Per/polyfluoroalkyl Substances Research Articles

Do PFCAs drive the establishment of thyroid cancer microenvironment? Effects of C6O4, PFOA and PFHxA exposure in two models of human thyroid cells in primary culture

BackgroundExposure to environmental pollutants is suspected to be one of the potential causes accounting for the increase in thyroid cancer (TC) incidence worldwide. Among the ubiquitous pollutants, per-polyfluoroalkyl substances (PFASs), were demonstrated to exert thyroid disrupting effects. Perfluoroalkyl carboxylates (PFCAs) represent a subgroup of PFAS and include perfluoro carboxylic acids (PFOA and PFHxA) and perfluoropolyether carboxylic acid (C6O4).The potential relationship between exposure to PFCAs and TC was not yet fully elucidated.This in vitro study investigated whether certain PFCAs (C6O4, PFOA, and PFHxA) can influence the composition of TC microenvironment. MethodsTwo models of normal thyroid cells in primary cultures: Adherent (A-NHT) and Spheroids (S-NHT) were employed. A-NHT and S-NHT were exposed to C6O4, PFOA or PFHxA (0; 0.01; 0.1, 1; 10; 100; 1000 ng/mL) to assess viability (WST-1 and AV/PI assay), evaluate spherification index (SI) and volume specifically in S-NHT. CXCL8 and CCL2 (mRNA and protein), and EMT-related genes were assessed in both models after exposure to PFCAs. ResultsPFHxA reduced the viability of both A-NHT and S-NHT. None of the PFCAs interfered with the volume or spherification process in S-NHT. CXCL8 and CCL2 mRNA and protein levels were differently up-regulated by each PFCAs, being PFOA and PFHxA the stronger inducers. Moreover, among the tested PFCAs, PFHxA induced a more consistent increase in the mRNA levels of EMT-related genes. Conclusions: This is the first evaluation of the effects of exposure to PFCAs on factors potentially involved in establishing the TC microenvironment. PFHxA modulated the TC microenvironment at three levels: cell viability, pro-tumorigenic chemokines, and EMT-genes. The results provide further evidence of the pro-tumorigenic effect of PFOA. On the other hand, a marginal effect was observed for C6O4 on pro-tumorigenic chemokines.

Per/Polyfluoroalkyl Substances (PFASs) in a Marine Apex Predator (White Shark, Carcharodon carcharias) in the Northwest Atlantic Ocean.

Per/polyfluoroalkyl substances (PFASs) are ubiquitous, highly persistent anthropogenic chemicals that bioaccumulate and biomagnify in aquatic food webs and are associated with adverse health effects, including liver and kidney diseases, cancers, and immunosuppression. We investigated the accumulation of PFASs in a marine apex predator, the white shark (Carcharodon carcharias). Muscle (N = 12) and blood plasma (N = 27) samples were collected from 27 sharks during 2018-2021 OCEARCH expeditions along the eastern coast of North America from Nova Scotia to Florida. Samples were analyzed for 47 (plasma) and 43 (muscle) targeted PFASs and screened for >2600 known and novel PFASs using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). Perfluoroalkyl carboxylates with carbon chain-length C11 to C14 were frequently detected above the method reporting limits in plasma samples, along with perfluorooctanesulfonate and perfluorodecanesulfonate. Perfluoropentadecanoate was also detected in 100% of plasma samples and concentrations were estimated semiquantitatively as no analytical standard was available. Total concentrations of frequently detected PFASs in plasma ranged from 0.56 to 2.9 ng mL-1 (median of 1.4 ng mL-1). In muscle tissue, nine targeted PFASs were frequently detected, with total concentration ranging from 0.20 to 0.84 ng g-1 ww. For all frequently detected PFASs, concentrations were greater in plasma than in muscle collected from the same organism. In both matrices, perfluorotridecanoic acid was the most abundant PFAS, consistent with several other studies. PFASs with similar chain-lengths correlated significantly among the plasma samples, suggesting similar sources. Total concentrations of PFASs in plasma were significantly greater in sharks sampled off of Nova Scotia than all sharks from other locations, potentially due to differences in diet. HRMS suspect screening tentatively identified 13 additional PFASs in plasma, though identification confidence was low, as no MS/MS fragmentation was collected due to low intensities. The widespread detection of long-chain PFASs in plasma and muscle of white sharks highlights the prevalence and potential biomagnification of these compounds in marine apex predators.

Sorption and diffusion of per-polyfluoroalkyl substances (PFAS) in high-density polyethylene geomembranes

The objective of this study is to investigate the fate and transport of per-polyfluoroalkyl substances (PFAS) through a high-density polyethylene (HDPE) geomembrane (GM) that is commonly used in landfill composite liner systems. Tests were conducted to measure the sorption and diffusion of per-polyfluoroalkyl substances (PFAS) with varying number of carbons in chain and functional groups on HDPE GM. Perfluoroalkyl carboxyl acids (PFCAs), perfluoroalkyl sulphonic acids (PFSAs), alkyl-sulfonamidoacetic acids (FOSAAs), fluorotelomer sulfonic acids (FtSAs), alkane sulfonamides (FOSA) and ether carboxylic acids (Gen X) were investigated in this study. The partition coefficients (Kd) on HDPE GM ranged from 3.8 to 98.3 L/kg. PFAS with amide and sulfonic functional groups showed stronger sorption than that of PFAS with carboxylic acid functional groups. Molecular weight directly affected the Kd for long-chained PFAS whereas the Kd of short-chained PFAS was not sensitive to molecular weight. The diffusion coefficients (Dg) of PFCAs and PFSAs through 0.1-mm HDPE GM were found to be in the orders of 10-18 to 10-17 m2/s. The Dg decreased with increasing molar mass and were also observed to be dependent on the functional group. Dg of PFSAs was lower than that of PFCAs for similar number of carbons in the chain. The estimated mass flux for PFAS in an intact 1.5-mm HDPE GM varied from 38.7 to 2080.8 ng/m2/year whereas the estimated diffusive breakthrough time for PFAS in intact 1.5-mm HDPE was 1526 years or longer.

Alcohols radicals can efficiently reduce recalcitrant perfluorooctanoic acid

Alcohols are commonly used as eluents for the regeneration of per/poly-fluoroalkyl substances (PFASs) adsorbents, but their potential effects on the subsequent treatment of these eluates have not been fully explored. This work investigated the effect of alcohols on perfluorooctanoic acid (PFOA) degradation by persulfate (PS) based advanced oxidation processes. The results showed that ethanol significantly promoted PFOA degradation in thermal/PS system. Under anoxic conditions, 25.5±1.4% or 91.2±1.6% of PFOA was degraded within 48 h in the absence or presence of ethanol. Electron paramagnetic resonance (EPR) detection, free radical quenching experiments, and chemical probe studies clearly demonstrated that the sulfate radicals (SO4•−) generated from PS activation would react with ethanol to form alcohol radicals, which could efficiently degrade PFOA. The transformation pathways of PFOA were proposed based on degradation products analysis and density function theory (DFT) calculation. The reaction between SO4•− and other alcohols could also induce the formation of alcohol radicals and facilitate to the degradation of PFOA. This work represents the positive roles of alcohols in the degradation of PFASs, providing new insights into developing simple and efficient treatments for PFASs eluate or PFAS-contaminated water.

The analysis of the migration of per and poly fluoroalkyl substances (PFAS) from food contact materials using ultrahigh performance liquid chromatography coupled to ion-mobility quadrupole time-of-flight mass spectrometry (UPLC- IMS-QTOF)

Per-poly fluoroalkyl substances (PFASs) are a group of synthetic fluorine compounds used in food packaging materials to repel water and fats. This study assessed the chemical migration of PFAS from different food contact materials, including cardboard, recycled cardboard, biopolymer, paper and Teflon trays, from various markets. Migration assays were conducted using Tenax® as a food simulant, which was optimized by subjecting it to three consecutive extractions with 3 mL of ethanol within an hour. The resulting extractions were combined and concentrated to 0.5 mL using a nitrogen stream. The analysis was performed using ultrahigh performance liquid chromatography (UPLC) coupled with ion-mobility (IMS) quadrupole-time-of-flight (QTOF) mass spectrometry, which provided a powerful and novel tool for identifying a library of targets containing collision cross section values (CCS) and increasing confidence in subsequent identifications. Eleven PFAS compounds belonging to the family of perfluorocarboxylic acid, perfluorosulfonic acid and perfluorooctanesulfonamidoacetic acid substances (PFCAs, PFSAs and FOSAAs) were found in packaging samples obtained from China, with migrant concentrations ranging 3.2 and 22.3 μg/kg. In contrast, no detectable levels of PFAS were observed in packaging samples obtained in Spain. All trays tested were deemed to be suitable for use as food contact materials due to the fact that their migrant values were lower than 0.025 mg/kg for PFOA and its salts, and lower than a maximum concentration of 1 mg/kg for PFOA-related compounds.

A bifunctional single-atom catalyst assisted by Fe2O3 for efficiently electrocatalytic perfluorooctanoic acid degradation by integrating reductive and oxidative processes

Concerns about the environmentally persistent and bioaccumulative per/polyfluoroalkyl substances (PFAS) in water are emerging since their potentially harmful effects on humans. However, the rapid mineralization and defluorination of PFAS are rarely achieved although various techniques have been developed. Hereby, a bifunctional single-atom catalyst (SAC) characterizing a Co-CN2 configuration is constructed, which can simultaneously induce the degradation of PFOA and reduce O2 to H2O2. Oxidative and reductive degradation are intergraded within one system for perfluorooctanoic acid (PFOA) degradation with the immobilized Fe2O3 as a Fenton catalyst. Consequently, 96.1% of PFOA is degraded over Co-CN2-Fe2O3 at −0.06 V in an H-cell equipped with a gas diffusion cathode. The defluorination efficiency reaches 95.9% in 120 min. The Co site shielding experiment combined with the ·OH quench experiment validates that both reductive and oxidative degradation processes are indispensable in rapid and complete PFOA mannerization and defluorination. A reduction and oxidation cooperative chain shortening mechanism is proposed for PFOA degradation based on the intermediates analysis and shielding experiment.

Per/polyfluoroalkyl substances modulate plasmid transfer of antibiotic resistance genes: A balance between oxidative stress and energy support

Emerging contaminants can accelerate the transmission of antibiotic resistance genes (ARGs) from environmental bacteria to human pathogens via plasmid conjugation, posing a great challenge to the public health. Although the toxic effects of per/polyfluoroalkyl substances (PFAS) as persistent organic pollutants have been understood, it is still unclear whether and how PFAS modulate the transmission of ARGs. In this study, we for the first time reported that perfluorooctanoic acid (PFOA), perfluorododecanoic acid (PFDoA) and ammonium perfluoro (2-methyl-3-oxahexanoate) (GenX) at relatively low concentrations (0.01, 0.1 mg/L) promoted the conjugative transfer of plasmid RP4 within Escherichia coli, while the plasmid conjugation was inhibited by PFOA, PFDoA and GenX at relatively high concentrations (1, 10 mg/L). The non-unidirectional conjugation result was ascribed to the co-regulation of ROS overproduction, enhanced cell membrane permeability, shortage of energy support as well as l-arginine pool depletion. Taking the well-known PFOA as an example, it significantly enhanced the conjugation frequency by 1.4 and 3.4 times at relatively low concentrations (0.01, 0.1 mg/L), respectively. Exposure to PFOA resulted in enhanced cell membrane permeability and ROS overproduction in donor cells. At high concentrations of PFOA (1, 10 mg/L), although enhanced oxidative stress and cell membrane permeability still occurred, the ATP contents in E. coli decreased, which contributed to the inhibited conjugation. Transcriptome analysis further showed that the expression levels of genes related to arginine biosynthesis (argA, argC, argF, argG, argI) and transport (artJ, artM, artQ) pathways were significantly increased. Intracellular l-arginine concentration deficiency were observed at high concentrations of PFOA. With the supplementary exogenous arginine, it was demonstrated that arginine upregulated conjugation transfer- related genes (trfAp, trbBp) and restores the cell number of transconjugants in PFOA-treated group. Therefore, the inhibited conjugation at high concentrations PFOA were attributed to the shortage of ATP and the depletion of L-arginine pool. These findings provide important insights into the effect environmental concentrations of PFAS on the conjugative transfer of ARGs, and update the regulation mechanism of plasmid conjugation, which is critical for the management of antibiotic resistance in aquatic environments.

Direct evidence of the important role of proteins in bioconcentration and biomagnification of PFASs in benthic organisms based on comparison with OPEs

Despite the wide acceptance that bioconcentration and biomagnification of per/polyfluoroalkyl substances (PFASs) is related to proteins in organisms, few direct evidences are available. Here, bioconcentration and biomagnification of 9 organophosphate esters (OPEs) and 16 PFASs, which have similar range of log Kow (octanol-water partitioning coefficient) values, were compared in the benthic food chain of biofilm-snail in Taihu Lake, China. The ∑OPEs level in water (150–23,036 ng/L) was significantly higher than ∑PFASs (57.3–351 ng/L). Although the logarithm of bioconcentration factors of both OPEs and PFASs in biofilm positively correlated with their log Kow, the slope of PFASs was 4 times of that of OPEs, which might be due to the strong interactions of PFASs with biofilm extracellular proteins. Additionally, PFASs exhibited distinctly greater biomagnification factors from biofilm to snails (3.09–17.8) than OPEs (0.39–3.48). Significant correlations between the concentrations and protein contents in snails were observed for most long-chain PFASs, but not for any OPEs. Multiple receptor models identified polyurethane foam (77.9 %) and food packaging/metal plating (56.9 %) were the primary sources of OPEs and PFASs in Taihu Lake, respectively. We provided strong and direct evidences that proteins facilitated bioconcentration and biomagnification of PFASs.

Sunlight-driven photocatalytic per- and polyfluoroalkyl substances degradation over zinc oxide/cellulose nanofiber catalyst using a continuous flow reactor

Recalcitrant pollutants in water with high resistance to natural degradation such as per/polyfluoroalkyl substances (PFAS) highlight the need for sustainable, cheap, and effective treatment approaches. Although photocatalysis under direct sunlight can be beneficial due to the usage of ambient conditions for the reaction, air as the oxidant, and sunlight as the energy source, identifying sustainable and sunlight photoactive materials and a process that is both scalable and industrially feasible are challenging. Herein, we report the use of ZnO/cellulose nanofiber (CNF) composites for the photodegradation of PFOA and PFOS upon irradiation by sunlight in a continuous flow photoreactor. HPLC/MS/MS and fluoride quantification using the SPADNS method were used to track the degradation of PFAS and by-product formation. Aqueous solutions of three different standard PFAS samples containing 1200 µg/L of PFOA, 800 µg/L PFOS, and a mixture of 900 µg/L of PFOA and 900 µg/L of PFOS, and a wastewater treatment plant sample with 2.5 µg/L of an environmental mixture of PFAS compounds present in urban wastewater were used for the photocatalytic degradation tests. The concentration of these pollutants and their by-products in these samples was reduced to 0.5 µg/L, 0.07 µg/L, 0.15 µg/L, and 0.3 µg/L with an EE/O figure of merit of 0.19, 0.28, 0.43, 0.88 kWh/m3 per order, respectively. It was observed that the standard mixture and the wastewater treatment plant samples were harder to degrade as compared to the standards containing one PFAS compound. Reusing the catalyst for three cycles showed less than 4% reduction in photodegradation over irradiation time. These findings emphasize the importance of location-specific design as the choice of photocatalyst is enabled by the UVA/B solar radiance characteristics present in Australia.

Pilot-scale expanded assessment of inorganic and organic tapwater exposures and predicted effects in Puerto Rico, USA

A pilot-scale expanded target assessment of mixtures of inorganic and organic contaminants in point-of-consumption drinking water (tapwater, TW) was conducted in Puerto Rico (PR) to continue to inform TW exposures and corresponding estimations of cumulative human-health risks across the US. In August 2018, a spatial synoptic pilot assessment of than 524 organic and 37 inorganic chemicals was conducted in 14 locations (7 home; 7 commercial) across PR. A follow-up 3-day temporal assessment of TW variability was conducted in December 2018 at two of the synoptic locations (1 home, 1 commercial) and included daily pre- and post-flush samples. Concentrations of regulated and unregulated TW contaminants were used to calculate cumulative in vitro bioactivity ratios and Hazard Indices (HI) based on existing human-health benchmarks. Synoptic results confirmed that human exposures to inorganic and organic contaminant mixtures, which are rarely monitored together in drinking water at the point of consumption, occurred across PR and consisted of elevated concentrations of inorganic contaminants (e.g., lead, copper), disinfection byproducts (DBP), and to a lesser extent per/polyfluoroalkyl substances (PFAS) and phthalates. Exceedances of human-health benchmarks in every synoptic TW sample support further investigation of the potential cumulative risk to vulnerable populations in PR and emphasize the importance of continued broad characterization of drinking-water exposures at the tap with analytical capabilities that better represent the complexity of both inorganic and organic contaminant mixtures known to occur in ambient source waters. Such health-based monitoring data are essential to support public engagement in source water sustainability and treatment and to inform consumer point-of-use treatment decision making in PR and throughout the US.

Phthalates, organotin compounds and per-polyfluoroalkyl substances in semiconfined areas of the Spanish coast: Occurrence, sources and risk assessment.

In this work two sensitive areas of the Spanish coast located in the Atlantic (Ria de Vigo) and Mediterranean (Mar Menor lagoon) have been studied regarding their contamination by phthalates, organotin compounds and per-polyfluoroalkyl substances (seawater and sediments) in two different campaigns (spring and autumn in 2015). PFAS and OTCs were detected in seawater and sediments at low concentrations (few ngL-1 or ngg-1), whereas PAEs were detected at levels two orders of magnitude higher, particularly in Mar Menor lagoon due to its semi-confined characteristics. However, PAEs and OTCs concentration in sediments were higher in Ría de Vigo than in Mar Menor lagoon as a consequence of the influence of the important urban nuclei and port in that area. The ecological risk assessment revealed that in both areas tributyltin, dibutyltin and diethylphthalate pose a significant risk in sediments, whereas in seawater tributyltin in both areas resulted in a high risk.

Synthesis and application of a green surfactant for the treatment of water containing PFAS/ hazardous metal ions

In this work, the effectiveness of a biodegradable and natural surfactant synthesized through a novel method has been studied through the ion flotation process to treat waters containing Per/Poly Fluoroalkyl Substances (PFAS) and heavy-metal ions. This cysteine-based surfactant, which is environmentally acceptable, showed considerable solubility and foaming ability over a wide range of pH. It also could remove 97–99(%) of 5 mg/L of cadmium, chromium, copper, nickel, zinc, and manganese ions in a single batch physicochemical process. Moreover, for the first time, a foam fractionation method in association with using this cysteine-based surfactant was applied for perfluorooctanoic acid (PFOA) removal from water. This surfactant was used as a co-surfactant and could readily remove 72% of PFOA (40 mg/L) from water. The characterization of the surfactant was undertaken using 1H NMR, FT-IR, elemental analysis, melting point, and determination of its critical micelle concentration (CMC). This environmentally friendly surfactant has high potential applications in green chemistry especially in the treatment of waters contaminated with PFAS/heavy-metal ions.

Efficient Photocatalytic PFOA Degradation over Boron Nitride

Concern over water contamination by per/polyfluoroalkyl substances (PFAS) has highlighted the lack of effective treatment approaches. Photocatalysis offers advantages of using ambient conditions fo...

Perfluoroalkyl Substances Increase Susceptibility of Northern Leopard Frog Tadpoles to Trematode Infection

Per/polyfluoroalkyl substances (PFAS) are contaminants of emerging concern that can impair immune function, yet few studies have tested whether exposure increases infection risk. Using laboratory experiments, we found that exposure to 10 ppb of perfluorohexanesulfonic acid increased trematode (Echinoparyphium lineage 3) infections in larval northern leopard frogs (Lithobates pipiens). However, there was no effect of perfluorooctanesulfonic acid. Our results demonstrate that PFAS can potentially enhance infection risk in natural systems. Environ Toxicol Chem 2021;40:689-694. © 2020 SETAC.

Mixed organic and inorganic tapwater exposures and potential effects in greater Chicago area, USA

Safe drinking water at the point of use (tapwater, TW) is a public-health priority. TW exposures and potential human-health concerns of 540 organics and 35 inorganics were assessed in 45 Chicago-area United States (US) homes in 2017. No US Environmental Protection Agency (EPA) enforceable Maximum Contaminant Level(s) (MCL) were exceeded in any residential or water treatment plant (WTP) pre-distribution TW sample. Ninety percent (90%) of organic analytes were not detected in treated TW, emphasizing the high quality of the Lake Michigan drinking-water source and the efficacy of the drinking-water treatment and monitoring. Sixteen (16) organics were detected in >25% of TW samples, with about 50 detected at least once. Low-level TW exposures to unregulated disinfection byproducts (DBP) of emerging concern, per/polyfluoroalkyl substances (PFAS), and three pesticides were ubiquitous. Common exceedances of non-enforceable EPA MCL Goal(s) (MCLG) of zero for arsenic [As], lead [Pb], uranium [U], bromodichloromethane, and tribromomethane suggest potential human-health concerns and emphasize the continuing need for improved understanding of cumulative effects of low-concentration mixtures on vulnerable sub-populations. Because DBP dominated TW organics, residential-TW concentrations are potentially predictable with expanded pre-distribution DBP monitoring. However, several TW chemicals, notably Pb and several infrequently detected organic compounds, were not readily explained by pre-distribution samples, illustrating the need for continued broad inorganic/organic TW characterization to support consumer assessment of acceptable risk and point-of-use treatment options.

Potential sources and sediment-pore water partitioning behaviors of emerging per/polyfluoroalkyl substances in the South Yellow Sea

Emerging per/polyfluoroalkyl substances (PFASs) have received great concerns, but there are few data in the coastal environment, which play an essential role in their global transport. In this study, surface water and sediment samples were collected in the South Yellow Sea close to Jiangsu Province China, and 26 legacy as well as emerging PFASs were investigated. Perfluorooctanoic acid (PFOA) and perfluorobutane sulfonate (PFBS) were predominant in the coastal water of the South Yellow Sea with a relatively higher level than other coastal regions in the world. PFBS and 6:2 fuorotelomer sulfonic acid (6:2 FTSA) were two major alternatives of perfluorooctane sulfonate (PFOS) which were used in textile surface treatment and fire-fighting foams, respectively. Multiple receptor models identified that fluoropolymer manufacture, textile and food packages were three major sources of PFASs in the South Yellow Sea. The partitioning behaviors of PFASs between sediment and pore water in the marine environment were compared, and the partitioning coefficients of hexafluoropropylene oxide trimer acid (HFPO-TA) and 6:2 chlorinated polyfluorinated ether sulfonic acid (6:2 F-53B) were reported for the first time, which exhibited stronger partition in sediment than their predecessors. The results provide important hints to understand the environmental transport of PFASs in the marine environment.

Prenatal exposure to chlorinated polyfluoroalkyl ether sulfonic acids and perfluoroalkyl acids: Potential role of maternal determinants and associations with birth outcomes.

Transplacental exposure to per/polyfluoroalkyl substances (PFASs) may impact fetal growth, but published evidence are still sparse and not in agreement. Moreover, little is known on the occurrence of emerging chlorinated polyfluorinated ether sulfonates (Cl-PFESAs, 6:2 and 8:2) in maternal-neonatal population. This study investigated eleven PFASs by analyzing 98 cord samples from Hangzhou, China. All target compounds can be transported across placenta, with highest median concentrations of 4.07, 1.05 and 0.731 ng/mL for PFOS, PFOA, and 6:2 Cl-PFESA. Older ages and higher pre-pregnancy BMI were associated with higher cord PFASs concentration; being primiparous was also significantly associated. Notably, after adjusting for potential confounders, PFOS was negatively associated with birth weight (β = -417.3 g, 95% CI: -742.1, -92.4, p = 0.011, per a log10 unit increase in exposure) and ponderal index (β = -0.005 g/cm3, 95% CI: -0.008, -0.002, p = 0.000). PFOS and PFHxS were also indicated to be associated with small for gestational age birth (SGA) (p < 0.05). Although no evidence of association was observed between Cl-PFESAs and birth outcomes in this study, the bioaccumulative properties and development toxicity of Cl-PFESAs deserve continuous concern.

Uptake and Depuration of Four Per/Polyfluoroalkyl Substances (PFASS) in Northern Leopard Frog Rana pipiens Tadpoles

Per/polyfluoroalkyl substances (PFASs) are persistent organic contaminants that are ubiquitous in surface waters. To date, their effects on aquatic systems, especially amphibians, are poorly understood. We examined the uptake and depuration of perfluorooctanesulfonate (PFOS), perfluorohexanesulfonate (PFHxS), perfluorooctanoic acid (PFOA), and 6:2 fluorotelomer sulfonate (6:2 FTS) in northern leopard frog (Rana pipiens) tadpoles. Whole-body concentrations were examined every 10 d during constant aqueous exposure to targeted concentrations of 10, 100, and 1000 μg/L for 40 d and for 30 d during depuration. Effects of PFAS exposure on length and development were also examined. Rapid uptake led to steady state concentrations by 10 d for most exposures. PFOS accumulated to the highest levels with whole-body bioconcentration factor (BCF) values at 40 d ranging from 19.6 to 119.3. The remaining PFASs were not found to bioconcentrate (BCF < 1.0 at 40 d). Furthermore, some BCF values decreased during the exposure ...

A North American and global survey of perfluoroalkyl substances in surface soils: Distribution patterns and mode of occurrence

The distribution of 32 per/polyfluoroalkyl substances (PFASs) in surface soils was determined at 62 locations representing all continents (North America n = 33, Europe n = 10, Asia n = 6, Africa n = 5, Australia n = 4, South America n = 3 and Antarctica n = 1) using ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) systems. Quantifiable levels of perfluoroalkyl carboxylates (PFCAs: PFHxA-PFTeDA) were observed in all samples with total concentrations ranging from 29 to 14,300 pg/g (dry weight), while perfluoroalkane sulfonates (PFSAs: PFHxS, PFOS and PFDS) were detected in all samples but one, ranging from <LOQ-3270 pg/g, confirming the global distribution of PFASs in terrestrial settings. The geometric mean PFCA and PFSA concentrations were observed to be higher in the northern hemisphere (930 and 170 pg/g) compared to the southern hemisphere (190 and 33 pg/g). Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were the most commonly detected analytes at concentrations up to 2670 and 3100 pg/g, respectively. The sum of PFCA homologues of PFOA commonly were roughly twice the concentration of PFOA. The PFCA and PFSA congener profiles were similar amongst most locations, with a few principal-component statistical anomalies suggesting impact from nearby urban and point sources. The ratio of even to odd PFCAs was consistent with the atmospheric oxidation of fluorotelomer-based precursors previously observed in laboratory and environmental studies. Given the soils were collected from locations absent of direct human activity, these results suggest that the atmospheric long-range transport (LRT) of neutral PFASs followed by oxidation and deposition are a significant source of PFCAs and PFSAs to soils.

Transformation of polyfluorinated compounds in natural waters by advanced oxidation processes.

The presence of perfluorocarboxylic acids (PFCAs) in source and finished drinking waters is a concern with studies showing bioaccumulation and adverse toxicological effects in wildlife and potentially humans. Per/Polyfluoroalkyl substances (PFAS) such as fluorotelomer alcohols have been identified as precursors for PFCAs in biological pathways. In this study, we investigated the fate of 6:2 and 8:2 homologues of the fluorotelomer unsaturated carboxylic acids (FTUCAs) during advanced oxidation process (AOPs). Results showed 6:2 FTUCA and 8:2 FTUCA transformed into 6-C PFCA (PFHxA) and 8-C PFCA (PFOA) respectively with very little other PFCA formation for all AOPs. The degradation of 6:2 FTUCA and 8:2 FTUCA was greater in the GW compared to SW for the ozone processes but similar for UV/H2O2. The formation of n-C PFCA followed O3>O3/H2O2 at same dose and UV/H2O2 had much lower formation at the doses tested. Non-targeted analysis with the LC-MS-qTOF indicated the production of other PFCAs which contribute to the total mass balance, although no intermediate product was discovered indicating a rapid and direct transformation from the FTUCAs to the PFCAs and/or significant volatilization of intermediates. With the use of AOPs essential to water reuse treatment schemes, this work raises concerns over the risk of potential formation of PFCAs in the treatment and their adverse health effects in finished drinking water.