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Determining health risks associated with per-/polyfluoroalkyl substances (PFASs) is a highly complex problem requiring massive efforts for scientists, risk assessors, and regulators. Among the most poorly understood pressing questions is the relative importance of pre-PFAAs, which are PFASs that degrade to highly persistent perfluoroalkyl acids. How many of the vast number of existing pre-PFAAs are relevant for direct human exposure, and what are the predominant exposure pathways? What evidence of direct exposure to pre-PFAAs is provided by human biomonitoring studies? How important are pre-PFAAs and their biotransformation products for human health risk assessment? This article outlines recent progress and recommendations toward widening the lens on human PFAS exposure to include the pre-PFAA subclass.

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. [ABSTRACT FROM AUTHOR]

Perfluoroalkyl sulfonamides (FASAs) and other FASA‐based per‐ and polyfluoroalkyl substances (PFASs) can transform into recalcitrant perfluoroalkyl sulfonates in vivo. We conducted high‐resolution mass spectrometry suspect screening of urine and tissues (kidney and liver) from mice dosed with an electrochemically fluorinated aqueous film‐forming foam (AFFF) to better understand the biological fate of AFFF‐associated precursors. The B6C3F1 mice were dosed at five levels (0, 0.05, 0.5, 1, and 5 mg kg−1 day−1) based on perfluorooctane sulfonate and perfluorooctanoate content of the AFFF mixture. Dosing continued for 10 days followed by a 6‐day depuration. Total oxidizable precursor assay of the AFFF suggested significant contributions from precursors with three to six perfluorinated carbons. We identified C4 to C6 FASAs and N‐glucuronidated FASAs (FASA‐N‐glus) excreted in urine collected throughout dosing and depuration. Based on normalized relative abundance, FASA‐N‐glus accounted for up to 33% of the total excreted FASAs in mouse urine, highlighting the importance of phase II metabolic conjugation as a route of excretion. High‐resolution mass spectrometry screening of liver and kidney tissue revealed accumulation of longer‐chain (C7 and C8) FASAs not detected in urine. Chain‐length–dependent conjugation of FASAs was also observed by incubating FASAs with mouse liver S9 fractions. Shorter‐chain (C4) FASAs conjugated to a much greater extent over a 120‐min incubation than longer‐chain (C8) FASAs. Overall, this study highlights the significance of N‐glucuronidation as an excretion mechanism for short‐chain FASAs and suggests that monitoring urine for FASA‐N‐glus could contribute to a better understanding of PFAS exposure, as FASAs and their conjugates are often overlooked by traditional biomonitoring studies. Environ Toxicol Chem 2024;43:2274–2284. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

This article discusses the transformation of environmental contaminants and the importance of understanding the reaction mechanisms, identifying novel products, and assessing the environmental implications. It highlights the challenges posed by synthetic substances released into the environment and the potential for these chemicals to transform into unknown products that may be more toxic or persistent than the parent compound. The article emphasizes the need for appropriate analytical techniques to detect and identify these transformation products. Several studies are highlighted that employ innovative analytical techniques to uncover the formation, occurrence, and environmental implications of transformation products in various contexts. The research presented in this series contributes to our understanding of emerging and novel organic contaminants and provides insights for improving environmental risk assessment. [Extracted from the article]

Polyethylene passive sampling was performed to quantify gaseous and freely dissolved polychlorinated biphenyls (PCBs) in the air and water of Lakes Erie and Ontario during 2011-2012. In view of differing physical characteristics and the impacts of historical contamination by PCBs within these lakes, spatial variation of PCB concentrations and air-water exchange across these lakes may be expected. Both lakes displayed statistically similar aqueous and atmospheric PCB concentrations. Total aqueous concentrations of 29 PCBs ranged from 1.5 pg L(-1) in the open lake of Lake Erie (site E02) in 2011 spring to 105 pg L(-1) in Niagara (site On05) in 2012 summer, while total atmospheric concentrations were 7.7-634 pg m(-3) across both lakes. A west-to-east gradient was observed for aqueous PCBs in Lake Erie. River discharge and localized influences (e.g., sediment resuspension and regional alongshore transport) likely dominated spatial trends of aqueous PCBs in both lakes. Air-water exchange fluxes of Σ7PCBs ranged from -2.4 (±1.9) ng m(-2) day(-1) (deposition) in Sheffield (site E03) to 9.0 (±3.1) ng m(-2) day(-1) (volatilization) in Niagara (site On05). Net volatilization of PCBs was the primary trend across most sites and periods. Almost half of variation in air-water exchange fluxes was attributed to the difference in aqueous concentrations of PCBs. Uncertainty analysis in fugacity ratios and mass fluxes in air-water exchange of PCBs indicated that PCBs have reached or approached equilibrium only at the eastern Lake Erie and along the Canadian shore of Lake Ontario sites, where air-water exchange fluxes dominated atmospheric concentrations.