Associations of cognitive function with recent and cumulative per- and polyfluoroalkyl substances exposure in firefighters

Abstract

Background: This pilot study aimed to examine associations between recent occupational exposure to per- and polyfluoroalkyl substances (PFAS) and domain-specific cognitive performance and explore whether cumulative perfluorooctane sulfonic acid (PFOS) modified these associations. Methods: Sixty-five actively serving firefighters in Central Texas (June 2023–March 2025) participated. Recent exposure was assessed using total concentrations (pg/µl) of perfluorobutanoic acid, perfluorobutane sulfonic acid, and PFOS measured in single post-incident wash-water samples from three sites (June–August 2024), with site-specific results extrapolated to all firefighters at each site. Cumulative exposure was measured using PFOS concentrations (pg/µl) in whole blood collected from February to March 2025. Cognitive outcomes included standardized z-scores for processing speed and global cognition derived from the NIH Toolbox Cognition Battery. Linear regression models evaluated PFAS–cognition associations, adjusting for covariates and testing interaction effects. Results: After adjustment, each doubling of cumulative PFOS corresponded to an estimated 11.1-point decline in processing speed (β = −1.07, 95% confidence interval = −1.59, −0.55, P < 0.001). Among firefighters with lower cumulative PFOS, higher recent PFAS exposure was associated with a 7.5-point reduction in processing speed. This effect was amplified with increasing cumulative PFOS (interaction β = 0.74, P = 0.01). No significant associations were observed for global cognition. Conclusion: PFAS exposure may differentially relate to cognitive domains in firefighters. Cumulative PFOS was associated with reduced processing speed and modified the impact of recent exposure. These preliminary findings warrant confirmation in larger studies and highlight the need to evaluate exposure mitigation strategies, including decontamination practices.