Per- and polyfluoroalkyl substances (PFAS) in United States tapwater: Comparison of underserved private-well and public-supply exposures and associated health implications

A novel method for detecting per- and polyfluoroalkyl substances (PFAS) by colorimetric emulsion extraction

Per- and polyfluoroalkyl substances (PFAS) are a class of fluorinated contaminants of concern due to their long environmental persistence, biological uptake and toxicological implications. Mass spectrometry is currently heavily utilized for PFAS analysis and is capable of precise and selective measurements down to parts per trillion (ppt). However, these are labor-intensive laboratory-only methods that require a substantial expertise and specialized equipment, resulting in high cost and long waiting periods which limit their utility in providing rapid, high-quantity and data rich (large number of samples) PFAS contamination screening capability at both local and regional scales. A rapid and fieldable screening method is needed to improve surveying efficiency to enable prioritization of resources where in-depth standard analysis is required. In this manuscript, a novel emulsion extraction methodology is introduced which isolates PFAS from aqueous media. When paired with colorimetric techniques, the method facilitates rapid detection of PFAS at concentrations ranging from part-per-million (ppm) to part-per-trillion (ppt) within minutes; herein, we demonstrate visual (naked eye) colorimetric detection of PFOA below 30 ppt. This semi-quantitative emulsion extraction method represents a new means for concentrating PFAS for both detection and remediation purposes in a cost-effective and scalable manner. The cost to construct the prototype kit used in this study-which is indefinitely reuseable-using commercially sourced components and 3D printed housing was less than $150, with material costs per test of less than $2. When fully developed, the kit may therefore be deployed to facilitate efficient screening for PFAS to expedite assessments in the field or in facilities, allowing for rapid identification of sites requiring more detailed laboratory analysis.

Exposure to Legacy Per- and Polyfluoroalkyl Substances from Diet and Drinking Water in California Adults, 2018-2020

People are exposed to per- and polyfluoroalkyl substances (PFAS) through multiple sources, with diet historically considered a major source in general populations. This study characterized legacy PFAS in serum from 700 California adults and examined contributions from diet and drinking water. We applied robust regression to estimate associations between nontransformed serum PFAS concentrations, self-reported food consumption, and drinking water PFAS concentrations measured under the USEPA's third Unregulated Contaminant Monitoring Rule (2013-2015). Detectable drinking water concentrations were associated with increased serum perfluorooctanoic acid (PFOA) (0.26 ng/mL; 95% CI: 0.077, 0.43), perfluorohexanesulfonic acid (PFHxS) (0.64 ng/mL; 95% CI: 0.058, 1.23), and perfluorooctanesulfonic acid (PFOS) (0.39 ng/mL; 95% CI: -0.76, 0.86). Seafood consumption was associated with increased perfluorononanoic acid (PFNA) (0.013 ng/mL; 95% CI: 0.0058, 0.021), perfluorodecanoic acid (PFDeA) (0.0059 ng/mL; 95% CI: 0.0026, 0.0092), and perfluoroundecanoic acid (PFUnDA) (0.010 ng/mL; 95% CI: 0.0054, 0.015), while eggs were associated with increased PFDeA (0.0035 ng/mL; 95% CI: 0.00010, 0.0069) and PFNA (0.0073 ng/mL; 95% CI: 0.00017, 0.014). Findings could indicate that dietary contributions may be less than those in earlier studies conducted in other populations, possibly due to shifts in PFAS production over the past 20 years, and that drinking water remains an important source of exposure to PFOA and PFHxS in this population.

Tapwater exposures, residential risk, and mitigation in a PFAS-impacted-groundwater community

Tapwater (TW) safety and sustainability are priorities in the United States. Per/polyfluoroalkyl substance(s) (PFAS) contamination is a growing public-health concern due to prolific use, widespread TW exposures, and mounting human-health concerns. Historically-rural, actively-urbanizing communities that rely on surficial-aquifer private wells incur elevated risks of unrecognized TW exposures, including PFAS, due to limited private-well monitoring and contaminant-source proliferation in urbanizing landscapes. Here, a broad-analytical-scope TW-assessment was conducted in a hydrologically-vulnerable, Mississippi River alluvial-island community, where PFAS contamination of the shallow-alluvial drinking-water aquifer has been documented, but more comprehensive contaminant characterization to inform decision-making is currently lacking. In 2021, we analyzed 510 organics, 34 inorganics, and 3 microbial groups in 11 residential and community locations to assess (1) TW risks beyond recognized PFAS issues, (2) day-to-day and year-to-year risk variability, and (3) suitability of the underlying sandstone aquifer as an alternative source to mitigate TW-PFAS exposures. Seventy-six organics and 25 inorganics were detected. Potential human-health risks of detected TW exposures were explored based on cumulative benchmark-based toxicity quotients (∑TQ). Elevated risks (∑TQ ≥ 1) from organic and inorganic contaminants were observed in all alluvial-aquifer-sourced synoptic samples but not in sandstone-aquifer-sourced samples. Repeated sampling at 3 sites over 52-55 h indicated limited variability in risk over the short-term. Comparable PFAS-specific ∑TQ for spatial-synoptic, short-term (3 days) temporal, and long-term (3 years quarterly) temporal samples indicated that synoptic results provided useful insight into the risks of TW-PFAS exposures at French Island over the long-term. No PFAS detections in sandstone-aquifer-sourced samples over a 3 year period indicated no PFAS-associated risk and supported the sandstone aquifer as an alternative drinking-water source to mitigate community TW-PFAS exposures. This study illustrated the importance of expanded contaminant monitoring of private-well TW, beyond known concerns (in this case, PFAS), to reduce the risks of a range of unrecognized contaminant exposures.

United States Environmental Protection Agency's Perfluorooctanoic Acid, Perfluorooctane Sulfonic Acid, and Related Per- and Polyfluoroalkyl Substances 2024 Drinking Water Maximum Contaminant Level: Part 1 - Analysis of Public Comments

In March 2023, the EPA proposed a 4.0 ppt maximum contaminant level (MCL) for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) (each) and a hazard index approach for four other PFAS. The EPA sought public feedback on the proposed MCL in early 2023 and received 1626 comment submissions via the PFAS docket website (Docket ID: EPA-HQ-OW-2022-0114). Final MCLs were promulgated on April 10, 2024. Our analysis of the PFAS docket identified 128 comments that had a reasonable degree of scientific merit, with 57 comments endorsing the regulations and 71 questioning the MCLs public health utility. Critics noted the lack of evidence for adverse health effects at low PFAS exposures, the rule's significant impact on the economy, and the EPA's selection of published papers which the Agency chose to support their views. Many well-substantiated comments highlighted that few, if any, adverse health effects were reported at doses as much as 100-1000 times above those associated with the proposed drinking water guidelines. We found that the comments which discussed the evidence linking PFAS exposures below 200 ppt in drinking water to adverse health effects were equivocal. Most of the well-documented science based comments indicated that the data did not justify setting a 4.0 ppt MCL. It was noted that the EPA MCL was quite different from drinking water standards in other countries (up to 8-140 fold lower). During the review, it became apparent that a 4.0 ppt MCL may have little effect on PFAS blood concentrations in most Americans since drinking water accounts for less than 20% of their total PFAS intake. Additionally, a significant portion of the American population consumes minimal amounts of tap water. Commenters noted that the financial burden for treatment and cleanup was much higher than what was reported in the justification for the final MCL which was submitted to the Office of Management and Budget (OMB) and eventually promulgated. It is possible that EPA underestimated the financial impact on the nation by up to 100 to 200-fold. Our analysis indicates that many, if not most, of the scientifically rigorous comments on the EPA's proposed MCL were not acknowledged or considered by the Agency. We conclude the article by offering sixteen recommendations for the EPA to consider if Congress or the courts choose to reopen the evaluation of these MCLs. These included convening an international expert panel, reevaluating the appropriateness of the LNT model for PFAS, ensuring adequate time for study quality assessment and cost-benefit analysis, considering an approach to implementing a series of MCLs, critically reevaluating scientific studies, adhering to EPA risk assessment guidelines, addressing SDWA compliance concerns, revisiting the Hazard Index approach, and ensuring thorough and transparent review of public comments.

United States Environmental Protection Agency's Perfluorooctanoic Acid, Perfluorooctane Sulfonic Acid, and Related Per- and Polyfluoroalkyl Substances 2024 Drinking Water Maximum Contaminant Level: Part 2 - Fifteen Misconceptions About the Health Hazards

This paper examines widely held beliefs about the six per- and polyfluoroalkyl substances (PFAS) addressed in the final U.S. Environmental Protection Agency's (EPA) rule on PFAS in drinking water (e.g., the Maximum Contaminant Levels - MCLs). Based on our understanding of the scientific literature and the comments submitted by stakeholders regarding the EPA's regulation that was promulgated in April 2024, we identified 15 misconceptions that had a weak scientific foundation. These are now memoralized in the MCLs for the six PFAS but remain debated due to ongoing ambiguous research findings. Many critics of the MCLs found the EPA's systematic review of the published relevant information, particularly the toxicology of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), to be inadequate. The following seven views are among the most important. First, the EPA asserted that the toxicology of these six chemicals was poorly understood and lacked sufficient data to determine a safe daily intake level for chronic health effects; nonetheless, they promulgated what may be the costliest environmental regulation to date. Notably, adverse effects remain difficult to demonstrate in occupationally exposed individuals even at blood concentrations 50-100 times higher than current background PFAS levels. Second, the Agency indicated that the epidemiology data showed that exposure to PFOA and PFOS caused kidney and potentially other cancers, yet the data were equivocal and do not support that assertion. Third, it was stated that specific non-cancer effects, such as heart disease, would be prevented under the promulgated rule; however, the studies that they relied upon do not show an increased incidence of heart disease even in highly exposed populations. Fourth, the Agency relied on animal data to support its views on the likely toxic effects in humans, despite ample toxicology data that animals, particularly rodents, are poor predictors of the human response to PFAS exposures. Fifth, the EPA predicted a reduction in healthcare expenditures that would offset much of the cost of complying with the MCL, but, they did not have adequate data to support this prediction. Sixth, the EPA suggested that these six PFAS act through a shared mechanism of action (i.e., PPARα pathway induction); however, data indicate that PPARα induction in humans may be 80% less than what is observed in rodents. Also, induction of the PPARα pathway is not a cause of systemic disease. Seventh, the Agency failed to disclose that achieving the new MCL would yield negligible reductions in blood PFAS levels even among highly exposed populations, given drinking water accounts for only 20% or less of total PFAS exposure. The survey that could answer that question, the EPA's fifth Unregulated Contaminant Monitoring Rule, was only 25% complete at the time the MCL was promulgated. Overall, our analysis concluded that while the EPA's intent to regulate these chemicals due to their environmental presence was necessary, the derivation of the MCLs and the alleged health effects was based on the application of the precautionary principle rather than robust scientific evidence.

Effectiveness of pitcher and bottle filters to remove poly- and perfluoroalkyl substances (PFAS) from drinking water

The occurrence of poly- and perfluoroalkyl substances (PFAS) in drinking water poses significant health risks. In this study the effectiveness of 12 popular pitcher and 5 bottle filters in removing 25 fluorinated contaminants from drinking water was evaluated. Twenty individual PFAS, outlined in Drinking Water Directive 2020/2184 as "Sum of PFAS" and 5 emerging PFAS, were considered. The average efficiency of PFAS removal by the tested filters ranged from 31 % to 99 % for the sum of 20 legacy compounds, and from 19 % to 99 % for emerging ones. Over 80 % reduction was recorded for 9 tested filters. In most examined cases, the filter efficiency increased with alkyl chain length for both perfluorinated carboxylic and sulfonic acids. Four filters were found to reduce the concentration of Σ20PFAS from 2000 ng/L to <100 ng/L, meeting the Directive's limit. Additionally, the best filtration bed decreased the sum of PFAS from 100 ng/L to <6 ng/L for model water and from 25 ng/L to 0.6 ng/L for real water, indicating ≥94 % removal efficiency in both cases. The Brunauer-Emmett-Teller (BET) surface area (SBET) and micropore volume were key factors influencing PFAS removal efficiency in the pitcher filter. The obtained results highlight important information regarding drinking water quality and safety.

Improving the Hydrophobicity of Powder Activated Carbon to Enhance the Adsorption Kinetics of Per- and Polyfluoroalkyl Substances

Per- and polyfluoroalkyl substances (PFAS) are difficult to treat by using conventional drinking water treatment technologies. Herein, we upgrade a commercially available powder activated carbon (PAC) via an acid wash and pyrolysis to amplify hydrophobicity and enhance PFAS adsorption. Minimal differences in overall surface area, micropore volume and area, and external surface area were observed between acid-washed and pyrolyzed PACs. X-ray photoelectron spectroscopy, contact angle measurements, and scanning electron microscopy evidenced ∼5% reduced oxygen content and noticeable hydrophobicity increases for the pyrolyzed PAC, without altering morphology. Adsorption isotherms of perfluorooctanoic acid (PFOA) showed no major increases to adsorption capacity, but more rapid adsorption kinetics of PFOA and perfluorobutanesulfonic acid (PFBS) to the pyrolyzed PAC, in both low and high PFAS concentration tests, were revealed in both reagent water and synthetic natural organic matter, with overall greater removal values (e.g., ∼90% removal vs 60%, in water after 1 h at 2 mg/L PFOA). PFOA and PFBS adsorption behavior adhered to pseudo-second-order kinetics (R 2 = 0.843-0.992). Density functional theory calculations quantitatively evaluated adsorption energies of PFOA and PFBS onto a graphene skeleton containing different organic functional groups, finding supportive outcomes. This work greater informs the importance of hydrophobicity for PFAS adsorption onto PAC.

Hold My Beer: The Linkage between Municipal Water and Brewing Location on PFAS in Popular Beverages

Beer has been a popular beverage for millennia. As water is a main component of beer and the brewing process, we surmised that the polyfluoroalkyl substances (PFAS) presence and spatial variability in drinking water systems are a PFAS source in beers. This is the first study to adapt EPA Method 533 to measure PFAS in beer from various regions, brewery types, and water sources. Statistical analyses were conducted to correlate PFAS in state-reported drinking water, and beers were analyzed by brewing location. PFAS were detected in most beers, particularly from smaller scale breweries located near drinking water sources with known PFAS. Perfluorosulfonic acids, particularly PFOS, were frequently detected, with PFOA or PFOS above U.S. EPA's Maximum Contaminant Limits in some beers. There was also a county-level correlation between the total PFAS, PFOA, and PFBS concentrations in drinking water and beers. Given that approximately 18% of U.S. breweries are located within zip codes with detectable PFAS in municipal drinking water, our findings, which link PFAS in beer to the brewery water source, are intended to help inform data-driven policies on PFAS in beverages for governmental agencies, provide insights for brewers and water utilities on treatment needs, and support informed decision-making for consumers.

Analyzing the Release of Per- and Polyfluoroalkyl Substances from Spent Granular Activated Carbons by Standard Leaching Procedures

The recent national primary drinking water regulation for per- and polyfluoroalkyl substances (PFAS) is expected to drive a nationwide increase in granular activated carbon (GAC) usage in water treatment facilities across the United States. Proper management of PFAS-laden GAC waste streams is essential to prevent potential recontamination. This study systematically evaluates PFOA and PFOS leaching from four commercial GACs using three standard batch leaching procedures. Our findings indicate that PFOA leached 1-2 orders of magnitude more than PFOS across all GAC types and leaching procedures. In general, PFAS leaching was more notable for alkaline leaching conditions, especially for wood-based GAC. Additionally, real groundwater spiked with an 8 PFAS mixture was used to load GAC for leaching propensity demonstration, and similar conclusions were reached, where leaching was generally greater for shorter-chain and more hydrophilic PFAS. PFBA exhibited the highest leaching (10.4%), followed by GenX (0.91%) and PFBS (0.75%), while minimal desorption (<0.02%) was observed for long-chain PFOA, PFOS, PFOSA, and PFNA. The study concluded that a complex interplay of multiple interactions between the GAC surface, PFAS molecules, and constituents of leaching solutions controls leaching.

Personal relevance moderates the effect of conflicting information on risk perception and behavioral outcomes

Conflicting information that arises from scientific disagreement poses challenges to effective risk communication. This study explores the impact of conflicting information on risk perception and downstream risk-mitigation behavioral intention and policy support. The research context is PFAS (per- and polyfluoroalkyl substances) contamination. We conducted an online experiment featuring a 2 (information type: conflicting vs. consistent) × 2 (personal relevance: high vs. low) between-subjects factorial design with 1232 American adult participants. Results indicated that exposure to conflicting information dampened risk perception, which subsequently reduced risk-mitigation behavioral intention and policy support, but only when participants perceived the risk from PFAS as less personally relevant. These findings underscore the importance of providing consistent information to the public on emerging environmental risks that bear uncertain health impacts.

Assessment of PFAS levels in drinking water: A case study from Poznań County (Poland)

Exposure to per- and polyfluoroalkyl substances (PFAS) through drinking water has emerged as a significant public health concern due to their persistent, bioaccumulative nature and adverse health effects. Drinking water is the primary non-occupational source of PFAS exposure. Recently, investigative journalism has alerted about the presumptive contamination of drinking water at various European sites, including Poland. However, direct data on PFAS concentrations in raw and treated drinking water in Poland remain scarce. Therefore, this study analyzed the concentrations of 20 PFAS in 18 drinking water samples from Poznań County in Greater Poland, where the contamination of drinking water with PFAS was also presumed. In most samples (14/18; 77.7 %), PFAS concentrations were below the method detection limit (<0.001 μg/L). Positive samples revealed total PFAS levels in the 0.0014-0.0041 μg/L range, decisively below the safety threshold established by the European Drinking Water Directive (<0.1 μg/L). Daily consumption of 1.5 or 2.0 L of water containing PFAS by a 70-kg adult would constitute 4.8-9.3 % or 6.4-18.6 % of tolerable intake set by the European Food Safety Authority. These findings suggest that drinking water in the studied area is not a significant source of PFAS exposure. Further research is recommended to assess PFAS contamination in drinking water across a broader geographic scope in Poland to better understand the national contamination status.

Associations between per-and polyfluoroalkyl substances (PFAS) and county-level cancer incidence between 2016 and 2021 and incident cancer burden attributable to PFAS in drinking water in the United States

BACKGROUND

Exposure to per- and polyfluoroalkyl substances (PFAS) has been linked with various cancers. Assessment of PFAS in drinking water and cancers can help inform biomonitoring and prevention efforts.

OBJECTIVE

To screen for incident cancer (2016-2021) and assess associations with PFAS contamination in drinking water in the US.

METHODS

We obtained county-level age-adjusted cancer incidence (2016-2021) from the Surveillance, Epidemiology, and End Results (SEER) Program. Data on PFAS levels in public drinking water systems were obtained from the Third (UCMR3; 2013-2015) and Fifth (UCMR5; 2023-2024) Unregulated Contaminant Monitoring Rule. UCMR3 measured PFOS, PFOA, PFNA, PFHxS, PFHpA, and PFBS. UCMR5 expanded measurements to include PFBA, PFHxA, PFPeA, and PFPeS. We created indicators of PFAS detection and, for UCMR5, concentrations above Maximum Contaminant Levels (MCLs). MCLs for PFOA and PFOS are 4 ng/L, and for PFNA and PFHxS are 10 ng/L. We used Poisson regression models to assess associations between PFAS detection or MCL violation and cancer incidence, adjusting for potential confounders. We estimated the number of attributable cancer cases.

RESULTS

PFAS in drinking water was associated with increased cancer incidence in the digestive, endocrine, oral cavity/pharynx, and respiratory systems. Incidence rate ratios (IRRs) ranged from 1.02 to 1.33. The strongest association was observed between PFBS and oral cavity/pharynx cancers (IRR: 1.33 [1.04, 1.71]). Among males, PFAS was associated with cancers in the urinary, brain, leukemia, and soft tissues. Among females, PFAS was associated with cancers in the thyroid, oral cavity/pharynx, and soft tissue. PFAS in drinking water is estimated to contribute to 4626 [95% CI: 1,377, 8046] incident cancer cases per year based on UCMR3 data and 6864 [95% CI: 991, 12,804] based on UCMR5.

IMPACT STATEMENT

The ecological study examined the associations between PFAS in drinking water measured in two waves (2013-2015 and 2023-2024) and cancer incidence between 2016 and 2021. We found that PFAS in drinking water was associated with cancers in the organ system including the oral cavity/pharynx, lung, digestive system, brain, urinary system, soft tissue, and thyroid. Some cancers have not been widely studied for their associations with PFAS. We also observed sex differences in the associations between PFAS and cancer risks. This is the first ecological study that examined PFAS exposure in drinking water and various cancer risks.

Prenatal per- and polyfluoroalkyl substance exposures and DNA methylation among newborns in the Environmental influences on Child Health Outcomes program

Gestation is a vulnerable window when exposure to per- and polyfluoroalkyl substances (PFAS) may impact child development and health. Epigenetic modification, including DNA methylation (DNAm), may be one mechanism linking prenatal PFAS exposure to offspring outcomes. We tested associations between prenatal PFAS and newborn DNAm in 1017 participants from 6 cohorts in the US Environmental influences on Child Health Outcomes consortium. Concentrations of PFAS [perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and perfluorodecanoic acid] were measured in maternal serum or plasma. DNAm was quantified in newborn dried blood spot or umbilical cord blood leukocytes using the Infinium HumanMethylation450 (450K) or MethylationEPIC (EPIC) arrays. We tested associations between prenatal PFAS and neonatal blood DNAm on the 450K (n = 772) and EPIC (n = 245) arrays; results were meta-analysed across the platforms. Regional changes in DNAm were investigated, and findings were checked for replication in the Michigan Mother-Infant Pairs (MMIP) cohort (n = 140). Following correction for false discovery rate (q = 0.1 for meta-analyses), we identified an association between PFHxS and one cytosine-guanine (CpG) mapped to CASC3 (q = 0.065) that replicated in MMIP (P = .006). PFOS was associated with six CpG sites, of which five were mapped to the genes KIAA1841, ABR, LEP, SERPINA1, and LOXL1. One differentially methylated region (DMR) was associated with prenatal PFOA exposure, and one DMR was associated with PFOS exposure. In this multicohort analysis including a diverse group from the USA, PFOA, PFOS, PFHxS, and PFNA exposures in pregnancy were associated with offspring DNAm, and the implications for children's health merit further exploration.

Serum PFAS and lipid concentrations in Ecuadorian adolescents

There is growing evidence that per- and polyfluoroalkyl substances (PFAS) may alter serum lipid concentrations; however, this topic is understudied in adolescents and Latin American populations. We aimed to characterize these associations among adolescents in Ecuador's main floricultural region. This cross-sectional study included 97 adolescents ages 11-17 years from Pedro Moncayo County, Ecuador. Generalized estimating equation models were applied to estimate the associations of serum perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) concentrations with serum lipids. Models were adjusted for age, gender, height, body mass index (BMI), acetylcholinesterase (AChE) activity, and hemoglobin concentrations. Significant inverse relationships between PFAS and triglycerides were observed in females (% lipid difference per 50% increase in: PFOS= -15.0% [95%CI: -24.72, -4.06], PFNA= -25.49% [-36.93, -12.00], and PFOA= -16.55% [-28.16, -3.07]) but not in males. No associations were observed between total cholesterol, high-density lipoprotein (HDL), or low-density lipoprotein (LDL) cholesterol and any PFAS. PFOS, PFOA, and PFNA were inversely associated with triglycerides in adolescent females but not males. Further characterization of gender-specific associations of PFAS and blood lipids in adolescents is warranted.

Removal of PFAS and pharmaceuticals from municipal wastewater using a novel β-cyclodextrin adsorbent over distinct contact times

Conventional adsorbents applied in wastewater treatment are ineffective at removing trace organic contaminants (TrOCs), including per and poly-fluoroalkyl substances (PFAS) and pharmaceuticals. Cross-linked β-cyclodextrin (β-CD) polymer adsorbents have demonstrated efficient removal of TrOCs and exhibit rapid kinetics and high adsorption capacity in wastewater. We evaluate the removal of a mixture of contaminants from wastewater by a styrene functionalized β-CD adsorbent (StyDex) through rapid small-scale column tests (RSSCTs). We found the kinetics observed in batch adsorption tests are maintained in RSSCTs. However, batch sorption kinetic constants did not match column breakthrough kinetics, due to an inability to describe complex flow-through behaviors. We correlated both batch kinetic constants and treatable bed volumes with hydrophobicity of target compounds, where PFOA and PFHxS had the highest affinity for StyDex in batch tests and the latest breakthroughs in RSSCTs. Breakthrough curves of five of the seven TrOCs were not affected by change in contact time. Conversely, decreasing the contact time led to earlier breakthrough of contaminants with the highest sorption affinity to StyDex: longer chained and sulfonated PFAS compounds. These effects were isolated in two-component competitive sorption experiments between PFOA and PFBA, and we observed the same preferential sorption of hydrophobic compounds identified in the multi-component mixture. Additionally, competitive adsorption-desorption increased with increasing contact times. We discuss how these findings are crucial for scale-up and large-scale testing of novel sorbents.

Per- and polyfluoroalkyl substances in environment and potential health impacts: Sources, remediation treatment and management, policy guidelines, destructive technologies, and techno-economic analysis

Per- and polyfluoroalkyl Substances (PFAS), also known as forever chemicals and ubiquitous persistence, pose significant public health challenges due to their potential toxicity, particularly in drinking water and soil contamination. However, PFAS occurrence and their concentrations in different environmental matrices vary globally, but factors influencing trends, transport, fate, toxicity, and interactions with co-contaminants remain largely unexplored. Therefore, this review critically examines the state-of-the-art worldwide PFAS sources, distribution, and pathways, and evaluates how PFASs are processed in wastewater treatment, generally, which causes severe problems with the quality and safety of drinking water. Importantly, the review also underscores health issues due to PFAS consumption and recent research trends on developing effective treatment strategies to manage PFAS contamination. Potential effects of PFAS were linked to urban land use and the proportion of wastewater effluent in streamflow. Besides, major emphasis was provided on challenges for conventional treatment, destructive technologies, environmental accumulation, precursor transformation, and cost-investment related to PFAS removal technologies. To combat PFAS contamination, this review proposes a framework that promotes the comprehensive identification of prevalent compounds, with a focus on their eradication through knowledge-based and targeted analysis. Additionally, it explores the ongoing debate surrounding PFAS laws and legal frameworks, offering ideas for enhancing contamination management. Lastly, this review provides a strategic plan for improving response and preparedness, serving as a foundation for addressing future environmental challenges and informing health risk assessments.

Statewide cumulative human health risk assessment of inorganics-contaminated groundwater wells, Montana, USA

Across the United States, rural residents rely on unregulated and generally unmonitored private wells for drinking water, which may pose serious health risks due to unrecognized contaminants. We assessed the nature, degree, and spatial distribution of cumulative health risks from inorganic contaminants in groundwater. Our analysis included nearly 84,000 data points from 6500+ wells, across 51 of Montana's 98 watersheds, using a public groundwater database. We compared a drinking water screening level cumulative risk assessment (CRA) for inorganics based on the U.S. Environmental Protection Agency (EPA) protective health thresholds (Maximum Contaminant Level Goals, Health Advisories [MCLG-HAs]) to a CRA based on EPA public supply enforceable Maximum Contaminant Levels (MCLs). Based on median concentrations of 19 inorganics (antimony, arsenic, barium, beryllium, boron, cadmium, chromium, copper, fluoride, manganese, molybdenum, nickel, nitrate, lead, selenium, strontium, thallium, uranium, zinc), 75% of watersheds had MCLG-HA-based cumulative risk values > 1.0; arsenic and uranium contributed the most risk, followed by strontium, fluoride, manganese and boron. Hence, this screening level (Tier I) CRA indicated widespread potential for unrecognized human health risk to private well users from inorganic contaminants considering both carcinogenic and non-carcinogenic risks. Sensitivity analysis showed that benchmarks applied (MCLG-HAs versus MCLs) exerted the largest control on results. Our findings identify priority regions for Tier 2 risk assessments to elucidate local sources and distributions of geogenic versus anthropomorphic contaminants. Our study is the first statewide assessment of cumulative health risk from groundwater that we are aware of, and results support increased statewide drinking water education and testing to reduce human health risks from contaminated private well water.

Effects of Physical and Chemical Aging of Colloidal Activated Carbon on the Adsorption of Per- and Polyfluoroalkyl Substances

Colloidal activated carbon (CAC) is an injectable adsorbent that sequesters per- and polyfluoroalkyl substances (PFAS) in the subsurface, serving as an in situ remediation technology for PFAS-impacted sites. However, the effectiveness of the CAC sorptive barrier could change over time due to alterations in its physicochemical properties induced by aging processes. In this study, the effects of CAC aging on surface properties of CAC and resulting impact on the adsorption behaviors of PFAS compounds were determined using four accelerated aging treatments, including wet-dry cycling (W/D), hydrogen peroxide (H), Fenton's reagent (F), and mineral acid (A). Fenton's reagent and mineral acid aging treatments showed a greater impact on the physical structure and chemical composition of CAC than either W/D-CAC and H-CAC. Aging the CAC lowered the CAC specific surface area and anion exchange capacity, increased surface oxygen content, and lowered the point of zero charge, suggesting negative impacts on the capacity of CAC for PFAS removal. This reduction in the sorption capacity was confirmed in batch sorption isotherm experiments. All aged CAC had lower PFAS adsorption in a multisolute system, including six PFAS compounds with different chain lengths (C4-C8) and functional groups (sulfonate or carboxylate), with the only exception being perfluorooctanesulfonic acid (PFOS). The results suggest that the aging process is an important, yet often overlooked, factor in determining the long-term effectiveness of the CAC sorptive barrier for PFAS removal, especially for shorter-chain hydrophilic PFAS. More research is needed to verify the influence of field-scale aging processes on the CAC performance and longevity.

Emerging Per- and Polyfluoroalkyl Substances in Tap Water from the American Healthy Homes Survey II

Humans experience widespread exposure to anthropogenic per- and polyfluoroalkyl substances (PFAS) through various media, which can lead to a wide range of negative health impacts. Tap water is an important source of exposure in communities with any degree of contamination but routine or large-scale PFAS monitoring often depends on targeted analytical methods limited to measuring specific PFAS. We analyzed 680 tap water samples from the American Healthy Homes Survey II for PFAS using non-targeted analysis (NTA) to expand the range of detectable PFAS. Based on detection frequency and relative abundance, about half of the identified PFAS were found only by NTA. We identified (with varying degrees of confidence) 75 distinct PFAS, including 57 exclusively detected by NTA. The identified PFAS are members of seven structural subclasses differentiated by their head groups and degree of fluorination. Clustering analysis categorized the PFAS into four coabundance groups dominated by specific PFAS subclasses. One group uniquely identified by NTA contains zwitterionic PFAS and other PFAS transformation products which are likely associated with aqueous firefighting foam contaminants in a small number of spatially correlated samples. These results help further characterize the scope of exposure to emerging PFAS experienced by the U.S. population via tap water and augment nationwide targeted-PFAS monitoring programs.

Utilization of Artificial Intelligence Coupled with a High-Throughput, High-Content Platform in the Exploration of Neurodevelopmental Toxicity of Individual and Combined PFAS

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used in various products, such as firefighting foams and non-stick cookware, due to their resistance to heat and degradation. However, these same properties make them persistent in the environment and human body, raising public health concerns. This study selected eleven PFAS commonly found in drinking water and exposed Caenorhabditis elegans to concentrations ranging from 0.1 to 200 µM to assess neurodevelopmental toxicity using a high-throughput, high-content screening (HTS) platform coupled with artificial intelligence for image analysis. Our findings showed that PFAS such as 6:2 FTS, HFPO-DA, PFBA, PFBS, PFHxA, and PFOS inhibited dopaminergic neuron activity, with fluorescence intensity reductions observed across concentrations from 0.1 to 100 µM. PFOS and PFBS also disrupted synaptic transmission, causing reduced motility and increased paralysis in aldicarb-induced assays, with the most pronounced effects at higher concentrations. These impairments in both neuron activity and synaptic function led to behavioral deficits. Notably, PFOS was one of the most toxic PFAS, affecting multiple neurodevelopmental endpoints. These results emphasize the developmental risks of PFAS exposure, highlighting the impact of both individual compounds and mixtures on neurodevelopment. This knowledge is essential for assessing PFAS-related health risks and informing mitigation strategies.

Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) from contaminated water and risk of childhood cancer in California, 2000-2015

Background

Few studies have investigated associations between per- and polyfluoroalkyl substances (PFAS) and childhood cancers. Detectable levels of PFAS in California water districts were reported in the Third Unregulated Contaminant Monitoring Rule for 2013-2015.

Methods

Geocoded residences at birth were linked to corresponding water district boundaries for 10,220 California-born children (aged 0-15 years) diagnosed with cancers (2000-2015) and 29,974 healthy controls. A pharmacokinetic model was used to predict average steady-state maternal serum concentrations of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) from contaminated drinking water. Adjusted odds ratios (AORs) and 95% confidence intervals (CIs) per doubling of background exposure were calculated for cancers with at least 90 cases.

Results

Predicted PFOS and PFOA maternal serum concentrations ranged from background (5 ng/ml PFOS and 2 ng/ml PFOA) to 22.89 ng/ml and 6.66 ng/ml, respectively. There were suggestive associations between PFOS and nonastrocytoma gliomas (n = 268; AOR = 1.26; 95% CI: 0.99, 1.60), acute myeloid leukemia (n = 500; AOR = 1.14; 95% CI: 0.94, 1.39), Wilms tumors (n = 556, AOR = 1.15; 95% CI: 0.96, 1.38), and noncentral system embryonal tumors (n = 2,880; AOR = 1.07; 95% CI: 0.98, 1.17), and between PFOA and non-Hodgkin lymphoma (n = 384; AOR = 1.19; 95% CI: 0.95, 1.49). Among children of Mexico-born mothers, there was increased risk of Wilms tumor (n = 101; AORPFOS = 1.52; 95% CI: 1.06, 2.18; AORPFOA = 1.59, 95% CI: 1.12, 2.24) and noncentral system embryonal tumors (n = 557; AORPFOS = 1.24, 95% CI: 1.03, 1.50; AORPFOA = 1.19, 95% CI: 0.98, 1.45).

Conclusion

Results suggest associations between predicted prenatal maternal PFAS serum concentrations and some childhood cancers. Future analyses are warranted.

Associations between per- and polyfluoroalkyl substances (PFAS) and female sexual function in a preconception cohort

BACKGROUND

Female sexual function is important for sexual well-being, general health, fertility, and relationship satisfaction. Distressing impairments in sexual function, clinically recognized as female sexual dysfunction (FSD), can manifest as issues with interest/desire, arousal, orgasm, and pain during vaginal penetration. Some evidence suggests that exposure to endocrine-disrupting chemicals may adversely affect female sexual function, but associations for per- and polyfluoroalkyl substances (PFAS) have not been previously evaluated.

OBJECTIVE

We investigated associations between serum PFAS concentrations and female sexual function among U.S. pregnancy planners.

METHODS

We used cross-sectional data from participants from Pregnancy Study Online (PRESTO), a prospective preconception cohort study. Participants reported sexual function and distress at baseline on two validated measures: a modified version of the Female Sexual Function Index-6 (FSFI-6) and the Female Sexual Distress Scale (FSDS). We quantified PFAS serum concentrations in samples collected in the preconception period (i.e., at baseline) using solid phase extraction-high performance liquid chromatography-isotope-dilution-mass spectrometry. Participants reported sociodemographic information on structured baseline questionnaires. We included 78 participants with complete PFAS and sexual function data and fit multivariable linear regression models to estimate mean differences in FSFI-6 scores (β) or percent differences (%) in FSDS scores per interquartile range (IQR) increase in PFAS concentrations, adjusting for age, annual household income, years of education, parity, and body mass index. We further investigated effect measure modification by parity (parous vs. nulliparous) in stratified models.

RESULTS

An IQR increase in perfluorohexanesulfonic acid was associated with a 1.0-point decrease (95% CI = -1.8, -0.1) in reported FSFI-6 scores, reflecting poorer sexual function. PFAS were consistently associated with lower FSFI-6 scores among parous participants. PFAS were also associated, though imprecisely, with greater sexual distress.

CONCLUSION

Some PFAS were associated with poorer sexual function among U.S. pregnancy planners, but future studies are needed to clarify the extent to which PFAS influences female sexual health.

Assessing PFAS in drinking water: Insights from the Czech Republic's risk-based monitoring approach

This study investigates the presence of perfluoroalkyl substances (PFAS) in the drinking water supplies in the Czech Republic using a risk-based monitoring approach. Tap water samples (n = 27) from sources close to areas potentially contaminated with PFAS were analysed. A total of 28 PFAS were measured using ultra-performance liquid chromatography with tandem mass spectrometry after solid phase extraction. Total PFAS concentrations (∑PFAS) varied from undetectable to 90.8 ng/L, with perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA) and perfluorobutane sulfonic acid (PFBS) being the most abundant, detected in over 70% of samples. Risk-based monitoring in drinking water showed that commercial wells had higher PFAS levels compared to tap water, particularly C4-C9 perfluorocarboxylic acids (PFCAs), possibly due to proximity to industrial areas. However, the hypothesis that risk-based monitoring is more effective than random monitoring was not confirmed, possibly because specific sources did not produce the target PFAS or because of the wide range and less obvious sources of potential contamination. The study also assessed exposure risks and compliance with regulatory thresholds. Weekly intake estimates for adults and children indicated that regular consumption of most contaminated water sample would exceed the tolerable weekly intake. Compared to EU regulations, none of the tap water samples exceeded the 'Sum of PFAS' parametric value of 100 ng/L, though one sample approached this limit. In addition, surface water samples from the Jizera River (n = 21) showed a wider range of PFAS, with C7-C10 PFCAs, PFBS, and perfluorooctane sulfonic acid (PFOS) in every sample, with higher PFOS concentrations at a median of 2.56 ng/L. ∑PFAS concentrations increased downstream, rising from 1.08 ng/L near the spring to 26 ng/L downstream. This comprehensive analysis highlights the need for detailed/areal monitoring to also address hidden or non-obvious sources of PFAS contamination.

Multidimensional library for the improved identification of per- and polyfluoroalkyl substances (PFAS)

As the occurrence of human diseases and conditions increase, questions continue to arise about their linkages to chemical exposure, especially for per-and polyfluoroalkyl substances (PFAS). Currently, many chemicals of concern have limited experimental information available for their use in analytical assessments. Here, we aim to increase this knowledge by providing the scientific community with multidimensional characteristics for 175 PFAS and their resulting 281 ion types. Using a platform coupling reversed-phase liquid chromatography (RPLC), electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI), drift tube ion mobility spectrometry (IMS), and mass spectrometry (MS), the retention times, collision cross section (CCS) values, and m/z ratios were determined for all analytes and assembled into an openly available multidimensional dataset. This information will provide the scientific community with essential characteristics to expand analytical assessments of PFAS and augment machine learning training sets for discovering new PFAS.

Enhanced spatial analysis assessing the association between PFAS-contaminated water and cancer incidence: rationale, study design, and methods

BACKGROUND

Cancer is a complex set of diseases, and many have decades-long lag times between possible exposure and diagnosis. Environmental exposures, such as per- and poly-fluoroalkyl substances (PFAS) and area-level risk factors (e.g., socioeconomic variables), vary for people over time and space. Evidence suggests PFAS exposure is associated with several cancers; however, studies to date have various limitations. Few studies have used rigorous spatiotemporal approaches, and, to our knowledge, none have assessed cumulative exposures given residential histories or incorporated chemical mixture modeling. Thus, spatiotemporal analysis using advanced statistical approaches, accounting for spatially structured and unstructured heterogeneity in risk, can be a highly informative strategy for addressing the potential health effects of PFAS exposure.

METHODS

Using population-based incident cancer cases and cancer-free controls in a 12-county area of southeastern Pennsylvania, we will apply Bayesian spatiotemporal analysis methods using historically reconstructed PFAS-contaminated water exposure given residential histories, and other potential cancer determinants over time. Bayesian group index models enable assessment of various mixtures of highly correlated PFAS chemical exposures incorporating mobility/residential history, and contextual factors to determine the association of PFAS-related exposures and cancer incidence.

DISCUSSION

The purpose of this paper is to describe the Enhanced PFAS Spatial Analysis study rationale, study design, and methods.

Out of sight, into the spotlight: Beyond the current state of science on per- and poly-fluoroalkyl substances in groundwater

Per- and poly-fluoroalkyl substances (PFAS) have emerged as a silent menace, infiltrating groundwater systems worldwide. Many countries, preoccupied with tackling legacy pollutants, have inadvertently neglected the emerging threat of PFAS. This review provides an exhaustive analysis beyond the current state of knowledge and sustainable pathways vis-a-vis addressing PFAS in groundwater systems globally. Despite the positive progression in PFAS research, significant knowledge gaps and paucity of data persist globally. Sampling trains, smart contaminant detectors, filters, and sensors offer promising pathways for the complete extraction and detection of novel and transformed PFAS species. Major hotspots are firefighting locations, landfills, and superfund sites. While studies have documented the global occurrence of PFAS in groundwater, with concentrations increasing over time and varying across regions, the factors influencing these trends, transport, fate, toxicity, and interactions with co-contaminants, remain largely unexplored. Advanced models accounting for environmental complexities and interactions are crucial for understanding PFAS migration in groundwater, however, their development is hindered by a scarcity of studies on the complexities and PFAS interactions. Emerging technologies, including nanotechnology, enzyme, genetic engineering, flexible treatment train, and machine learning algorithms present exciting opportunities for PFAS treatment, however, their cost-effectiveness, scalability, and long-term stability must be thoroughly investigated. Sustainable management requires addressing nomenclature inconsistencies and developing region-specific mitigative measures. These serve as a clarion call for the scientific community, policymakers, and stakeholders to unite in confronting the formidable challenges posed by PFAS contamination, as the fate of our groundwater resources and the well-being of countless lives hang in the balance.

Examining disparities in PFAS plasma concentrations: Impact of drinking water contamination, food access, proximity to industrial facilities and superfund sites

BACKGROUND

Most of the US population is exposed to per- and polyfluorinated substances (PFAS) through various environmental media and these sources of PFAS exposure coupled with disproportionate co-localization of PFAS-polluting facilities in under-resourced communities may exacerbate disparities in PFAS-associated health risks.

METHOD

We leveraged two cohorts in Southern California with 8 PFAS concentrations measured in plasma. We obtained PFAS water testing data from the Third Unregulated Contaminant Monitoring Rule and state monitoring data, census tract-level information on food access using the Food Access Research Atlas, the location of Superfund sites on the National Priorities List, and data on facilities known to release PFAS pollutants. These data were then spatially linked to the participants' home addresses.

RESULTS

In the first cohort, we found that detections of PFOS, PFOA, and PFHxS in drinking water were associated with 1.54 ng/mL (95% CI: 0.77, 2.32), 0.47 ng/mL (0.25, 0.68), and 1.16 ng/mL (0.62, 1.71) increase in plasma PFOS, PFOA, and PFHxS. The presence of Superfund sites was associated with higher plasma concentrations of PFOS, PFHxS, PFPeS, and PFHpS (betas [95% CIs]: 0.96 [0.21, 1.71], 0.9 [0.22, 1.58], 0.04 [0.02, 0.06] and 0.05 [0.02, 0.09], respectively). Each additional PFAS-polluting facility present in the neighborhood was associated with a 0.9 ng/mL (0.03, 0.15) increase in the concentration of PFOS. In the other cohort, we found that the presence of Superfund sites was associated with higher plasma PFDA, PFHpS, PFOS (betas [95% CIs]: 0.03 [0.01, 0.06], 0.05 [0.01, 0.09], and 1.96 [0.31, 3.62]). Neighborhood low access to food was associated with a 2.51 ng/mL (0.7, 4.31) increase in plasma PFOS, 0.6 ng/mL (0.16, 1.06) increase in plasma PFOA and 0.06 (0.02, 0.1) increase in plasma PFHpS.

CONCLUSION

Reducing sources of PFAS exposure in under-resourced neighborhoods may help reduce disparities in human exposure levels.

Evaluating the effectiveness of community-informed resource dissemination at increasing knowledge and testing rates among private well water owners in a statewide population

BACKGROUND

Threats to groundwater quality pose health risks to private well owners. Knowledge gaps are the main reason for low testing rates. Yet, few studies have examined the extent to which community-informed resource distribution increases knowledge and promotes private well testing.

OBJECTIVES

Evaluate the effectiveness of resource dissemination in promoting increased knowledge and private well testing.

METHODS

Community-informed resources were developed that included 6 domains: regulation, testing recommendations, local resources, rationale for testing, state and federal resources, and mitigation actions. They were disseminated to n = 1423 Survey of the Health of Wisconsin participants. Participants completed evaluations at the time of dissemination and one year later. Logistic regression models examined knowledge and behavior changes because of the resource sheet by demographics.

RESULTS

About 50% of respondents reported increased knowledge on most domains of the resource sheet; 80% reported increased knowledge on at least one domain. About 13% tested their well in the last year because of the resource sheet. Because of the resource sheet, seeking out information in the last year was 2.47 (95% CI: 1.04-5.87) times higher among those ≥65 years of age after adjustment, and private well testing was 5.46 (95% CI: 2.15-13.9) times higher among households with ≥$100,000 annual income.

DISCUSSION

Direct information distribution to private well owners can benefit many rural residents and promote well testing. Findings from this study highlight outreach disparities to private well owners. Future work should identify unique barriers and motivators to testing, and preferred communication media, among low-income and younger private well-owners.

The trends of per-and polyfluoroalkyl substances (pfas) in drinking water systems in Maryland, United States

Per- and polyfluoroalkyl substances (PFAS) have become a major concern in water quality management because of their persistence in the environment and associated health risks. In Maryland, the diverse water resources and densely populated areas, faces unique challenges culminating from PFAS contamination. This research paper presents a comprehensive overview of PFAS contamination trends in Maryland's drinking water systems across four distinct phases, spanning from 2019 to 2022, it highlights the trends of PFAS contamination, environmental and public health risks, and strategies for effective management. Utilizing data from extensive monitoring efforts conducted in the state, the study reveals a persistent and evolving environmental health challenge characterized by the dominance of different PFAS compounds, particularly PFOS and PFOA, found at concerning concentrations. Mean concentrations of total PFOA/PFOS across the sampling periods were at 18.78 ng/L, 7.28 ng/L, 14.60 ng/L, 12.46 ng/L, significantly surpassing the EPA's 2024 maximum contaminant levels of 4 ng/L for PFOA and PFOS. Despite fluctuations observed across sampling phases, PFAS levels consistently surpass EPA health advisory levels, indicating widespread contamination. Potential sources, such as industrial sites and wastewater treatment plants, underscore the need for robust regulatory enforcement and innovative remediation strategies to safeguard public health. The findings emphasize the necessity for continuous monitoring and multi-faceted mitigation approaches to address PFAS contamination effectively, ensuring the safety of Maryland's water resources and the health of its residents.

Predicted Potential for Aquatic Exposure Effects of Per- and Polyfluorinated Alkyl Substances (PFAS) in Pennsylvania's Statewide Network of Streams

Per- and polyfluoroalkyl substances (PFAS) are contaminants that can lead to adverse health effects in aquatic organisms, including reproductive toxicity and developmental abnormalities. To assess the ecological health risk of PFAS in Pennsylvania stream surface water, we conducted a comprehensive analysis that included both measured and predicted estimates. The potential combined exposure effects of 14 individual PFAS to aquatic biota were estimated using the sum of exposure-activity ratios (ΣEARs) in 280 streams. Additionally, machine learning techniques were utilized to predict potential PFAS exposure effects in unmonitored stream reaches, considering factors such as land use, climate, and geology. Leveraging a tailored convolutional neural network (CNN), a validation accuracy of 78% was achieved, directly outperforming traditional methods that were also used, such as logistic regression and gradient boosting (accuracies of ~65%). Feature importance analysis highlighted key variables that contributed to the CNN's predictive power. The most influential features highlighted the complex interplay of anthropogenic and environmental factors contributing to PFAS contamination in surface waters. Industrial and urban land cover, rainfall intensity, underlying geology, agricultural factors, and their interactions emerged as key determinants. These findings may help to inform biotic sampling strategies, water quality monitoring efforts, and policy decisions aimed to mitigate the ecological impacts of PFAS in surface waters.

The impact of early life exposure to individual and combined PFAS on learning, memory, and bioaccumulation in C. elegans

Per- and Polyfluoroalkyl Substances (PFAS) are a group of water-soluble chemicals used for decades with important industrial and commercial applications. Due to their chemical and thermal stability, persistence in the environment, and widespread human exposure, PFAS become an important concern for public health. In this study, eleven highly prevalent PFAS and a reference mixture were selected according to various drinking water sources. The nematode, Caenorhabditis elegans, were exposed to PFAS at 0.1, 1, 10, 100, and 200 μM, and the toxic effects on learning & memory along with the bioaccumulation were investigated using a high-throughput screening (HTS) platform. Our results showed that perfluorooctanesulfonic acid (PFOS) and perfluorobutanesulfonic acid (PFBS) exhibited significant inhibitory effects (p < 0.05) on learning and memory in both time points at concentrations between 100 and 200 μmol/L. After 48 h of exposure, every PFAS resulted in an inhibition of learning and memory with a concentration of 200 μmol/L. Furthermore, the PFOS and PFBS had the highest bioaccumulation levels after 48 h of exposure. These findings provide valuable insight into the developmental adverse effects associated with exposure and the bioaccumulation of both individual and mixtures of PFAS.

Mixed contaminant exposure in tapwater and the potential implications for human-health in disadvantaged communities in California

Water is an increasingly precious resource in California as years of drought, climate change, pollution, as well as an expanding population have all stressed the state's drinking water supplies. Currently, there are increasing concerns about whether regulated and unregulated contaminants in drinking water are linked to a variety of human-health outcomes particularly in socially disadvantaged communities with a history of health risks. To begin to address this data gap by broadly assessing contaminant mixture exposures, the current study was designed to collect tapwater samples from communities in Gold Country, the San Francisco Bay Area, two regions of the Central Valley (Merced/Fresno and Kern counties), and southeast Los Angeles for 251 organic chemicals and 32 inorganic constituents. Sampling prioritized low-income areas with suspected water quality challenges and elevated breast cancer rates. Results indicated that mixtures of regulated and unregulated contaminants were observed frequently in tapwater throughout the areas studied and the types and concentrations of detected contaminants varied by region, drinking-water source, and size of the public water system. Multiple exceedances of enforceable maximum contaminant level(s) (MCL), non-enforceable MCL goal(s) (MCLG), and other health advisories combined with frequent exceedances of benchmark-based hazard indices were also observed in samples collected in all five of the study regions. Given the current focus on improving water quality in socially disadvantaged communities, our study highlights the importance of assessing mixed-contaminant exposures in drinking water at the point of consumption to adequately address human-health concerns (e.g., breast cancer risk). Data from this pilot study provide a foundation for future studies across a greater number of communities in California to assess potential linkages between breast cancer rates and tapwater contaminants.

Binary and quaternary mixtures of perfluoroalkyl substances (PFAS) differentially affect the immune response to influenza A virus infection

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic organofluorine compounds that persist indefinitely in the environment and bioaccumulate throughout all trophic levels. Biomonitoring efforts have detected multiple PFAS in the serum of most people. Immune suppression has been among the most consistent effects of exposure to PFAS. PFAS often co-occur as mixtures in the environment, however, few studies have examined immunosuppression of PFAS mixtures or determined whether PFAS exposure affects immune function in the context of infection. In this study, mixtures containing two or four different PFAS and a mouse model of infection with influenza A virus (IAV) were used to assess immunotoxicity of PFAS mixtures. PFAS were administered via the drinking water as either a binary mixture of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) or quaternary mixture of PFOS, PFOA, perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA). The results indicated that the binary mixture affected the T-cell response, while the quaternary mixture affected the B-cell response to infection. These findings indicate that the immunomodulatory effects of PFAS mixtures are not simply additive, and that the sensitivity of immune responses to PFAS varies by cell type and mixture. The study also demonstrates the importance of studying adverse health effects of PFAS mixtures.

Per- and polyfluoroalkyl substances (PFAS) and hypertensive disorders of Pregnancy- integration of epidemiological and mechanistic evidence

BACKGROUND

Hypertensive disorders of pregnancy (HDP) remain a significant global health burden despite medical advancements. HDP prevalence appears to be rising, leading to increased maternal and fetal complications, mortality, and substantial healthcare costs. The etiology of HDP are complex and multifaceted, influenced by factors like nutrition, obesity, stress, metabolic disorders, and genetics. Emerging evidence suggests environmental pollutants, particularly Per- and polyfluoroalkyl substances (PFAS), may contribute to HDP development.

OBJECTIVE

This review integrates epidemiological and mechanistic data to explore the intricate relationship between PFAS exposure and HDP.

EPIDEMIOLOGICAL EVIDENCE

Studies show varying degrees of association between PFAS exposure and HDP, with some demonstrating positive correlations, particularly with preeclampsia. Meta-analyses suggest potential fetal sex-specific differences in these associations.

MECHANISTIC INSIGHTS

Mechanistically, PFAS exposure appears to disrupt vascular hemodynamics, placental development, and critical processes like angiogenesis and sex steroid regulation. Experimental studies reveal alterations in the renin-angiotensin system, trophoblast invasion, oxidative stress, inflammation, and hormonal dysregulation - all of which contribute to HDP pathogenesis. Elucidating these mechanisms is crucial for developing preventive strategies.

THERAPEUTIC POTENTIAL

Targeted interventions such as AT2R agonists, caspase inhibitors, and modulation of specific microRNAs show promise in mitigating adverse outcomes associated with PFAS exposure during pregnancy.

KNOWLEDGE GAPS AND FUTURE DIRECTIONS

Further research is needed to comprehensively understand the full spectrum of PFAS-induced placental alterations and their long-term implications for maternal and fetal health. This knowledge will be instrumental in developing effective preventive and therapeutic strategies for HDP in a changing environmental landscape.

Associations between per- and poly-fluoroalkyl substance (PFAS) exposure and immune responses among women in the California Teachers study: A cross-sectional evaluation

INTRODUCTION

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants that have been linked to a number of health outcomes, including those related to immune dysfunction. However, there are limited numbers of epidemiological-based studies that directly examine the association between PFAS exposure and immune responses.

METHODS

In this cross-sectional study nested in the California Teachers Study cohort, we measured nine PFAS analytes in serum. Of the 9 analytes, we further evaluated four (PFHxS [perfluorohexane sulfonate], PFNA [perfluorononanoic acid], PFOA [perfluorooctanoic acid], PFOS [perfluorooctanesulfonic acid]) that had detection levels of > 80 %, in relation to 16 systemic inflammatory/immune markers and corresponding immune pathways (Th1 [pro-inflammatory/macrophage activation], B-cell activation, and T-cell activation). Study participants (n = 722) were female, completed a questionnaire regarding various health measures and behaviors, and donated a blood sample between 2013-2016. The association between PFAS analytes and individual immune markers and pathways were evaluated by calculating odds ratios (OR) and 95 % confidence intervals (CI) in a logistic regression model. PFAS analytes were evaluated both as a dichotomous exposure (above or below the respective median) and as a continuous variable (per 1 unit increase [ng/mL]).

RESULTS

The prevalence of detecting any PFAS analyte rose with increasing age, with the highest PFAS prevalence observed among those aged 75 + years and the lowest PFAS prevalence observed among those aged 40-49 years (study participant age range: 40-95 years). Significant associations with BAFF (B-cell activating factor) levels above the median were observed among participants with elevated (defined as above the median) levels of PFHxS (OR=1.53), PFOA (OR=1.43), and PFOS (OR=1.40). Similarly, there were statistically significant associations between elevated levels of PFHxS and TNFRII (tumor necrosis factor receptor 2) levels (OR=1.78) and IL2Rα (interleukin 2 receptor subunit alpha) levels (OR=1.48). We also observed significant inverse associations between elevated PFNA and sCD14 (soluble cluster of differentiation 14) (OR=0.73). No significant associations were observed between elevated PFNA and any immune marker. Evaluation of PFAS exposures as continuous exposures in association with dichotomized cytokines were generally consistent with the dichotomized associations.

CONCLUSIONS

PFAS exposure was associated with altered levels of circulating inflammatory/immune markers; the associations were specific to PFAS analyte and immune marker. If validated, our results may suggest potential immune mechanisms underlying associations between the different PFAS analytes and adverse health outcomes.

Development and application of a non-targeted analysis method using GC-MS and LC-MS for identifying chemical contaminants in drinking water via point-of-use filters

While many chemicals are regulated and routinely monitored in drinking water, they represent just a portion of all contaminants that may be present. Typical drinking water analyses involve sampling one liter or less of water, which could lead to trace level contaminants going undetected. In this study, a method was developed for using point-of-use activated carbon block drinking water filters as sampling devices. The filters were extracted to remove chemicals that were collected, and then analyzed by non-targeted analysis via liquid chromatography and gas chromatography high-resolution mass spectrometry. Extraction efficiencies were assessed by spiking and recovery experiments to better understand the chemical space coverage. To test the method's applicability to real-world samples, filters from a small-scale pilot study were collected from individuals in New York, NY and Atlanta, GA and analyzed. Twenty tentatively identified chemical candidates were confirmed by comparison to chemical standards. Principal components analysis was performed on the full set of filtered chemical features to explore how geographic and temporal differences in samples impact drinking water composition. Product use categories for confirmed chemicals were explored to determine potential sources of contaminants.

Aggregation, Not Micellization: Perfluorooctanoic Acid, Perfluorobutanesulfonic Acid, and Potassium Perfluorooctanesulfonate Behavior in Aqueous Solution

Surface tension, conductivity, and dynamic light scattering (DLS) measurements were used to examine the surface and bulk solution behaviors of three members of the PFAS family, perfluorooctanoic acid (PFOA), perfluorobutanesulfonic acid (PFBS), and the potassium salt of perfluorooctanesulfonic acid (PFOS). Measurements were carried out in solutions having variable (acidic) pH and in solutions buffered to pH = 8.0. Surface tension data show traditional soluble surfactant behavior, and results illustrate that PFOA, PFBS, and PFOS surface activity depends sensitively on solution phase pH. The tightly packed monolayers formed by PFOA in mildly acidic solutions imply that the surface pH of PFOA solutions is several units lower than bulk. Results from conductivity experiments generally show increasing conductivity with increasing bulk solution surfactant concentration. In pH = 8.0 solutions, changes in conductivity slope with surfactant concentration suggest the onset of micelle formation at concentrations <1 mM, markedly lower than reported in literature. In general, apparent critical micelle concentrations (CMCs) determined from conductivity data agree with similar predictions made from surface tension results. DLS measurements show that at concentrations close to the predicted PFAS CMCs, objects with diameters ≤10 nm start to form. However, unlike micelles, these objects continue to grow with increasing bulk solute concentration. These aggregates form structures having diameters of 50-150 nm. Aggregate size shrinks modestly as solution phase temperature increases, and this behavior is reversible. Cryo-EM images of PFOA solutions confirm a broad distribution of particles, supporting the DLS measurements. Findings reported in this work represent the first evidence that these three EPA-regulated PFAS surfactants form aggregates rather than micelles in solution. Findings also begin to reconcile differences in reported surface behaviors that have led to CMC predictions in the literature varying by more than an order of magnitude.

Per- and polyfluoroalkyl substances (PFAS) in drinking water in Southeast Los Angeles: Industrial legacy and environmental justice

Per- and polyfluoroalkyl substances (PFAS) are persistent chemicals of increasing concern to human health. PFAS contamination in water systems has been linked to a variety of sources including hydrocarbon fire suppression activities, industrial and military land uses, agricultural applications of biosolids, and consumer products. To assess PFAS in California tap water, we collected 60 water samples from inside homes in four different geographic regions, both urban and rural. We selected mostly small water systems with known history of industrial chemical or pesticide contamination and that served socioeconomically disadvantaged communities. Thirty percent of the tap water samples (18) had a detection of at least one of the 32 targeted PFAS and most detections (89 %) occurred in heavily industrialized Southeast Los Angeles (SELA). The residents of SELA are predominately Latino and low-income. Concentrations of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) ranged from 6.8 to 13.6 ng/L and 9.4-17.8 ng/L, respectively in SELA and were higher than State (PFOA: 0.007 ng/L; PFOS: 1.0 ng/L) and national health-based goals (zero). To look for geographic patterns, we mapped potential sources of PFAS contamination, such as chrome plating facilities, airports, landfills, and refineries, located near the SELA water systems; consistent with the multiple potential sources in the area, no clear spatial associations were observed. The results indicate the importance of systematic testing of PFAS in tap water, continued development of PFAS regulatory standards and advisories for a greater number of compounds, improved drinking-water treatments to mitigate potential health threats to communities, especially in socioeconomically disadvantaged and industrialized areas.

Molecular designing of potential environmentally friendly PFAS based on deep learning and generative models

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are widely used across a spectrum of industrial and consumer goods. Nonetheless, their persistent nature and tendency to accumulate in biological systems pose substantial environmental and health threats. Consequently, striking a balance between maximizing product efficiency and minimizing environmental and health risks by tailoring the molecular structure of PFAS has become a pivotal challenge in the fields of environmental chemistry and sustainable development. To address this issue, a computational workflow was proposed for designing an environmentally friendly PFAS by incorporating deep learning (DL) and molecular generative models. The hybrid DL architecture MolHGT+ based on heterogeneous graph neural network with transformer-like attention was applied to predict the surface tension, bioaccumulation, and hepatotoxicity of the molecules. Through virtual screening of the PFAS master database using MolHGT+, the findings indicate that incorporating the siloxane group and betaine fragment can effectively decrease both the bioaccumulation and hepatotoxicity of PFAS while preserving low surface tension. In addition, molecular generative models were employed to create a structurally diverse pool of novel PFASs with the aforementioned hit molecules serving as the initial template structures. Overall, our study presents a promising AI-driven method for advancing the development of environmentally friendly PFAS.

Predictions of groundwater PFAS occurrence at drinking water supply depths in the United States

Per- and polyfluoroalkyl substances (PFAS), known colloquially as "forever chemicals," have been associated with adverse human health effects and have contaminated drinking water supplies across the United States owing to their long-term and widespread use. People in the United States may unknowingly be drinking water that contains PFAS because of a lack of systematic analysis, particularly in domestic water supplies. We present an extreme gradient-boosting model for predicting the occurrence of PFAS in groundwater at the depths of drinking water supply for the conterminous United States. Our model results indicate that 71 million to 95 million people in the conterminous United States potentially rely on groundwater with detectable concentrations of PFAS for their drinking water supplies before any treatment.

Statistical Mapping of PFOA and PFOS in Groundwater throughout the Contiguous United States

Per-and polyfluoroalkyl substances (PFAS) are synthetic chemicals that are increasingly being detected in groundwater. The negative health consequences associated with human exposure to PFAS make it essential to quantify the distribution of PFAS in groundwater systems. Mapping PFAS distributions is particularly challenging because a national patchwork of testing and reporting requirements has resulted in sparse and spatially biased data. In this analysis, an inhomogeneous Poisson process (IPP) modeling approach is adopted from ecological statistics to continuously map PFAS distributions in groundwater across the contiguous United States. The model is trained on a unique data set of 8910 PFAS groundwater measurements, using combined concentrations of two PFAS analytes. The IPP model predictions are compared with results from random forest models to highlight the robustness of this statistical modeling approach on sparse data sets. This analysis provides a new approach to not only map PFAS contamination in groundwater but also prioritize future sampling efforts.

Conflicted and Relevant: Systematic Processing of Information on PFAS Contamination

Per- and polyfluoroalkyl substances (PFAS) contamination is an emerging environmental and public health crisis. Thus, it is crucial to understand public risk perception and communication behaviors surrounding this issue. Guided by the heuristic-systematic model of information processing, this study explores the impact of conflicting information and personal relevance on information insufficiency and information processing. Through an online experiment, 1,062 U.S. adults were randomly assigned to one of four conditions as part of a 2 (information type: conflicting vs. consistent) × 2 (personal relevance: high vs. low) between-subjects factorial design. Both main effect and interaction effect were detected. Specifically, information insufficiency was highest among participants in the high personal relevance and consistent information condition. Personal relevance also had a main effect on information processing. Conflicting information indirectly elevated information processing through increased information insufficiency, but only when personal relevance was low. These findings suggest the importance of providing consistent and personally relevant information related to the risk of PFAS contamination.

Gestational PFAS exposure and newborn size: The modifying effect of cord blood fatty acids

Per- and polyfluoroalkyl substances (PFASs) can disrupt lipid metabolism, and changes in cord blood fatty acid composition have been observed in small newborns. Emerging evidence suggests that exposure to PFASs during pregnancy is linked to decreased newborn size, although the evidence is not consistent. The modifying effect of fatty acids on the associations of gestational PFAS exposure with newborn size is still unknown. Here we show that the nutritional status of the fetus, as indicated by the level of fatty acids in the cord blood, mitigates the adverse effects of gestational PFAS exposure on the size of the newborn. Our study confirms the adverse developmental effects of PFASs and identifies emerging short-chain PFASs as the primary drivers of reduced newborn size, despite their lower exposure burden compared to legacy PFASs. Additionally, we find the protective role of cord blood fatty acids, suggesting potential strategies for mitigating the detrimental effects of emerging environmental exposures on human health. Our findings provide new evidence of the potential toxicity of emerging PFASs and call for further toxicity evaluations of these pollutants for regulatory purposes. Future studies should consider the complex interaction between exposure and nutrition within the human body, particularly during the first thousand days of life, to promote lifelong health.

Development, validation, and clinical assessment of a liquid chromatography-tandem mass spectrometry serum assay for per- and polyfluoroalkyl substances (PFAS) recommended by the National Academies of Science, Engineering, and Medicine (NASEM)

Per- and polyfluoroalkyl substances (PFAS) are widely used in industry, residential, and consumer products. Studies have shown associations between high PFAS exposure and adverse health effects. In 2022, the National Academies of Science, Engineering, and Medicine (NASEM) published Guidance on PFAS Exposure, Testing, and Clinical Follow-up providing laboratory and clinical direction. The Guidance suggests nine PFAS should be measured in serum or plasma specimens and summed to provide a total PFAS concentration using a NASEM-recommended method. Follow-up clinical recommendations are based on the calculated PFAS NASEM summation. We developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in accordance with NASEM recommendations but distinguished by the ability to separate closely related structural isomers. As part of our validation, PFAS prevalence was evaluated in a population survey comprised of clinical donor and remnant specimens (n = 1023 in total). In this study, 82.2% of the specimens had PFAS NASEM summations of 2 to < 20 ng/mL and 2.5% had a summation ≥ 20 ng/mL. The median PFAS NASEM summation was 4.65 ng/mL in this study, lower than the 7.74 ng/mL median observed in the 2017-2020 Centers for Disease Control and Prevention, National Health and Nutrition Examination Survey (n = 3072). This lower median PFAS NASEM summation may reflect a decline in PFAS population levels over time or sample population exposure differences.

Protection over restoration to ensure water sustainability

Plastics pollution, persistent chemical contamination and inadequately treated wastewater are three key aspects that hinder access to safe and affordable water for all. We argue that a strong priority on pollution avoidance, research for remediation, and tighter regulation and monitoring must be implemented to make progress.

Carbon Adsorbent Properties Impact Hydrated Electron Activity and Perfluorocarboxylic Acid (PFCA) Destruction

Carbon-based adsorbents used to remove recalcitrant water contaminants, including perfluoroalkyl substances (PFAS), are often regenerated using energy-intensive treatments that can form harmful byproducts. We explore mechanisms for sorbent regeneration using hydrated electrons (eaq -) from sulfite ultraviolet photolysis (UV/sulfite) in water. We studied the UV/sulfite treatment on three carbon-based sorbents with varying material properties: granular activated carbon (GAC), carbon nanotubes (CNTs), and polyethylenimine-modified lignin (lignin). Reaction rates and defluorination of dissolved and adsorbed model perfluorocarboxylic acids (PFCAs), perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA), were measured. Monochloroacetic acid (MCAA) was employed to empirically quantify eaq - formation rates in heterogeneous suspensions. Results show that dissolved PFCAs react rapidly compared to adsorbed ones. Carbon particles in solution decreased aqueous reaction rates by inducing light attenuation, eaq - scavenging, and sulfite consumption. The magnitude of these effects depended on adsorbent properties and surface chemistry. GAC lowered PFOA destruction due to strong adsorption. CNT and lignin suspensions decreased eaq - formation rates by attenuating light. Lignin showed high eaq - quenching, likely due to its oxygenated functional groups. These results indicate that desorbing PFAS and separating the adsorbent before initiating PFAS degradation reactions will be the best engineering approach for adsorbent regeneration using UV/sulfite.

Identification and quantification of novel per- and polyfluoroalkyl substances (PFAS) contamination in a Great Lakes urban-dominated watershed

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic organic fluoro-compounds that are oil-, water-, and flame-resistant, making them useful in a wide range of commercial and consumer products, as well as resistant to environmental degradation. To assess the impact of urbanization and wastewater treatment processes, surface water and sediment samples were collected at 27 sites within the Great Lakes in the Lake Huron to Lake Erie corridor (HEC), an international waterway including the highly urbanized Detroit and Rouge Rivers. Samples were analyzed for 92 PFAS via UHPLC-MS/MS. Our previous data in the HEC found the highest amount of PFAS contamination at the Rouge River mouth. In addition to evaluating the input of the Rouge River into the HEC, we evaluated the transport of PFAS into the HEC from other major tributaries. PFAS were detected in both surface water and sediment at all sites in this study, with a total of 10 congeners quantified in all surface water samples and 16 congeners quantified in all sediment samples, indicating ubiquitous contamination. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were pervasive in the HEC as these two compounds were detected in all sites and matrices, often at concentrations above the US EPA's recommended lifetime interim updated health advisories. Surface water samples contained more perfluorohexanoic acid (PFHxA) than any other congener, with average aqueous PFHxA across all surface water samples exceeding the average concentration previously reported in the Great Lakes. Sediment samples were dominated by PFOS, but novel congeners, notably 3-Perfluoropentyl propanoic acid (FPePA), were also quantified in sediment. The Rouge River and other tributaries contribute significantly to the PFAS burden in the HEC including Lake Erie. Overall, our results indicate the need for expanding toxicological research and risk assessment focused on congeners such as PFHxA and PFAS mixtures, as well as regulation that is tighter at the onset of production and encompasses PFAS as a group at a national level.

Current Challenges in Monitoring Low Contaminant Levels of Per- and Polyfluoroalkyl Substances in Water Matrices in the Field

The Environmental Protection Agency (EPA) of the United States recently released the first-ever federal regulation on per- and polyfluoroalkyl substances (PFASs) for drinking water. While this represents an important landmark, it also brings about compliance challenges to the stakeholders in the drinking water industry as well as concerns to the general public. In this work, we address some of the most important challenges associated with measuring low concentrations of PFASs in drinking water in the field in real drinking water matrices. First, we review the "continuous monitoring for compliance" process laid out by the EPA and some of the associated hurdles. The process requires measuring, with some frequency, low concentrations (e.g., below 2 ppt or 2 ng/L) of targeted PFASs, in the presence of many other co-contaminants and in various conditions. Currently, this task can only (and it is expected to) be accomplished using specific protocols that rely on expensive, specialized, and laboratory-scale instrumentation, which adds time and increases cost. To potentially reduce the burden, portable, high-fidelity, low-cost, real-time PFAS sensors are desirable; however, the path to commercialization of some of the most promising technologies is confronted with many challenges, as well, and they are still at infant stages. Here, we provide insights related to those challenges based on results from ab initio and machine learning studies. These challenges are mainly due to the large amount and diversity of PFAS molecules and their multifunctional behaviors that depend strongly on the conditions of the media. The impetus of this work is to present relevant and timely insights to researchers and developers to accelerate the development of suitable PFAS monitoring systems. In addition, this work attempts to provide water system stakeholders, technicians, and even regulators guidelines to improve their strategies, which could ultimately translate in better services to the public.

PFAS remediation: Evaluating the infrared spectra of complex gaseous mixtures to determine the efficacy of thermal decomposition of PFAS

Due to their widespread production and known environmental contamination, the need for the detection and remediation of per- and polyfluoroalkyl substances (PFAS) has grown quickly. While destructive thermal treatment of PFAS at low temperatures (e.g., 200-500 °C) is of interest due to lower energy and infrastructure requirements, the range of possible degradation products remains underexplored. To better understand the low temperature decomposition of PFAS species, we have coupled gas-phase infrared spectroscopy with a multivariate curve resolution (MCR) analysis and a database of high-resolution PFAS infrared reference spectra to characterize and quantify a complex mixture resulting from potassium perfluorooctanesulfonate (PFOS-K) decomposition. Beginning at 375 °C, nine prevalent decomposition products (namely smaller perfluorocarbon species) are identified and quantified.

Per- and polyfluoroalkyl substances (PFAS) in paired tap water and house dust from United States homes

Most people in the United States have been exposed to per- and polyfluoroalkyl substances (PFAS) which have been linked to a wide array of adverse health conditions in adults and children. The consumption of contaminated drinking water is an important human exposure pathway to PFAS. Residential sources also contribute to PFAS exposure through dermal contact and ingestion of house dust, which acts as an aggregate of chemicals from sources like furnishing materials and consumer products. The U.S. Department of Housing and Urban Development (HUD) conducted the first nationwide survey of residential hazards called the American Healthy Homes Survey (AHHS) in 2005, followed by a second survey (AHHS II) in 2017. The U.S. Environmental Protection Agency (EPA) collaborated with HUD on both efforts and subsequently analyzed PFAS in household tap water and house dust collected from the same homes during the AHHS II study. This study leverages these paired samples to investigate potentially important exposure sources and pathways in the residential environment. Here we report results for paired household tap water and house dust samples from 241 homes for 13 and 16 PFAS chemicals, respectively. All 13 targeted chemicals were detected in the household tap water samples with detections ranging from 100 % for PFBS to 1 % for PFNS, and all 16 targeted chemicals were detected in the house dust samples with detections ranging from 97 % for PFOA to 9 % for PFNS. Four chemicals (PFOA, PFOS, PFHxS, and PFHpA) were measured above the limit of detection in at least 50 % of the samples in both media. All households had at least one of the targeted PFAS detected in both their tap water and house dust. Results provided evidence that geographical factors, such as proximity to ambient contamination sources, were main drivers of PFAS contamination in tap water, while PFAS contamination in house dust was driven mainly by within-home sources. Exposure estimates calculated from the measured PFAS concentrations highlight the importance of addressing potential sources of exposure to PFAS within homes in addition to ambient sources affecting communities' drinking water, particularly to reduce children's exposure to these chemicals.