6:2 and 8:2 fluorotelomer alcohol anaerobic biotransformation in digester sludge from a WWTP under methanogenic conditions.

6:2 FTOH and 8:2 FTOH [FTOHs, F(CF2)nCH2CH2OH, n = 6, 8] are the principal polyfluorinated raw materials used to manufacture FTOH-based products, which may be released to WWTPs during their product life cycle. For the first time, anaerobic biotransformation of FTOHs and key biotransformation intermediates in WWTP digester sludge under methanogenic conditions was investigated. 6:2 FTOH was transformed to 6:2 FTCA, [F(CF2)6CH2COOH, 32-43 mol %], 6:2 FTUCA [F(CF2)5CF═CHCOOH, 1.8-8.0 mol %], and 5:3 acid [F(CF2)5CH2CH2COOH, 18-23 mol %] by day 90 and day 176 in two separate studies. 8:2 FTOH was transformed by day 181 to 8:2 FTCA (18 mol %), 8:2 FTUCA (5.1 mol %), and 7:3 acid (27 mol %). 6:2 and 8:2 FTOH anaerobic biotransformation led to low levels of perfluorohexanoic acid (PFHxA, ≤0.4 mol %) and perfluorooctanoic acid (PFOA, 0.3 mol %), respectively. 6:2 FTUCA anaerobic biotransformation led to a newly identified novel transient intermediate 3-fluoro 5:3 acid [F(CF2)5CFHCH2COOH] and 5:3 acid, but not 5:2 sFTOH [F(CF2)5CH(OH)CH3] and α-OH 5:3 acid [F(CF2)5CH2CH(OH)COOH], two precursors leading to PFPeA (perfluoropentanoic acid) and PFHxA. Thus, FTOH anaerobic biotransformation pathways operated by microbes in the environment was likely inefficient at shortening carbon chains of FTOHs to form PFCAs (perfluorinated carboxylic acids). These results imply that anaerobic biotransformation of FTOH-based products may produce polyfluorinated acids, but is not likely a major source of PFCAs detected in anaerobic environmental matrices such as anaerobic digester sludge, landfill leachate, and anaerobic sediment under methanogenic conditions.

Aerobic soil biotransformation of 6:2 fluorotelomer iodide.

6:2 FTI [F(CF2)6CH2CH2I] is a principal industrial raw material used to manufacture 6:2 FTOH [F(CF2)6CH2CH2OH] and 6:2 FTOH-based products and could enter aerobic environments from possible industrial emissions where it is manufactured. This is the first study to assess 6:2 FTI aerobic soil biotransformation, quantify transformation products, and elucidate its biotransformation pathways. 6:2 FTI biotransformation led to 6:2 FTOH as a key intermediate, which was subsequently biotransformed to other significant transformation products, including PFPeA [F(CF2)4COOH, 20 mol % at day 91], 5:3 acid [F(CF2)5CH2CH2COOH, 16 mol %], PFHxA [F(CF2)5COOH, 3.8 mol %], and 4:3 acid [F(CF2)4CH2CH2COOH, 3.0 mol %]. 6:2 FTI biotransformation also led to a significant level of PFHpA [F(CF2)6COOH, 16 mol % at day 91], perhaps via another putative intermediate, 6:2 FTUI [F(CF2)6CH ═ CHI], whose molecular identity and further biotransformation were not verified because of the lack of an authentic standard. Total recovery of the aforementioned per- and polyfluorocarboxylates accounted for 59 mol % of initially applied 6:2 FTI by day 91, in comparison to 56 mol % when soil was dosed with 6:2 FTOH, which did not lead to PFHpA. Thus, were 6:2 FTI to be released from its manufacture and undergo soil microbial biotransformation, it could form PFPeA, PFHpA, PFHxA, 5:3 acid, and 4:3 acid in the environment.

6:2 Fluorotelomer iodide in vitro metabolism by rat liver microsomes: comparison with [1,2-(14)C] 6:2 fluorotelomer alcohol.

6:2 Fluorotelomer iodide [6:2 FTI, F(CF2)6CH2CH2I] is the industrial raw material used to manufacture 6:2 fluorotelomer alcohol [6:2 FTOH, F(CF2)6CH2CH2OH] and 6:2 FTOH-based products. During its manufacture and industrial use, workers may be exposed to via oral, dermal or inhalation of 6:2 FTI. Therefore it is useful to understand how 6:2 FTI may be metabolized and into what transformation products. 6:2 FTI in vitro rat liver microsomal metabolism was explored for the first time to compare its biotransformation potential with that of [1,2-(14)C] 6:2 FTOH [F(CF2)6(14)CH2(14)CH2OH]. 6:2 FTI and 6:2 FTOH metabolite yields were determined in closed-bottle systems using Sprague Dawley and Wistar Han rat microsomes after incubation at 37 °C for up to 6h with NADPH (reduced form of nicotinamide adenine dinucleotide phosphate)-addition and NADPH-regenerating systems, respectively. 5:3 acid [F(CF2)5CH2CH2COOH] was the most abundant metabolite for 6:2 FTI (3.3-6.3 mol%) and 6:2 FTOH (9-12 mol%). Perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), and perfluorohexanoic acid (PFHxA) in sum accounted for 1.3-2.2 mol% from 6:2 FTI and 2.7-4.4 mol% from 6:2 FTOH biotransformation. Perfluoroheptanoic acid (PFHpA) accounted for 0.14-0.36 mol% from 6:2 FTI but only 0.01-0.06 mol% from 6:2 FTOH biotransformation. These results suggest that mammalian systems exposed to 6:2 FTI or 6:2 FTOH would form 5:3 acid, PFBA, PFPeA, PFHxA as the primary stable metabolites, whereas more PFHpA would be expected from 6:2 FTI biotransformation.

6:2 fluorotelomer alcohol biotransformation in an aerobic river sediment system.

The 6:2 FTOH [F(CF(2))(6)CH(2)CH(2)OH] is a major raw material being used to replace 8:2 FTOH [F(CF(2))(8)CH(2)CH(2)OH] to make FTOH-based products for industrial and consumer applications. A novel aerobic sediment experimental system containing 20 g wet sediment and 30 mL aqueous solution was developed to study 6:2 FTOH biotransformation in river sediment. 6:2 FTOH was dosed into the sediment to follow its biotransformation and to analyze transformation products over 100 d. The primary 6:2 FTOH biotransformation in the aerobic sediment system was rapid (T(1/2)<2d). 5:3 acid [F(CF(2))(5)CH(2)CH(2)COOH] was observed as the predominant polyfluorinated acid on day 100 (22.4 mol%), higher than the sum of perfluoropentanoic acid (10.4 mol%), perfluorohexanoic acid (8.4 mol%), and perfluorobutanoic acid (1.5 mol%). Perfluoroheptanoic acid was not observed during 6:2 FTOH biotransformation. The 5:3 acid can be further degraded to 4:3 acid [F(CF(2))(4)CH(2)CH(2)COOH, 2.7 mol%]. This suggests that microbes in the river sediment selectively degraded 6:2 FTOH more toward 5:3 and 4:3 acids compared with soil. Most of the observed 5:3 acid formed bound residues with sediment organic components and can only be quantitatively recovered by post-treatment with NaOH and ENVI-Carb™ carbon. The 6:2 FTCA [F(CF(2))(6)CH(2)COOH], 6:2 FTUCA [F(CF(2))(5)CF=CHCOOH], 5:2 ketone [F(CF(2))(5)C(O)CH(3)], and 5:2 sFTOH [F(CF(2))(5)CH(OH)CH(3)] were major transient intermediates during 6:2 FTOH biotransformation in the sediment system. These results suggest that if 6:2 FTOH or 6:2 FTOH-based materials were released to the river or marine sediment, poly- and per-fluorinated carboxylates could be produced.

6:2 Fluorotelomer alcohol aerobic biotransformation in activated sludge from two domestic wastewater treatment plants.

6:2 Fluorotelomer alcohol [6:2 FTOH, F(CF2)6CH2CH2OH] is a major basic chemical being used to manufacture FTOH-based products. After the end of use, 6:2 FTOH-based products may be released to domestic wastewater treatment plants (WWTPs) as a first major environmental entry point. Activated sludge collected from two WWTPs was dosed with 6:2 FTOH to investigate its biotransformation rate and to identify major transformation products. The volatile 5:2 sFTOH [F(CF2)5CH(OH)CH3] is the most abundant transformation product and accounted for an average of 40mol% of initially dosed 6:2 FTOH after two months of incubation with activated sludge, with 30mol% detected in the headspace. PFPeA [F(CF2)4COOH] averaged 4.4mol% after two months, 2.4-7 times lower than that in sediment and soils. The much lower level of PFPeA formed in activated sludge compared with soil indicates that microbial populations in activated sludge may lack enzymes or suitable environment conditions to promote rapid 5:2 sFTOH decarboxylation to form PFPeA, resulting in more 5:2 sFTOH partitioned to the headspace. PFHxA [F(CF2)5COOH] and 5:3 [F(CF2)5CH2CH2COOH] acid are major non-volatile transformation products in activated sludge. For example, PFHxA averaged 11mol% after two months, which is about 30% higher compared with sediment and soils, suggesting that microbes in WWTPs may utilize similar pathways as that in sediment and soils to convert 5:2 sFTOH to PFHxA. 5:3 Acid averaged 14mol% after two months, comparable to that in soils and slightly lower than in sediment, further confirming that 5:3 acid is a unique product of 6:2 FTOH biotransformation in the environment.

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.

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.

Aerobic biodegradation of [14C] 6:2 fluorotelomer alcohol in a flow-through soil incubation system.

The aerobic biodegradation of [1,2-(14)C] 6:2 FTOH [F(CF(2))(6)(14)CH(2)(14)CH(2)OH] in a flow-through soil incubation system is described. Soil samples dosed with [1,2-(14)C] 6:2 FTOH were analyzed by liquid scintillation counting, LC/ARC (liquid chromatography/accurate radioisotope counting), LC/MS/MS, and thermal combustion to account for 6:2 FTOH and its transformation products over 84 d. Half of the [1,2-(14)C] 6:2 FTOH disappeared from soil in 1.3 d, undergoing simultaneous microbial degradation and partitioning of volatile transformation product(s) and the 6:2 FTOH precursor into the air phase. The overall (14)C (radioactivity) mass balance in live and sterile treatments was 77-87% over 84-d incubation. In the live test system, 36% of total (14)C dosed was captured in the airflow (headspace), 25% as soil-bound residues recovered via thermal combustion, and 16% as soil extractable. After 84 d, [(14)C] 5:2 sFTOH [F(CF(2))(5)CH(OH)(14)CH(3)] was the dominant transformation product with 16% molar yield and primarily detected in the airflow. The airflow also contained [1,2-(14)C] 6:2 FTOH and (14)CO(2) at 14% and 6% of total (14)C dosed, respectively. The other significant stable transformation products, all detected in soil, were 5:3 acid [F(CF(2))(5)CH(2)CH(2)COOH, 12%], PFHxA [F(CF(2))(5)COOH, 4.5%] and PFPeA [F(CF(2))(4)COOH, 4.2%]. Soil-bound residues as well as conjugates between fluorinated transformation products and dissolved soil components were only observed in the live test system and absent in the sterile soil, suggesting that such binding and complexation are microbially or enzymatically driven processes. At day 84, 5:3 acid is postulated to be the major transformation product in soil-bound residues, which may not be available for further biodegradation in soil environment.

Hydrolytic stability of terephthaloyl chloride and isophthaloyl chloride.

The phthaloyl chloride isomers, terephthaloyl chloride (TCl) and isophthaloyl chloride (ICl), are high production volume chemicals used in polymers to impartflame resistance, chemical resistance, and temperature stability and as water scavengers. In these studies, we determined the hydrolytic stability of TCl and ICl and their hydrolysis products in aqueous solutions. Hydrolysis rates for TCl and ICl were initially determined by gas chromatography/flame ionization detection in water buffered at pH 4.0, 7.0, and 9.0 and 0 degrees C for up to 30 min. Subsequent studies determined the products from TCl and ICl hydrolysis. The parent phthaloyl chlorides (TCl and ICl), their intermediate hydrolysis products (designated as the "half-acids"), and their stable hydrolysis products (terephthalic acid (TPA) and isophthalic acid (IPA)) were determined by high-performance liquid chromatography. The half-lives (t(1/2)) of TCl and ICl ranged from an average of 1.2 to 2.2 min and from 2.2 to 4.9 min, respectively, at pH 4-9 and 0 degrees C. The observed first-order rate constants (k(obs)) ranged from an average of 530 to 1100 (x 10(5) s(-1)) for TCl and 240 to 520 (x 10(5) s(-1)) for ICl. Both phthaloyl chlorides formed their respective short-lived intermediates, in which one of the two carboxylic acid chloride functionalities reacts with water to form the carboxylic acid ("half-acid"). Subsequently, the half-acids underwent further hydrolysis so that greater than 90% of the initial phthaloyl chloride hydrolyzed in less than 60 min at 0 degrees C. The hydrolysis products TPA and IPA were hydrolytically stable, undergoing no further transformations after 20 min at pH 7 and 25 degrees C. This work demonstrated that TCl, ICl, and their respective half-acids will not be persistent in aqueous systems for a time sufficient to have a sustained toxicological effect on aquatic organisms (less than 1 h). Performing additional aquatic toxicity studies, biodegradation studies, and potentially mammalian studies on TCl and ICl are unnecessary since the existing information on TPA and IPA with the hydrolysis data presented here is sufficient to address questions on the fate and effects of these two substances in aqueous environments.