Seafood-Linked and Sex-Specific Signatures of Legacy and Emerging PFAS Body Burden During Dietary Transition in Sichuan, China

Per- and polyfluoroalkyl substances (PFASs) are persistent contaminants of concern in food safety and human exposure assessment. Aquatic foods are important components of dietary diversification, but their association with internal PFAS burden remains unclear in inland populations. Of the 1294 participants initially recruited, 1292 with complete demographic information were included in the final analyses. Serum concentrations of 22 PFASs were measured by solid-phase extraction coupled with UPLC-MS/MS, and nine PFASs detected in more than 75% of samples were analyzed. Dietary intake frequency, sociodemographic characteristics, and lifestyle factors were collected using structured questionnaires. Multivariable linear regression and sex-stratified analyses were performed. Seafood-related food groups showed the most consistent positive associations with serum PFAS levels. Frequent consumption of shellfish, shrimp, crabs, fish, and seaweed was associated with higher concentrations of long-chain PFASs, including PFDA, PFNA, PFHxS, PFOS, and PFOA, while shrimp and crab intake was also positively associated with 6:2 Cl-PFESA. These associations were generally stronger in males, suggesting sex-related heterogeneity in the relationship between seafood intake and PFAS body burden. These findings suggest that seafood consumption is associated with distinct PFAS body-burden profiles in inland adults and may support integrated biomonitoring, dietary assessment, and food-contaminant surveillance.