Socioeconomic Disparities in PFAS Exposure and Susceptibility to Diabetes in Chinese Adults: A Nationwide Cross-Sectional Study.

Emerging evidence indicates that socioeconomic status (SES) shapes not only patterns of environmental exposure but also the susceptibility to environmental hazards. Per- and polyfluoroalkyl substances (PFAS) represent a distinctive case in which socioeconomically disadvantaged populations often exhibit lower exposure levels, raising critical questions about how such exposure patterns translate into health inequalities, particularly for diabetes. Using cross-sectional data from 10 302 adults participating in the China National Human Biomonitoring (CNHBM) program, we examined socioeconomic disparities in serum PFAS concentrations and assessed whether lower SES is associated with stronger PFAS-diabetes associations among Chinese adults. We found that individuals with higher SES exhibited 4-10% higher serum concentrations of PFOA, PFUnDA, PFHxS, PFHpS, PFOS, and 6:2 Cl-PFESA (all p values <0.05). In contrast, associations between PFAS exposure and diabetes were generally stronger among low-SES participants. Across multiple PFAS, odds ratios for diabetes in the low-SES group were 0-17% greater relative to the high-SES group, with statistically significant effect modification observed for PFUnDA, PFOS, and 6:2 Cl-PFESA. These findings indicate that socioeconomic disadvantage may be associated with greater susceptibility, even at lower exposure levels, underscoring the importance of considering differential susceptibility when assessing environmental health risks and advancing health equity.