PFAS in the middle reaches of the Yangtze River, China: Tracking emerging alternatives and identifying priority control candidates based on their potential health implications

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants of global concern, yet systematic investigations into their occurrence and associated health risks in surface waters, particularly source waters, remain scarce. This study examined the distribution profiles and potential exposure risks of PFAS in the Yangtze River, Han River, and source water in the middle reaches of the Yangtze River (Hubei Province), including 19 legacy PFAS and 37 emerging PFAS. Our results revealed marked seasonal variations, with higher total PFAS concentrations observed in the dry season (Yangtze River: 100.23 ng/L; Han River: 65.47 ng/L) compared to the wet season (Yangtze River: 36.74 ng/L; Han River: 42.37 ng/L). Source water in northern Hubei exhibited the highest contamination levels, with a dry-season concentration of 104.77 ng/L. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) remained dominant, underscoring their environmental persistence despite regulatory measures. Flux estimates revealed a clear downstream increase in PFAS loads in both rivers, largely driven by emerging alternatives. Priority substance screening identified PFOA, PFOS, perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorodecanoic acid (PFDA), and hexafluoropropylene oxide dimer acid (HFPO-DA) as key compounds of concern. Chronic exposure to these substances at environmentally relevant concentrations has been associated with adverse health outcomes raising concerns about the safety of drinking water sources. These findings highlight the dynamic behavior of PFAS in river systems and provide critical insights for source water protection and health-oriented risk management.