Sex-specific association of per- and polyfluoroalkyl substances (PFAS) exposure with vitamin D concentrations in older adults in the USA: an observational study

Background: Per- and polyfluoroalkyl substances (PFAS) are commonly utilized in consumer products. While earlier studies have suggested potential impacts of certain PFAS on serum concentrations of vitamin D, these investigations were constrained to a limited set of conventional PFAS. Moreover, they did not specifically focus on populations with longer duration of PFAS exposure and potentially higher blood PFAS levels, such as older adults, and lacked adequate evidence to examine sex-related disparities.

Methods: This observational investigation utilized cross-sectional data obtained from the U.S. NHANES spanning the years 2003 to 2018. Survey-weighted multiple regression models were employed to evaluate the relationship between PFAS exposure and vitamin D concentrations. Multi-pollutant models were employed to evaluate the association between PFAS mixtures and vitamin D concentrations. Subsequently, environmental risk scores (ERS) were constructed to gauge associations with vitamin D concentrations. ERS was computed through a weighted linear combination of PFAS, utilizing calculations from ridge regression and adaptive elasticity network (adENET) methodologies. All analyses were stratified by sex.

Results: The study encompassed 3,853 older adults. Our analysis revealed a negative association between PFOA, PFOS, PFNA, and MeFOSAA and serum vitamin D concentrations. In analyses examining mixed exposures, various models consistently indicated an inverse association between PFAS mixed exposure and vitamin D concentrations. Moreover, an increase in ERS of PFAS across the interquartile range was associated with a decrease in vitamin D concentrations (Q4 vs. Q1, adENET: β: -0.083, 95% CI: -0.117, -0.048; ridge regression: β: -0.077, 95% CI: -0.111, -0.042). Notably, these associations were exclusively observed within the female population.

Conclusions: Our study indicates that heightened exposure to PFAS correlates with diminished serum vitamin D concentrations in females aged 60 years and older, evident in both single and mixed exposures. These findings find support in in vitro mechanistic studies, suggesting that PFAS may impact the metabolism of 25(OH)D, consequently affecting vitamin D concentrations.