N‐glucuronidation and Excretion of Perfluoroalkyl Sulfonamides in Mice Following Ingestion of Aqueous Film‐Forming Foam

Abstract

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;00:1–11. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.