Aerobic biotransformation of 6:2 fluorotelomer sulfonate in soils from two aqueous film-forming foam (AFFF)-impacted sites

Although 6:2 fluorotelomer sulfonate (6:2 FTS) is a common ingredient in aqueous film-forming foam (AFFF) formulations, its environmental fate at AFFF-impacted sites remains poorly understood. This study investigated the biotransformation of 6:2 FTS in microcosms prepared with soils collected from two AFFF-impacted sites; the former Loring Air Force Base (AFB) and Robins AFB. The half-life of 6:2 FTS in Loring soil was 43.3 days; while >60 mol% of initially spiked 6:2 FTS remained in Robins soil microcosms after a 224-day incubation. Differences in initial sulfate concentrations and the depletion of sulfate over the incubation likely contributed to the different 6:2 FTS biotransformation rates between the two soils. At day 224, stable transformation products, i.e., C4C7 perfluoroalkyl carboxylates, were formed with combined molar yields of 13.8 mol% and 1.2 mol% in Loring and Robins soils, respectively. Based on all detected transformation products, the biotransformation pathways of 6:2 FTS in the two soils were proposed. Microbial community analysis suggests that Desulfobacterota microorganisms may promote 6:2 FTS biotransformation via more efficient desulfonation. In addition, species from the genus Sphingomonas, which exhibited higher tolerance to elevated concentrations of 6:2 FTS and its biotransformation products, are likely to have contributed to 6:2 FTS biotransformation. This study demonstrates the potential role of biotransformation processes on the fate of 6:2 FTS at AFFF-impacted sites and highlights the need to characterize site biogeochemical properties for improved assessment of 6:2 FTS biotransformation behavior.

Behavioral outcomes and exposure to perfluoroalkyl substances among children aged 6-13 years: The TEDDY child study

BACKGROUND

Although some studies report that exposure to per- and polyfluoroalkyl substances (PFAS) during pregnancy and early life stages of a child could adversely impact neurodevelopment, literature shows mixed evidence.

OBJECTIVES

Using an ecological framework for human development, we assessed the association of risk factors for environmental PFAS exposure and childhood PFAS concentrations with behavioral difficulties among school-age children exposed to PFAS from birth, while also controlling for the important influence of the parenting and familial environment.

METHODS

The study participants included 331 school-age children (6-13 years) born in a PFAS-contaminated area in the Veneto Region (Italy). We study the associations between environmental risk factors of maternal PFAS exposure (residential time, consumption of tap water, residence in Red zone A or B), and breastfeeding duration with parent assessments of children's behavioral problems (using the Strengths and Difficulties Questionnaire [SDQ]), adjusting for socio-demographic, parenting and familial variables. The direct relationships between serum blood PFAS concentrations and SDQ scores was evaluated in a subset of children (n = 79), both with single PFAS and weighted quantile sum (WQS) regressions.

RESULTS

Poisson regression models reported positive associations between high consumption of tap water and externalizing SDQ scores (Incidence Rate Ratio [IRR]: 1.18; 95% confidence interval [CI]: 1.04-1.32) and total difficulty scores (IRR: 1.14; 95% CI: 1.02-1.26). Childhood perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) were associated with higher internalizing SDQ scores (4th vs. 1st quartile, PFOS IRR: 1.54, 95% CI: 1.06-2.25), externalizing scores (4th vs. 1st quartile, PFHxS IRR: 1.59, 95% CI: 1.09-2.32), and total difficulty scores (4th vs. 1st quartile, PFOS IRR: 1.37, 95% CI: 1.05-1.71; PFHxS IRR: 1.54, 95% CI: 1.09-1.90). The WQS regressions confirmed the associations reported by single-PFAS analyses.

CONCLUSIONS

We observed cross-sectional associations of tap water consumption and childhood PFOS, and PFHxS concentrations with greater behavioral difficulties.

6:2 Chlorinated Polyfluoroalkyl Ether Sulfonates Exert Stronger Thyroid Homeostasis Disruptive Effects in Newborns than Perfluorooctanesulfonate: Evidence Based on Bayesian Benchmark Dose Values from a Population Study

Growing toxicologic evidence suggests that emerging perfluoroalkyl substances (PFASs), like chlorinated polyfluoroalkyl ether sulfonate (Cl-PFESA), may be as toxic or more toxic than perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA). However, further investigations are needed in terms of the human health risk assessment. This study examined the effects of emerging and legacy PFAS exposure on newborn thyroid homeostasis and compared the thyroid disruption caused by 6:2 Cl-PFESA and PFOS using a benchmark dose approach. The health effects of mixture and individual exposure were estimated using the partial least-squares (PLS) model and linear regression, respectively. A Bayesian benchmark dose (BMD) analysis determined the BMD value for adverse effect comparison between 6:2 Cl-PFESA and PFOS. The median (interquartile range) concentrations of 6:2 Cl-PFESA (0.573 [0.351-0.872] ng/mL), PFOS (0.674 [0.462-1.007] ng/mL), and PFOA (1.457 [1.034, 2.405] ng/mL) were found to be similar. The PLS model ranked the PFAS variables' importance in projection (VIP) scores as follows: 6:2 Cl-PFESA > PFOS > PFOA. Linear regression showed that 6:2 Cl-PFESA had a positive association with free triiodothyronine (FT3, P = 0.006) and triiodothyronine (T3, P = 0.014), while PFOS had a marginally significant positive association with FT3 alone (P = 0.042). The BMD analysis indicated that the estimated BMD10 for 6:2 Cl-PFESA (1.01 ng/mL) was lower than that for PFOS (1.66 ng/mL) in relation to a 10% increase in FT3. These findings suggest that 6:2 Cl-PFESA, an alternative to PFOS, has a more pronounced impact on newborns' thyroid homeostasis compared to PFOS and other legacy PFASs.

Perfluorinated compound correlation between human serum and drinking water: Is drinking water a significant contributor?

Perfluorinated compounds (PFASs) are a new artificial chemical. Due to its substantial toxicity and complex degradation in the natural environment, monitoring PFASs has become a hot issue for many researchers. Currently, the relationship between the concentration of PFASs in serum and the concentration of PFASs in drinking water is unclear. This paper aims to study the concentration levels of PFASs in drinking water and residents' serum in a city in northern China and the relationship between them. The results show that the concentration of PFASs in drinking water is low, and the average concentrations of perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) were 2.57 ± 0.69 ng/L and 0.30 ng/L, respectively, which were lower than the limits specified in China's newly introduced Standards for drinking water quality (GB 5749-2022). In the serum of residents, PFOA and PFOS were the two PFASs with the highest concentration. Spearman correlation analysis showed that perfluorohexane sulfonate (PFHxS) and PFOS concentrations were positively correlated with age, and PFHxS, PFOA, PFNA, and PFOS varied with sex. At the same time, the correlation analysis also showed no correlation between PFAS in drinking water and serum, indicating that drinking water was not the main factor causing the physical burden of PFAS in residents. The HI method was used to assess the health risks of PFASs to human beings. The risk entropy of all PFASs for human hepatotoxicity and reproductive toxicity is below 1.

Spatio-temporal trends in livestock exposure to per- and polyfluoroalkyl substances (PFAS) inform risk assessment and management measures

The migration of per- and polyfluoroalkyl substances (PFAS) onto agricultural properties has resulted in the accumulation of PFAS in livestock. The environmental determinants of PFAS accumulation in livestock from the grazing environment are poorly understood, resulting in limited capacity to manage livestock exposure and subsequent transfer of PFAS through the food chain. Analytical- (n = 978 samples of soil, water, pasture, and serum matrices), farm management/practice- and livestock physiology data were collated and interrogated from environmental PFAS investigations across ten farms, from four agro-ecological regions of Victoria (Australia). Statistical analysis identified perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) as key analytes of concern for livestock bioaccumulation. PFOS and PFHxS concentrations in livestock drinking water were positively correlated with serum concentrations while other intake pathways (pasture and soil) had weaker correlations. Seasonal trends in PFAS body burden (serum concentrations) were identified and suggested to be linked to seasonal grazing behaviours and physiological water requirements. The data showed for the first time that livestock exposure to PFAS is dynamic and with relatively short elimination half-lives, there is opportunity for exposure management. Meat from cattle, grazed on PFAS impacted sites, may exceed health-based guideline values for PFAS, especially for markets with low limits (like the European Commission Maximum Limits or EC MLs). This study found that sites with mean livestock drinking water concentrations as low as 0.003 μg PFOS/L may exceed the EC ML for PFOS in cattle meat. Risk assessment can be used to prioritise site cleanup and development of management plans to reduce PFAS body burden by considering timing of stock rotation and/or supplementation of primary exposure sources.

Joint effects of per- and polyfluoroalkyl substance alternatives and heavy metals on renal health: A community-based population study in China

BACKGROUND

Previous studies have indicated that chlorinated polyfluorinated ether sulfonic acids (Cl-PFESAs), when used as an alternative to per- and polyfluoroalkyl substances (PFASs), result in kidney toxicity. However, their co-exposure with heavy metals, has not yet been described.

OBJECTIVES

To explore the joint effects of Cl-PFESAs and heavy metal exposure on renal health in Chinese adults, and identify specific pollutants driving the associations.

METHODS

Our sample consists of 1312 adults from a cross-sectional survey of general communities in Guangzhou, China. We measured Cl-PFESAs, legacy PFASs (perfluorooctanoic acid [PFOA] and perfluorooctane sulfonated [PFOS]), and heavy metals (arsenic, cadmium, and lead). The relationship between single pollutant and glomerular filtration rate (eGFR) and the odds ratio (OR) of chronic kidney disease (CKD) was studied using Generalized additive models (GAMs). Bayesian Kernel Machine Regression (BKMR) models were applied to assess joint effects of Cl-PFESAs and heavy metals. Additionally, we conducted a sex-specific analysis to determine the modification effect of this variable.

RESULTS

In single pollutant models, CI-PFESAs, PFOA, PFOS and arsenic were negatively associated with eGFR. Additionally, PFOA and heavy metals were positively correlated with the OR of CKD. For example, the estimated change with 95% confidence intervals (CI) of eGFR at from the highest quantile of 6:2 Cl-PFESA versus the lowest quantile was -5.65 ng/mL (95% CI: -8.21, -3.10). Sex played a role in modifying the association between 8:2 Cl-PFESA, PFOS and eGFR. In BKMR models, pollutant mixtures had a negative joint association with eGFR and a positive joint effect on CKD, especially in women. Arsenic appeared to be the primary contributing pollutant.

CONCLUSION

We provide epidemiological evidence that Cl-PFESAs independently and jointly with heavy metals impaired kidney health. More population-based human and animal studies are needed to confirm our results.

Environmentally relevant concentrations of F-53B induce eye development disorders-mediated locomotor behavior in zebrafish larvae

The perfluorooctane sulfonate alternative, F-53B, induces multiple physiological defects but whether it can disrupt eye development is unknown. We exposed zebrafish to F-53B at four different concentrations (0, 0.15, 1.5, and 15 μg/L) for 120 h post-fertilization (hpf). Locomotor behavior, neurotransmitters content, histopathological alterations, morphological changes, cell apoptosis, and retinoic acid signaling were studied. Histology and morphological analyses showed that F-53B induced pathological changes in lens and retina of larvae and eye size were significantly reduced as compared to control. Acridine orange (AO) staining revealed a dose-dependent increase in early apoptosis, accompanied by upregulation of p53, casp-9 and casp-3 genes. Genes related to retinoic acid signaling (aldh1a2), lens developmental (cryaa, crybb, crygn, and mipa) and retinal development (pax6, rx1, gant1, rho, opn1sw and opn1lw) were significantly downregulated. In addition, behavioral responses (swimming speed) were significantly increased, while no significant changes in the neurotransmitters (dopamine and acetylcholine) level were observed. Therefore, in this study we observed that exposure to F-53B inflicted histological and morphological changes in zebrafish larvae eye, induced visual motor dysfunctions, perturbed retinoid signaling and retinal development and ultimately triggering apoptosis.

Bioaccumulation and trophic magnification of emerging and legacy per- and polyfluoroalkyl substances (PFAS) in a St. Lawrence River food web

Research on per- and polyfluoroalkyl substances (PFAS) in freshwater ecosystems has focused primarily on legacy compounds and little is still known on the presence of emerging PFAS. Here, we investigated the occurrence of 60 anionic, zwitterionic, and cationic PFAS in a food web of the St. Lawrence River (Quebec, Canada) near a major metropolitan area. Water, sediments, aquatic vegetation, invertebrates, and 14 fish species were targeted for analysis. Levels of perfluorobutanoic acid (PFBA) in river water exceeded those of perfluorooctanoic acid (PFOA) or perfluorooctane sulfonate (PFOS), and a zwitterionic betaine was observed for the first time in the St. Lawrence River. The highest mean PFAS concentrations were observed for the benthopelagic top predator Smallmouth bass (Micropterus dolomieu, Σ₆₀PFAS ∼ 92 ± 34 ng/g wet weight whole-body) and the lowest for aquatic plants (0.52-2.3 ng/g). Up to 33 PFAS were detected in biotic samples, with frequent occurrences of emerging PFAS such as perfluorobutane sulfonamide (FBSA) and perfluoroethyl cyclohexane sulfonate (PFECHS), while targeted ether-PFAS all remained undetected. PFOS and long-chain perfluorocarboxylates (C10-C13 PFCAs) dominated the contamination profiles in biota except for insects where PFBA was predominant. Gammarids, molluscs, and insects also had frequent detections of PFOA and fluorotelomer sulfonates, an important distinction with fish and presumably due to different metabolism. Based on bioaccumulation factors >5000 and trophic magnification factors >1, long-chain (C10-C13) PFCAs, PFOS, perfluorodecane sulfonate, and perfluorooctane sulfonamide qualified as very bioaccumulative and biomagnifying. Newly monitored PFAS such as FBSA and PFECHS were biomagnified but moderately bioaccumulative, while PFOA was biodiluted.

Exposure to per- and polyfluoroalkyl substances as a risk factor for gestational diabetes mellitus through interference with glucose homeostasis

Per- and polyfluoroalkyl substances (PFASs) are hypothesized to trigger gestational diabetes mellitus (GDM) through modulation of glucose metabolism. However, studies investigating links between joint PFASs to GDM are limited and led to discrepant conclusions. This study included 171 women with GDM development in pregnancy and 169 healthy controls from Hangzhou, China between October 2020 and September 2021. By using the solid-phase extraction (SPE)-ultra performance liquid chromatography-tandem-mass-spectrometry (UPLC/MS-MS), 15 PFASs were detected to be widely distributed in maternal serum, with highest median concentrations of 7.43, 4.23, and 3.64 ng/mL for perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and 6:2 chlorinated polyfluorinated ether sulfonates (6:2 Cl-PFESA). Multivariable logistic regressions suggested that the adjusted odds ratios (ORs) with 95% confidence intervals (CI) of GDM for second and highest tertiles of PFOA were 2.57 (1.24, 4.86), p = 0.001 and 1.98 (1.06, 3.65), p = 0.023. Compared with the reference tertile, the ORs of GDM were also significantly increased at the highest tertile of perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoA), PFOS and 6:2Cl-PFESA. Multiple linear regressions further indicated that exposure to these PFASs congeners were positively associated with continuous glycemic outcomes of fasting blood glucose (FBG), 1-h, and 2-h glucose after 75 g oral glucose tolerance (OGTT) test as well as glycohemoglobin (HbA1c). Nevertheless, perfluorohexane sulfonic acid (PFHxS), 4:2 fluorotelomer sulfonates (FTSs), and 3H-perfluoro-3-[(3-methoxy-propoxy) propanoic acid] (ADONA) exhibited protective effects on some of these glycemic outcomes. When assessing the PFASs as mixtures by conducting the Bayesian kernel machine regression (BKMR), the risks of GDM and values of glycemic outcomes increased significantly as the concentrations of the PFASs mixture increased, with PFOA being the largest contributor. We therefore propose that although the effects on glucose homeostasis varied between different PFAS congeners, the elevated combined exposures to PFASs may be associated with substantially increased GDM risks by altering glucose metabolism.

Environmental exposure to legacy poly/perfluoroalkyl substances, emerging alternatives and isomers and semen quality in men: A mixture analysis

BACKGROUND/OBJECTIVES

Multiple studies have examined the relationship between PFAS and semen quality, but none has explored the associations of PFAS mixture that includes emerging alternatives and branched isomers.

METHODS

22 PFAS, including 10 linear legacy PFAS, 7 branched isomers, 3 short chain alternatives and 2 components of F53B [e.g., 6:2 chlorinated polyfluorinated ether sulfonate (Cl-PFESA)] were quantified in blood plasma among 740 healthy men. Five semen quality parameters (i.e., volume, count, concentration, total motility and progressive rate) were assessed. Multiple linear regression and three multiple pollutant models (i.e., adaptive elastic net regression, quantile based g-computation, and XGBoost method) were used to assess the associations of individual PFAS and PFAS mixture with semen quality and the potential interactive effects among congeners.

RESULTS

After adjusting for selected confounders, perfluorobutane sulfonate (PFBS) and perfluorohexane sulfonate (PFHxS) presented significant and negative associations with sperm count [β_AENET = -0.09 (95%CI: -0.14, -0.03) for PFBS, and -0.16 (95%CI: -0.25, -0.07) for PFHxS] and sperm concentration [-0.04 (95%CI: -0.08, -0.001) for PFBS and -0.11 (95%CI: -0.17, -0.04) for PFHxS]. 6:2 Cl-PFESA showed negative associations with total motility (-2.33, 95%CI: -3.80, -0.86) and progressive rate (-1.46, 95%CI: -2.79, -0.12). But perfluoroheptanesulfonic acid (PFHpS) was positively associated with sperm count and concentration. These associations were supported by the importance assessment of these four congeners in XGBoost analyses. However, no associations were found between PFAS mixture or branched isomers and semen quality; nor were there significant interactions among PFAS congeners.

CONCLUSIONS

In the current cross-sectional study, we found that two emerging PFAS replacements (i.e., 6:2 Cl-PFESA and PFBS) and PFHxS exposure were associated with reduced semen concentration, total sperm count and motility in men. Meanwhile, significant positive associations between PFHpS and sperm count and concentration were also observed. But there were no consistent associations between PFAS mixture, branched isomers and semen quality.

Aerobic biotransformation of 6:2 fluorotelomer sulfonate by Dietzia aurantiaca J3 under sulfur-limiting conditions

The polyfluorinated alkyl substance 6:2 fluorotelomer sulfonate (6:2 FTS) has been detected in diverse environments impacted by aqueous film-forming foams used for firefighting. In this study, a bacterial strain (J3) using 6:2 FTS as a sulfur source was isolated from landfill leachate previously exposed to polyfluoroalkyl substances in New South Wales, Australia. Strain J3 shares 99.9% similarity with the 16S rRNA gene of Dietzia aurantiaca CCUG 35676^T. Genome sequencing yielded a draft genome sequence of 37 contigs with a G + C content of 69.7%. A gene cluster related to organic sulfur utilisation and assimilation was identified, that included an alkanesulfonate monooxygenase component B (ssuD), an alkanesulfonate permease protein (ssuC), an ABC transporter (ssuB), and an alkanesulfonate-binding protein (ssuA). Proteomic analyses comparing strain J3 cultures using sulfate and 6:2 FTS as sulfur source indicated that the ssu gene cluster was involved in 6:2 FTS biodegradation. Upregulated proteins included the SsuD monooxygenase, the SsuB transporter, the ABC transporter permease (SsuC), an alkanesulfonate-binding protein (SsuA), and a nitrilotriacetate monooxygenase component B. 6:2 Fluorotelomer carboxylic acid (6:2 FTCA) and 6:2 fluorotelomer unsaturated acid (6:2 FTUA) were detected as early degradation products in cultures (after 72 h) while 5:3 fluorotelomer acid (5:3 FTCA), perfluorohexanoic acid (PFHxA) and perfluoropentanoic acid (PFPeA) were detected as later degradation products (after 168 h). This work provides biochemical and metabolic insights into 6:2 FTS biodegradation by the Actinobacterium D. aurantiaca J3, informing the fate of PFAS in the environment.

Legacy and Emerging Poly- and Perfluoroalkyl Substances in Finless Porpoises from East China Sea: Temporal Trends and Tissue-Specific Accumulation

Perfluoroalkyl sulfonates (PFSAs), perfluoroalkyl carboxylates (PFCAs), and emerging alternatives and precursors of these compounds were determined in tissues of finless porpoise (Neophocaena asiaeorientalis sunameri) collected from East China Sea in 2009-2010 and 2018-2019. The median hepatic concentrations of emerging poly- and perfluoroalkyl substances (PFASs), including 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), 8:2 chlorinated polyfluorinated ether sulfonate (8:2 Cl-PFESA), 2,3,3,3-tetrafluoro-2-propanoate (HFPO-DA), and 4,8-dioxa-3H-perfluorononanoate (ADONA) were 16.2, 2.16, < LOQ (limit of quantification) and < LOQ ng/g ww (wet weight), respectively. The concentrations of legacy substances, perfluorooctanesulfonate (PFOS), and perfluorooctanoate (PFOA), were 86.9 and 1.95 ng/g ww, respectively. The liver concentrations of 6:2 Cl-PFESA, HFPO-DA, and perfluorohexanesulfonate (PFHxS) increased with time between 2009-2010 and 2018-2019. Further, concentrations of PFOA showed a declining trend in finless porpoise, whereas PFOS and its precursor (i.e., perfluorooctane sulfonamide [FOSA]) showed an increasing trend with time between 2009-2010 and 2018-2019. Analysis of PFASs in nine different tissues/organs of finless porpoise (i.e., liver, heart, intestine, spleen, kidney, stomach, lung, muscle, and skin) revealed a similar distribution pattern between 6:2 Cl-PFESA and PFOS; however, the tissue distribution patterns differed between HFPO-DA and PFOA. The concentrations of PFAS alternatives in kidney were similar or lower than the prototype compounds PFOS and PFOA (i.e., 8:2 Cl-PFESA < 6:2 Cl-PFESA ≈ PFOS; HFPO-DA < PFOA), implying slow renal excretion of PFAS alternatives as that of legacy PFASs. The estimates of body burdens of PFASs in porpoises suggested comparable accumulation of PFAS alternatives and legacy PFSAs and PFCAs. This study provides novel information on temporal trends and tissue distribution of emerging PFASs in marine mammals in China.

Tissue-Specific Uptake, Depuration Kinetics, and Suspected Metabolites of Three Emerging Per- and Polyfluoroalkyl Substances (PFASs) in Marine Medaka

Restrictions on legacy per- and polyfluoroalkyl substances (PFASs) have led to the widespread use of emerging PFASs. However, their toxicokinetics have rarely been reported. Here, tissue-specific uptake and depuration kinetics of perfluoroethylcyclohexanesulfonate (PFECHS) and 6:2 and 8:2 chlorinated polyfluoroalkyl ether sulfonates (Cl-PFESAs) were studied in marine medaka (Oryzias melastigma). The fish were exposed to these substances for 28 days (0.2 μg/L), followed by a clearance period of 14 days. The depuration constant (k_d) of PFECHS [0.103 ± 0.009 day^-1 (mean ± standard deviation)] was reported for the first time. Among the six studied tissues, the highest concentrations of 6:2 Cl-PFESA, 8:2 Cl-PFESA, and PFECHS were found in the liver [1540, 1230, and 188 ng (g of wet weight)^-1, respectively] on day 28 while the longest residence times were found in the eyes (t_1/2 values of 21.7 ± 4.3, 23.9 ± 1.5, and 17.3 ± 0.8 days, respectively). No significant positive correlation was found between the bioconcentration factors of the studied PFASs and the phospholipid or protein contents in different tissues of the studied fish. Potential metabolites of Cl-PFESAs, i.e., their hydrogen-substituted analogues (H-PFESAs), were identified by time-of-flight mass spectrometry. However, the biotransformation rates were low (<0.19%), indicating the poor capacity of marine medaka to metabolize Cl-PFESAs to H-PFESAs.

Quantifying Indirect Contribution from Precursors to Human Body Burden of Legacy PFASs Based on Paired Blood and One-Week Duplicate Diet

The restriction on legacy perfluoroalkyl substances (PFASs) has led to increasing application and contamination of their precursors and novel alternatives. However, the indirect contribution from precursors has not been well characterized. In this study, 24 PFASs were measured in the paired human blood and urine from general volunteers (n = 20), as well as their corresponding exposure matrices (7 day duplicate diet, drinking water and dust). Perfluorooctanoic acid (PFOA) was predominant, followed by 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA), contributing 21.6-47.0 and 6.6-20.0% of the total concentrations, respectively. Total oxidable precursor (TOP) assay and isomeric analysis coupled with a toxicokinetic model suggested that around 19% of perfluorooctane sulfonate (PFOS) in human was contributed by its precursors. The strong correlation between the estimated daily intake (EDI) and human blood concentration for 6:2 Cl-PFESA suggested that it was mainly contributed by direct exposure. The bioavailability of 6:2 Cl-PFESA in the food matrices was estimated as 18.6% by comparing the estimated and measured blood concentrations, implying that human exposure might be overestimated if the bioavailability of PFASs in food was not considered. Assuming that they had a similar bioavailability, it was estimated that ca. 20% of PFOS body burden was from indirect exposure to its precursors, which was supported by TOP assay.

Effect of substrate concentrations on aerobic biotransformation of 6:2 fluorotelomer sulfonate (6:2 FTS) in landfill leachate

Biotransformation of 6:2 fluorotelomer sulfonate (FTS) results in the formation of short-chain (C4 - C6) perfluorocarboxylic acids (PFCAs) in landfill leachate. Although leachate substrate concentrations (i.e., organic carbon, ammonia) vary widely, their effects on 6:2 FTS biotransformation and PFCAs formation are unknown. This study investigated the effect of organic carbon and ammonia concentration in 6:2 FTS aerobic biotransformation and PFCA formation in leachate. Biotransformation experiments were conducted with sediment collected from a landfill leachate ditch, to which deionized (DI) water and various amounts of leachate were added. Microbial community analysis using 16S rRNA indicated that while phylum Proteobacteria dominated the bacterial composition throughout the 60 days, Actinobacteria increased with time. Many genera from Proteobacteria and Actinobacteria can synthesize a wide array of enzymes, indicating that these phyla are likely to play an important role in 6:2 FTS biotransformation. Higher biotransformation of 6:2 FTS was observed in leachate-added microcosms (∼21%), compared to DI water microcosm (∼14%), likely reflecting the substrate dependency of 6:2 FTS biotransformation. Substrate limiting conditions in DI water microcosm resulted in slightly greater formation of ∑(C4 - C6) PFCAs (∼14 mol%), compared with leachate added microcosms (10-13 mol%). The findings suggest that dilution of landfill leachate, (e.g., during wet seasons), likely results in reduced 6:2 FTS biotransformation and increased PFCAs formation compared to dry conditions. Observed formation of C7 - C8 PFCAs in the live microcosms suggested that landfills act as secondary sources of legacy PFCAs (e.g., perfluorooctanoic acid) in the environment.

Efficient sorptive removal of F-53B from water by layered double hydroxides: Performance and mechanisms

Chlorinated polyfluoroalkyl ether sulfonates (trade name F-53B) has been detected in various environmental matrices, and reported to be equally or more toxic than perfluorooctane sulfonate. Efficient sorptive removal of F-53B from water by two types of layered double hydroxides (LDHs), NO₃^--LDH and sodium dodecyl sulfate modified NO₃^--LDH (SDS-LDH), was demonstrated in this study. Both LDHs removed F-53B in several minutes and had sorption capacities of over 860 mg/g. SDS-LDH exhibited a greater F-53B uptake than NO₃^--LDH under the influence of different solution chemistry, including pH 3-11, or in the presence of competing anions or co-contaminants, primarily due to the higher surface areas and the presence of SDS for SDS-LDH. Batch experiments, structural characterization, molecular dynamics simulations, and density functional theory calculations were combined to explore the sorption mechanisms, which mainly include ion exchange (specifically, O-H⋯O/F hydrogen bond), C-F/Cl⋯H hydrogen bond, and micellar sorption (occurring at high initial F-53B concentrations). Accordingly, we propose to improve the sorption performance of LDHs by increasing their surface areas and modifying LDHs to produce more hydrogen bond sites, as well as exfoliating LDHs into two dimensional nanosheets to eliminate the steric hindrance for the micellar formation of F-53B or other per- and polyfluoroalkyl substances.

Legacy and emerging per- and polyfluoroalkyl substances (PFASs) in the coastal environment of Korea: Occurrence, spatial distribution, and bioaccumulation potential

Contamination by per- and polyfluoroalkyl substances (PFASs) is of great concern in global environments. Due to strong regulation of legacy PFASs, emerging PFASs including alternatives and precursors have been introduced to the industrial market. In this study, legacy and emerging PFASs were measured in seawater, sediment, and bivalves collected along the Korean coast to investigate the occurrence, distribution, contamination sources, and bioaccumulation potential of PFASs. Wide concentration ranges of legacy PFASs were detected in multiple environmental samples, indicating widespread contamination. C8-based PFASs (e.g., PFOA and PFOS) were still major contaminants in all of the environmental samples. Some precursors, such as 8:2 fluorotelomer sulfonate (8:2 FTS) and N-ethyl-perfluorooctane sulfonamidoacetic acid (N-EtFOSAA), and perfluoro-2-propoxypropanoic potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (F-53B), an alternative to PFOS, were detected in sediment or bivalve samples, implying a shift in consumption patterns from legacy to emerging PFASs. The highest concentrations of PFASs in environmental samples were found at the locations near industrial complexes, such as those for the semi-conductor, paper mill, automobile, and metal-plating industry. This result indicates that PFAS contamination is associated with intensive industrial activities in the coastal environment. Matrix-dependent contamination and profiles of PFASs were observed. Seawater was dominated by short-chained PFASs as a prompt reflection of regulation, while the sediment and bivalves were dominated by long-chained PFASs. Carbon-chain length was a major factor governing environmental behavior and bioaccumulation of PFASs. This was the first nation-wide survey on legacy and emerging PFASs in the coastal environment of Korea.

Subchronic exposure of environmentally relevant concentrations of F-53B in mice resulted in gut barrier dysfunction and colonic inflammation in a sex-independent manner

F-53B (6:2 chlorinated polyfluorinated ether sulfonate) is currently recognized as a safe alternative to long-chain PFASs in China. However, an increasing number of studies have recently authenticated its biotoxicological effects. In this study, for evaluating the gut toxicity of F-53B in mammals, both female and male mice were orally exposed to 0, 1, 3, or 10 μg/L F-53B for 10 weeks. Our results showed that F-53B significantly accumulated in the colon, ileum and serum when exposed to 10 μg/L F-53B for 10 weeks. F-53B exposure not only increased the transcriptional levels of ion transport-related genes but could also interact with the CFTR protein directly. Interestingly, subchronic F-53B exposure also increased the transcription of mucus secretion-related genes, but the protein level of Muc2 decreased after F-53B exposure, indicating that there was a compensatory phenomenon after mucus barrier injury. Furthermore, F-53B exposure also induced colonic inflammation associated with gut microbiota dysbiosis in the colon. Taken together, our results indicated that the potential gut toxicity of F-53B and almost all of the changed parameters were significantly affected in both female and male mice, suggesting that F-53B could disturb the gut barrier without sex dependence in mice.

Fate of 6:2 fluorotelomer sulfonic acid in pumpkin (Cucurbita maxima L.) based on hydroponic culture: Uptake, translocation and biotransformation

6:2 fluorotelomer sulfonic acid (6:2 FTSA) is currently used as an alternative to perfluorooctanesulfonate (PFOS) and is widely detected in the environment. The uptake, translocation and biotransformation of 6:2 FTSA in pumpkin (Cucurbita maxima L.) were investigated by hydroponic exposure for the first time. The root concentration factor (RCF) of 6:2 FTSA was 2.6-24.2 times as high as those of perfluoroalkyl acids (PFAAs) of the same or much shorter carbon chain length, demonstrating much higher bioaccumulative ability of 6:2 FTSA in pumpkin roots. The translocation capability of 6:2 FTSA from root to shoot depended on its hydrophobicity. Six terminal perfluorocarboxylic acid (PFCA) metabolites, including perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), perfluorobutanoic acid (PFBA), perfluoropropionic acid (PFPrA) and trifluoroacetic acid (TFA) were found in pumpkin roots and shoots. PFHpA was the primary metabolite in roots, while PFBA was the major product in shoots. 1-aminobenzotriazole (ABT), a cytochromes P450 (CYPs) suicide inhibitor, could decrease the concentrations of PFCA products with dose-dependent relationships in pumpkin tissues, implying the role of CYP enzymes involved in plant biotransformation of 6:2 FTSA. This study indicated that the application of 6:2 FTSA can lead to the occurrence of PFCAs (C2-C7) in plants.

A tunable assay for modulators of genome-destabilizing DNA structures

Regions of genomic instability are not random and often co-localize with DNA sequences that can adopt alternative DNA structures (i.e. non-B DNA, such as H-DNA). Non-B DNA-forming sequences are highly enriched at translocation breakpoints in human cancer genomes, representing an endogenous source of genetic instability. However, a further understanding of the mechanisms involved in non-B DNA-induced genetic instability is needed. Small molecules that can modulate the formation/stability of non-B DNA structures, and therefore the subsequent mutagenic outcome, represent valuable tools to study DNA structure-induced genetic instability. To this end, we have developed a tunable Förster resonance energy transfer (FRET)-based assay to detect triplex/H-DNA-destabilizing and -stabilizing ligands. The assay was designed by incorporating a fluorophore-quencher pair in a naturally-occurring H-DNA-forming sequence from a chromosomal breakpoint hotspot in the human c-MYC oncogene. By tuning triplex stability via buffer composition, the assay functions as a dual-reporter that can identify stabilizers and destabilizers, simultaneously. The assay principle was demonstrated using known triplex stabilizers, BePI and coralyne, and a complementary oligonucleotide to mimic a destabilizer, MCRa2. The potential of the assay was validated in a 384-well plate with 320 custom-assembled compounds. The discovery of novel triplex stabilizers/destabilizers may allow the regulation of genetic instability in human genomes.

Chronic exposure to 6:2 chlorinated polyfluorinated ether sulfonate acid (F-53B) induced hepatotoxic effects in adult zebrafish and disrupted the PPAR signaling pathway in their offspring

As a Chinese-specific alternative to perfluorooctane sulfonate (PFOS), 6:2 chlorinated polyfluorinated ether sulfonate (commercial name: F-53B) has been used in the metal plating industry for over 40 years. This prevalence of use has resulted in its subsequent detection within the environment, wildlife, and humans. Despite this, however, its hepatotoxic effects on aquatic organisms remain unclear. Here, we characterized the impacts of long-term F-53B exposure on adult zebrafish liver and their offspring. Results showed that the concentration of F-53B was greater in the F0 liver than that in the gonads and blood. Furthermore, males had significantly higher liver F-53B levels than females. Hepatomegaly and obvious cytoplasmic vacuolation indicated that F-53B exposure induced liver injury. Compared to control, liver triglyceride levels decreased by 30% and 33.5% in the 5 and 50 μg/L-exposed males and 22% in 50 μg/L-exposed females. Liver transcriptome analysis of F0 adult fish found 2175 and 1267 differentially expressed genes (DEGs) in the 5 μg/L-exposed males and females, respectively. Enrichment analyses further demonstrated that the effects of F-53B on hepatic transcripts were sex-dependent. Gene Ontology showed that most DEGs were involved in multicellular organism development in male fish, whereas in female fish, most DEGs were related to metabolic processes and gene expression. qRT-PCR analysis indicated that the PPAR signaling pathway likely contributed to F-53B-induced disruption of lipid metabolism in F0 adult fish. In F1 larvae (5 days post fertilization), the transcription of pparα increased, like that in F0 adult fish, but most target genes showed the opposite expression trends as their parents. Taken together, our research demonstrated chronic F-53B exposure adversely impacts zebrafish liver, with disruption of PPAR signaling pathway dependent on sex and developmental stage.

Uptake and elimination of emerging polyfluoroalkyl substance F-53B in zebrafish larvae: Response of oxidative stress biomarkers

6:2 chlorinated polyfluorinated ether sulfonate (F-53B) has been widely applied as a mist suppressant to replace perfluorooctane sulfonate (PFOS) in the metal plating industry in China for decades. Recently, F-53B has been frequently identified in the aquatic environment and wild-caught fish. However, studies on the uptake and elimination kinetics, and the toxicological effects of F-53B were very scarce. In this study, zebrafish larvae (72 h post fertilization, hpf) were exposed to F-53B (10, 100 μg/L) for 48 h, followed by a 24 h of depuration to examine both the dynamics of accumulation and elimination of F-53B and responses of antoxidant defense system in fish. The results showed that F-53B rapidly accumulated in zebrafish larvae in a concentration and time-dependent manner with BCF values of 3612-3615, but was eliminated slowly (half-life ranged from 241.5 to 258.6 h). F-53B exposure induced oxidative stress in zebrafish larvae, as reflected by the reduction in the GSH and MDA contents, CAT, SOD, CuZn-SOD, and GSH-ST activities, and the increase in GSH-Px activity as well as CAT and SOD protein levels. However, these oxidative stress markers were restored to control levels except for a decrease in protein level of SOD after depuration. Collectively, the results of this work indicate that F-53B behaves like PFOS and is bioaccumulative and persistent in zebrafish larvae, and further induced oxidative stress responses.

Elevated concentrations of perfluorohexanesulfonate and other per- and polyfluoroalkyl substances in Baiyangdian Lake (China): Source characterization and exposure assessment

Novel 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) and legacy PFASs, such as perfluorohexane sulfonate (PFHxS), have been used to replace perfluorooctane sulfonate (PFOS), a known persistent organic pollutant. Thus, it is critical to understand these PFOS alternatives regarding their sources and concentrations in the natural environment. In this study, 41 surface water samples as well as edible aquatic organisms were collected from Baiyangdian Lake, the largest freshwater lake in Hebei Province, China. Perfluorooctanoate acid (PFOA) and PFHxS were the predominant PFASs detected in the surface water, reaching concentrations of 8 397.23 ng/L and 1 478.03 ng/L, respectively, with PFHxS accounting for the greatest proportion (∼80.00%) in most water samples. PFHxS (mean: 87.53 ng/g) and PFOS (mean: 35.94 ng/g) were also the most prevalent compounds detected in aquatic organisms. Estimated daily intake (EDI) values of PFOS (16.56 ng/kg bw/d) and PFHxS (16.11 ng/kg bw/d) via aquatic food and drinking water were the highest among PFASs, indicating potential exposure risks to residents. In addition, fish product consumption was the important exposure pathway for residents to PFOA, PFHxS, PFOS, and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA). This study reports on the highest PFHxS levels ever recorded in surface water, suggesting that further quantification of PFHxS in human serum and assessment of its health risks to local residents are warranted and critical.

Multiple approaches to assess the effects of F-53B, a Chinese PFOS alternative, on thyroid endocrine disruption at environmentally relevant concentrations

A Chinese perfluorooctane sulfonate (PFOS) substitute frequently detected in the environment, 6:2 chlorinated polyfluorinated ether sulfonate (F-53B), has a similar structure to PFOS and it is proposed to cause thyroid dysfunction. To further confirm this hypothesis, the effects of F-53B on the thyroid endocrine system and underlying mechanisms were investigated in vitro and in vivo using rat pituitary GH3 cells and developing zebrafish, respectively. In GH3 cells, F-53B enhanced cell proliferation in a dose-dependent manner, indicative of thyroid receptor agonistic activity. In zebrafish larvae, F-53B exposure induced significant developmental inhibition and increased thyroxine (T₄) but not 3,5,3'-triiodothyronine (T₃) levels accompanied by a decrease in thyroglobulin (TG) protein and transcript levels of most genes involved in the hypothalamic-pituitary-thyroid (HPT) axis. Interestingly, T₄ levels remained significantly increased while TG protein and gene transcription levels were markedly upregulated after depuration. Molecular docking studies revealed that F-53B binds to transthyretin (TTR) by forming hydrogen bonds with Lys123 and Lys115, thereby interfering with thyroid hormone homeostasis. Our collective in vitro, in vivo and in silico studies provide novel evidence that F-53B disrupts the thyroid endocrine system at environmentally relevant concentrations, which cannot be recovered after depuration. Given the persistence of F-53B in the environment, the long-term consequences of thyroid hormone disruption by this chemical warrant further investigation.

Worldwide drinking water occurrence and levels of newly-identified perfluoroalkyl and polyfluoroalkyl substances

In the last decade or so, concerns have arisen with respect to the widespread occurrence of perfluoroalkyl acids (PFAAs) in the environment, food, drinking water, and humans. In this study, the occurrence and levels of a large range of perfluoroalkyl and polyfluoroalkyl substances (PFASs) were investigated in drinking water (bottled and tap water samples) from various locations around the world. Automated off-line solid phase extraction followed by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry was used to analyze PFASs of various chain lengths and functional groups. In total, 29 target and 104 suspect-target PFASs were screened in drinking water samples (n=97) from Canada and other countries (Burkina Faso, Chile, Ivory Coast, France, Japan, Mexico, Norway, and the USA) in 2015-2016. Out of the 29 PFASs quantitatively analyzed, perfluorocarboxylates (PFCAs: C_4/14), perfluoroalkane sulfonates (PFSAs: C₄, C₆, C₈), and perfluoroalkyl acid precursors (e.g., 5:3 fluorotelomer carboxylate (5:3 FTCA)) were recurrently detected in drinking water samples (concentration range: <LOD to 39ngL^-1). Tap water samples from Canada showed noteworthy differences depending on their source; for instance, ∑₂₉PFASwas significantly greater in those produced from the Great Lakes/St. Lawrence River ecosystem than those produced from other types of sources (14 versus 5.3ngL^-1, respectively). A suspect-target screening approach indicated that other perfluoroalkane sulfonamides (FBSA, FHxSA), perfluoroethyl cyclohexane sulfonate (PFECHS), ultrashort chain (C₂-C₃) PFSAs (PFEtS, PFPrS), and two additional PFSAs (PFPeS (C₅) and PFHpS (C₇)) were repeatedly present in tap water samples (concentration ranges: <LOD to 4.0ngL^-1). To the authors' best knowledge, this constitutes the first observation of a cyclic perfluoroalkane sulfonate (PFECHS) and C₄-C₆ perfluoroalkane sulfonamides (FBSA, FHxSA) in drinking water. According to the newly updated US EPA health advisory for PFOS and PFOA (70ngL^-1), the drinking water samples collected in the present monitoring would not pose a health risk to consumers as regards PFAA levels.

Perfluoroalkyl acids in surface sediments of the East China Sea

The occurrence of 17 target PFAA analytes was determined in surface sediments (n = 37) of the East China Sea and potential influencing factors were examined. ΣPFAAs ranged from 0.41 ng/g dw to 3.06 ng/g dw, with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) as the most abundant perfluorocarboxylic acid and perfluoroalkyl sulfonate, respectively. PFAAs in the sediments were strongly influenced by terrigenous input. Analysis of the relationship between dynamic influence factors and PFAA concentrations showed that the characteristics of PFAA distribution were rather complex. ΣPFAA concentrations and TOC were positively correlated (p < 0.0001). Circumfluence also influenced the whole PFAA distribution and seasonal variation. In addition, correlation analysis suggested that log K_oc values increased with increasing perfluoroalkyl chain length. Given the rapid economic development of eastern coastal cities of China, the environmental hazards of land source pollution cannot be ignored.

Depuration of perfluoroalkyl substances from the edible tissues of wild-caught invertebrate species

Detection and quantification of poly- and perfluoroalkyl substances (PFASs) in aquatic organisms is increasing, particularly for saltwater species. Depuration can remove PFASs from the tissues of some species once they are removed from the contaminant source, but it is not known if this process occurs for saltwater crustaceans. Such information is important for managing human health risks for exploited migratory species following exposure. We present the results of a depuration trial for School Prawn (Metapenaeus macleayi) and Mud Crab (Scylla serrata), two commercially important crustaceans in Australia. Perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorooctanoic acid (PFOA) were present in samples of both species collected following exposure under natural conditions in contaminated estuaries. Depuration was tested in uncontaminated water for 33days. PFOA was present at levels close to LOR in both species, and was not detected after 4.5h and 72h in School Prawn and Mud Crab respectively. PFHxS was rapidly depurated by School Prawn, and had a depuration half-life of 5.7h. PFOS was also depurated by School Prawn, with a depuration half-life of 158.5h. PFHxS and PFOS concentrations were highly variable in Mud Crab both at the start, and during the depuration experiment, and a depuration model could not be fitted to the data. For School Prawn, depuration of total PFASs to the relevant screening value for protection of human health (9.1μgkg^-1) occurred within 7.1h. Rapid depuration of PFASs in School Prawn indicates that human health risks associated with consumption may decrease as this species migrates away from the contamination source. Further research is required to better understand the relationships between contaminant load and life-history characteristics (such as growth, reproduction, and moult cycle) in Mud Crab, and future work should target broader time frames for depuration in this species.

Distribution of perfluoroalkyl compounds in Osaka Bay and coastal waters of Western Japan

Perfluoroalkyl acids (PFAAs) including perfluoroalkyl sulfonates (PFSAs) and perfluoroalkyl carboxylates (PFCAs) were analyzed in sediment samples taken from Ajifu Waterway in Osaka city, from Osaka Bay, and from Kagoshima Bay, as well as in fifteen seawater samples collected from Osaka Bay and coastal waters of Western Japan. In all sediment samples, only PFCAs were detected, and the highest concentration was determined in Ajifu Waterway, where ΣPFAA was 58990 ng kg^-1 dry weight. The total concentrations of PFAAs in sea water samples ranged between the limit of quantification and 53.4 ng L^-1, and perfluorohexanoic acid was the most prevalent and had the highest concentration of 37 ng L^-1. The changes in the patterns and concentrations of PFAAs in Osaka Bay and coastal waters of Western Japan indicate that the PFAAs in surface waters are influenced by sources from Keihanshin Metropolitan Area, mainly the Yodo River basin, and the dilution effect which naturally occurs during their transport to the Pacific Ocean.

Updated national emission of perfluoroalkyl substances (PFASs) from wastewater treatment plants in South Korea

A nationwide emission estimate of perfluoroalkyl substances (PFASs) from wastewater treatment plants (WWTPs) is required to understand the source-receptor relationship of PFASs and to manage major types of WWTPs. In this study, the concentrations of 13 PFASs (8 perfluorocarboxylic acids, 3 perfluoroalkane sulfonates, and 2 intermediates) in wastewater and sludge from 81 WWTPs in South Korea were collected. The emission pathways of PFASs were redefined, and then the national emission of PFASs from WWTPs was rigorously updated. In addition to the direct calculations, Monte Carlo simulations were also used to calculate the likely range of PFAS emissions. The total (Σ₁₃PFAS) emission (wastewater + sludge) calculated from the direct calculation with mean concentrations was 4.03 ton/y. The emissions of perfluorooctanoic acid (PFOA, 1.19 ton/y) and perfluorooctane sulfonate (PFOS, 1.01 ton/y) were dominant. The Monte Carlo simulations suggested that the realistic national emission of Σ₁₃PFASs is between 2 ton/y and 20 ton/y. Combined WWTPs treating municipal wastewater from residential and commercial areas were identified as a major emission source, contributing 65% to the total PFAS emissions. The Han and Nakdong Rivers were the primary contaminated rivers, receiving 89% of the total PFAS discharge from WWTPs. The results and methodologies in this study can be useful to establish a management policy for PFASs.

Evaluation of anionic surfactant concentrations in US effluents and probabilistic determination of their combined ecological risk in mixing zones

Alcohol sulfates (AS), alcohol ethoxysulfates (AES), linear alkyl benzenesulfonates (LAS) and methyl ester sulfonates (MES) are anionic surfactants that are widely used in household detergents and consumer products resulting in over 1 million tons being disposed of down the drain annually in the US. A monitoring campaign was conducted which collected grab effluent samples from 44 wastewater treatment plants (WWTPs) across the US to generate statistical distributions of effluent concentrations for anionic surfactants. The mean concentrations for AS, AES, LAS and MES were 5.03±4.5, 1.95±0.7, 15.3±19, and 0.35±0.13μg/L respectively. Since each of these surfactants consist of multiple homologues that differ in their toxicity, the concentration of each homologue measured in an effluent sample was converted into a toxic unit (TU) by normalizing to the predicted no effect concentration (PNEC) derived from high tier effects data (mesocosm studies). The statistical distributions of the combined TUs in the effluents were used in combination with distributions of dilution factors for WWTP mixing zones to conduct a US-wide probabilistic risk assessment for the aquatic environment for each of the surfactants. The 90th percentile level of TUs for AS, AES, LAS and MES in mixing zones were 1.89×10^-2, 2.73×10^-3, 2.72×10^-2, and 3.65×10^-5 under 7Q10 (lowest river flow occurring over a 7day period every 10years) low flow conditions. Because these surfactants have the same toxicological mode of action, the TUs were summed and the aquatic safety for anionic surfactants as a whole was assessed. At the 90th percentile level under the conservative 7Q10 low flow conditions the forecasted TUs were 4.21×10^-2 which indicates that there is a significant margin of safety for the class of anionic surfactants in US aquatic environments.

Occurrence and distribution of perfluoroalkyl acids (PFAAs) in surface water and sediment of a tropical coastal area (Bay of Bengal coast, Bangladesh)

This study reports the first evidence of perfluoroalkyl acids (PFAAs) in surface waters and sediments collected from the coastal area of Bangladesh. Fifteen target PFAAs, including C4-14-PFCAs (perfluoroalkyl carboxylates) and C4, C6, C8, and C10-PFSAs (perfluoroalkyl sulfonates), were quantified by HPLC-MS/MS. The ΣPFAAs in surface water and sediment samples were in the range of 10.6 to 46.8ng/L and 1.07 to 8.15ng/gdw, respectively. PFOA in water (3.17-27.8ng/L) and PFOS in sediment samples (0.60-1.14ng/gdw) were found to be the most abundant PFAAs, and these concentrations were comparable to or less than most other reported values, particularly those recorded from the coastal areas of China, Japan, Korea and Spain. The majority of the monitored PFAAs did not show clear seasonal variation. The southeastern part (Cox's Bazar and Chittagong) of the Bangladeshi coastal area was more contaminated with PFAAs than the southern (Meghna Estuary) and southwestern parts (Sundarbans). Industrial and municipal wastewater effluents, ship breaking and port activities were identified as potential sources of the PFAA contamination in this region. Field-based sediment water distribution coefficients (KD) were calculated and corrected for organic carbon content (KOC), which reduced the variability between samples. The values of log KD (1.63-2.88) and log KOC (4.02-5.16) were higher than previously reported values, which may indicate that the partitioning of PFAAs in a tropical coastal ecosystem is different from other ecosystems, such as temperate and sub-tropical regions. Although a preliminary environmental hazard assessment indicated that PFOA or PFOS levels do not currently exceed the acute safety thresholds, we should keep in mind that they are bioavailable and can accumulate in the food chain. Therefore, the ubiquity of PFAAs in the coastal area of Bangladesh warrants further studies characterizing their specific sources and the potential long-term risks they present to both humans and wildlife.

Wine metabolomics reveals new sulfonated products in bottled white wines, promoted by small amounts of oxygen

The impact of minute amounts of oxygen in the headspace on the post-bottling development of wine is generally considered to be very important, since oxygen can either damage or improve the quality of wine. This project aimed to gain new experimental evidence about the chemistry of the interaction between wine and oxygen. The experimental design included 216 bottles of 12 different white wines produced from 6 different cultivars (Inzolia, Muller Thurgau, Chardonnay, Grillo, Traminer and Pinot gris). Half of them were bottled using the standard industrial process with inert headspace and the other half without inert gas and with extra headspace. After 60 days of storage at room temperature, the wines were analysed using an untargeted LC-MS method. The use of a detailed holistic analysis workflow, with several levels of quality control and marker selection, gave 35 metabolites putatively induced by the different amounts of oxygen. These metabolite markers included ascorbic acid, tartaric acid and various sulfonated compounds observed in wine for the first time (e.g. S-sulfonated cysteine, glutathione and pantetheine; and sulfonated indole-3-lactic acid hexoside and tryptophol). The consumption of SO2 mediated by these sulfonation reactions was promoted by the presence of higher levels of oxygen on bottling.

Perfluoroalkyl sulfonates and carboxylic acids in liver, muscle and adipose tissues of black-footed albatross (Phoebastria nigripes) from Midway Island, North Pacific Ocean

The Great Pacific Garbage Patch (GPGP) is a gyre of marine plastic debris in the North Pacific Ocean, and nearby is Midway Atoll which is a focal point for ecological damage. This study investigated 13 C4-C16 perfluorinated carboxylic acids (PFCAs), four (C4, C6, C8 and C10) perfluorinated sulfonates and perfluoro-4-ethylcyclohexane sulfonate [collectively perfluoroalkyl acids (PFAAs)] in black-footed albatross tissues (collected in 2011) from Midway Atoll. Of the 18 PFCAs and PFSAs monitored, most were detectable in the liver, muscle and adipose tissues. The concentrations of PFCAs and PFSAs were higher than those in most seabirds from the arctic environment, but lower than those in most of fish-eating water birds collected in the U.S. mainland. The concentrations of the PFAAs in the albatross livers were 7-fold higher than those in Laysan albatross liver samples from the same location reported in 1994. The concentration ranges of PFOS were 22.91-70.48, 3.01-6.59 and 0.53-8.35 ng g(-1) wet weight (ww), respectively, in the liver, muscle and adipose. In the liver samples PFOS was dominant, followed by longer chain PFUdA (8.04-18.70 ng g(-1) ww), PFTrDA, and then PFNA, PFDA and PFDoA. Short chain PFBA, PFPeA, PFBS and PFODA were below limit of quantification. C8-C13 PFCAs showed much higher composition compared to those found in other wildlife where PFOS typically predominated. The concentrations of PFUdA in all 8 individual albatross muscle samples were even higher than those of PFOS. This phenomenon may be attributable to GPGP as a pollution source as well as PFAA physicochemical properties.

Aquatic hazard, bioaccumulation and screening risk assessment for 6:2 fluorotelomer sulfonate

This study assessed the aquatic toxicity and bioaccumulation potential of 6:2 fluorotelomer sulfonate (6:2 FTSA). Acute and chronic aquatic hazard endpoints indicate 6:2 FTSA is not classified for aquatic hazard according to GHS or European CLP legislation. The aqueous bioconcentration factors for 6:2 FTSA were <40 and the dietary assimilation efficiency, growth corrected half-life and dietary biomagnification factor (BMF) were 0.435, 23.1d and 0.295, respectively. These data indicate that 6:2 FTSA is not bioaccumulative in aquatic organisms. Comparison of PNECs with the reported surface water concentrations (non-spill situations) suggests low risk to aquatic organisms from 6:2 FTSA. Future studies are needed to elucidate the biotic and abiotic fate of commercial AFFF surfactants in the environment.

Isomer profiles of perfluoroalkyl substances in water and soil surrounding a chinese fluorochemical manufacturing park

Despite that China is the largest global manufacturer of perfluoroalkyl substances (PFASs), the manufacturing methods and isomer purity of these chemicals are generally unknown. Here, sampling was conducted around a major fluorochemical manufacturing park in China in 2012, including soil and water collection inside the park, including from a wastewater treatment plant (WWTP), as well as in surrounding rivers and soil (∼15 km radius). Perfluoroalkyl sulfonates (PFSAs) were lower than perfluoroalkyl carboxylates (PFCAs) in all samples, and short-chain (C4-C6) PFCAs were predominant. Perfluoroalkyl phosphonates and phosphate diesters were occasionally detected, but at low detection frequency. Branched isomers of perfluorobutanesulfonate (PFBS) are reported for the first time, accounting for 15-27% of total PFBS in water. An enrichment of isopropyl-PFOA (28%) was found in WWTP influent, suggesting its manufacturing primarily by isopropyl telomerization. More numerous branched isomers were observed for the longer C9-C13 PFCAs (e.g., C12 PFCA had 16 branched isomers), including high proportions of one major branched isomer (likely isopropyl), possibly as impurities from isopropyl-PFOA manufacturing. Overall, short-chain perfluorinated acids were the predominant PFASs being released, but PFOA was still a major chemical in use at this site, primarily from isopropyl telomerization.

Ornamental plants for micropollutant removal in wetland systems

The objective of this paper was to evaluate the efficiency of micropollutant removal, such as Cu, Zn, carbamazepine, and linear alkylbenzene sulfonates (LAS), through the use of a subsurface vertical flow constructed wetland system with ornamental plants. Zantedeschia aethiopica, Canna indica, Carex hirta, Miscanthus sinensis, and Phragmites australis were selected and planted in lysimeters filled up with gravel. The lysimeters were completely saturated with synthetic wastewater (N 280 mg L(-1), P 30 mg L(-1), Cu 3.6 mg L(-1), Zn 9 mg L(-1), carbamazepine 5 μg L(-1), linear alkylbenzene sulfonates 14 mg L(-1)), and the leaching water was collected for analysis after 15, 30, and 60 days in winter-spring and spring-summer periods. Nutrients (N and P) and heavy metals decreased greatly due to both plant activity and adsorption. C. indica and P. australis showed the highest metal content in their tissues and also the greatest carbamazepine and LAS removal. In these plants, the adsorption/degradation processes led to particularly high oxidative stress, as evidenced by the significantly high levels of ascorbate peroxidase activity detected. Conversely, Z. aethiopica was the less efficient plant in metal and organic compound removal and was also less stressed in terms of ascorbate peroxidase activity.

Reactivity and fate of secondary alkane sulfonates (SAS) in marine sediments

This research is focused on secondary alkane sulfonates (SAS), anionic surfactants widely used in household applications that access aquatic environments mainly via sewage discharges. We studied their sorption capacity and anaerobic degradation in marine sediments, providing the first data available on this topic. SAS partition coefficients increased towards those homologues having longer alkyl chains (from up to 141 L kg(-1) for C14 to up to 1753 L kg(-1) for C17), which were those less susceptible to undergo biodegradation. Overall, SAS removal percentages reached up to 98% after 166 days of incubation using anoxic sediments. The degradation pathway consisted on the formation of sulfocarboxylic acids after an initial fumarate attack of the alkyl chain and successive β-oxidations. This is the first study showing that SAS can be degraded in absence of oxygen, so this new information should be taken into account for future environmental risk assessments on these chemicals.

Concentrations and trends of perfluorinated chemicals in potential indoor sources from 2007 through 2011 in the US

Certain perfluorinated chemicals (PFCs) in consumer products used indoors are potential indoor PFCs sources and have been associated with developmental toxicity and other adverse health effects in laboratory animals (Lao et al., 2007). The concentrations of selected PFCs including perfluorooctanoic acid (PFOA) and other perfluorocarboxylic acids (PFCAs), in 35 selected consumer products that are commonly used in indoors were measured from the year of 2007 through 2011. The products collected included carpet, commercial carpet-care liquids, household carpet/fabric-care liquids, treated apparel, treated home textiles, treated non-woven medical garments, floor waxes, food-contact paper, membranes for apparel, and thread-sealant tapes. They were purchased from retail outlets in the United States between March 2007 and September 2011. The perfluorocarboxylic acid (PFCA) contents in the products have shown an overall downward trend. However, PFOA (C8) could still be detected in many products that we analyzed. Reductions of PFCAs were shown in both short-chain PFCAs (sum of C4 to C7) and long-chain PFCAs (sum of C8 to C12) over the study period. There were no significant changes observed between short-chain PFCAs and long-chain PFCAs. Fourteen products were analyzed to determine the amounts of perfluoroalkyl sulfonates (PFASs) they contained. These limited data show the pronounced increase of perfluoro-butane sulfonate (PFBS), an alternative to perfluorooctanoic sulfonate (PFOS), in the samples. A longer and wider range of study will be required to confirm this observed trend.

First report of a Chinese PFOS alternative overlooked for 30 years: its toxicity, persistence, and presence in the environment

This is the first report on the environmental occurrence of a chlorinated polyfluorinated ether sulfonate (locally called F-53B, C8ClF16O4SK). It has been widely applied as a mist suppressant by the chrome plating industry in China for decades but has evaded the attention of environmental research and regulation. In this study, F-53B was found in high concentrations (43-78 and 65-112 μg/L for the effluent and influent, respectively) in wastewater from the chrome plating industry in the city of Wenzhou, China. F-53B was not successfully removed by the wastewater treatments in place. Consequently, it was detected in surface water that receives the treated wastewater at similar levels to PFOS (ca. 10-50 ng/L) and the concentration decreased with the increasing distance from the wastewater discharge point along the river. Initial data presented here suggest that F-53B is moderately toxic (Zebrafish LC50-96 h 15.5 mg/L) and is as resistant to degradation as PFOS. While current usage is limited to the chrome plating industry, the increasing demand for PFOS alternatives in other sectors may result in expanded usage. Collectively, the results of this work call for future assessments on the effects of this overlooked contaminant and its presence and fate in the environment.

First report of a Chinese PFOS alternative overlooked for 30 years: its toxicity, persistence, and presence in the environment

This is the first report on the environmental occurrence of a chlorinated polyfluorinated ether sulfonate (locally called F-53B, C8ClF16O4SK). It has been widely applied as a mist suppressant by the chrome plating industry in China for decades but has evaded the attention of environmental research and regulation. In this study, F-53B was found in high concentrations (43-78 and 65-112 μg/L for the effluent and influent, respectively) in wastewater from the chrome plating industry in the city of Wenzhou, China. F-53B was not successfully removed by the wastewater treatments in place. Consequently, it was detected in surface water that receives the treated wastewater at similar levels to PFOS (ca. 10-50 ng/L) and the concentration decreased with the increasing distance from the wastewater discharge point along the river. Initial data presented here suggest that F-53B is moderately toxic (Zebrafish LC50-96 h 15.5 mg/L) and is as resistant to degradation as PFOS. While current usage is limited to the chrome plating industry, the increasing demand for PFOS alternatives in other sectors may result in expanded usage. Collectively, the results of this work call for future assessments on the effects of this overlooked contaminant and its presence and fate in the environment.

Determination and occurrence of secondary alkane sulfonates (SAS) in aquatic environments

A new methodology has been developed for the determination of secondary alkane sulfonates (SAS), an anionic surfactant, in environmental matrices. Sediment and sludge samples were extracted using pressurized liquid extraction and sonication, whereas wastewater and surface water samples were processed using solid-phase extraction. Extraction recoveries were acceptable for both aqueous (78-120%) and solid samples (83-100%). Determination of SAS was carried out by high or ultra performance liquid chromatography - mass spectrometry using ion trap and time-of-flight detectors. The methodology was applied to samples from Guadalete River (SW Spain), where SAS concentrations below 1 μg L(-1) were measured in surface water, and from 72 to 9737 μg kg(-1) in sediments. Differential partitioning was observed for SAS homologues as those having a longer hydrocarbon chain which preferentially sorbed onto particulate matter. A preliminary environmental risk assessment also showed that SAS measured levels were not harmful to the aquatic community in the sampling area.

Perfluoroalkyl acids (PFAAs) in riverine and coastal sediments of Laizhou Bay, North China

This study investigates the concentrations and distributions of perfluoroalkyl acids (PFAAs), including perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulphonates (PFSAs), in surface sediments from Laizhou Bay and its adjacent rivers. ∑PFAAs showed much higher levels in the river sediment (with a mean of 5.25 ng/g dw) than in the coastal sediment (with a mean of 0.76 ng/g dw). Perfluorooctanoic acid (PFOA) was the predominant compound, accounting for 50% to 97% of ∑PFAA concentrations in 70% of the samples. The highest concentrations were detected in the Xiaoqing River, possibly due to the rapid development of the nearby fluorochemical industry. Hydrodynamics strongly influenced the distribution of PFAAs in Laizhou Bay. The hydrophilic property of shorter-chained PFAAs (C≤8) allowed them to be transported to the inner bay via currents, to adsorb onto suspended sediment and then to be deposited. The Xiaoqing River showed the highest PFOA concentration (76.9 ng/g dw) among the bodies of sediment that had been studied worldwide, which might pose a potential threat for the benthic organisms of this river.

Passive sampling of perfluorinated acids and sulfonates using polar organic chemical integrative samplers

The applicability of a polar organic chemical integrative sampler (POCIS) for detection and determination of perfluorinated acids and sulfonates in water was studied under field conditions. Standard POCIS configurations (i.e., pharmaceutical and pesticide) were deployed in effluent from a wastewater treatment plant for 1, 2, and 3 weeks. Ten of 15 target compounds were found in POCIS, five of which were quantified in wastewater. Pest-POCIS appeared more effective for the sampling, while Pharm-POCIS had a more rapid uptake kinetic, which leads to faster saturation or equilibrium. The results showed that the pesticide configuration is probably more suitable for the sampling of this class of compounds. Based on average concentration in water over the sampling period and amount of compound adsorbed in the POCIS, we calculated sampling rates for five studied compounds and obtained values of 0.034 to 0.222 L day(-1).

Perfluoroalkyl compounds in municipal WWTPs in Tianjin, China--concentrations, distribution and mass flow

BACKGROUNDS

Perfluorinated compounds (PFCs) have drawn much attention due to their environmental persistence, ubiquitous existence, and bioaccumulation potential. Wastewater treatment plants (WWTPs) are fundamental utilities in cities, playing an important role in preventing water pollution by lowering pollution load in waste waters. However, some of the emerging organic pollutants, like PFCs cannot be efficiently removed by traditional biological technologies in WWTPs, and some even increase in effluents compared to influents due to the incomplete degradation of precursors. Hence, WWTPs are considered to be a main point source in cities for PFCs that enter the aquatic environment. However, the mass flow of PFCs from WWTPs has seldom been analyzed for a whole city. Hence, in the present study, 11 PFCs including series of perfluoroalkyl carboxylic acids (PFCAs, C4-C12) and two perfluoroalkyl sulfonates (PFASs, C6 and C8) were measured in WWTP influents and effluents and sludge samples from six municipal WWTPs in Tianjin, China. Generation and dissipation of the target PFCs during wastewater treatment process and their mass flow in effluents were discussed.

RESULTS

All the target PFCs were detected in the six WWTPs, and the total PFC concentration in different WWTPs was highly influenced by the population density and commercial activities of the corresponding catchments. Perfluorooctanoic acid (PFOA) was the predominant PFC in water phase, with concentrations ranging from 20 to 170 ng/L in influents and from 30 to 145 ng/L in effluents. Concentrations of perfluoroalkyl sulfonates decreased substantially in the effluent compared to the influent, which could be attributed to the sorption onto sludge, whereas concentrations of PFOA and some other PFCAs increased in the effluent in some WWTPs due to their weaker sorption onto solids and the incomplete degradation of precursors. Perfluorooctane sulfonic acid (PFOS) was the predominant PFC in sludge samples followed by PFOA, and their concentrations ranged from 42 to 169 g/kg and from 12 to 68 g/kg, respectively. Sludge-wastewater distribution coefficients (log K(d)) ranged from 0.62 to 3.87 L/kg, increasing with carbon chain length of the homologues. The mass flow of some PFCs in the effluent was calculated, and the total mass flow from all the six municipal WWTPs in Tianjin was 26, 47, and 3.5 kg/year for perfluorohexanoic acid, PFOA, and PFOS, respectively.

Highly elevated levels of perfluorooctane sulfonate and other perfluorinated acids found in biota and surface water downstream of an international airport, Hamilton, Ontario, Canada

Per- and poly-fluorinated compounds (PFCs), which include perfluorinated carboxylates (PFCAs) and sulfonates (PFSAs) and various precursors, are used in a wide variety of industrial, commercial and domestic products. This includes aqueous film forming foam (AFFF), which is used by military and commercial airports as fire suppressants. In a preliminary assessment prior to this study, very high concentrations (>1 ppm wet weight) of the PFSA, perfluorooctane sulfonate (PFOS), were discovered in the plasma of snapping turtles (Chelydra serpentina) collected in 2008 from Lake Niapenco in southern Ontario, Canada. We presently report on a suite of C(6) to C(15) PFCAs, C(4), C(6), C(8) and C(10) PFSAs, several PFC precursors (e.g. perfluorooctane sulfonamide, PFOSA), and a cyclic perfluorinated acid used in aircraft hydraulic fluid, perfluoroethylcyclohexane sulfonate (PFECHS) in surface water from the Welland River and Lake Niapenco, downstream of the John C. Munro International Airport, Hamilton, Ontario, Canada. Amphipods, shrimp, and water were sampled from the Welland River and Lake Niapenco, as well as local references. The same suite of PFCs in turtle plasma from Lake Niapenco was compared to those from other southern Ontario sites. PFOS dominated the sum PFCs in all substrates (e.g., >99% in plasma of turtles downstream the Hamilton Airport, and 72.1 to 94.1% at all other sites). PFOS averaged 2223(±247.1SE) ng/g in turtle plasma from Lake Niapenco, and ranged from 9.0 to 171.4 elsewhere. Mean PFOS in amphipods and in water were 518.1(±83.8)ng/g and 130.3(±43.6) ng/L downstream of the airport, and 19.1(±2.7) ng/g and 6.8(±0.5) ng/L at reference sites, respectively. Concentrations of selected PFCs declined with distance downstream from the airport. Although there was no known spill event or publicly reported use of AFFF associated with a fire event at the Hamilton airport, the airport is a likely major source of PFC contamination in the Welland River.

Biogeochemical dynamics of perfluorinated alkyl acids and sulfonates in the River Seine (Paris, France) under contrasting hydrological conditions

The biogeochemical dynamics of 15 perfluorinated compounds (PFCs) were investigated in a heavily urbanised river (River Seine, Paris, France). The target compounds included C4-C10 sulfonates and C5-C14 acids; eleven PFCs were detected and ∑PFCs ranged between 31 and 91 ng L(-1) (median: 47 ng L(-1)). The molecular pattern was dominated by the perfluoroalkyl sulfonates PFHxS and PFOS (>54% of ∑PFCs), which were the only PFCs quantified in both the dissolved and particulate phases. For these PFCs, the sorbed fraction positively correlated with suspended sediment levels. Total PFC levels negatively correlated with river flow rate, which varied between 150 and 640 m(3) s(-1). This suggests the predominance of point sources (likely WWTP effluent discharge), but a contribution of non-point sources such as combined sewer overflow could not be excluded. The annual PFC mass flow was estimated at 500 kg, which is less than observed for other large European rivers.

Molecular characterization of effluent organic matter identified by ultrahigh resolution mass spectrometry

Effluent dissolved organic matter (EfOM) collected from the secondary-treated wastewater of the Orange County Sanitation District (OCSD) located in Fountain Valley, California, USA was compared to natural organic matter collected from the Suwannee River (SRNOM), Florida using ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Furthermore, the two different treatment processes at OCSD, activated sludge and trickling filter, were separately investigated. The blend of these two effluents was further evaluated after it had passed through the microfiltration process of the Advanced Water Purification Facility (AWPF) at Orange County Water District (OCWD). EfOM contained 872 different m/z peaks that were unambiguously assigned to exact molecular formulae containing a single sulfur atom and carbon, hydrogen and oxygen atoms (CHOS formulae). In contrast, the SRNOM sample only contained 152 CHOS formulae. The trend in CHO molecular compositions was opposite with 2500 CHO formulae assigned for SRNOM but only about 1000 for EfOM. The CHOS-derived mass peaks with highest abundances in EfOM could be attributed to surfactants such as linear alkyl benzene sulfonates (LAS), their co-products dialkyl tetralin sulfonates (DATS) and their biodegraded metabolites such as sulfophenyl carboxylic acids (SPC). The differences between the treatments were found minor with greater differences between sampling dates than treatment methods used.

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.

Spatial distribution of polyfluoroalkyl compounds in dab (Limanda limanda) bile fluids from Iceland and the North Sea

The spatial distribution of polyfluoroalkyl compounds (PFCs) was investigated in dab (Limanda limanda) bile fluids collected from Iceland and the North Sea. Concentrations of various PFCs, including perfluorinated sulfonates (C(4)-C(6), C(8) PFSAs), perfluorinated carboxylic acids (C(9)-C(14) PFCAs) and n-methyl perfluorooctane sulfonamidoethanol (MeFOSE), were quantified. Perfluorooctane sulfonate (PFOS) was the predominant compound with highest concentrations along the Danish and German coast (mean 9.36ng/g wet weight (ww)). Significantly lower PFOS concentrations were found at the other sampling stations in the North Sea and Iceland (p<0.01, t-test). Conversely, the spatial distribution of the PFCAs in Iceland and the North Sea was more uniform. The most abundant PFCA was perfluorononanoic acid (PFNA), while the mean concentration decreased with increasing chain length from 4.7 ng/g ww for PFNA to 0.04 ng/g ww for perfluorotetradecanoic acid (PFTeDA). Overall, the different spatial distribution of PFCs indicates different origin of sources and different transportation mechanism.

Occurrence of perfluoroalkyl carboxylates and sulfonates in drinking water utilities and related waters from the United States

The prevalence and persistence of perfluoroalkyl compounds (PFCs) in environmental and biological systems has been well documented, and a rising number of reports suggest that certain PFCs can result in adverse health effects in mammals. As traditional water sources become increasingly impacted by waste discharge and the demand for planned potable reuse grows, there is recent interest in determining PFC occurrence in drinking water supplies. Here we report monitoring results from drinking water treatment facility samples collected across the United States, and from associated surface, ground, and wastewater sources. Using automated solid phase extraction (SPE) and isotope-dilution liquid chromatography/tandem mass spectrometry (LC/MS-MS), samples were screened for perfluorohexanoic acid (PFHxA), perfluorohexanesulfonate (PFHxS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS), perfluorononanoic acid (PFNA) perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUdA), and perfluorododecanoic acid (PFDoA). Method reporting limits (MRLs) were established at 1.0 ng/L for all monitored PFCs except PFOA, for which the MRL was set at 5.0 ng/L given elevated procedural and instrumental background levels. PFOS was the only investigated PFC detected in minimally impacted surface waters, with individual site averages of 2.0 ng/L and lower. Conversely, wastewater treatment plant (WWTP) effluents and other highly impacted waters had almost 100% detection frequency for all PFCs except PFUdA and PFDoA, which were not detected above MRL in any samples. Of the investigated PFCs, PFOA averaged the highest overall concentration at any site at 115 ng/L. Substantial impacts from treated wastewater generally caused increased summed PFC concentrations at downstream drinking water facilities, although levels and distribution suggest geographical variability. No discernible differences between influent and effluent PFC levels were observed for drinking water facilities. Removal of PFCs, however, was observed at an indirect potable reuse facility using microfiltration and reverse osmosis for wastewater treatment, in which case all PFC levels in effluents were below the MRL.