Expanding PFAS Identification\nwith Transformation\nProduct Libraries: Nontargeted Analysis Reveals Biotransformation\nProducts in Mice

Per- and polyfluoroalkyl substances (PFAS) are widely\nused persistent\nsynthetic chemicals that have been linked to adverse health effects.\nWhile the behavior of PFAS has been evaluated in the environment,\nour understanding of reaction products in mammalian systems is limited.\nThis study identified biological PFAS transformation products and\ngenerated mass spectral libraries to facilitate an automated search\nand identification. The biological transformation products of 27 PFAS,\nspanning 5 chemical subclasses (alcohols, sulfonamides, carboxylic\nacids, ethers, and esters), were evaluated following enzymatic reaction\nwith mouse liver S9 fractions. Four major pathways were identified\nby liquid chromatography-high-resolution mass spectrometry: glucuronidation,\nsulfation, dealkylation, and oxidation. Class-based fragmentation\nrules and associated PFAS transformation product libraries were generated\nand integrated into an automated nontargeted PFAS data analysis software\n(FluoroMatch). Fragmentation was additionally predicted for the potential\ntransformation products of more than 2,500 PFAS in the EPA CompTox\nChemicals Dashboard PFASSTRUCTv4. Generated mass spectral libraries\nwere validated by applying FluoroMatch to a data set of urine from\naqueous film-forming foam (AFFF)-dosed mice. Toxicity predictions\nshowed identified PFAS transformation products to be potential developmental\nand mutagenic toxicants. This research enables more comprehensive\nPFAS characterization in biological systems, which will improve the\nassessment of exposures and evaluation of the associated health impacts.