Bioaccumulation of Novel Per- and Polyfluoroalkyl Substances (PFASs) in Mice Dosed with an Aqueous Film-Forming Foam (AFFF).

Per- and polyfluoroalkyl substances (PFASs) are widespread in the blood of the general human population, and their bioaccumulation is of considerable scientific and regulatory interest. PFAS exposure resulting from aqueous film-forming foam (AFFF) ingestion is poorly understood due to the complexity of AFFF mixtures and the presence of polyfluorinated substances that may undergo metabolic transformation. C57BL/6 mice were dosed with an AFFF primarily containing electrochemically fluorinated PFASs for 10 days, followed by a 6 day depuration. Urine was collected throughout the study and serum was collected post-depuration. Samples were analyzed via high-resolution mass spectrometry (HRMS). Relative to the dosing solution, C6 and C7 perfluoroalkyl sulfonates (PFSAs) were enriched in dosed mouse serum, suggesting in vivo transformation of sulfonamide precursors. Some substituted C8 PFSAs (keto-PFOS, hydrogen-PFOS, and unsaturated PFOS) appeared to be more bioaccumulative than linear perfluorooctane sulfonate (L-PFOS), or were formed in vivo from unidentified precursors. A series of seven peaks in dosed mouse serum were tentatively identified as sulfonimide dimers that were either a minor component of the AFFF, or were formed via metabolism of other AFFF components. This work highlights the importance of sulfonamide precursors in contributing to bioaccumulation of AFFF-associated PFSAs, and identifies several classes of potentially bioaccumulative novel PFASs that warrant further investigation.