Polyfluoroalkyl Substances Compounds Research Articles

Exploring Solar Energy Solutions for Per‐ and Polyfluoroalkyl Substances Degradation: Advancements and Future Directions in Photocatalytic Processes

Concerns about per‐ and polyfluoroalkyl substances (PFAS) pollution are escalating globally due to the discovery of their widespread environmental distribution, accompanied by their migration, bioaccumulation, and toxic potential for plants, animals, and humans. Several technologies have been developed for their remediation since standard water treatment methods often fail. However, these approaches require large energy consumption and, at times, exacerbate environmental issues. In this context, photocatalytic degradation holds promise as a reliable technological solution for PFAS mineralization. However, to date, it primarily relies on the degradation of perfluorooctanoic acid using high‐energy gap semiconductor oxides that necessitate high‐power artificial ultraviolet sources for excitation and, at times, the use of strong chemical oxidants. This review examines chemical‐free catalysts and mechanisms recently documented in the literature to outline a roadmap for the realization of solar‐driven mineralization of all PFAS compounds. To this end, conventional wide‐bandgap semiconductor oxides are delved into and strategies to extend their spectral absorbance while enhancing charge separation with a focus on the proposed degradation pathways are explored, that are fundamental to designing technologically relevant photodegradation systems.

Exploring the impact of prenatal perfluoroalkyl and polyfluoroalkyl substances exposure on blood pressure in early childhood: A longitudinal analysis

Previous research investigating the correlation between prenatal exposure to per- and polyfluoroalkyl substances (PFAS) and subsequent blood pressure (BP) in offspring has yielded limited and contradictory findings. This study was conducted to investigate the potential relationship between maternal PFAS levels during pregnancy and subsequent BP in early childhood. A total of 129 expectant mothers from the Shanghai Birth Cohort were included in the study. Using high-performance liquid chromatography/tandem mass spectrometry, we measured ten PFAS compounds in maternal plasma throughout the pregnancy. When the children reached the age of 4, we examined their systolic BP (SBP) and diastolic BP (DBP), along with mean arterial pressure (MAP) and pulse pressure (PP). Data interpretation employed multiple linear and logistic regression models, complemented by Bayesian kernel machine regression (BKMR).We found that the majority of PFAS concentrations remained stable during pregnancy. The linear and BKMR models indicated a positive relationship between the PFAS mixture in maternal plasma and offspring's DBP and MAP, with perfluorohexanesulphonic acid (PFHxS) having the most significant influence (PFHxS and DBP [first trimester:β=3.03, 95%CI: (1.01,5.05); second trimester: β=2.35, 95%CI: (0.94,3.75); third trimester: β=2.57, 95%CI:(0.80,4.34)]; MAP [first trimester:β=2.55, 95%CI: (0.64,4.45); second trimester: β=2.28, 95%CI: (0.95,3.61); third trimester: β=2.35, 95%CI:(0.68,4.01)]). Logistic regression highlighted an increased risk of prehypertension and hypertension in offspring with higher maternal PFHxS concentrations during all three trimesters [first trimester: OR=2.53, 95%CI:(1.11,5.79), second trimester: OR=2.05, 95%CI:(1.11,3.78), third trimester: OR=3.08, 95%CI:(1.40,6.79)]. A positive correlation was identified between the half-lives of PFAS and the odds ratio (OR) of prehypertension and hypertension in childhood (β=0.139, P=0.010). In conclusion, this research found maternal plasma PFAS concentrations to be positively associated with BP in offspring, with PFHxS showing the most significant influence. This correlation remained consistent throughout pregnancy, and this effect was proportional to the half-lives of PFAS.

Extracorporeal Removal of Per- and Polyfluoroalkyl Substances by Hemoadsorption: In vitro Kinetic Model

Introduction: Per- and polyfluoroalkyl substances (PFAS) are known water pollutants leading to potential public health consequences. High blood levels of PFAS have been associated with several pathological conditions including testicular and kidney cancer. Classic extracorporeal therapies have demonstrated limited efficiency, and new approaches should be explored. In this study, we studied the possible role of hemoadsorption to achieve a fast, safe, and effective removal of PFAS from blood in patients with high blood levels. Methods: We developed an in vitro model of hemoadsorption to test the potential of PFAS removal by extracorporeal treatment. We recirculated a highly polluted batch of water (4 L) through a sorbent cartridge (Jafron Medical, Zhuhai, China) for 120 min at a flow of 150 mL/min. We collected samples at different time points and analyzed 39 different PFAS compounds. Results: For the PFAS compounds with concentrations significantly above normal, we observed a removal ratio close to 90% already within the first 60 min of circulation leading to almost complete elimination of all pollutants at 120 min. Conclusions: The in vitro model of hemoadsorption suggests the possible application in vivo of this technique to reduce/normalize the concentrations of PFAS in patients exposed to water or environmental pollution.

Unveiling per- and polyfluoroalkyl substance contamination in Chinese paper products and assessing their exposure risk

The contamination characteristics, migration patterns and health risks of per- and polyfluoroalkyl substances (PFAS) were investigated in 66 Chinese paper products by using target and non-target screening methods. Among 57 target PFASs, 5 and 6 PFASs were found in the hygiene paper products (<LOQ-12.6 ng/g) and stationery paper products (<LOQ-8.8 ng/g), respectively. A total of 25 PFASs were detected in the 39 food contact paper products, with the highest concentration of 1630 ng/g. Suspect and non-target analysis have found 28 PFASs with confidence levels 1–3, 132 certain PFAS compounds (level 4) and 56 homologue groups (level 5), containing newly identified long-chain polyfluorocarboxylic acid (9:3/11:3FTCA, 11:3/13:3FTUCA) and X:2 FTOH-Sulfate. A potential transformation relationship between the detected PFAS was proposed, starting from X:2 FTOH and finally transforming to CnF2n+1COOH. Microwave heating can increase the release of PFAS in popcorn bags and convert long-chain PFAS into short-chain ones. The migration experiments indicated that the ethanol in food simulants can increase the migration of PFAS, and short-chain PFAS exhibits a greater migration trend. The estimated daily intake (EDI) values for 6 of 18 paper bowls/plates exceeded the recommendation of 0.63 ng/kg bw/day by the European Food Safety Authority (EFSA), posing a potential threat to human health.

Integrating high-throughput phenotypic profiling and transcriptomic analyses to predict the hepatosteatosis effects induced by per- and polyfluoroalkyl substances

Per- and polyfluoroalkyl substances (PFAS) is a large compound class (n > 12,000) that is extensively present in food, drinking water, and aquatic environments. Reduced serum triglycerides and hepatosteatosis appear to be the common phenotypes for different PFAS chemicals. However, the hepatosteatosis potential of most PFAS chemicals remains largely unknown. This study aims to investigate PFAS-induced hepatosteatosis using in vitro high-throughput phenotype profiling (HTPP) and high-throughput transcriptomic (HTTr) data. We quantified the in vitro hepatosteatosis effects and mitochondrial damage using high-content imaging, curated the transcriptomic data from the Gene Expression Omnibus (GEO) database, and then calculated the point of departure (POD) values for HTPP phenotypes or HTTr transcripts, using the Bayesian benchmark dose modeling approach. Our results indicated that PFAS compounds with fully saturated C-F bonds, sulfur- and nitrogen-containing functional groups, and a fluorinated carbon chain length greater than 8 have the potential to produce biological effects consistent with hepatosteatosis. PFAS primarily induced hepatosteatosis via disturbance in lipid transport and storage. The potency rankings of PFAS compounds are highly concordant among in vitro HTPP, HTTr, and in vivo hepatosteatosis phenotypes (ρ = 0.60–0.73). In conclusion, integrating the information from in vitro HTPP and HTTr analyses can accurately project in vivo hepatosteatosis effects induced by PFAS compounds.

Adsorbent Materials Used for the Treatment of Per‐ and Poly‐fluoroalkyl Substances (PFAS): A Short Review

AbstractPFAS, or per‐ and polyfluoroalkyl substances, have received considerable attention due to their persistence in the environment and potential health risks. To address this problem, adsorption has emerged as an effective method for removing PFAS compounds from water. This review provides a comprehensive analysis of various adsorbents used for PFAS removal, including activated carbon, ion exchange resins, clay, and emerging materials such as covalent and metal‐organic framework adsorbents. The effectiveness of these adsorbents in removing PFAS compounds is discussed, along with the factors influencing their adsorption, such as pH, competitive matters, and temperature.This article is protected by copyright. All rights reserved

Texture Analysis as a Discriminating Tool: Unmasking Rodlet Cell Degranulation in Response to a Contaminant of Emerging Concern.

Contaminants of emerging concern (CECs) have garnered significant attention due to their potential impacts on ecology, wildlife, and human health. The interest in these contaminants arises from their inadequate regulation or lack of routine monitoring in natural environments. Among them, per- and polyfluoroalkyl substances (PFAS) are of particular concern due to their notable propensity to accumulate within the kidney, significantly influencing the excretion of these pollutants. Rodlet cells (RCs) have emerged as promising indicators of immunotoxicity in response to chemical stressors. A prior comprehensive study extensively detailed the effects of sub-chronic exposure to perfluorooctanoic acid (PFOA), a well-known PFAS compound, on RCs located in the hematopoietic tissue of the common carp kidney. Even at concentrations commonly found in the environment, PFOA exhibited a significant impact on the distribution patterns of RCs, concurrently enhancing exocytosis activity. The assessment of PFOA-induced RC degranulation employed texture analysis combined with linear discriminant analysis (LDA) to differentiate between various experimental exposure groups. The investigation encompassed three fish groups: an unexposed group, a group exposed to an environmentally relevant PFOA concentration (200 ng L-1), and a group exposed to a higher PFOA concentration (2 mg L-1). Texture analysis was conducted on high-resolution color (RGB) images obtained from light microscopy of ultrathin sections from five fish per experimental group, stained with toluidine blue. This analysis facilitated the quantification of potential cytoplasmic alterations associated with degranulation, encompassing all three RGB channels. The data subjected to LDA enabled the identification of the most distinctive texture characteristics, providing a reliable, objective, and reproducible method to differentiate between experimental groups. Remarkably, 98.0% of both the original and cross-validated cases were correctly classified. However, only one unexposed case was misclassified as a fish exposed to a 200 ng L-1 PFOA concentration, constituting the single false positive in the analysis. Utilizing texture analysis and LDA to quantify RC degranulation offers a dependable approach for assessing immunotoxicity within experimental models of toxicological and environmental pathology. This underscores the scientific significance of employing a morphological approach in such investigations.

Combined adsorption and electrochemical oxidation of perfluorooctanoic acid (PFOA) using graphite intercalated compound

Perfluorooctanoic acid (PFOA) is a bioaccumulative synthetic chemical containing strong C–F bonds and is one of the most common per- and polyfluoroalkyl substances (PFAS) detected in the environment. Graphite intercalated compound (GIC) flakes were used to adsorb and degrade PFOA through electrochemical oxidation. The adsorption followed the Langmuir model with a loading capacity of 2.6 µg PFOA g−1 GIC and a second-order kinetics (3.354 g µg−1 min−1). 99.4% of PFOA was removed by the process with a half-life of 15 min. When PFOA molecules broke down, they released various by-products, such as short-chain perfluoro carboxylic acids like PFHpA, PFHxA, and PFBA. This breakdown indicates the cleavage of the perfluorocarbon chain and the release of CF2 units, suggesting a transformation or degradation of the original compound into these smaller acids. Shorter-chain perfluorinated compounds had slower degradation rates compared to longer-chain ones. Combining these two methods (adsorption and in situ electrochemical oxidation) was found to be advantageous because adsorption can initially concentrate the PFOA molecules, making it easier for the electrochemical process to target and degrade them. The electrochemical process can potentially break down or transform the PFAS compounds into less harmful substances through oxidation or other reactions.

Per- and poly-fluoroalkyl substances removal in multi-barrier advanced water purification system for indirect potable reuse.

The study evaluated the removal efficacy of per- and poly-fluoroalkyl substances (PFAS) across various advanced water treatment (AWT) processes in a field-scale AWT train using secondary effluent samples from a full-scale water reclamation facility (WRF). Samples collected from April to October 2020 revealed PFCAs as the dominant PFAS compounds in the WRF secondary effluent, with PFPeA having the highest average concentration and PFSAs in notably lower amounts. Temporal fluctuations in total PFAS concentrations peaked in September 2020, which may reflect the seasonality in PFAS discharges related to applications like AFFFs and pesticides. In assessing AWT processes, coagulation-flocculation-clarification-filtration system showed no notable PFAS reduction, while ozonation resulted in elevated PFBS and PFBA concentrations. Biological activated carbon (BAC) filtration effectively removed long-chain PFAS like PFOS and PFHxS but saw increased concentrations of short-chain PFAS post-treatment. Granular activated carbon (GAC) filtration was the most effective treatment, reducing all PFSAs below the detection limits and significantly decreasing most PFCAs, though short-chain PFCAs persisted. UV treatment did not remove short-chain PFCAs such as PFBA, PFPeA, and PFHxA. The findings highlight the efficacy of AWT processes like GAC in PFAS reduction for potable reuse, but also underscore the challenge presented by short-chain PFAS, emphasizing the need for tailored treatment strategies. PRACTITIONER POINTS: Secondary effluents showed higher concentrations of PFCAs compared to PFSAs. Advanced water treatment effectively removes long-chain PFAS but not short-chain. Ozonation may contribute to formation of short-chain PFAS. BAC is less effective on short-chain PFAS, requiring further GAC treatment.

Associations between serum per- and polyfluoroalkyl substances and thyroid hormones in Chinese adults: A nationally representative cross-sectional study

Disruption of thyroid homeostasis has been indicated in human studies on the effects of per- and polyfluoroalkyl substances (PFASs). However, limited research exists on this topic within the general Chinese population. Based on a substantial and representative sample of the Chinese adult population, our study provides insight into how PFASs specifically affect thyroid homeostasis. The study included 10 853 participants, aged 18 years and above, sampled from nationally representative data provided by the China National Human Biomonitoring (CNHBM). Weighted multiple linear regression and restricted cubic spline (RCS) models were used to explore the associations between eight individual PFAS concentrations and total thyroxine (T4), total triiodothyronine (T3), and the T4/T3 ratio. Bayesian kernel machine regression (BKMR) and quantile-based g-computation (qgcomp) were employed to explore the joint and independent effects of PFASs on thyroid homeostasis. Both individual PFASs and PFAS mixtures exhibited a significant inverse association with serum T3 and T4 levels, and displayed a positive association with the T4/T3 ratio. Perfluoroundecanoic acid (PFUnDA) [–0.07 (95 % confidence interval (CI): –0.08, –0.05)] exhibited the largest change in T3 level. PFUnDA also exhibited a higher weight compared to other PFAS compounds in qgcomp models. Additionally, a critical exposure threshold for each PFAS was identified based on nonlinear dose–response associations; beyond these thresholds, the decreases in T3 and T4 levels plateaued. Specifically, for perfluoroheptane sulfonic acid (PFHpS) and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), an initial decline in hormone levels was observed, followed by a slight increase when concentrations surpassed 0.7 ng/mL and 2.5 ng/mL, respectively. Sex-specific effects were more pronounced in females, and significant associations were observed predominantly in younger age groups. These insights contribute to our understanding of how PFAS compounds impact thyroid health and emphasize the need for further research and environmental management measures to address these complexities.

P1143 Per- and poly-fluoroalkyl substances (PFAS) exposure is associated with later occurrence of inflammatory bowel disease

Abstract Background Environmental chemical exposures are increasingly acknowledged as risk factors for inflammatory bowel disease (IBD). Per- and poly-fluoroalkyl substances (PFAS), a large class of persistent fluorinated organic chemicals, widely used in the modern environment, may be implicated in IBD etiology, but data are conflicting. Methods We investigated the association of PFAS mixture concentrations in pre-diagnostic serum with adult-onset IBD in a pilot study within the pre-clinical Proteomic Evaluation and Discovery in an IBD Cohort of Tri-service Subjects (PREDICTS) study. This is a nested case-control study of military personnel with Crohn’s disease (CD), ulcerative colitis (UC), and age-, sex-, and race-matched healthy controls with serum samples obtained at four-time points 1-10 years prior to IBD diagnosis. Using untargeted liquid-chromatography high-resolution mass spectrometry analytical approach, we conducted an untargeted metabolomic analysis and semiquantitative measurement of fluorinated compounds, including legacy PFAS and emerging PFAS chemicals. We used weighted quantile sum regression models adjusted for confounders to study the association of PFAS as a mixture with the odds of CD and UC at each time point. Results Our study sample included individuals with CD, UC, and matched healthy controls (n=25, each group, 4 samples per individual). Baseline characteristics were similar across cases and controls. We identified nine well known PFAS compounds and 27 other known fluorinated compounds. The chemical mixture of fluorinated compounds, including the known PFAS, in the serum samples within one year of diagnosis was associated with higher odds of CD and UC [odds ratio (OR) 2.13, 95% CI 1.33, 3.41, and 1.76, 95% CI 1.15, 2.68, respectively] per one unit increase in decile. These associations remained consistent for the PFAS mixture measured in serum at all four time points up to 10 years prior to diagnosis for both CD and UC (Figure). Major contributors to the overall mixture indices included legacy PFAS, as well as emerging PFAS chemicals. Conclusion We observed a substantial increase in the odds of CD and UC among individuals with higher serum PFAS mixture levels up to 10 years prior to diagnosis. Studies to understand underlying mechanisms are ongoing.

The U.S. PFAS exposure burden calculator for 2017–2018: Application to the HOME Study, with comparison of epidemiological findings from NHANES

BackgroundThe 2017–2018 U.S. PFAS exposure burden calculator was designed to provide a summary exposure score for per- and polyfluoroalkyl substances (PFAS) mixtures using targeted PFAS analyte data. Its aim was to place PFAS burden score estimates onto a common scale based on nationally representative U.S. reference ranges from 2017 to 2018, enabling comparisons of overall PFAS burden scores across studies even if they did not measure the same set of PFAS analytes. ObjectiveTo use the U.S. PFAS exposure burden calculator for comparing the same mixture of PFAS compounds in similarly aged adolescents and their associations with cardiometabolic outcomes in the HOME Study and NHANES between 2015 and 2018. MethodsWe applied the PFAS burden calculator to 8 PFAS analytes measured in the serum of adolescents from the HOME Study (Cincinnati, Ohio; age range 11–14 years; years: 2016–2019; n = 207) and NHANES (US; age range 12–14 years; years 2015–2018; n = 245). We used the non-parametric Mann-Whitney U test and chi-squared test to compare the two study samples. In both studies, we examined associations of PFAS burden scores with the same cardiometabolic outcomes, adjusted for the same core set of covariates using regression analyses. We conducted sensitivity analyses to verify robustness of exposure-outcome associations, by accounting for measurement error of PFAS burden scores. ResultsPFAS burden scores were significantly different (p = 0.004) between the HOME Study (median: 0.00, interquartile range − 0.37, 0.34) and the NHANES samples (median: 0.04, IQR -0.11, 0.54), while no significant difference was found for PFAS summed concentrations (p = 0.661). In the HOME Study, an interquartile (IQR) increase in PFAS burden score was associated with higher total cholesterol [7.0 mg/dL, 95% CI: 0.6, 13.4]; HDL [2.8 mg/dL, 95% CI: 0.4, 5.2]; LDL [5.9 mg/dL, 95% CI: 0.5, 11.3], insulin [0.1 log(mIU/L), 95% CI: 0.01, 0.2], and HOMA-IR [0.1, 95% CI: 0.01, 0.2]. In NHANES, an IQR increase in PFAS burden score was associated with higher diastolic blood pressure [2.4 mmHg, 95% CI: 0.4, 4.4] but not with other outcomes. Sensitivity analyses in the HOME Study and NHANES were consistent with the main findings. ConclusionsPerformance of the U.S. PFAS exposure burden calculator was similar in a local versus national sample of adolescents, and may be a useful tool for the assessment of PFAS mixtures across studies.

A high-throughput small volume matrix based calibration using isotope dilution liquid chromatography tandem mass spectrometry analysis for 42 per and polyfluoroalkyl substances in groundwater

A novel method for the determination of per- and polyfluoroalkyl substances (PFAS) in groundwater is presented using a subsample, matrix-matched calibrators, 96-well plate solid phase extraction (SPE), and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Accuracy, precision, measurement of uncertainty (MOU), method detection limit (MDL), method quantitation limit (MQL), analytical measurement range, interferences/ion suppression, and analyte stability were determined as part of the in-house method validation. The method quantitates 42 PFAS compounds from nine different compound classes. Accuracy for the reference material (RM) and matrix spike (MS) ranged from 52.3 to 117.8 %, and precision for the MS and matrix spike duplicate (MSD) had a coefficient of variation (CV) from 2.0 % to 23.3 %. MDLs spanned from 0.07 to 1.97 ng L−1, with MQLs ranging from 0.20 to 5.90 ng L−1. Suppression studies determined that iron and manganese have effects on analytes that do not have paired isotopically labeled standards. The results from the in-house validation indicated that this Michigan Department of Health and Human Services laboratory developed test meets the necessary accuracy, precision, MDL, MQL and reporting limits requirement established by the laboratory's quality system essentials (QSEs) and select criteria from the Department of Defense (DoD) Quality Systems Manual for Environmental Laboratories and American Industrial Hygiene Association Laboratory Accreditation Program, LLC (AIHA LAP, LLC) accrediting International Standard Organization (ISO/IEC 17025:2017) check list.

Comprehensive Determination of 28 PFAS Compounds in Oyster Tissue: A QuEChERS Sample Preparation Coupled with UPLC-MS/MS

Per- and polyfluoroalkyl substances (PFAS) are known to bioaccumulate in aquatic organisms, such as shellfish, and have been linked to adverse human health outcomes. Increasing attention has been focused on method development for the detection of PFAS in various media; however, these methods are typically tedious, require high solvent volumes, and are time consuming. The present method used a Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction approach and analysis by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) to detect 28 PFAS in Eastern oyster (Crassostrea virginica) tissue. This method was validated using limit of detection, limit of quantitation, and precision and accuracy studies. Limits of detection ranged from 0.2 to 5.8 ng g−1, limits of quantitation ranged from 0.66 to 19.2 ng g−1, and recoveries spanned 52.1–105.9% at the 100 ng mL−1 analyte level. Analysis of 12 unknown oyster composite samples revealed the detection of PFHxA, PFPeS, PFOA, PFHpA and PFOS and at least two compounds were detected in each oyster sample. This validated method proved to be an efficient and environmentally friendly sample preparation method for PFAS analysis in complex tissue media, such as oysters.

Legacy and emerging per- and polyfluoroalkyl substances in the Shuidong bay of South China: Occurrence, partitioning behavior, and ecological risks

With the phase-out of legacy per- and polyfluoroalkyl substances (PFASs), PFAS alternatives have been increasingly used in industrial production and daily life. However, available information on the occurrence of PFASs and PFAS alternatives in semi-enclosed bays remains limited. As a representative semi-enclosed bay in Guangdong Province, China, Shuidong Bay has experienced severe anthropogenic pollution (industrial, shipping, cultural, and domestic) in recent decades. Water pollution in Shuidong Bay has worsened, and PFASs have been identified as ubiquitous environmental pollutants in this bay. In this study, 23 PFASs, including 5 emerging PFASs, were analyzed in water, suspended particulate matter (SPM), and sediment samples collected from Shuidong Bay. We determined that perfluorobutanoic acid (PFBA) was the predominant PFAS compound in seawater, whereas 6:2 fluorotelomer sulfonic acid (FTS) and perfluorooctane sulfonamide acetate (FOSAA) were dominant in SPM and sediment, respectively. The sediment–water partitioning coefficients were greatly dependent on the perfluorinated carbon chain length. Chlorophyll a concentration had a significant effect on the dissolved concentrations of PFASs in seawater. The ecological risk assessment indicated that the PFASs detected in the seawater and sediment samples posed no considerable risks to aquatic organisms. This study provides a valuable reference for evaluating PFAS contamination in Shuidong Bay and conducting ecological risk assessments for aquatic organisms.

Profiling research on PFAS in wildlife: Systematic evidence map and bibliometric analysis

Abstract Per‐ and polyfluoroalkyl substances (PFAS) are a large group of synthetic chemicals that have been in use for over 70 years. Their ubiquitous distribution and harmful effects pose a threat to wildlife worldwide. To provide a comprehensive synopsis and show the gaps and gluts of existing research on PFAS exposure in wildlife, we created a systematic map and bibliographic analysis of the literature. We followed our protocol to conduct a systematic literature search on Scopus, Web of Science and five other databases. In two steps (title/abstract/keywords and full‐text), we screened peer‐reviewed empirical articles, preprints and theses in English that studied the concentration of at least one of 34 PFAS compounds in free‐ranging wildlife or their parts/products. Following the protocol, we extracted data and performed a critical appraisal. We included 581 publications. From the first and only paper in 2001, there was a linear annual increase to 54 papers in 2021. While PFOS (97% of studies), PFOA (91%) and long‐chain PFAS in general were the most measured, few studies investigated new‐generation PFAS (e.g. GenX and ADONA). Across the studied 1042 species from 26 taxonomic classes, the most frequent were the common carp (Cyprinus carpio, 8%), polar bear (Ursus maritimus, 6%) and European perch (Perca fluviatilis, 5%). Most sampling took place in the United States (17%), Norway (13%), Canada (12%) and China (10%), which were also the main publishing countries. Polar regions attracted significant research interest from countries all around the globe. Aquatic habitats (marine: 31%, freshwater: 28%) of temperate zones were the most common locations for sample collection. We encourage researchers to work towards closing the following gaps: investigating new‐generation PFAS, assessing PFAS in mid‐ and low‐income countries and performing more long‐term studies, especially on invertebrates. We note the recent rise in studies on the physiological consequences of PFAS exposure and encourage further work on this crucial topic. Furthermore, we recommend that the statement of potential and actual conflicts of interest, and the provision of raw data and analysis code should be made compulsory by all journals and routinely enforced. This practice will mitigate conflict of interest and ensure reproducibility.

Exploring the variability of PFAS in urban sewage: a comparison of emissions in commercial versus municipal urban areas.

Per- and polyfluoroalkyl substances (PFAS) are recognized for their persistence and ubiquitous occurrence in different environmental compartments. Conventional wastewater treatment plants (WWTPs) cannot effectively remove PFAS from wastewater, and a better understanding of the occurrence and sources of PFAS in this medium would enable effective source abatement. We compared sewage from urban areas exhibiting differentiating characteristics with respect to activities in their catchments. These included a sewer that serves primarily a municipal area, with no commercial activities involving PFAS emissions being identified, another sewer with a strong influence of commercial activities potentially related to PFAS emissions, and the influent of the whole city sewage network. The year-long monitoring campaign consisted of flow-proportional, monthly composite samples and targeted analysis of 29 PFAS compounds. Principal component analysis was used to investigate the relationships between selected PFAS and standard water quality parameters such as ammonium, a known tracer of urine and thus of typical municipal wastewater. Notable findings were seen for PFOS and 6:2 FTS, whose concentrations were most negatively correlated with ammonium. Ammonium concentration data allowed for a normalized per-person median load calculation, which resulted in loads of the observed PFAS ranging from below 0.4 up to 4.7 μg per person per day. Both the commercial area sewer and the city influent exhibited significantly higher (p < 0.05) median loads (>0.9 μg per person per day) in the case of 6:2 FTS and PFOS, compared to the municipal sewer (<0.6 μg per person per day). No statistically significant difference was found for other compounds, such as PFBA, PFHxA, PFOA, and PFHxS. We argue that this approach demonstrates that PFAS can differ in speciation and quantity within an urban wastewater setting, and consideration of both municipal and commercial activities is needed for a proper understanding of sources and emission pathways within the urban environment.

Elucidating Key Characteristics of PFAS Binding to Human Peroxisome Proliferator-Activated Receptor Alpha: An Explainable Machine Learning Approach.

Per- and polyfluoroalkyl substances (PFAS) are widely employed anthropogenic fluorinated chemicals known to disrupt hepatic lipid metabolism by binding to human peroxisome proliferator-activated receptor alpha (PPARα). Therefore, screening for PFAS that bind to PPARα is of critical importance. Machine learning approaches are promising techniques for rapid screening of PFAS. However, traditional machine learning approaches lack interpretability, posing challenges in investigating the relationship between molecular descriptors and PPARα binding. In this study, we aimed to develop a novel, explainable machine learning approach to rapidly screen for PFAS that bind to PPARα. We calculated the PPARα-PFAS binding score and 206 molecular descriptors for PFAS. Through systematic and objective selection of important molecular descriptors, we developed a machine learning model with good predictive performance using only three descriptors. The molecular size (b_single) and electrostatic properties (BCUT_PEOE_3 and PEOE_VSA_PPOS) are important for PPARα-PFAS binding. Alternative PFAS are considered safer than their legacy predecessors. However, we found that alternative PFAS with many carbon atoms and ether groups exhibited a higher affinity for PPARα. Therefore, confirming the toxicity of these alternative PFAS compounds with such characteristics through biological experiments is important.

Advanced oxidation processes may transform unknown PFAS in groundwater into known products

Per- and polyfluoroalkyl substances (PFAS) are a group of fluorinated organic contaminants classified as persistent in the aquatic environment. Early studies using targeted analysis approaches to evaluate the degradation of PFAS by advanced oxidation processes (AOP) in real water matrices may have been misinterpreted due to the presence of undetected or unknown PFAS in these matrices. The aims of the present study were to (1) screen selected commercially available AOPs (UV, UV + H2O2, O3/H2O2) and UV photocatalysis in a pilot system using commercially used and novel photocatalysts (TiO2, boron nitride [BN]) for removing PFAS contaminants and (2) evaluate their role on the conversion of non-detected/unknown to known PFAS compounds in real groundwater used as drinking water supplies. Results indicated that, while AOPs have the potential to achieve removal of the EPA method 533 target PFAS compounds (PFDA [100%], PFNA [100%], PFOA [85–94%], PFOS [25–100%], PFHxS [3–100%], PFPeS [100%], PFBS [100%]), AOPs transformed non-detected/unknown longer-chain PFAS compounds to detectable shorter-chain ones under very high-dose AOP operating conditions, leading to an increase in ∑PFAS concentration ranging from 95% to 340%. As emerging PFAS treatment processes transition from lab-scale investigations of target PFAS to pilot testing of real water matrices, studies will need to consider impact of the presence of non-target long-chain PFAS to transform into targeted PFAS compounds. A promising approach to address the potential risks and unforeseen consequences could involve an increased reliance on adsorbable organic fluorine (AOF) analysis before and after advanced oxidation process (AOP) treatment.

Early-life exposure to perfluoroalkyl substances and serum antibody concentrations towards common childhood vaccines in 18-month-old children in the Odense Child Cohort

Exposure to per- and polyfluoroalkyl substances (PFAS) has been associated with reduced antibody response to childhood vaccinations. Previous studies have mostly focused on antibodies against diphtheria or tetanus, while fewer studies have assessed antibodies toward attenuated viruses, such as measles, mumps or rubella (MMR). Therefore, we set out to determine associations between prenatal and early postnatal PFAS exposure and vaccine-specific Immunoglobulin G (IgG) in the background-exposed Odense Child Cohort. Blood samples were drawn in pregnancy at gestation weeks 8–16 and from the offspring at age 18 months. In the maternal serum samples we quantified perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA). In the offspring serum samples we quantified the same five PFAS compounds and IgG towards diphtheria, tetanus and MMR. A total of 880 and 841 children were included in the analyses of diphtheria and tetanus or MMR, respectively. Multiple linear regression models were used for estimation of difference in virus-specific IgG per doubling of PFAS concentrations. Maternal PFAS concentrations were non-significantly inversely associated with most vaccine-specific antibody concentrations. Likewise, child PFAS concentrations were associated with non-significant reductions of antibodies towards tetanus and MMR. A significant reduction in the percent difference in mumps antibody concentration per doubling of child PFNA (−9.2% (95% confidence interval: −17.4;-0.2)), PFHxS (−8.3% (−15.0;-1.0) and PFOS (−7.9% (−14.8;-0.4) was found. These findings are of public health concern, as inadequate response towards childhood vaccines may represent a more general immune dysfunction.