Perfluoroalkyl and polyfluoroalkyl substances (PFASs) in consumer products in Norway - a pilot study

Advancing PFAS characterization: Development and optimization of a UV-H2O2-TOP assay for improved PFCA chain length preservation and organic matter tolerance

As per- and polyfluoroalkyl substances (PFAS) infiltrate the environment via industrial, commercial, and domestic sources, the demand for robust, cost-effective, and straightforward analytical assays intensifies to enhance PFAS characterization and quantification. To address this demand, this study introduces a novel UV-H2O2-TOP assay, identifying optimal parameters such as pH (5-9), oxidant concentration (500 mM H2O2), activation rate (63 mM H2O2 h-1), and an acceptable total organic carbon (TOC) limit (~1000 mg/L TOC) to achieve maximum PFAA precursor conversion. Additional work was performed further optimizing the UV-TOP assay, by confirming its superiority to heat activation, identifying the effectiveness of different persulfate salts, and investigating different concentrations of sodium persulfate and sodium hydroxide at a 1:2.5 ratio on PFCA yield. Our investigation concluded by applying the UV-H2O2-TOP assay, using sodium persulfate as the TOP assay oxidant, to 6:2 FTS and five different AFFF samples. High-resolution mass spectrometry and an expanded analytical suite support sample analysis, facilitating direct quantification of ultra-short chain perfluoroalkyl carboxylates (PFCAs) and common fluorotelomer compounds including 5:3/5:1:2 fluorotelomer betaine and 6:2 fluorotelomer sulfonamido betaine. Results highlight several advantages of this tandem UV-activated method, including enhanced preservation of perfluoroalkyl chains (post-oxidation of 6:2 fluorotelomer sulfonate resulted in 28 % PFHpA, 47 % PFHxA, 25 % C3-C5 PFCA), capacity to handle high TOC limits (1000 mg/L TOC), and ability to incorporate higher persulfate concentrations in a single oxidation cycle.

Discovery of perfluoroalkyl sulfonyl quaternary ammonium substances in the environment and their environmental behaviors

A variety of per- and polyfluoroalkyl substances (PFASs) have been released into the environment via wastewater treatment plant (WWTP) effluent, with current target and nontarget analytical methods typically focusing on negatively ionized PFASs while largely overlooking positively ionized ones. In this study, five cationic PFASs, perfluoroalkyl sulfonyl quaternary ammonium substances (PFAQASs), were first identified in surface water impacted by the WWTP effluent, applying a metabolomics-based nontarget analysis method. Environmental behaviors of identified novel PFAQASs were further investigated. In surface water, sediment, and fish (Coilia mystus) samples collected from the Yangtze River, 8:3 PFAQA was consistently the predominant PFAQASs, with the mean concentrations of 90 ng/L (< LOD-558 ng/L), 92 ng/g dw (< LOD-421 ng/g dw), and 2.3 ng/g ww (< LOD-4.6 ng/g ww), respectively. This study highlights the necessity to discover other cationic PFASs in the environment. Among PFAQASs, 8:4 PFAQA (4.2, range 3.4 - 4.6) had the highest mean sediment-water partitioning coefficient (log Koc), followed by 8:3 PFAQA (3.9, 2.8 - 4.5) and 6:3 PFAQA (3.7, 3.3 - 4.1). The log Koc of PFAQASs showed a general increase trend with the increasing carbon chain length. Mean bioaccumulation factor (BAF) values of PFAQASs calculated in the collected fish from the Yangtze River ranged from 1.9 ± 0.32 (4:3 PFAQA) to 2.9 ± 0.34 (8:4 PFAQA). The mean BAF values of PFAQASs generally increased with the carbon chain length. Further studies are warranted to elucidate the environmental fate, potential toxicity, and human exposure implications for these identified novel PFASs.

Thermal desorption - gas chromatography - mass spectrometry (TD-GC-MS) analysis of PFAS used in food contact materials

Per- and polyfluoroalkyl substances (PFAS) are used in food contact materials (FCMs), e.g. as production aids in the fabrication of PTFE based coatings for kitchenware or as additives in paper and board. Growing concerns about the environment and health related to PFAS have led to an increasing interest in monitoring PFAS levels in FCMs as well as their migration into food. In this study, method development for the analysis of PFAS by thermal desorption - gas chromatography - mass spectrometry (TD-GC-MS) was done. In addition to fluorotelomer alcohols (FTOHs), which are the only PFAS commonly analysed by GC-MS, it was proven that perfluorocarboxylic acids (PFCAs) and per- and polyfluoroether carboxylic acids (PFECAs) as well as their thermolysis products, perfluoroethers (PFEs) and perfluoroalkenes, can be analysed by GC-MS without prior derivatization. Screening for PFCAs and FTOHs was possible by electron impact ionization (EI) using group specific SIM fragments. Confirmation of identity has been done by EI scans as well as chemical ionization (CI) SIM measurements. LODs (limits of detection) of PFCAs, FTOHs and PFECAs in the TD-GC-MS instrument were in the low pg range. Thermal degradation of PFCAs and PFECAs during TD-GC-MS measurement was investigated.

Impact of tightening environmental regulations against long-chain perfluoroalkyl acids on composition of durable water repellents containing side-chain fluorinated polymers

Tightening of environmental regulations against long-chain perfluoroalkyl acids (PFAAs) since the 2000s may have led to significant increases in the occurrence of short-chain PFAAs in the environment. Understanding the impact of the regulations on composition of durable water repellents (DWRs) is imperative to guide implementation of pragmatic actions during their use and end-of-life treatment. Substantial decreases in the frequencies of detection and concentrations of long-chain PFAAs and long-chain PFAA-precursors, and substantial increases in those of short-chain PFAAs and short-chain PFAA-precursors, have been observed in the impurities and hydrolysis products of side-chain fluorinated polymers (SCFPs). Comparison of profiles among the DWRs containing fluorinated ingredients in 2011 indicated that DWRs containing C8F17- and C10F21-SCFPs were the dominant products and accounted for 90 % of the samples, whereas DWRs containing C4F9- and C6F13-SCFPs were the dominant products and accounted for 70 % of the samples collected in 2021. Tightening of the regulations have caused decreasing applications of long-chain SCFPs and increasing use of short-chain SCFPs in DWRs containing fluorinated ingredients. The ingredients of one DWR were changed from PFAS-free alternatives to short-chain SCFPs, whereas those of another DWR were changed from short-chain SCFPs to PFAS-free alternatives. The presence of unexplained extractable organic fluorine has been observed in DWRs containing fluorinated ingredients, which may be difficult to be hydrolyzed and form known compounds. A historical series of DWRs available from before and after the tightening of regulations and a multifaceted analytical technique consisting of combustion ion chromatographic and mass spectrometric approaches combined with two extraction techniques involving ultrasonic treatment and alkaline hydrolysis revealed the impact of tightening regulations on composition of DWRs.

Concentration and health risk assessment of per- and polyfluoroalkyl substances in cosmetic and personal care products

Per and polyfluoroalkyl substances (PFAS) are toxicologically concerning because of their potential to bioaccumulate and their persistence in the environment and the human body. We determined PFAS levels in cosmetic and personal care products and assessed their health risks. We investigated the trends in concentrations and types of PFAS contaminants in cosmetic and personal care products before and after perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were added to the list of persistent organic pollutants. The total PFAS concentration ranged from 1.98 to 706.75 ng g-1. The hazard quotients (HQs) for PFOA, PFOS and perfluorobutanesulfonic acid (PFBS) were lower than 1, indicating no appreciable risk to consumers. Assuming the simultaneous use of all product types and the worst-case scenario for calculations, perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids (PFSAs) also had hazard indices lower than 1. We found that adverse effects are unlikely to occur when each type of cosmetic is used separately, or even when all product types are used together. Nevertheless, the persistence and bioaccumulation characteristics of additional PFAS present in cosmetics continue to be a cause for concern. Further research is necessary to investigate the long-term impacts of using such cosmetics and the associated risks to human health.

Using machine learning to classify the immunosuppressive activity of per- and polyfluoroalkyl substances

Per- and polyfluoroalkyl substances (PFASs), one of the persistent organic pollutants, have immunosuppressive effects. The evaluation of this effect has been the focus of regulatory toxicology. In this investigation, 146 PFASs (immunosuppressive or nonimmunosuppressive) and corresponding concentration gradients were collected from literature, and their structures were characterized by using Dragon descriptors. Feature importance analysis and stepwise feature elimination are used for feature selection. Three machine learning (ML) methods, namely Random Forest (RF), Extreme Gradient Boosting Machine (XGB), and Categorical Boosting Machine (CB), were utilized for model development. The model interpretability was explored by feature importance analysis and correlation analysis. The findings indicated that the three models developed have exhibited excellent performance. Among them, the best-performing RF model has an average AUC score of 0.9720 for the testing set. The results of the feature importance analysis demonstrated that concentration, SpPosA_X, IVDE, R2s, and SIC2 were the crucial molecular features. Applicability domain analysis was also performed to determine reliable prediction boundaries for the model. In conclusion, this study is the first application of ML models to investigate the immunosuppressive activity of PFASs. The variables used in the models can help understand the mechanism of the immunosuppressive activity of PFASs, allow researchers to more effectively assess the immunosuppressive potential of a large number of PFASs, and thus better guide environmental and health risk assessment efforts.

Comprehensive assessment of per and polyfluoroalkyl substances (PFAS) contamination in groundwater of Kamrup, Assam, India: occurrence, health risks, and metabolomic insights

Per-and polyfluoroalkyl substances (PFAS) are synthetic chemicals that are known for their environmental persistence and adverse health effects. This study comprehensively assessed PFAS contamination in the Kamrup region of Assam, India, focusing on its presence in groundwater and associated health risks. The analysis detected 12 PFAS in groundwater samples from both the Kamrup Metro and Rural regions. In Kamrup Rural, Perfluorohexanoic acid (PFHxA), perfluorononanoic acid (PFNA), and perfluorooctanesulfonic acid (PFOS) were prevalent, whereas in Kamrup Metro, PFNA and PFOS were dominant, based on detection frequencies. These findings are noteworthy, as they demonstrate the widespread presence of PFAS in groundwater, a vital source of drinking water in the region. The assessment of PFAS health risks in India involved hazard quotient calculations for different age groups. Perfluorobutanesulfonic acid (PFBS) posed the highest risk, ranking children > boys > men > girls > women. Overall, ∑PFAS had low hazard (HQ: 0.27-0.41). Further, this study assessed PFBS and PFOS toxicity in human kidney epithelial cell lines (HEK293T) cells, revealing that PFBS was more cytotoxic than PFOS. The study examined the metabolomics of HEK293T cells after PFBS exposure, revealing significant alterations in lipid metabolism, particularly glycerophospholipids, potentially affecting cellular function and health. These findings underscore the importance of monitoring PFAS contamination in drinking water sources, especially in regions such as Kamrup, where groundwater is a primary source. Our metabolomics results show significant health effects at the cellular level, raising concerns about the impact of PFAS exposure on human health. This study highlights PFAS contamination in Kamrup, Assam's groundwater and its health risks, providing valuable insights for policymakers and public health management.

Legacy and alternative per- and polyfluoroalkyl substances (PFAS) alter the lipid profile of HepaRG cells

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used in various industrial and consumer products. They have gained attention due to their ubiquitous occurrence in the environment and potential for adverse effects on human health, often linked to immune suppression, hepatotoxicity, and altered cholesterol metabolism. This study aimed to explore the impact of ten individual PFAS, 3 H-perfluoro-3-[(3-methoxypropoxy) propanoic acid] (PMPP/Adona), ammonium perfluoro-(2-methyl-3-oxahexanoate) (HFPO-DA/GenX), perfluorobutanoic acid (PFBA), perfluorobutanesulfonic acid (PFBS), perfluorodecanoic acid (PFDA), perfluorohexanoic acid (PFHxA), perfluorohexanesulfonate (PFHxS), perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), and perfluorooctanesulfonic acid (PFOS) on the lipid metabolism in human hepatocyte-like cells (HepaRG). These cells were exposed to different concentrations of PFAS ranging from 10 µM to 5000 µM. Lipids were extracted and analyzed using liquid chromatography coupled with mass spectrometry (LC- MS-QTOF). PFOS at 10 µM and PFOA at 25 µM increased the levels of ceramide (Cer), diacylglycerol (DAG), N-acylethanolamine (NAE), phosphatidylcholine (PC), and triacylglycerol (TAG) lipids, while PMPP/Adona, HFPO-DA/GenX, PFBA, PFBS, PFHxA, and PFHxS decreased the levels of these lipids. Furthermore, PFOA and PFOS markedly reduced the levels of palmitic acid (FA 16.0). The present study shows distinct concentration-dependent effects of PFAS on various lipid species, shedding light on the implications of PFAS for essential cellular functions. Our study revealed that the investigated legacy PFAS (PFOS, PFOA, PFBA, PFDA, PFHxA, PFHxS, and PFNA) and alternative PFAS (PMPP/Adona, HFPO-DA/GenX and PFBS) can potentially disrupt lipid homeostasis and metabolism in hepatic cells. This research offers a comprehensive insight into the impacts of legacy and alternative PFAS on lipid composition in HepaRG cells.

Vapor-phase transport of per and polyfluoroalkyl substances: Processes, modeling, and implications

An increasing number of studies have demonstrated the presence of per and polyfluoroalkyl substances (PFAS) in the vapor phase. It is therefore important to consider the potential for vapor-phase transport of PFAS in soil and the vadose zone and to investigate the processes impacting the retention and transport of volatile PFAS in soil. It is also critically important to evaluate existing models and develop new models as needed for their application to PFAS vapor-phase transport. The objectives of the present work were to provide an overview of vapor-phase transport processes and modeling, with a specific focus on their relevance for PFAS, and to discuss implications for mass discharge to groundwater, vapor intrusion, and soil vapor extraction. Decades of research have been devoted to the retention and transport of legacy volatile organic contaminants in the vadose zone. This work provides an abundant source of information concerning the many factors and processes of relevance, and insights into the development and application of mathematical modeling. However, given the unique properties of PFAS, there is a need to conduct research to investigate vapor-phase transport of PFAS and to develop PFAS-specific models. We highlight with illustrative examples that vapor-phase transport can be significantly more rapid than aqueous-phase advective transport, which can result in enhanced mass discharge to groundwater.

Per- and polyfluoroalkyl substances and human health outcomes: An umbrella review of systematic reviews with meta-analyses of observational studies

BACKGROUND

Although evidence on the association between per- and polyfluoroalkyl substances (PFASs) and human health outcomes has grown exponentially, specific health outcomes and their potential associations with PFASs have not been conclusively evaluated.

METHODS

We conducted a comprehensive search through the databases of PubMed, Embase, and Web of Science from inception to February 29, 2024, to identify systematic reviews with meta-analyses of observational studies examining the associations between the PFASs and multiple health outcomes. The quality of included studies was evaluated using the A Measurement Tool to Assess Systematic Reviews (AMSTAR) tool, and credibility of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) criteria. The protocol of this umbrella review (UR) had been registered in PROSPERO (CRD 42023480817).

RESULTS

The UR identified 157 meta-analyses from 29 articles. Using the AMSTAR measurement tool, all articles were categorized as of moderate-to-high quality. Based on the GRADE assessment, significant associations between specific types of PFASs and low birth weight, tetanus vaccine response, and triglyceride levels showed high certainty of evidence. Moreover, moderate certainty of evidence with statistical significance was observed between PFASs and health outcomes including lower BMI z-score in infancy, poor sperm progressive motility, and decreased risk of preterm birth as well as preeclampsia. Fifty-two (33%) associations (e.g., PFASs and gestational hypertension, cardiovascular disease, etc) presented low certainty evidence. Additionally, eighty-five (55%) associations (e.g., PFASs with infertility, lipid metabolism, etc) presented very low certainty evidence.

CONCLUSION

High certainty of evidence supported that certain PFASs were associated with the incidence of low birth weight, low efficiency of the tetanus vaccine, and low triglyceride levels.

In vitro screening of understudied PFAS with a focus on lipid metabolism disruption

Per- and polyfluoroalkyl substances (PFAS) are man-made chemicals used in many industrial applications. Exposure to PFAS is associated with several health risks, including a decrease in infant birth weight, hepatoxicity, disruption of lipid metabolism, and decreased immune response. We used the in vitro cell models to screen six less studied PFAS [perfluorooctane sulfonamide (PFOSA), perfluoropentanoic acid (PFPeA), perfluoropropionic acid (PFPrA), 6:2 fluorotelomer alcohol (6:2 FTOH), 6:2 fluorotelomer sulfonic acid (6:2 FTSA), and 8:2 fluorotelomer sulfonic acid (8:2 FTSA)] for their capacity to activate nuclear receptors and to cause differential expression of genes involved in lipid metabolism. Cytotoxicity assays were run in parallel to exclude that observed differential gene expression was due to cytotoxicity. Based on the cytotoxicity assays and gene expression studies, PFOSA was shown to be more potent than other tested PFAS. PFOSA decreased the gene expression of crucial genes involved in bile acid synthesis and detoxification, cholesterol synthesis, bile acid and cholesterol transport, and lipid metabolism regulation. Except for 6:2 FTOH and 8:2 FTSA, all tested PFAS downregulated PPARA gene expression. The reporter gene assay also showed that 8:2 FTSA transactivated the farnesoid X receptor (FXR). Based on this study, PFOSA, 6:2 FTSA, and 8:2 FTSA were prioritized for further studies to confirm and understand their possible effects on hepatic lipid metabolism.

Fluorescence Turn-on Detection of Perfluorooctanoic Acid (PFOA) by Perylene Diimide-Based Metal-Organic Framework

A novel, water-stable, perylene diimide (PDI) based metal-organic framework (MOF), namely, U-1, has been synthesized for selective and sensitive detection of perfluorooctanoic acid (PFOA) in mixed aqueous solutions. The MOF shows highly selective fluorescence turn-on detection via the formation of a PFOA-MOF complex. This PFOA-MOF complex formation was confirmed by various spectroscopic techniques. The detection limit of the MOF for PFOA was found to be 1.68 μM in an aqueous suspension. Upon coating onto cellulose paper, the MOF demonstrated a significantly lower detection limit, down to 3.1 nM, which is mainly due to the concentrative effect of solid phase extraction (SPE). This detection limit is lower than the fluorescence sensors based on MOFs previously reported for PFAS detection. The MOF sensor is regenerable and capable of detecting PFOA in drinking and tap water samples. The PDI-MOF-based sensor reported herein represents a novel approach, relying on fluorescence turn-on response, that has not yet been thoroughly investigated for detecting per- and polyfluoroalkyl substances (PFAS) until now.

Analysis of Legacy and Novel Neutral Per- and Polyfluoroalkyl Substances in Soils from an Industrial Manufacturing Facility

Per- and polyfluoroalkyl substances (PFASs) have been detected in an array of environmental media due to their ubiquitous use in industrial and consumer products as well as potential release from fluorochemical manufacturing facilities. During their manufacture, many fluorotelomer (FT) facilities rely on neutral intermediates in polymer production including the FT-alcohols (FTOHs). These PFAS are known to transform to the terminal acids (perfluoro carboxylic acids; PFCAs) at rates that vary with environmental conditions. In the current study on soils from a FT facility, we employed gas chromatography coupled with conventional- and high-resolution mass spectrometry (GC-MS and GC-HRMS) to investigate the profile of these precursor compounds, the intermediary secondary alcohols (sFTOHs), FT-acrylates (FTAcr), and FT-acetates (FTAce) in soils around the former FT-production facility. Of these precursors, the general trend in detection intensity was [FTOHs] > [sFTOHs] > [FTAcrs], while for the FTOHs, homologue intensities generally were [12:2 FTOH] > [14:2 FTOH] > [16:2 FTOH] > [10:2 FTOH] > [18:2 FTOH] > [20:2 FTOH] > [8:2 FTOH] ∼ [6:2 FTOH]. The corresponding terminal acids were also detected in all soil samples and positively correlated with the precursor concentrations. GC-HRMS confirmed the presence of industrial manufacturing byproducts such as FT-ethers and FT-esters and aided in the tentative identification of previously unreported dimers and other compounds. The application of GC-HRMS to the measurement and identification of precursor PFAS is in its infancy, but the methodologies described here will help refine its use in tentatively identifying these compounds in the environment.

Per- and polyfluoroalkyl substances (PFAS) in senior care facilities and older adult residents

Per- and polyfluoroalkyl substances (PFAS) are fluorinated organic compounds used in a variety of consumer products and industrial applications that persist in the environment, bioaccumulate in biological tissues, and can have adverse effects on human health, especially in vulnerable populations. In this study, we focused on PFAS exposures in residents of senior care facilities. To investigate relationships between indoor, personal, and internal PFAS exposures, we analyzed 19 PFAS in matched samples of dust collected from the residents' bedrooms, and wristbands and serum collected from the residents. The median ∑PFAS concentrations (the sum of all PFAS detected in the samples) measured in dust, wristbands, and serum were 120 ng/g, 0.05 ng/g, and 4.0 ng/mL, respectively. The most abundant compounds in serum were linear- and branched-perfluorooctane sulfonic acid (L-PFOS and B-PFOS, respectively) at medians of 1.7 ng/mL and 0.83 ng/mL, respectively, followed by the linear perfluorooctanoic acid (L-PFOA) found at a median concentration of 0.59 ng/mL. Overall, these three PFAS comprised 80 % of the serum ∑PFAS concentrations. A similar pattern was observed in dust with L-PFOS and L-PFOA found as the most abundant PFAS (median concentrations of 13 and 7.8 ng/g, respectively), with the overall contribution of 50 % to the ∑PFAS concentration. Only L-PFOA was found in wristbands at a median concentration of 0.02 ng/g. Significant correlations were found between the concentrations of several PFAS in dust and serum, and in dust and wristbands, suggesting that the indoor environment could be a significant contributor to the personal and internal PFAS exposures in seniors. Our findings demonstrate that residents of assisted living facilities are widely exposed to PFAS, with several PFAS found in blood of each study participant and in the assisted living environment.

A review of the occurrence and microbial transformation of per- and polyfluoroalkyl substances (PFAS) in aqueous film-forming foam (AFFF)-impacted environments

Aqueous film-forming foams (AFFFs) have been extensively used for extinguishing hydrocarbon-fuel fires at military sites, airports, and fire-training areas. Despite being a significant source of per- and polyfluoroalkyl substances (PFAS), our understanding of PFAS occurrence in AFFF formulations and AFFF-impacted environments is limited, as is the impact of microbial transformation on the environment fate of AFFF-derived PFAS. This literature review compiles PFAS concentrations in electrochemical fluorination (ECF)- and fluorotelomer (FT)-based AFFFs and provides an overview of PFAS occurrence in AFFF-impacted environments. Our analysis reveals that AFFF use is a predominant point source of PFAS contamination, including primary precursors (polyfluoroalkyl substances as AFFF components), secondary precursors (polyfluoroalkyl transformation products of primary precursors), and perfluoroalkyl acids (PFAAs). Moreover, there are discrepancies between PFAS concentration profiles in AFFFs and those measured in AFFF-impacted media. For example, primary precursors constitute 52.6 % and 99.5 % of PFAS mass in ECF- and FT-based AFFFs, respectively, whereas they represent only 0.7 % total mass in AFFF-impacted groundwater. Conversely, secondary precursors, which constitute <1 % of PFAS in AFFFs, represent 4.0-27.8 % of PFAS in AFFF-impacted environments. The observed differences in PFAS levels between AFFFs and environmental samples are likely due to in-situ biotransformation processes. Biotransformation rates and pathways reported for AFFF-derived primary and secondary precursors varied among different classes of precursors, consistent with the PFAS occurrence in AFFF-impacted environments. For example, readily biodegradable primary precursors, N-dimethyl ammonio propyl perfluoroalkane sulfonamide (AmPr-FASA) and n:2 fluorotelomer thioether amido sulfonate (n:2 FtTAoS), were rarely detected in AFFF-impacted environments. In contrast, key secondary precursors, perfluoroalkane sulfonamides (FASAs) and n:2 fluorotelomer sulfonate (n:2 FTS), were widely detected, which was attributed to their resistance to biotransformation. Key knowledge gaps and future research priorities are presented to better understand the occurrence, fate, and transport of AFFF-derived PFAS in the environment and to design more effective remediation strategies.

Per- and polyfluoroalkyl substances (PFAS) exposure in plasma and their blood-brain barrier transmission efficiency-A pilot study

Per- and polyfluoroalkyl substances (PFAS) have been shown to penetrate the blood-brain barrier (BBB) and accumulate in human brain. The BBB transmission and accumulation efficiency of PFAS, as well as the potential health risks from human co-exposure to legacy and emerging PFAS due to differences in transport efficiency, need to be further elucidated. In the present pilot study, 23 plasma samples from glioma patients were analyzed for 17 PFAS. The concentrations of PFAS in six paired brain tissue and plasma samples were used to calculate the BBB transmission efficiency of PFAS (RPFAS). This RPFAS analysis was conducted with utmost care and consideration amid the limited availability of valuable paired samples. The results indicated that low molecular weight PFAS, including short-chain and emerging PFAS, may have a greater potential for accumulation in brain tissue than long-chain PFAS. As an alternative to perfluorooctane sulfonic acid (PFOS), 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) exhibited brain accumulation potential similar to that of PFOS, suggesting it may not be a suitable substitute concerning health risk in brain. The BBB transmission efficiencies of perfluorooctanoic acid, PFOS, and 6:2 Cl-PFESA showed similar trends with age, which may be an important factor influencing the entry of exogenous compounds into the brain. A favorable link between perfluorooctane sulfonamide (FOSA) and the development and/or progression of glioma may be implicated by a strong positive correlation (r2 = 0.94; p < 0.01) between RFOSA and Ki-67 (a molecular marker of glioma). However, a causal relationship between RFOSA and glioma incidence were not established in the present study. The present pilot study conducted the first examination of BBB transmission efficiency of PFAS from plasma to brain tissue and highlighted the importance of reducing and/or controlling exposure to PFAS.

Poly- and perfluoroalkyl substances (PFASs) in amphibians and reptiles - exposure and health effects

Poly- and perfluoroalkyl substances (PFASs) are commonly used in various industries and everyday products, including clothing, electronics, furniture, paints, and many others. PFASs are primarily found in aquatic environments, but also present in soil, air and plants, making them one of the most important and dangerous pollutants of the natural environment. PFASs bioaccumulate in living organisms and are especially dangerous to aquatic and semi-aquatic animals. As endocrine disruptors, PFASs affect many internal organs and systems, including reproductive, endocrine, nervous, cardiovascular, and immune systems. This manuscript represents the first comprehensive review exclusively focusing on PFASs in amphibians and reptiles. Both groups of animals are highly vulnerable to PFASs in the natural habitats. Amphibians and reptiles, renowned for their sensitivity to environmental changes, are often used as crucial bioindicators to monitor ecosystem health and environmental pollution levels. Furthermore, the decline in amphibian and reptile populations worldwide may be related to increasing environmental pollution. Therefore, studies investigating the exposure of amphibians and reptiles to PFASs, as well as their impacts on these organisms are essential in modern toxicology. Summarizing the current knowledge on PFASs in amphibians and reptiles in a single manuscript will facilitate the exploration of new research topics in this field. Such a comprehensive review will aid researchers in understanding the implications of PFASs exposure on amphibians and reptiles, guiding future investigations to mitigate their adverse effects of these vital components of ecosystems.

A source-based framework to estimate the annual load of PFAS in municipal wastewater

Per- and Polyfluoroalkyl substances (PFAS) are a class of persistent chemicals, whose impact has been observed in various environmental compartments. Wastewater treatment plants (WWTPs) are considered a major emission pathway of PFAS, specifically in the context of the aquatic environment. The goal of this study was to develop a compartmentalized, source-based load estimation model of 7 PFAS within the municipal wastewater influent. Consumer statistics, data from literature on PFAS concentrations and release during use, and specific sampling activities for environmental flows in the related city were used to estimate per capita emission loads. Model results were compared with loads obtained through the monitoring campaign at the municipal WWTP influent. A wide range of discrepancies (≈5 % to ≈90 %) between loads observed in the WWTP influent and source based model estimates was noticed. The loads less accounted by the model were associated with sulfonic acids (PFSAs), whereas for carboxylic acids (PFCAs) most of the observed loads could be reasonably explained by the model, with even an overestimation of nearly 5 % noted for PFNA. Higher heterogeneity in sources was observed in the PFCA group, with a noticeable dominance in the share of consumer products. PFSAs had less of a consumer product input (<20 %), with the rest of the modelled load being attributed to environmental inputs. A large gap of unknown loads of PFSAs indicates a need for examination of other, not yet quantified activities that can potentially explain the remainder of the observed load. Especially commercial activities are considered as potential additional sources for PFSAs. These findings signify the importance of PFAS that originate from both consumer products, as well as environmental inputs in the overall load contribution into the sewage, while identifying the need for further investigation into commercial sources of PFAS emitted into the municipal wastewater.

Exposure to per- and polyfluoroalkyl substance and metabolic syndrome: A nationally representative cross-sectional study from NHANES, 2003-2018

Per- and polyfluoroalkyl substances(PFAS) are widespread organic pollutants with endocrine-disrupting effects on human health, but the association of PFAS exposure with metabolic syndrome remains conflicting. National Health and Nutrition Examination Survey(NHANES) program was utilized to evaluate the association of individual PFAS exposure and metabolic disorders and further determined the joint effect of PFAS co-exposures. 13921 participants and five PFAS exposures(PFHxS, MPAH, PFDE, PFNA, and PFUA) were included for analysis. The association between individual PFAS and metabolic syndrome varied in the specific PFAS and the specific metabolic disorder examined. PFHxS was negatively associated with obesity(Q4; OR = 0.75; P < 0.001), but positively associated with hyperlipidemia (Q3; OR = 1.2; P = 0.013). PFUA was negatively associated with obesity (Q4; OR = 0.6; P < 0.001), hyperlipidemia (Q3; OR = 0.85; P = 0.03), and non-alcoholic fatty liver disease (NAFLD, Q4; OR = 0.64; P = 0.015), but positively associated with hyperglycemia(Q3; OR = 1.27; P = 0.004). Furthermore, PFAS co-exposures were negatively associated with obesity(OR = 0.63; P < 0.001) and NAFLD(OR = 0.85; P = 0.021), and positively associated with hyperlipidemia(OR = 1.05; P = 0.022), but not significantly associated with hyperglycemia or hypertension. Overall, there was a negative association between PFAS co-exposures and metabolic severity score(β = -0.15; P < 0.001). Subgroup analysis stratified by gender and obesity consistently showed the negative association of PFAS co-exposures with metabolic severity score, and the positive association with hyperlipidemia. However, subgroup analysis showed a negative association with NAFLD in females but not in males, and a negative association with hyperglycemia in the obesity group, but not in the non-obesity group. Collectively, our study showed a negative association of PFAS co-exposures with metabolic syndrome severity score, but did not support a consistent association between PFAS co-exposures and individual components of metabolic syndrome. Additionally, there were gender-specific as well as BMI-specific differences in these associations. Further studies are needed to rule out the reverse causality and clarify the relationship of PFAS co-exposures with the specific metabolic disorder.

Are Chinese mitten crabs (Eriocheir sinensis) suitable as biomonitor or bioindicator of per- and polyfluoroalkyl substances (PFAS) pollution?

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment. In Flanders, the bioaccumulation in aquatic organisms is currently being monitored using European perch and European eel. Since both are native species, there is an ethical need to search for other suitable biomonitors. This study aims to investigate whether the invasive Chinese mitten crab could be used in biomonitoring programs by assessing PFAS accumulation in hepatopancreas, muscle tissue, and carapace. Furthermore, we correlated accumulated concentrations to those in the local abiotic environment. Concentrations in the crabs (highest average ∑PFAS concentration of 688 ± 505 ng/g ww) were often higher than those in crab species from other regions across the globe, confirming that Flanders is highly polluted with PFAS. Concentrations in the crabs did not reflect those in the abiotic environment. This implies that biomonitoring is necessary to investigate the impact of PFAS pollution on organisms in aquatic ecosystems, as important data is missing when only the abiotic environment is monitored. The accumulation profiles differed between the invasive crab and the native European perch and European eel, potentially due to a different ecology and trophic position. Since all three species provide complementary information on the PFAS pollution, a multi-species approach in biomonitoring is recommended. Overall, our results show that the crabs can be used as biomonitor, but more information is necessary to confirm their suitability as bioindicator.

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.

Occurrence, mass loading, and post-control temporal trend of legacy perfluoroalkyl substances (PFASs) in the middle and lower Yangtze River

Present study focused on per- and polyfluoroalkyl substances (PFASs) occurrence in dry and wet seasons in the middle and lower Yangtze River (YZR) and changing temporal trends after years of control. Results revealed that perfluorooctanoic acid (PFOA) was 75 % of total PFAS concentrations (∑11PFASs). ∑11PFASs were ranged 0.20-28.49 ng/L and 1.17-112.84 μg/kg in water and sediment. The logKoc of perfluoroalkyl carboxylic acids was positive with the carbon chain length (p < 0.05, r2 = 0.78). A meta-analysis of results from 16 peer-reviewed publications about PFASs in the YZR showed that fluorochemical industries strongly influenced the high PFAS levels in the detected scenes. PFOA was still the primary pollutant. Individual PFAS in the lower reach was higher than those in the middle reach. The mass loading of PFASs imported into the sea was 10.80 t/y. This study will help develop effective approaches for controlling emerging pollutants in the YZR.

A critical review of perfluoroalkyl and polyfluoroalkyl substances (PFAS) landfill disposal in the United States

Landfills manage materials containing per- and polyfluoroalkyl substances (PFAS) from municipal solid waste (MSW) and other waste streams. This manuscript summarizes state and federal initiatives and critically reviews peer-reviewed literature to define best practices for managing these wastes and identify data gaps to guide future research. The objective is to inform stakeholders about waste-derived PFAS disposed of in landfills, PFAS emissions, and the potential for related environmental impacts. Furthermore, this document highlights data gaps and uncertainties concerning the fate of PFAS during landfill disposal. Most studies on this topic measured PFAS in liquid landfill effluent (leachate); comparatively fewer have attempted to estimate PFAS loading in landfills or other effluent streams such as landfill gas (LFG). In all media, the reported total PFAS heavily depends on waste types and the number of PFAS included in the analytical method. Early studies which only measured a small number of PFAS, predominantly perfluoroalkyl acids (PFAAs), likely report a significant underestimation of total PFAS. Major findings include relationships between PFAS effluent and landfill conditions - biodegradable waste increases PFAS transformation and leaching. Based on the results of multiple studies, it is estimated that 84% of PFAS loading to MSW landfills (7.2 T total) remains in the waste mass, while 5% leaves via LFG and 11% via leachate on an annual basis. The environmental impact of landfill-derived PFAS has been well-documented. Additional research is needed on PFAS in landfilled construction and demolition debris, hazardous, and industrial waste in the US.

Comparison of aggregated exposure to perfluorooctanoic acid (PFOA) from diet and personal care products with concentrations in blood using a PBPK model - Results from the Norwegian biomonitoring study in EuroMix

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) constitute a large group of compounds that are water, stain, and oil repellent. Numerous sources contribute to the blood levels of PFAS in the European population. The main contributor for perfluorooctanoic acid (PFOA) is food, house dust, consumer products and personal care products (PCPs).

OBJECTIVES

The purpose of the present work is to calculate the dietary and dermal external exposure to PFOA, estimate the aggregated internal exposure from diet and PCPs using a PBPK model, and compare estimates with measured concentrations.

METHODS

Detailed information on diet and PCP use from the EuroMix study is combined with concentration data of PFOA in food and PCPs in a probabilistic exposure assessment. A physiologically based pharmacokinetic model (PBPK) was further refined by incorporating a dermal exposure pathway, and changes in the kidney and faecal excretion.

RESULTS

The aggregated internal exposure using the PBPK model shows that the major contributor to the internal exposure is diet for both males and females. The estimated internal exposure of PFOA for the EuroMix population was in the same range but lower than the measured blood concentrations using the lower bound (LB) external exposure estimates, showing that the LB estimates are underestimations. For seven females the internal exposure of PFOA were higher from PCPs than from diet.

CONCLUSION

PCPs and diet contributed in the same range to the internal PFOA exposure for several women participating in EuroMix. This calls for additional studies on exposure to PFOA and possibly other PFAS from PCPs, especially for women. Overall, PBPK modelling was shown as valuable tool in understanding the sources of PFOA exposure and in guiding risk assessments and regulatory decisions.

Measurement of fluorotelomer alcohols based on solid phase microextraction followed by gas chromatography-mass spectrometry and its application in solid waste study

This work developed a method based on solid phase microextraction followed by gas chromatography/mass spectrometry (SPME-GC/MS) for the measurement of fluorotelomer alcohols (FTOHs) in gas samples. The method quantification limit (MQL) is 6-7 ng/L for 6:2 fluorotelomer alcohols (6:2 FTOH) and 8:2 fluorotelomer alcohols (8:2 FTOH). In contrast to common methods such as thermal desorption combined with GC-MS, it needs neither pre-concentration equipment nor large sample volume. The extraction-evaporation-GC/MS is commonly used in literature for FTOHs measurement in solids samples. We developed a method to measure FTOHs in solid samples by adding solvent extraction prior to headspace SPME-GC/MS. The extraction-headspace SPME-GC/MS method has a quantification limit of 40-43 ng per gram for 6:2 FTOH and 8:2 FTOH in solid samples. This is comparable to the MQLs for the extraction-evaporation-GC/MS method. Removing the solvent evaporation step decreased the risk of contamination and loss of analytes. The developed methods were successfully used in three examples of solid waste study: 1) measuring 6:2 FTOH and 8:2 FTOH above the MQL in gas emissions from a closed landfill, 2) finding 6:2 FTOH above MQL in 9 of 31 solid consumer products, and 3) finding that the release of 6:2 FTOH in simulated landfills containing popcorn bags was linear at a rate of 3.15 ng/g popcorn bags-day and that partial 6:2 FTOH was from the hydrolysis of precursors.

Prevalence and Source Tracing of PFAS in Shallow Groundwater Used for Drinking Water in Wisconsin, USA

Samples from 450 homes with shallow private wells throughout the state of Wisconsin (USA) were collected and analyzed for 44 individual per- and polyfluoroalkyl substances (PFAS), general water quality parameters, and indicators of human waste as well as agricultural influence. At least one PFAS was detected in 71% of the study samples, and 22 of the 44 PFAS analytes were detected in one or more samples. Levels of PFOA and/or PFOS exceeded the proposed Maximum Contaminant Levels of 4 ng/L, put forward by the U.S. Environmental Protection Agency (EPA) in March 2023, in 17 of the 450 samples, with two additional samples containing PFHxS ≳ 9 ng/L (the EPA-proposed hazard index reference value). Those samples above the referenced PFAS levels tend to be associated with developed land and human waste indicators (artificial sweeteners and pharmaceuticals), which can be released to groundwater via septic systems. For a few samples with levels of PFOA, PFOS, and/or PFHxS > 40 ng/L, application of wastes to agricultural land is a possible source. Overall, the study suggests that human waste sources, septic systems in particular, are important sources of perfluoroalkyl acids, especially ones with ≤8 perfluorinated carbons, in shallow groundwater.

Implications of circular textile policies for the future regulation of hazardous substances in textiles in the European Union

The textile industry's business model is currently unsustainable and systemic changes must be made. The transition to a circular textile economy can be a major lever for this. However, it faces multiple issues, including the (in)ability of current legislations to provide sufficient protection regarding hazardous chemicals in recirculating materials. It is therefore crucial to identify legislative gaps that prevent the implementation of a safe circular textile economy, and to identify which chemicals could jeopardize this process. With this study, we aim to identify hazardous substances that could be found in recirculated textiles, to identify and discuss gaps in current regulations covering chemicals in textiles, and to suggest solutions to ensure better safety of circular textiles. We compile and analyze data on 715 chemicals and their associated functions, textile production stage, and hazard data. We also present how chemicals have been regulated over time and discuss regulations' strengths and weaknesses in the perspective of circular economy. We finally discuss the recently proposed Ecodesign regulation, and which key point should be included in the future delegated acts. We found that most of the compiled chemicals present at least one recognized or suspected hazard. Among them, there were 228 CMR (carcinogenic, mutagenic, reprotoxic substances), 25 endocrine disruptors, 322 skin allergens or sensitizers, and 51 respiratory allergens or sensitizers. 30 chemicals completely or partially lack hazard data. 41 chemicals were found to present a risk for consumers, among which 15 recognized or suspected CMR and 36 recognized or suspected allergens/sensitizers. Following the analysis of regulations, we argue that an improved risk assessment of chemicals should consider chemicals specific hazardous properties and product's multiple life cycles, instead of being limited to the product's end-of-life stage. We especially argue that implementing a safe circular textile economy requires that chemicals of concern are eliminated from the market.

Using Geospatial Data and Random Forest To Predict PFAS Contamination in Fish Tissue in the Columbia River Basin, United States

Decision makers in the Columbia River Basin (CRB) are currently challenged with identifying and characterizing the extent of per- and polyfluoroalkyl substances (PFAS) contamination and human exposure to PFAS. This work aims to develop and pilot a methodology to help decision makers target and prioritize sampling investigations and identify contaminated natural resources. Here we use random forest models to predict ∑PFAS in fish tissue; understanding PFAS levels in fish is particularly important in the CRB because fish can be a major component of tribal and indigenous people diet. Geospatial data, including land cover and distances to known or potential PFAS sources and industries, were leveraged as predictors for modeling. Models were developed and evaluated for Washington state and Oregon using limited available empirical data. Mapped predictions show several areas where detectable concentrations of PFAS in fish tissue are predicted to occur, but prior sampling has not yet confirmed. Variable importance is analyzed to identify potentially important sources of PFAS in fish in this region. The cost-effective methodologies demonstrated here can help address sparsity of existing PFAS occurrence data in environmental media in this and other regions while also giving insights into potentially important drivers and sources of PFAS in fish.

Geographic and demographic variability in serum PFAS concentrations for pregnant women in the United States

BACKGROUND

While major pathways of human PFAS exposure are thought to be drinking water and diet, other pathways and sources have also been shown to contribute to a person's cumulative exposure. However, the degree of contribution of these other sources to PFAS body burdens is still not well understood and occurrence data for PFAS in conssumer products and household materials are sparse. Questionnaire data concordant with biomonitoring may improve understanding of associations between other PFAS exposure pathways and exposure in human populations.

OBJECTIVE

This study aims to better understand maternal and early-life exposures to PFAS from various potential sources and pathways in the context of household and community level characteristics.

METHODS

PFAS data from the National Children's Study (NCS) Vanguard Data and Sample Archive Access System were analyzed from serum of 427 pregnant women residing in 7 counties throughout the United States. Location and self-reported questionnaire responses were used to analyze variability in serum concentrations based on demographics, housing characteristics, behaviors, and geography. Spatial mapping analyses incorporated publicly available data to further hypothesize potential sources of exposure in two NCS counties.

RESULTS

Location was associated with serum concentrations for all PFAS chemicals measured. Questionnaire responses for race/ethnicity, income, education level, number of household members, drinking water source, home age, and fast-food consumption were associated with PFAS levels. Statistical differences were observed between participants with the same questionnaire responses but in different locations. Spatial mapping analyses suggested that participants' proximity to local point sources can overshadow expected trends with demographic information.

SIGNIFICANCE

By increasing understanding of maternal and early-life PFAS exposures from various potential sources and pathways, as well as highlighting the importance of proximity to potential sources in identifying vulnerable populations and locations, this work reveals environmental justice considerations and contributes to risk management strategies that maximize public health protection.

IMPACT

This work increases understanding of maternal and early-life PFAS exposures, reveals environmental justice considerations, and contributes to study design and risk management strategies.

The decomposition and emission factors of a wide range of PFAS in diverse, contaminated organic waste fractions undergoing dry pyrolysis

Current treatment options for organic waste contaminated with per- and polyfluoroalkyl substances (PFAS) are generally limited to incineration, composting or landfilling, all resulting in emissions. Dry pyrolysis is a promising emerging alternative to these practices, but there is uncertainty related to the fate of PFAS during this process. The present work first developed a robust method for the determination of PFAS in complex matrices, such as sewage sludge and biochar. Then, a mass balance was established for 56 different PFAS during full-scale pyrolysis (2-10 kg biochar hr^-1, 500-800 °C) of sewage sludges, food waste reject, garden waste and waste timber. PFAS were found in all wastes (56-3651 ng g^-1), but pyrolysis resulted in a ≥ 96.9% removal. Residual PFAS (0.1-3.4 ng g^-1) were detected in biochars obtained at temperatures up to 750 °C and were dominated by long chain PFAS. Emitted PFAS loads ranged from 0.01 to 3.1 mg tonne^-1 of biochar produced and were dominated by short chain PFAS. Emissions made up < 3% of total PFAS-mass in the wastes. Remaining uncertainties are mainly related to the presence of thermal degradation products in flue gas and condensation oils.

Per- and Polyfluoroalkyl Substances in Personal Hygiene Products: The Implications for Human Exposure and Emission to the Environment

Per- and polyfluoroalkyl substances (PFAS) have been related to reproductive toxicity in humans, but their occurrence in some specific personal hygiene products, i.e., sanitary pads, panty liners, tampons, paper diapers, menstrual cups, and bactericidal liquids, has not been extensively studied. This work investigated 31 representative PFAS in six categories of such personal hygiene products (n = 91). Perfluorinated carboxylic acids were the primary PFAS found in the samples, accounting for over 85% of the total concentrations of PFAS. Paper diapers contained the highest sum of PFAS concentrations (64.6 ng/g) followed by sanitary pads (52.3 ng/g) and menstrual cups (21.1 ng/g). The estimated exposure doses of perfluorooctanoic acid through dermal absorption from the use of menstrual cups and paper diapers for infants (adults) were 0.77 and 2.1 (1.2) ng/kg-bw/day, which contributed more than normal dust ingestion. The estimated emission of paper diapers and sanitary pads into the environment was 2.58 and 322 kg/year with an assumed leaching rate of 100%. The potential exposure of PFAS through the use of personal hygiene products observed in this work suggests a previously unreported exposure pathway of these chemicals to humans.

Exposure to perfluoroalkyl substances and women's fertility outcomes in a Singaporean population-based preconception cohort

OBJECTIVES

Experimental models have demonstrated a link between exposure to perfluoroalkyl substances (PFAS) and decreased fertility and fecundability; however, human studies are scarce. We assessed the associations between preconception plasma PFAS concentrations and fertility outcomes in women.

METHODS

In a case-control study nested within the population-based Singapore Preconception Study of Long-Term Maternal and Child Outcomes (S-PRESTO), we measured PFAS in plasma collected in 2015-2017 from 382 women of reproductive age trying to conceive. Using Cox proportional hazards regression (fecundability ratios [FRs]) and logistic regression (odds ratios [ORs]) models, we assessed the associations of individual PFAS with time-to-pregnancy (TTP), and the likelihoods of clinical pregnancy and live birth, respectively, over one year of follow-up, adjusting for analytical batch, age, education, ethnicity, and parity. We used Bayesian weighted quantile sum (BWQS) regression to assess the associations of the PFAS mixture with fertility outcomes.

RESULTS

We found a 5-10 % reduction in fecundability per quartile increase of exposure to individual PFAS (FRs [95 % CIs] for clinical pregnancy = 0.90 [0.82, 0.98] for PFDA; 0.88 [0.79, 0.99] for PFOS; 0.95 [0.86, 1.06] for PFOA; 0.92 [0.84, 1.00] for PFHpA). We observed similar decreased odds of clinical pregnancy (ORs [95 % CIs] = 0.74 [0.56, 0.98] for PFDA; 0.76 [0.53, 1.09] for PFOS; 0.83 [0.59, 1.17] for PFOA; 0.92 [0.70, 1.22] for PFHpA) and live birth per quartile increases of individual PFAS and the PFAS mixture (ORs [95 % CIs] = 0.61 [0.37, 1.02] for clinical pregnancy, and 0.66 [0.40, 1.07] for live birth). Within the PFAS mixture, PFDA followed by PFOS, PFOA, and PFHpA were the biggest contributors to these associations. We found no evidence of association for PFHxS, PFNA, and PFHpS and the fertility outcomes examined.

CONCLUSIONS

Higher PFAS exposures may be associated with decreased fertility in women. The potential impact of ubiquitous PFAS exposures on infertility mechanisms requires further investigation.

Dietary and maternal sociodemographic determinants of perfluoroalkyl and polyfluoroalkyl substance levels in pregnant women

Diet, including drinking water, and demographic characteristics have been associated with PFAS exposure levels in the general population. But data in pregnant women are scarce. We aimed to examine the PFAS levels in relation to these factors in early pregnancy and included 2545 pregnant women in early pregnancy from the Shanghai Birth Cohort. Ten PFAS were measured using high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS-MS) in plasma samples at around 14 weeks of gestation. Geometric mean (GM) ratios were used to estimate the associations between demographic characteristics, food intake and source of drinking water and concentrations of nine PFAS with a detection rate of at least 70%, and the total perfluoroalkyl carboxylic acids (∑PFCA), perfluoroalkyl sulfonic acids (∑PFSA) and all the PFAS concentrations (∑PFAS). Median concentrations of plasma PFAS ranged from 0.03 ng/mL for PFBS to 11.56 ng/mL for PFOA. In the multivariable linear models, maternal age, parity, parental education level, marine fish, freshwater fish, shellfish, shrimps, crabs, animal kidneys, animal liver, eggs, and bone soup in early pregnancy were positively associated with plasma concentrations of certain PFAS. Whereas pre-pregnancy BMI, plant-based foods, and drinking bottled water were negatively associated with some PFAS concentrations. In summary, this study suggested that fish and seafood, animal offal, and high-fat foods (eggs and bone soup) were significant sources of PFAS. PFAS exposure may be reduced by consuming more plant-based foods and potential interventions, such as drinking water treatment.

Perfluoroalkyl substance exposure is associated with asthma and innate immune cell count in US adolescents stratified by sex

Exposure to perfluoroalkyl substances (PFAS) may be harmful to humans; however, previous studies have been inconsistent regarding the potential for PFAS-induced immunosuppresion. This study explored the relationship between PFAS exposure and risks of asthma, wheezing, and immunosuppression in 12-19 year-olds using the National Health and Nutrition Examination Survey (NHANES) data. Logistic regression models were used to reveal associations between serum PFAS levels and risks of asthma, wheezing, asthma attack, and emergency department visits. Pearson's correlation was used to determine the relationship between serum PFAS levels and leukocyte count. Data were also stratified by sex. We found that medium-low levels of serum perfluorooctane sulfonate (PFOS) (6.90-12.40 ng/mL) and serum perfluorooctanoic acid (PFOA) (2.43-3.60 ng/mL) were negatively related, respectively, to current asthma and wheezing in boys, and to wheezing in girls. Meanwhile, boys with medium-high levels (1.50-3.00 ng/mL) of serum perfluorohexanesulfonate (PFHxS) had a high risk of wheezing. Among asthmatic participants, both medium-high levels (3.75-5.07 ng/mL) of serum PFOA and high levels (> 3.92 ng/mL) of PFHxS correlated with asthma attacks in boys; likewise, medium-low levels (0.70-0.99 ng/mL) of serum PFNA correlated with asthma attacks in girls. Also, PFOA and PFNA levels were weakly positively correlated with basophil count, whereas PFOS levels were weakly negatively correlated with eosinophils in asthmatic boys, indicating that basophils may be important in the immune response to PFAS exposure among asthmatics.

Sources, Fate, and Detection of Dust-Associated Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS): A Review

The occurrence of sand and dust storms (SDSs) is essential for the geochemical cycling of nutrients; however, it is considered a meteorological hazard common to arid regions because of the adverse impacts that SDSs brings with them. One common implication of SDSs is the transport and disposition of aerosols coated with anthropogenic contaminants. Studies have reported the presence of such contaminants in desert dust; however, similar findings related to ubiquitous emerging contaminants, such as per- and poly-fluoroalkyl substances (PFAS), have been relatively scarce in the literature. This article reviews and identifies the potential sources of dust-associated PFAS that can accumulate and spread across SDS-prone regions. Furthermore, PFAS exposure routes and their toxicity through bioaccumulation in rodents and mammals are discussed. The major challenge when dealing with emerging contaminants is their quantification and analysis from different environmental media, and these PFAS include known and unknown precursors that need to be quantified. Consequently, a review of various analytical methods capable of detecting different PFAS compounds embedded in various matrices is provided. This review will provide researchers with valuable information relevant to the presence, toxicity, and quantification of dust-associated PFAS to develop appropriate mitigation measures.

The use of gas chromatography - high resolution mass spectrometry for suspect screening and non-targeted analysis of per- and polyfluoroalkyl substances

This study is a workflow development for the analysis, identification, and categorization of per- and polyfluoroalkyl substances (PFAS) using gas chromatography-high resolution mass spectrometry (GC-HRMS) with non-targeted analysis (NTA) and suspect screening techniques. The behavior of various PFAS in a GC-HRMS was studied with regards to retention indices, ionization susceptibility, fragmentation patterns, etc. A custom PFAS database was constructed from 141 diverse PFAS. The database contains mass spectra from electron ionization (EI) mode, as well as MS and MS/MS spectra from positive and negative chemical ionization (PCI and NCI, respectively) modes. Common fragments of PFAS were identified across a diverse set of 141 PFAS analyzed. A workflow for suspect screening of PFAS and partially fluorinated products of incomplete combustion/destruction (PICs/PIDs) was developed which utilized both the custom PFAS database and external databases. PFAS and other fluorinated compounds were identified in both a challenge sample (designed to test the identification workflow) and incineration samples suspected to contain PFAS and fluorinated PICs/PIDs. The challenge sample resulted in a 100% true positive rate (TPR) for PFAS which were present in the custom PFAS database. Several fluorinated species were tentatively identified in the incineration samples using the developed workflow.

Assessing aerobic biotransformation of 8:2 fluorotelomer alcohol in aqueous film-forming foam (AFFF)-impacted soils: Pathways and microbial community dynamics

Production of 8:2 fluorotelomer alcohol (8:2 FTOH) for industrial and consumer products, including aqueous film-forming foams (AFFFs) used for firefighting, has resulted in its widespread occurrence in the environment. However, the fate of 8:2 FTOH at AFFF-impacted sites remains largely unknown. Using AFFF-impacted soils from two United States Air Force Bases, microcosm experiments evaluated the aerobic biotransformation of 8:2 FTOH (extent and byproduct formation) and the dose-response on microbial communities due to 8:2 FTOH exposure. Despite different microbial communities, rapid transformation of 8:2 FTOH was observed during a 90-day incubation in the two soils, and 7:2 secondary fluorotelomer alcohol (7:2 sFTOH) and perfluorooctanoic acid (PFOA) were detected as major transformation products. Novel transformation products, including perfluoroalkane-like compounds (1H-perfluoroheptane, 1H-perfluorohexane, and perfluoroheptanal) were identified by liquid chromatography-high resolution mass spectrometry (LC-HRMS) and used to develop aerobic 8:2 FTOH biotransformation pathways. Microbial community analysis suggests that species from genus Sphingomonas are potential 8:2 FTOH degraders based on increased abundance in both soils after exposure, and the genus Afipia may be more tolerant to and/or involved in the transformation of 8:2 FTOH at elevated concentrations. These findings demonstrate the potential role of biological processes on PFAS fate at AFFF-impacted sites through fluorotelomer biotransformation.

1 H-Nuclear Magnetic Resonance Metabolomics Analysis of Arabidopsis thaliana Exposed to Perfluorooctanoic Acid and Perfluoroctanesulfonic Acid

Perfluorinated alkyl substances (PFAS) are ubiquitous environmental contaminants that are widely used in consumer products and fire suppression foams. The presence of PFAS in ground and surface water can create a route for PFAS to enter the soil, exposing ecosystems (including agroecosystems), where they will move through the food web via biomagnification. The toxicity of PFAS to plants, particularly in agricultural ecosystems, is of emerging concern due to the application of biosolids that are often contaminated with PFAS. Nevertheless, due to the low concentrations of PFAS in most agricultural soils, the direct impact of PFAS on plant health is not well understood. We used ¹ H-nuclear magnetic resonance (NMR) metabolomics to explore the effects of exposure of two key PFAS, perfluorooctanoic acid and perfluorooctanesulfonic acid, on Arabidopsis thaliana, a model organism. We found that Arabidopsis exhibited an accumulation of multiple metabolites, including soluble sugars (glucose and sucrose), multiple amino acids, and tri-carboxylic acid (TCA) cycle intermediates, suggesting that PFAS exposure impacts the metabolism of plants by causing an accumulation of stress-related amino acids and soluble sugars that drives increased activity of the TCA cycle. The present study shows that ¹ H-NMR metabolomics is a viable tool for investigating changes in the metabolic profile of plants exposed to PFAS and can be used to illuminate the stress response of plants in a high-throughput, nonbiased manner. Environ Toxicol Chem 2023;42:663-672. © 2022 SETAC.

Legacy and emerging poly- and perfluoroalkyl substances in wastewater treatment plant and receiving water: abundance, removal, and potential ecological risk

Poly- and perfluoroalkyl substances (PFASs) are toxic persistent organic pollutants and bioaccumulative chemicals, which affect the environment and ecology. PFASs in the wastewater treatment plant (WWTP) and receiving river downstream were investigated. Fourteen out of eighteen PFASs were detected, ranging from 197 to 0.14 ng L^-1. The main pollutants were 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoro-propoxy) propanoic acid (HFPO-DA), perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA). The concentration of HFPO-DA (181 ng L^-1) was the highest in influent, which indicated the use and emission of PFASs in the sewage collection region of WWTP changed from legacy to emerging ones. However, PFOS from catering wastewater as the main source was dominant PFASs in the reclaimed water. Biological treatment could be effective in the removal of PFASs, especially for HFPO-DA. HFPO-DA could directly bind to cytochrome P450 and bring potential ecotoxicity to the surrounding environment, and the ecological risk of degradation products should be under consideration. Coagulation might result in PFASs release from sludge. More attention should be paid to sewage treatment process decision of WWTP for the control of PFASs.

Effects of physicochemical properties and co-existing zinc agrochemicals on the uptake and phytotoxicity of PFOA and GenX in lettuce

Even though the potential toxicity and treatment methods for per- and polyfluoroalkyl substances (PFAS) have attracted extensive attention, the plant uptake and accumulation of PFAS in edible plant tissues as a potential pathway for human exposure received little attention. Our study in a hydroponic system demonstrated that perfluorooctanoic acid (PFOA) and its replacing compound, 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propanoic acid (GenX) displayed markedly different patterns of plant uptake and accumulation. For example, the root concentration factor (RCF) of PFOA in lettuce is almost five times of that of GenX while the translocation factor (TF) of GenX is about 66.7% higher than that for PFOA. The co-presence of zinc amendments affected the phyto-effect of these two compounds and their accumulation in plant tissues, and the net effect on their plant accumulation depended on both the properties of Zn amendments and PFAS. Zinc oxide nanoparticles (ZnONPs) at 100 mg/L did not affect the uptake of PFOA in either lettuce roots or shoots; however, Zn2+ at the same concentration significantly increased PFOA accumulation in both tissues. In contrast, both Zn amendments significantly lowered the accumulation of GenX in lettuce roots, but only ZnONPs significantly hindered the GenX accumulation in lettuce shoots. The co-exposure to ZnONPs and PFOA/GenX resulted in lower oxidative stress than the plants exposed to PFOA or GenX alone. However, both zinc agrochemicals with or without PFAS led to lower root dry biomass. The results shed light on the property-dependent plant uptake of PFAS and the potential impact of co-existing nanoagrochemicals and their dissolved ions on plant uptake of PFOA and GenX.

Quantitative relationships of perfluoroalkyl acids in drinking water associated with serum concentrations above background in adults living near contamination hotspots in Sweden

Contaminated drinking water (DW) is a major source of exposure to per- and polyfluoroalkyl substances (PFAS) at locations around PFAS production/use facilities and military airports. This study aimed to investigate quantitative relationships between concentrations in DW and serum of nine perfluoroalkyl acids (PFAAs) in Swedish adult populations living near contamination hotspots. Short-chained (PFPeA, PFHxA, PFHpA, and PFBS) and long-chained PFAAs (PFOA, PFNA, PFDA, PFHxS and PFOS) were measured in DW and serum. We matched DW and serum concentrations for a total of 398 subjects living or working in areas receiving contaminated DW and in one non-contaminated area. Thereafter, linear regression analysis with and without adjustments for co-variates was conducted. This enabled to derive (i) serum concentrations at background exposure (C_B) from sources other than local DW exposure (i.e. food, dust and textiles) at 0 ng/L DW concentration, (ii) population-mean PFAA serum:water ratios (SWR) and (iii) PFAA concentrations in DW causing observable elevated serum PFAA concentrations above background variability. Median concentrations of the sum of nine PFAAs ranged between 2.8 and 1790 ng/L in DW and between 7.6 and 96.9 ng/mL in serum. DW concentration was the strongest predictor, resulting in similar unadjusted and adjusted regression coefficients. Mean C_B ranged from <0.1 (PFPeA, PFHpA, PFBS) to 5.1 ng/mL (PFOS). Serum concentrations increased significantly with increasing DW concentrations for all PFAAs except for PFPeA with SWRs ranging from <10 (PFHxA, PFHpA and PFBS) to 111 (PFHxS). Observed elevated serum concentrations above background variability were reached at DW concentrations between 24 (PFOA) and 357 ng/L (PFHxA). The unadjusted linear regression predictions agreed well with serum concentrations previously reported in various populations exposed to low and high DW levels of PFOA, PFHxS and PFOS. The quantitative relationships derived herein should be helpful to translate PFAA concentrations in DW to concentrations in serum at the population level.

Detection and differentiation of per- and polyfluoroalkyl substances (PFAS) in water using a fluorescent imprint-and-report sensor array

Widespread industrial use of per- and polyfluoroalkyl substances (PFAS) as surfactants has led to global contamination of water sources with these persistent, highly stable chemicals. As a result, humans and wildlife are regularly exposed to PFAS, which have been shown to bioaccumulate and cause adverse health effects. Methods for detecting PFAS in water are currently limited and primarily utilize mass spectrometry (MS), which is time-consuming and requires expensive instrumentation. Thus, new methods are needed to rapidly and reliably assess the pollution level of water sources. While some fluorescent PFAS sensors exist, they typically function in high nanomolar or micromolar concentration ranges and focus on sensing only 1-2 individual PFAS. Our work aims to address this problem by developing a fluorescent sensor for both individual PFAS, as well as complex PFAS mixtures, and demonstrate its functionality in tap water samples. Here we show that dynamic combinatorial libraries (DCLs) with simple building blocks can be templated with a fluorophore and subsequently used as sensors to form an array that differentially detects each PFAS species and various mixtures thereof. Our method is a high-throughput analysis technique that allows many samples to be analyzed simultaneously with a plate reader. This is one of the first examples of a fluorescent PFAS sensor array that functions at low nanomolar concentrations, and herein we report its use for the rapid detection of PFAS contamination in water.

Bioaccumulation of perfluoroalkyl substances in the Lake Erie food web

The bioaccumulation and biomagnification of perfluoroalkyl substances (PFAS) in the Lake Erie food web was investigated by analyzing surface water and biological samples including 10 taxa of fish species, 2 taxa of benthos and zooplankton. The carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopic composition and fatty acids profiles of biological samples were used to evaluate the food web structure and assess the biomagnification of PFAS. Perfluorooctane sulfonate (PFOS) dominated the total PFAS (ΣPFAS) concentration (50-90% of ΣPFAS concentration), followed by C9-C11 perfluorinated carboxylic acids (PFCAs). The highest PFOS concentrations (79 ± 4.8 ng/g, wet weight (wwt)) and ΣPFAS (88 ± 5.2 ng/g, wwt) were detected in yellow perch (Perca flavescens). The C8-C14 PFAS biomagnification factors (BMFs) between apex piscivorous fish and prey fish were found to be generally greater than 1, indicative of PFAS biomagnification, while biodilution (BMF<1) was observed between planktivorous fish and zooplankton. Trophic magnification factors (TMFs) of C8-C14 PFCA were not correlated with perfluoroalkyl chain length. The C4-C9 PFAS were detected in the surface water of Lake Erie, and PFBA was found to have the highest concentrations (2.1-2.8 ng/L) among all PFAS detected. The log of bioaccumulation factor (BAF) was found to generally increase with increasing log K_ow for C6, 8, and 9 PFAS in all selected species from three tropic levels.

Targeted PFAS analyses and extractable organofluorine - Enhancing our understanding of the presence of unknown PFAS in Norwegian wildlife

With the current possible presence of thousands of PFAS compounds in industrial emissions, there is an increasing need to assess the impacts of PFAS regulation of conventional PFAS on one hand and the exposure to emerging and yet unknown PFAS on the other. Today's analytical methodologies using targeted approaches are not sufficient to determine the complete suite of PFAS present. To evaluate the presence of unknown PFAS, we investigated in this study the occurrence of an extended range of target PFAS in various species from the marine and terrestrial Norwegian environment, in relation to the extractable organofluorine (EOF), which yields the total amount of organofluorine. The results showed a varying presence of extractable fluorinated organics, with glaucous gull eggs, otter liver and polar bear plasma showing the highest EOF and a high abundance of PFAS as well. The targeted PFAS measurements explained 1% of the organofluorine for moose liver as the lowest and 94% for otter liver as the highest. PFCAs like trifluoroacetic acid (TFA, reported semi-quantitatively), played a major role in explaining the organic fluorine present. Emerging PFAS as the perfluoroethylcyclohexane sulfonate (PFECHS), was found in polar bear plasma in quantifiable amounts for the first time, confirming earlier detection in arctic species far removed from emission sources. To enable a complete organic fluorine mass balance in wildlife, new approaches are needed, to uncover the presence of new emerging PFAS as cyclic- or ether PFAS together with chlorinated PFAS as well as fluorinated organic pesticides and pharmaceuticals.

Paints: A Source of Volatile PFAS in Air─Potential Implications for Inhalation Exposure

Paints are widely used in indoor settings yet there are no data for volatile per- and polyfluoroalkyl substances (PFAS) for paints or knowledge if paints are potentially important sources of human exposure to PFAS. Different commercial paints (n = 27) were collected from local hardware stores and analyzed for volatile PFAS by gas chromatography-mass spectrometry (GC-MS), nonvolatile PFAS by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-qTOF), and total fluorine by ¹⁹F nuclear magnetic resonance spectroscopy (NMR). Diluted paint required clean up to remove 6:2 fluorotelomer phosphate diester (diPAP), which thermally transforms into 6:2 FTOH at 280 °C (GC inlet temperature). Only 6:2 FTOH (0.9-83 μg/g) and 6:2 diPAP (0.073-58 μg/g) were found in five exterior and nine interior paints and only accounted for a maximum of 17% of total fluorine. Upon drying, 40% of the FTOH mass was lost, and the loss was verified by measurements of the cumulative FTOH mass measured in the air of a small, confined space over a 3 h period. Based on the liquid paint results, the ConsExpo model was used for potential exposure assessment and one commercial paint exceeded the chosen reference dose (5 μg/kg-day) for children and adults, indicating the potential for human exposure during painting.

Fluorine-Containing Covalent Organic Frameworks: Synthesis and Application

Covalent organic frameworks (COFs) are a type of crystalline porous polymers that possess ordered structures and eternal pores. Because of their unique structural characteristics and diverse functional groups, COFs have been used in various application fields, such as adsorption, catalysis, separation, ion conduction, and energy storage. Among COFs, the fluorine-containing COFs (fCOFs) have been developed for special applications by virtue of special physical and chemical properties resulting from fluorine element, which is a nonmetallic halogen element and possesses strong electronegativity. In the organic chemistry field, introducing fluorine into chemicals enables those chemicals to exhibit many interesting properties, and fluorine chemistry increasingly plays an important role in the history of chemical development. The introduction of fluorine in COFs can enhance the crystallinity, porosity, and stability of COFs, making COFs having superior performances and some new applications. In this review, the synthesis and application of fCOFs are systematically summarized. The application involves photocatalytic production of hydrogen peroxide, photocatalytic water splitting, electrocatalytic CO₂ reduction, adsorption for different substances (H₂ , pesticides, per-/polyfluoroalkyl substances, polybrominated diphenyl ethers, bisphenols, and positively charged organic dye molecules), oil-water separation, energy storage (e.g., zinc-ion batteries, lithium-sulfur batteries), and proton conduction. Perspectives of remaining challenges and possible directions for fCOFs are also discussed.

Are cosmetics a significant source of PFAS in Europe? product inventories, chemical characterization and emission estimates

In this study, emission of per- and polyfluoroalkyl substances (PFAS) from the use of cosmetics in the European Economic Area (EEA; not including Lichtenstein and Iceland) was estimated for the first time. Using the European Commission database for information on cosmetic substances and ingredients (CosIng) ∼170 structures containing at least -CF₂- or -CF₃ were identified as ingredients in cosmetics on the European market. These structures were then cross referenced against the Cosmetic Database "CosmEthics" to identify PFAS-containing products. Among these products, polytetrafluoroethylene (PTFE) and C9-15 fluoroalcohol phosphate were the most frequently listed PFAS ingredients. Thereafter, a sample of 45 cosmetics spanning 5 product categories was purchased in Sweden and characterized for total fluorine (TF), extractable organofluorine (EOF), and target PFAS. Using measured concentrations, the share of PFAS-containing products in each product category, sales data from Cosmetics Europe, as well as other parameters and assumptions, the annual emission of PFAS from cosmetics after use was estimated. Annual EEA-wide TF and EOF-based emissions ranged from ∼17-38 000 kg F per year and 37-5100 kg F per year, respectively, representing combined emission to wastewater and solid waste (low to high emission scenario). Sum perfluoroalkyl carboxylic acid (PFCA) emissions were considerably lower (21 kg ∑PFCAs per year; high scenario). While TF- and EOF-based emissions are significant, they are considerably lower than estimates of TF emission from washing of PFAS-coated textiles in the EU. This work provides the first estimate of PFAS emissions from cosmetics and highlights the importance of using a multi-platform analytical approach for PFAS emission estimates.

Long-distance transport of per- and polyfluoroalkyl substances (PFAS) in a Swedish drinking water aquifer

Use of per- and polyfluoroalkyl substance (PFAS)-containing aqueous film-forming foams (AFFF) at firefighting training sites (FFTS) has been linked to PFAS contamination of drinking water. This study investigated PFAS transport and distribution in an urban groundwater aquifer used for drinking water production that has been affected by PFAS-containing AFFF. Soil, sediment, surface water and drinking water were sampled. In soil (n = 12) at a FFTS with high perfluorooctane sulfonate (PFOS) content (87% of ∑PFAS), the ∑PFAS concentration (n = 26) ranged from below detection limit to 560 ng g^-1 dry weight. In groundwater (n = 28), the ∑PFAS concentration near a military airbase FFTS reached 1000 ng L^-1. Principal component analysis (PCA) identified the military FFTS as the main source of PFAS contamination in drinking water wellfields >10 km down-gradient. Groundwater samples taken close to the military FFTS site showed no ∑PFAS concentration change between 2013 and 2021, while a location further down-gradient showed a transitory 99.6% decrease. Correlation analysis on PFAS composition profile indicated that this decrease was likely caused by dilution from an adjacent conflating aquifer. ∑PFAS concentration reached 15 ng L^-1 (PFOS 47% and PFHxS 41% of ∑PFAS) in surface river water (n = 6) and ranged between 1 ng L^-1 and 8 ng L^-1 (PFHxS 73% and PFBS 17% of ∑PFAS) in drinking water (n = 4). Drinking water had lower PFAS concentrations than the wellfields due to PFAS removal at the water treatment plant. This demonstrates the importance of monitoring PFAS concentrations throughout a groundwater aquifer, to better understand variations in transport from contamination sources and resulting impacts on PFAS concentrations in drinking water extraction areas.

Biotransformation of 8:2 Fluorotelomer Alcohol in Soil from Aqueous Film-Forming Foams (AFFFs)-Impacted Sites under Nitrate-, Sulfate-, and Iron-Reducing Conditions

The environmental fate of per- and polyfluoroalkyl substances (PFAS) in aqueous film-forming foams (AFFFs) remains largely unknown, especially under the conditions representative of natural subsurface systems. In this study, the biotransformation of 8:2 fluorotelomer alcohol (8:2 FTOH), a component of new-generation AFFF formulations and a byproduct in fluorotelomer-based AFFFs, was investigated under nitrate-, iron-, and sulfate-reducing conditions in microcosms prepared with AFFF-impacted soils. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high-resolution mass spectrometry (HRMS) were employed to identify biotransformation products. The biotransformation was much slower under sulfate- and iron-reducing conditions with >60 mol % of initial 8:2 FTOH remaining after ∼400 days compared to a half-life ranging from 12.5 to 36.5 days under nitrate-reducing conditions. Transformation products 8:2 fluorotelomer saturated and unsaturated carboxylic acids (8:2 FTCA and 8:2 FTUA) were detected under all redox conditions, while 7:2 secondary fluorotelomer alcohol (7:2 sFTOH) and perfluorooctanoic acid (PFOA) were only observed as transformation products under nitrate-reducing conditions. In addition, 1H-perfluoroheptane (F(CF₂)₆CF₂H) and 3-F-7:3 acid (F(CF₂)₇CFHCH₂COOH) were identified for the first time during 8:2 FTOH biotransformation. Comprehensive biotransformation pathways for 8:2 FTOH are presented, which highlight the importance of accounting for redox condition and the related microbial community in the assessment of PFAS transformations in natural environments.

Investigating the cytotoxic redox mechanism of PFOS within Hep G2 by hyperspectral-assisted scanning electrochemical microscopy

Perfluorooctane sulfonate (PFOS) is one of the most lethal per- and poly-fluoroalkyl substances (PFAS). Generally, exposure effects are studied through case-controlled studies, cohort studies, or cell assays. Unfortunately, most studies involving two-dimensional cell cultures require cell lysis or fixation. For in vitro studies, fluorescence microscopy has been useful, but methods to simultaneously discern phototoxic effects during an experiment are limited. Here, we use hepatocarcinoma (Hep G2) cells to examine the redox mechanism of PFOS cytotoxicity in vitro, while using hyperspectral-assisted scanning electrochemical microscopy (SECM) to differentiate between PFOS and redox mediator induced stress. Specifically, we correlate an increase in the electrochemical response of ferrocenemethanol oxidation with an increase in intracellular reactive oxygen species. Corresponding hyperspectral images of redox indicative-fluorophores implicate superoxide in the cytotoxic redox mechanism.