Unraveling the Exposure Spectrum of PFAS in Fluorochemical Occupational Workers: Structural Diversity, Temporal Trends, and Risk Prioritization.

Despite extensive poly/perfluoroalkyl substance (PFAS) discovery studies in various samples, the exposure spectrum in fluorochemical occupational workers remains largely unexplored. Here, serum samples from 28 workers at a fluorochemical facility were analyzed using nontarget techniques, identifying 64 PFAS classes, including 15 novel ones such as pentafluorosulfur ether-substituted perfluoroalkyl sulfonic acids, hydrogen-substituted perfluoroalkylamines, and perfluoroalkylsulfonyl protocatechualdehyde esters. Temporal trend analyses (2008-2018) revealed stable levels for most PFAS but an increase in perfluorobutanoic acid (PFBA) and perfluorohexanesulfonic acid (PFHxS), suggesting industrial shifts from long-chain PFAS to short-chain homologues in China since the early 2010s. Commonly reported structurally modified PFAS (e.g., hydrogen/carbonyl/chlorine substitution, ether insertion, and unsaturation) were likely historical byproducts of legacy PFAS production rather than intentionally manufactured alternatives. A Toxicological Priority Index-based risk assessment, integrating mobility, persistence, and bioaccumulation indices, identified perfluoroalkylamines, di(perfluoroakyl sulfonyl)imides, structurally modified perfluoroalkyl sulfonic acids/carboxylic acids, and perfluoroalkylsulfonamidoacetic acids as high-risk PFAS chemicals. Overall, structurally modified PFAS exhibited higher mobility but lower persistence and bioaccumulation than legacy PFAS, except for chlorinated variants, which showed increased bioaccumulation potential. This study highlights critical gaps in the spectrum of historically emitted PFAS and emphasizes the need for large-scale monitoring and extensive risk assessments to manage emerging PFAS.