Discovery of Previously Unreported Per- and Polyfluoroalkyl Substances (PFAS) in Pooled Australian Human Serum Using Nontarget Analysis.

Humans may be exposed to thousands of per- and polyfluoroalkyl substances (PFAS), yet only a small fraction of these are regularly monitored, potentially underestimating the associated risks. This study employed high-resolution mass spectrometry (HRMS)-based nontarget analysis to investigate previously unreported PFAS in pooled serum from Australians. Samples collected between 2002 and 2021 from men aged > 30 years in the general population (GP, n = 27) and firefighters (FF, n = 18), categorized into three age groups (31-45, 46-60, and ≥ 60), were analyzed. Fourteen PFAS were identified or structurally annotated, including six known (level 1a-1b) and seven suspects (level 2b-3a). Additionally, six suspects with CHF2 or CF3 functionalities were tentatively annotated. Two previously unreported PFAS in human serum, hydrogen-substituted 2:1 perfluoroether sulfonic acid (2:1 H-PFESA) and hexafluoro-1,2-propanediol (HFPrD), were detected in 42% and 56% of samples, respectively. Further analysis of these two compounds in broader GP serum pools, including six age groups and both sexes, revealed their presence even in children under five, with relatively high intensities. No clear temporal, age, sex, or occupation-related trends were observed, suggesting widespread ongoing population exposure. These findings underscore the need for expanded HRMS-based monitoring to better assess human PFAS exposure.