Bioaccumulation of Novel Per- and Polyfluoroalkyl Substances in Mice Dosed with an Aqueous Film-Forming Foam

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. 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-perfluorooctane
sulfonate (PFOS), hydrogen-PFOS, and unsaturated PFOS] appeared to
be more bioaccumulative than linear PFOS, or were formed in vivo from
unidentified precursors. A series of seven peaks in dosed mouse serum
was 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.