 FTAc incubations, general carboxylesterase activity was determined using paranitrophenyl acetate (PNPA) as the substrate with formation of paranitrophenol monitored using an ultraviolet-vis spectrometer. In the 8:2 FTAc incubations, the degradation of the parent compound and 8:2 fluorotelomer alcohol (FTOH) formation was monitored by gas chromatography-mass spectrometry. Incubations were performed in triplicate, over a range of concentrations encompassing two orders of magnitude, and the initial rate of 8:2 FTOH or paranitrophenol formation was determined. Enzyme kinetic parameters were determined by plotting the initial rate versus concentration, using nonlinear regression analysis. The maximum initial velocities of the enzyme-catalyzed reaction (V(max)) in the PNPA incubations were 614 ± 18 nmol/min/mg and 147 ± 16 nmol/min/mg for the liver and stomach fractions, respectively. These values are much faster than other phase I and II metabolism reactions. The calculated intrinsic clearance rates (CL(int)) for the 8:2 FTAc incubations were 1.7 and 0.40 ml/min/mg protein, respectively. These results show that the esterase activity toward the 8:2 FTAc is only fourfold greater in the liver as compared with the stomach. These trends demonstrate the potential for considerable extrahepatic metabolism of the 8:2 FTAc before uptake into the internal tissues, ultimately limiting the overall bioaccumulation.

Biotransformation of the 8:2 fluorotelomer acrylate in rainbow trout. 1. In vivo dietary exposure

The bioaccumulation and biotransformation of the 8:2 fluorotelomer acrylate (C(8) F(17) CH(2) CH(2) OC(O)CH = CH(2) , 8:2 FTAc) was investigated in rainbow trout via dietary exposure. The 8:2 FTAc is a monomer used in the manufacture of fluorinated polymers and has been widely detected in the atmosphere. The parent 8:2 FTAc and suspected intermediate and terminal metabolites were monitored in liver, blood, kidney, bile, and feces during the 5-d uptake and 8-d elimination phases using gas chromatography-mass spectrometry (GC-MS)- and liquid chromatography-tandem mass spectrometry (LC-MS/MS)- based methods. Very low levels of the 8:2 FTAc were detected in the internal tissues and feces, suggesting that the 8:2 FTAc was rapidly biotransformed in the gut or liver. Similarly, low concentrations of the 8:2 fluorotelomer alcohol (FTOH) were accumulated in the fish tissues. The 8:2 saturated fluorotelomer carboxylate (FTCA) was formed in the highest concentration, reaching steady-state tissue concentrations of approximately 1,000 to 1,400 ng/g wet weight. The 8:2 FTUCA and 7:3 FTCA were also accumulated in high levels, at levels approximately 10-fold lower than the 8:2 FTCA. Both the 7:3 FTCA and perfluorooctanoate (PFOA) showed increasing levels throughout the uptake phase and into the initial stages of the elimination phase, indicating continued formation through precursors still present in the body. Perfluorononanoate (PFNA) was formed in low nanogram per gram wet weight levels. The intermediate and terminal metabolites were also detected in the bile and feces, indicating an important elimination pathway for these compounds. In addition, the 8:2 FTOH glucuronide conjugate was measured in relatively high concentrations in the bile and feces. The results of the current study demonstrated a scenario in which a biologically labile compound is biotransformed to terminal metabolites that are much more biologically persistent.

Fluorotelomer ethoxylates: sources of highly fluorinated environmental contaminants part I: biotransformation

Polyethoxylated 2-perfluoroalkylethanols ('fluorotelomer ethoxylates', F-(CF(2)-CF(2)-)(x)-(CH(2)-CH(2)-O)(y)-H, FTEO) are an important class of non-ionic fluorinated surfactants, which have been disregarded as potential source of per- and polyfluorinated organic pollutants despite their high production and application amounts. A commercial mixture of FTEO with a perfluoroalkyl chain length between 6 and 10 carbon atoms and an ethoxymer distribution between 0 and 13 was subjected to a biodegradation test. Monitoring of the aerobic biotransformation process by HPLC-ESI-MS/MS showed that FTEO are rapidly transformed with a half-life of approximately 1d. Structural elucidation of the biotransformation products with the help of hybrid quadrupole--linear ion trap tandem mass spectrometry revealed oxidation to the respective carboxylic acid followed by sequential shortening of ethoxylate units which led to FTEO carboxylates (FTEOC). The conversion rate of FTEOC was found to diminish with decreasing number of ethoxylate units and virtually ceased for compounds with seven intact ethoxy units. These short-chain FTEOC were not further degraded within 48d. Nonetheless, perfluorohexanoic acid (PFHxA) and perfluorooctanoic acid (PFOA) were detected, whose formation is ascribed to degradation of residual fluorotelomer alcohols present in the commercial product. This article represents the first of two parts of a series concerning FTEO. Whilst this part is clearly focused on results of a biodegradation study of FTEO, part two will pinpoint analytical aspects, synthesis of biotransformation products and first evidence of environmental presence of the biotransformation products.

Fate of fluorotelomer acids in a soil-water microcosm

Fluorotelomer carboxylic acids (FTCAs) and the corresponding unsaturated acids (FTUCAs) are known intermediates in the biodegradation of industrially produced fluorotelomer alcohols (FTOHs) to environmentally persistent perfluorinated carboxylic acids (PFCAs). The FTCAs and FTUCAs are of concern for their toxicity, reactivity, and unknown disposition in the environment. The fate of these compounds was investigated in a simple sediment-water microcosm system. Microcosms were spiked with 8:2 FTCA, 10:2 FTCA, 8:2 FTUCA, or 10:2 FTUCA, after which sediment and water samples were collected over time and analyzed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The FTCAs and FTUCAs investigated in the present study were observed to degrade rapidly, and sorption of these analytes to sediment was found to be greater for the 10:2 telomer acids compared with the corresponding 8:2 telomer acids. Identifiable degradation products of FTCAs and FTUCAs were observed; however, an overall molar balance could not be achieved. The observed reactivity and lability of these analytes may contribute to the low levels of FTCAs detected in environmental samples.

Degradation studies of new substitutes for perfluorinated surfactants

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are manmade, stable perfluorosurfactants. The properties of perfluoroalkylated compounds that cause them to persist in the environment are also the properties that made them attractive compounds for industrial usage for over 50 years. Due to the unique properties of the carbon-fluorine bond and the polarity of perfluoroalkyl groups, potential substitutes to replace perfluorinated surfactants in most cases continue to be perfluoroalkyl based. Thus, issues of persistence in the environment remain. There is a need to test emerging new substitute surfactants for biodegradability. This study involved degradability measurements of emerging perfluorinated surfactant substitutes. The stability of the substitutes of perfluorinated surfactants was tested by employing advanced oxidation processes, which were based on degradation by ultraviolet lamp, hydrogen peroxide, or both, followed by conventional tests, among them an automated method based on the manometric respirometry test (OECD 301 F; OxiTop), closed-bottle test (OECD 301 D), and standardized fixed-bed bioreactor on perfluorobutane sulfonate, fluorosurfactant Zonyl, two fluoraliphatic esters (NOVEC FC-4430 and NOVEC FC-4432), and 10-(trifluoromethoxy) decane 1 sulfonate. Most of these new surfactants are well established in the marketplace and have been used in several applications as alternatives to PFOS- and PFOA-based surfactants. Ready biodegradation tests for fluoroaliphatic esters, the fluorosurfactant Zonyl, perfluorobutane sulfonate, and 10-(trifluoromethoxy) decane-1-sulfonate using the manometric respirometry test (OxiTop) did not meet the ready biodegradability test criteria. However, 10-(trifluoromethoxy) decane-1-sulfonate was observed to be degradable when a standardized fixed-bed bioreactor test was applied.

Elucidating the pathways of poly- and perfluorinated acid formation in rainbow trout

Several studies have shown that fluorotelomer-based compounds can be metabolized to poly- and perfluorinated carboxylates, such as perfluorooctanoate (PFOA). Research has predominately focused on the 8:2 fluorotelomer alcohol (8:2 FTOH), however, the biotransformation pathway is not well understood. Specifically, there is uncertainty regarding the biological fate of the 8:2 fluorotelomer unsaturated carboxylate (FTUCA) and 7:3 fluorotelomer saturated carboxylate (FTCA). The objective of this study was to further elucidate the pathway for 8:2 FTOH biotransformation through dosing rainbow trout with three 8:2 FTOH metabolism intermediates: the 7:3 FTCA (CF(3)(CF(2))(6)CH(2)CH(2)COO(-)), 8:2 FTCA (CF(3)(CF(2))(7)CH(2)COO(-)), and 8:2 FTUCA (CF(3)(CF(2))(6)CF horizontal lineCHCOO(-)). This study represents the first investigation of these three labile intermediate metabolites in an in vivo system. The parent compounds were dosed via the diet and the parent compounds and intermediates were monitored in the blood and liver during the 7-day uptake phase and 10-day elimination phase. Exposure to the 7:3 FTCA did not result in the formation and accumulation of PFOA, but resulted in low levels of the 7:3 FTUCA and perfluoroheptanoate, a novel finding. PFOA was formed in the 8:2 FTCA and 8:2 FTUCA dosing. In addition, the 7:3 FTCA was formed during exposure to both the 8:2 FTCA and 8:2 FTUCA. Elimination half-lives were 5.1 d (95% confidence interval: 3.1-14 d) for 7:3 FTCA, 1.2 d (1.1-1.3 d) for 8:2 FTCA, and 0.39 d (0.31-0.53 d) for 8:2 FTUCA. The observed differences in the elimination half-life may be the result of differences in either the depuration or metabolism rate. Based on the findings of this study, and reported analogous literature pathways, we proposed a "beta-like-oxidation" pathway for PFOA formation proceeding from the 8:2 FTUCA > 7:3 beta-keto acid > 7:2 ketone > PFOA. Alternatively PFOA could be formed directly through the beta-oxidation of the 7:3 beta-keto acid.

Investigating the biodegradability of perfluorooctanoic acid

Perfluorooctanoic acid (PFOA) is an industrial chemical that has become disseminated globally in aquatic and terrestrial habitats, humans, and wildlife. Understanding PFOA's biodegradability (susceptibility to microbial metabolic attack) is a crucial element in developing an informed strategy for predicting and managing this compound's environmental fate. Reasoning that PFOA might be susceptible to reductive defluorination by anaerobic microbial communities, we embarked on a 2-phase experimental approach examining the potential of five different microbial communities (from a municipal waste-water treatment plant, industrial site sediment, an agricultural soil, and soils from two fire training areas) to alter PFOA's molecular structure. A series of primarily anaerobic incubations (up to 259d in duration) were established with acetate, lactate, ethanol, and/or hydrogen gas as electron donors and PFOA (at concentrations of 100 ppm and 100 ppb) as the electron acceptor. Cometabolism of PFOA during reductive dechlorination of trichloroethene (TCE) and during reduction of nitrate, iron, sulfate, and methanogenesis were also examined. Endpoints of potential PFOA transformation included release of fluoride and detection of potential transformation products by LC/Orbitrap MS and LC/accurate radioisotope counting in a (14)C radiotracer study. The strongest indication of PFOA transformation occurred during its potential cometabolism at the 100 ppb concentration during reductive dechlorination of TCE. Despite an extensive search for transformation products to corroborate potential cometabolism of PFOA, we were unable to document any alteration of PFOA's chemical structure. We conclude that, under conditions examined, PFOA is microbiologically inert, hence environmentally persistent.

Biodegradation of polyfluoroalkyl phosphates as a source of perfluorinated acids to the environment

Wastewater treatment plants (WWTPs) have been identified as a major source of perfluorocarboxylates (PFCAs) to aqueous environments. The observed increase in PFCA mass flows from WWTP influent to effluent suggests the biodegradation of commercial fluorinated materials within the WWTP. Commercial fluorinated surfactants are used as greaseproofing agents in food-contact paper products as well as leveling and wetting agents. As WWTPs are likely the major fate of these surfactants, their biodegradation may be a source of PFCA production. One class of commercial surfactants, the polyfluoroalkyl phosphates (PAPs), have been observed in WWTP sludge. While PAPs have been shown to degrade into PFCAs in a rat model, the present study investigates their microbial fate to determine whether the biodegradation of PAPs within a WWTP-simulated system will contribute to the load of PFCAs released. PAPs are applied commercially in mixed formulations of different chain lengths and substitution at the phosphate center. The effect of chain length and phosphate substitution on the biodegradation of PAPs was investigated by incubating mixtures of 4:2, 6:2, 8:2, and 10:2 monosubstituted PAPs (monoPAPs) in an aerobic microbial system and by separately incubating the 6:2 monoPAP and 6:2 disubstituted PAP (diPAP) for 92 days. Headspace sampling revealed production of the fluorotelomer alcohols (FTOHs) from the hydrolysis of the PAP phosphate ester linkages. Analysis of the aqueous phase revealed microbial transformation of the PAPs to the final PFCA products was possible. The majority of the oxidation products observed were consistent with previous investigations that have suggested fluorotelomer precursor compounds degrade predominantly via a beta-oxidation-like mechanism. However, in this study, the detection of odd-chain PFCAs suggests that other pathways may be important. The present study demonstrated microbially mediated biodegradation of PAPs to PFCAs. This observation, together with the diPAP concentrations observed in WWTP sludge, suggest PAPs-containing commercial products may be a significant contributor to the increased PFCA mass flows observed in WWTP effluents.

Identifying new persistent and bioaccumulative organics among chemicals in commerce

The goal of this study was to identify commercial chemicals that might be persistent and bioaccumulative (P&B) and that were not being considered in current Great Lakes, North American, and Arctic contaminant measurement programs. We combined the Canadian Domestic Substance List (DSL), a list of 3059 substances of "unknown or variable composition complex reaction products and biological materials" (UVCBs), and the U.S. Environmental Protection Agency (U.S. EPA) Toxic Substances Control Act (TSCA) Inventory Update Rule (IUR) database for years 1986, 1990, 1994, 1998, 2002, and 2006 yielding a database of 22263 commercial chemicals. From that list, 610 chemicals were identified by estimates from U.S EPA EPISuite software and using expert judgment. This study has yielded some interesting and probable P&B chemicals that should be considered for further study. Recent studies, following up our initial reports and presentations on this work, have confirmed the presence of many of these chemicals in the environment.

Tissue distribution and maternal transfer of poly- and perfluorinated compounds in Chinese sturgeon (Acipenser sinensis): implications for reproductive risk

It is critical to investigate the tissue distribution and maternal transfer of poly- and perfluorinated compounds (PFCs) in wild fish for assessing potential effects on ecosystems. Concentrations of 23 PFCs in nine organs and egg were measured in 16 17- to 25-year-old female Chinese sturgeon (Acipenser sinensis, an anadromous fish), that died during propagation. Three polyfluorinated amides were detected in stomach, intestine, and gills and 7:3 FTCA was specifically accumulated in liver. The greatest total concentration of PFCs in egg was 35.1 +/- 10.4 ng/g ww and was predominated by perfluorooctane sulfonate (PFOS) and perfluorotridecanoate acid (PFTriDA). The longer-chain C(11)-C(14) and C(16) perfluorinated carboxylates were more accumulated in Chinese sturgeon than PFOS, partly due to the increasing trends of PFCAs with fish age. Maternal transfer ratios of PFCs expressed as ratios of concentrations in the egg to those in the liver ranged from 0.79 (perfluorooctanoate) to 5.5 (PFTriDA), depending on their carbon chain lengths or protein-water coefficients. The PFOS equivalent of PFC mixtures, calculated by multiplying the relative potency factor of each PFC to PFOS by the corresponding concentration, ranged from 90.6 to 262 ng/g. The hazard quotient was 0.20, implying potential reproductive effects of PFCs on Chinese sturgeon.

Biodegradation of fluorinated alkyl substances

The incorporation of fluorine into organic molecules entails both positive and adverse effects. Although fluorine imparts positive and unique properties such as water-and oil-repellency and chemical stability, adverse effects often pervade members of this compound class. A striking property of long perfluoroalkyl chains is their very pronounced environmental persistence. The present review is the first one designed to summarize recent accomplishments in the field of biodegradation of fluorine-containing surfactants, their metabolites, and structural analogs. The pronounced scientific and public interest in these chemicals has given impetus to undertake numerous degradation studies to assess the sources and origins of different fluorinated analog chemical known to exist in the environment. It was shown that biodegradation plays an important role in understanding how fluorinated substances reach the environment and, once they do, what their fate is. Today, PFOS and PFOA are ubiquitously detected as environmental contaminants. Their prominence as contaminants is mainly due to their extreme persistence, which is linked to their perfluoroalkyl chain length. It appears that desulfonation of a highly fluorinated surfactants can be achieved if an α-situated H atom, in relation to the sulfonate group, is present, at least under sulfur-limiting conditions. Molecules that are less heavily fluorinated can show very complex metabolic behavior, as is the case for fluorotelomer alcohols. These compounds are degraded via different but simultaneous pathways, which produce different stable metabolites, one of which is the respective perfluoroalkanoate (8:2-FTOH is transformed to PFOA). Preliminary screening tests indicate that fluorinated functional groups, such as the trifluoromethoxy group and the p-(trifluoromethyl)phenoxy group, may be useful implementations in novel, environmentally benign fluorosurfactants. More specifically, trifluoromethoxy groups constitute a substitute for those that have been used in the past; this functionality is degradable when it appears in structures that are normally subject to biodegradation. Other compounds tested did not meet this criterion. Interdisciplinary investigations on fluorinated surfactants are still very much needed and will certainly continue during the next many years. For instance, the role of fluorinated polymers in contributing small fluorinated molecules to the environmental burden still has not been fully understood.

6-2 Fluorotelomer alcohol aerobic biodegradation in soil and mixed bacterial culture

The first studies to explore 6-2 fluorotelomer alcohol [6-2 FTOH, F(CF(2))(6)CH(2)CH(2)OH] aerobic biodegradation are described. Biodegradation yields and metabolite concentrations were determined in mixed bacterial culture (90d) and aerobic soil (180d). 6-2 FTOH primary degradation half-life was less than 2d in both. The overall mass balance in mixed bacterial culture (day 90) was approximately 60%. At day 90, the molar yield was 6% for 6-2 FTA [F(CF(2))(6)CH(2)COOH], 23% for 6-2 FTUA [F(CF(2))(5)CFCHCOOH], 16% for 5-2 sFTOH [F(CF(2))(5)CHOHCH(3)], 6% for 5-3 acid [F(CF(2))(5)CH(2)CH(2)COOH], and 5% for PFHxA [F(CF(2))(5)COOH]. The overall mass balance in aerobic soil was approximately 67% (day 180). At day 180, the major terminal metabolites were PFPeA, [F(CF(2))(4)COOH, 30%], PFHxA (8%), PFBA [F(CF(2))(3)COOH, 2%], and 5-3 acid (15%). A new metabolite 4-3 acid [F(CF(2))(4)CH(2)CH(2)COOH] accounted for 1%, 6-2 FTOH for 3%, and 5-2 sFTOH for 7%. Based on 8-2 FTOH aerobic biodegradation pathways, PFHxA was expected in greatest yield from 6-2 FTOH degradation. However, PFPeA was observed in greatest yield in soil, suggesting a preference for alternate degradation pathways. Selected metabolites were also studied in aerobic soil. 5-3 Acid degraded to only 4-3 acid with a molar yield of 2.3%. 5-2 sFTOH degraded to PFPeA and PFHxA, and 5-2 FT Ketone [F(CF(2))(5)COCH(3)] degraded to 5-2 sFTOH, suggesting that 5-2 sFTOH is the direct precursor to PFPeA and PFHxA. Another new metabolite, 5-3 ketone aldehyde [F(CF(2))(5)COCH(2)CHO] was also identified in mixed bacterial culture. The formation of PFBA, PFPeA, and 4-3 acid indicates that multiple -CF(2)- groups in 6-2 FTOH were removed during microbial biodegradation.

Congener-specific organic carbon-normalized soil and sediment-water partitioning coefficients for the C1 through C8 perfluoroalkyl carboxylic and sulfonic acids

Organic carbon-normalized soil and sediment-water partitioning coefficients (K(oc)) were estimated for all C(1) through C(8) perfluoroalkyl carboxylic (PFCA) and sulfonic (PFSA) acid congeners. The limited experimental K(oc) data set for the straight chain C(7) through C(10) PFCAs and C(8) and C(10) PFSAs was correlated to SPARC and ALOGPS computationally estimated octanol-water partitioning/distribution constants and used to predict K(oc) values for both branched and linear C(1) through C(8) isomers. Branched and linear congeners in this homologue range are generally expected to have K(oc) values > 1, leading to their accumulation in organic matter on sediments and soils, retardation during ground and pore water flow, and the preferential association with dissolved organic matter in aquatic systems. Both increasing perfluoroalkyl chain length and linearity increase K(oc) values with substantial intra- and inter-homologue variation and interhomologue mixing. Variability in K(oc) values among the PFCA and PFSA congeners will likely lead to an enrichment of more linear and longer-chain isomers in organic matter fractions, resulting in aqueous phases fractionated towards shorter-chain branched congeners. The expected magnitude of fractionation will require inclusion in source apportionment models and risk assessments. A comparison of representative established quantitative structure property relationships for estimating K(oc) values from octanol-water partitioning constants suggests that these equilibrium partitioning frameworks may be applicable towards modeling PFCA and PFSA environmental fate processes.

Perfluoroalkyl sulfonic and carboxylic acids: a critical review of physicochemical properties, levels and patterns in waters and wastewaters, and treatment methods

Perfluorinated acids (PFAs) are an emerging class of environmental contaminants present in various environmental and biological matrices. Two major PFA subclasses are the perfluorinated sulfonic acids (PFSAs) and carboxylic acids (PFCAs). The physicochemical properties and partitioning behavior for the linear PFA members are poorly understood and widely debated. Even less is known about the numerous branched congeners with varying perfluoroalkyl chain lengths, leading to confounding issues around attempts to constrain the properties of PFAs. Current computational methods are not adequate for reliable multimedia modeling efforts and risk assessments. These compounds are widely present in surface, ground, marine, and drinking waters at concentrations that vary from pg L(-1) to microg L(-1). Concentration gradients of up to several orders of magnitude are observed in all types of aquatic systems and reflect proximity to known industrial sources concentrated near populated regions. Some wastewaters contain PFAs at mg L(-1) to low g L(-1) levels, or up to 10 orders of magnitude higher than present in more pristine receiving waters. With the exception of trifluoroacetic acid, which is thought to have both significant natural and anthropogenic sources, all PFSAs and PFCAs are believed to arise from human activities. Filtration and sorption technologies offer the most promising existing removal methods for PFAs in aqueous waste streams, although sonochemical approaches hold promise. Additional studies need to be conducted to better define opportunities from evaporative, extractive, thermal, advanced oxidative, direct and catalyzed photochemical, reductive, and biodegradation methods. Most PFA treatment methods exhibit slow kinetic profiles, hindering their direct application in conventional low hydraulic residence time systems.

Degradability of an acrylate-linked, fluorotelomer polymer in soil

Fluorotelomer polymers are used in a broad array of products in modern societies worldwide and, if they degrade at significant rates, potentially are a significant source of perfluorooctanoic acid (PFOA) and related compounds to the environment To evaluate this possibility, we incubated an acrylate-linked fluorotelomer polymer in soil microcosms and monitored the microcosms for possible fluorotelomer (FT) and perfluorinated-compound (PFC) degradation products using GC/MS and LC/MS/MS. This polymer scavenged FTs and PFCs aggressively necessitating development of a multistep extraction using two solvents. Aged microcosms accumulated more FTs and PFCs than were present in the fresh polymer indicating polymer degradation with a half-life of about 870-1400 years for our coarse-grained test polymer. Modeling indicates that more-finely grained polymers in soils might have half-lives of about 10-17 years assuming degradation is surface-mediated. In our polymer-soil microcosms, PFOA evidently was lost with a half-life as short as 130 days, possibly by polymer-catalyzed degradation. These results suggest that fluoratelomer-polymer degradation is a significant source of PFOA and other fluorinated compounds to the environment.

Linear free energy relationship based estimates for the congener specific relative reductive defluorination rates of perfluorinated alkyl compounds

Linear free energy relationships (LFERs) were developed to estimate the congener specific relative rates of reductive defluorination for a suite of perfluorinated compound (PFC) classes. The LFERs were based on the semiempirically calculated lowest unoccupied molecular orbital energy (ELUMO) using gas and aqueous phase computations with the PM6 and RM1 methods. PFC classes in the modeling effort included the C1 through C8 perfluoroalkyl sulfonates (PFSAs), carboxylates (PFCAs), sulfonyl fluorides (PFSFs), sulfonamides and their derivatives (SAs), and the perfluorotelomer alcohols (PFTAls), olefins (PFTOls), and acids (PFTAcs). Gas and aqueous phase calculations using the PM6 method predict that branched PFSA, PFCA, and PFSF congeners will have more rapid reductive defluorination kinetics than their linear counterparts. The RM1 method predicts that only PFSFs will display intrahomologue dependent branching effects. For the PFSAs and PFSFs, both the PM6 and RM1 methods predict no significant difference in mean rates of reductive defluorination between the homologue groups. For the PFCAs, the PM6 method suggests no significant difference in inter-homologue mean rates of reductive defluorination, whereas the RM1 method predicts a significant increase with a lengthening perfluoroalkyl chain. All approaches used suggest that the intrahomologue variability in reduction rates increases with increasing chain length for PFSAs, PFCAs, and PFSFs, implying that the larger homologue groups in these classes will see a more rapid linearization of the congener profiles under reducing conditions than their lower homologue counterparts. Chain length has a negligible effect on the estimated rates of SA reductive defluorination, but a significant role for the fluorotelomer derivatives. Ratios of rates between the C8:C1 straight chain telomeric congeners are expected to range up to 200-fold depending on the computational combination. The kinetics for reductively defluorinating PFC starting materials will likely be 2 to 3 orders of magnitude more rapid than for most of the partially defluorinated degradation products. Significant quantities of partially defluorinated PFCs are thus expected to be observed under steady state conditions during reductive treatment processes, leading to a potentially significant reservoir of these compounds residing in reducing environmental and biological systems.

Observation of a commercial fluorinated material, the polyfluoroalkyl phosphoric acid diesters, in human sera, wastewater treatment plant sludge, and paper fibers

Sources of human exposure to perfluorinated carboxylic acids (PFCAs) are not well-characterized. Polyfluoroalkyl phosphoric acids (PAPs) are fluorinated surfactants used in human food contact paper products. PAPs can migrate into food and food simulants, and their bioavailability and biotransformation into PFCAs has been demonstrated using a rat model. To characterize human exposure to PAP materials, we analyzed pooled human sera samples collected in 2004 and 2005 (n = 10) and 2008 (n = 10) from the midwestern United States for the 4:2 through 10:2 PAP diesters (diPAPs). The 2004 and 2005 sera samples contained 4.5 microg/L total diPAPs, with the 6:2 diPAP dominating the congener profile at 1.9 +/- 0.4 microg/L DiPAP concentrations observed in the 2004 and 2005 human sera samples were similar to those of the C8 to C11 PFCAs (0.13 +/- 0.01 to 4.2 +/- 0.3 microg/L) monitored in the same samples. 6:2 diPAP was also consistently observed in the 2008 human sera samples at a mean concentration of 0.63 +/- 0.13 microg/L As diPAPs have been shown to degrade to PFCAs in vivo, our observation of diPAPs in human sera may be a direct connection between the legacy of human PFCA contamination and PAPs commercial applications. Wastewater treatment plant (WWTP) sludge and paper fibers were analyzed for diPAPs as a proxy for human use and potential exposure to diPAPs. DiPAPs were observed in WWTP sludge at concentrations ranging from 47 +/- 22 to 200 +/- 130 ng/g, a range similar to perfluorooctane sulfonic acid (PFOS) (100 +/- 70 ng/g) and greater than the C8 to C11 PFCAs (1.6 +/- 0.6 to 0.17 +/- 0.10 ng/g) observed in the same samples. DiPAPs were observed in paper fiber extracts at concentrations ranging from 34 +/- 30 to 2200 +/- 400 ng/g. The high diPAP concentrations in WWTP sludge suggest PAP materials may be prevalent in our daily lives.

Temporal trends of polyfluoroalkyl compounds in harbor seals (Phoca vitulina) from the German Bight, 1999-2008

Temporal trends of polyfluoroalkyl compounds (PFCs) were examined in liver samples from harbor seals (Phoca vitulina) collected from the German Bight (1999-2008). Concentrations of various PFCs, including C(4)-C(10) perfluoroalkyl sulfonates (PFSAs), perfluorooctane sulfinate (PFOSi), perfluorooctane sulfonamide (FOSA) and C(8)-C(15) perfluoroalkyl carboxylic acids (PFCAs) were quantified. Perfluorooctane sulfonate (PFOS) was the predominant compound with a maximum concentration of 3676 ng g(-1) ww (1996), making up on average 94% of the measured PFCs. Significantly higher concentrations were found in <7 month old in comparison to >or=7 month old harbor seals for C(6)-C(8) PFSAs, perfluorododecanoic acid (PFDoDA) and FOSA, whereas perfluorodecanoic acid (PFDA) showed significantly lower concentrations in the younger harbor seals (p<0.05). These results suggest a transplacental transfer of PFCs to the foetus and/or consumption of different contaminated food. Regression analysis of logarithmic transformed PFC mean concentrations indicated a significant temporal trend with decreasing concentrations for C(5)-C(7) PFSAs (p<0.001), PFOSi (p=0.028), FOSA (p<0.001) and perfluorooctanoic acid (PFOA) (p=0.031) between 1999 and 2008. Furthermore, PFOS decreased by 49% between 1999 and 2008, which correspond with decreasing concentration levels of its metabolic precursors PFOSi and FOSA of 83% and 95% in the same time period. However, the decreasing trend of PFOS is not significant (p=0.067). The reason for the decline during the past 10 years could be an effect of the replacement of these PFCs by shorter chained and less bioaccumulative compounds. But the observations of increasing perfluorodecane sulfonate (PFDS) levels (p=0.070), the high concentrations of PFOS and constant levels of C(9)-C(13) PFCAs indicates that further work on the reduction of environmental emissions of PFCs are necessary.

8-2 fluorotelomer alcohol aerobic soil biodegradation: pathways, metabolites, and metabolite yields

The biodegradation pathways and metabolite yields of [3-(14)C] 8-2 fluorotelomer alcohol [8-2 FTOH, F(CF(2))(7)(14)CF(2)CH(2)CH(2)OH) in aerobic soils were investigated. Studies were conducted under closed (static) and continuous headspace air flow to assess differences in degradation rate and metabolite concentrations in soil and headspace. Aerobic degradation pathways in soils were in general similar to those in aerobic sludge and bacterial culture. (14)C mass balance was achieved in soils incubated for up to 7 months. Up to 35% (14)C dosed was irreversibly bound to soils and was only recoverable by soil combustion. The average PFOA yield was approximately 25%. Perfluorohexanoic acid (PFHxA) yield reached approximately 4%. (14)CO(2) yield was 6.8% under continuous air flow for 33 days. Three metabolites not previously identified in environmental samples were detected: 3-OH-7-3 acid [F(CF(2))(7)CHOHCH(2)COOH], 7-2 FT ketone [F(CF(2))(7)COCH(3)] and 2H-PFOA [F(CF(2))(6)CFHCOOH]. No perfluorononanoic acid (PFNA) was observed. The formation of 2H-PFOA, PFHxA, and (14)CO(2) shows that multiple -CF(2)- groups were removed from 8-2 FTOH. 7-3 Acid [F(CF(2))(7)CH(2)CH(2)COOH] reached a yield of 11% at day 7 and did not change thereafter. 7-3 Acid was incubated in aerobic soil and did not degrade to PFOA. 7-2 sFTOH [F(CF(2))(7)CH(OH)CH(3)], a transient metabolite, was incubated and degraded principally to PFOA. 7-3 Acid may be a unique metabolite from 8-2 FTOH biodegradation. The terminal ratio of PFOA to 7-3 acid ranged between 1.8-2.5 in soils and 0.6-3.2 in activated sludge, sediment, and mixed bacterial culture. This ratio may be useful in evaluating environmental samples to distinguish the potential contribution of 8-2 FTOH biodegradation to PFOA observed versus PFOA originating from other sources.

Computational approaches may underestimate pK(a) values of longer-chain perfluorinated carboxylic acids: Implications for assessing environmental and biological effects

Acidity constants were calculated using the semiempirical PM6 pK(a) estimation method for all C(2) through C(9) perfluoroalkyl carboxylate (PFCA) congeners and the straight-chain C(10) through C(13) isomers. According to the PM6 estimates, the linear congeners within each PFCA homologue group have the highest pK(a) values by up to 6 units depending on the degree of branching in the perfluoroalkyl chain. In general, the higher the degree of branching in the perfluoroalkyl chain within a homologue group, the lower the estimated pK(a) value. When the branching is closest to the terminal carboxylate group, the effect on the calculated pK(a) is greatest. Although the PM6 calculated pK(a) values agree well with previously reported estimates for selected linear PFCA congeners using the SPARC and COSMOtherm approaches, all computational approaches only show good agreement with reported experimental values for short chain PFCAs (C(2) through C(5)). Increasing divergences are observed between calculated and experimental results by up to several pK(a) units as the perfluoroalkyl chain length increases beyond C(5). The findings demonstrate a need for additional experimental pK(a) measurements for an expanded set of both linear and branched PFCA congeners to confirm previous experimental reports that are potentially in error, and upon which to calibrate existing computational methods and environmental, toxicological, and waste treatment method models.

Complete multinuclear magnetic resonance characterization of a set of polyfluorinated acids and alcohols

A complete (1)H, (19)F, and (13)C NMR assignment of a homologous series of polyfluorinated acids and alcohols is reported. These assignments were obtained chiefly through single and multiple-bond (1)H-(13)C and (19)F-(13)C correlation experiments (HSQC, HMBC). (19)F NOESY experiments were required for assignment of two compounds with diastereotopic (19)F nuclei in the CF(2)chain of the molecule.

Total fluorine, extractable organic fluorine, perfluorooctane sulfonate and other related fluorochemicals in liver of Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides) from South China

The concentrations of 10 PFCs (perfluorinated compounds: PFOS, PFHxS, PFOSA, N-EtFOSA, PFDoDA, PFUnDA, PFDA, PFNA, PFOA, and PFHpA) were measured in liver samples of Indo-Pacific humpback dolphins (Sousa chinensis) (n=10) and finless porpoises (Neophocaena phocaenoides) (n=10) stranded in Hong Kong between 2003 and 2007. PFOS was the dominant PFC in the tissues at concentrations ranging at 26-693 ng/g ww in dolphins and 51.3-262 ng/g ww in porpoises. A newly developed combustion ion chromatography for fluorine was applied to measure total fluorine (TF) and extractable organic fluorine (EOF) in these liver samples to understand PFC contamination using the concept of mass balance analysis. Comparisons between the amounts of known PFCs and EOF in the livers showed that a large proportion (approximately 70%) of the organic fluorine in both species is of unknown origin. These investigations are critical for a comprehensive assessment of the risks of these compounds to humans and other receptors.

Perfluorooctane sulfonate (PFOS) and other fluorochemicals in fish blood collected near the outfall of wastewater treatment plant (WWTP) in Beijing

Perfluorinated compounds (PFCs) were measured in zooplankton and five fish species collected from Gaobeidian Lake, which receives discharge from wastewater treatment plant (WWTP) in Beijing, China. The mean total PFCs in five fish were in the order: crucian carp>common carp>leather catfish>white semiknife carp>tilapia. Perfluorooctane sulfonate (PFOS) occurred at the greatest concentrations, with mean concentrations ranging from 5.74 to 64.2 ng/ml serum. Perfluorodecanoic acid (PFDA) was the second dominant PFC in fish samples except for common carp in which perfluorooctane sulfonamide (PFOSA) was dominant. A positive linear relationship (r(2)=0.85, p<0.05) was observed between lnPFOS concentrations (ln ng/ml) and trophic level (based on delta15N) if tilapia was excluded. The risk assessment showed that PFOS might not pose an immediate risk to fish in Gaobeidian Lake.

Estimating the contribution of precursor compounds in consumer exposure to PFOS and PFOA

The exposure of humans to perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) was quantified with emphasis on assessing the relative importance of metabolic transformation of precursor compounds. A Scenario-Based Risk Assessment (SceBRA) approach was used to model the exposure to these compounds from a variety of different pathways, the uptake into the human body and resulting daily doses. To capture the physiological and behavioral differences of age and gender, the exposure and resulting doses for seven consumer groups were calculated. The estimated chronic doses of a general population of an industrialized country range from 3.9 to 520 ng/(kg day) and 0.3 to 140 ng/(kg day) for PFOS and PFOA, respectively. The relative importance of precursor-based doses of PFOS and PFOA was estimated to be 2-5% and 2-8% in an intermediate scenario and 60-80% and 28-55% in a high-exposure scenario. This indicates that sub groups of the population may receive a substantial part of the PFOS and PFOA doses from precursor compounds, even though they are of low importance for the general population. Similar to a preceding study, uptake of perfluorinated acids from contaminated food and drinking water was identified as the most important pathway of exposure for the general population. The biotransformation yields of telomer-based precursors and to a lesser extent perfluorooctanesulfonylfluoride-based precursors were identified as influential parameters in the uncertainty analysis. Fast food consumption and fraction of food packaging paper treated with PFCs were influential parameters for determining the doses of PFOA.