Increasing disparities in human exposure to perfluorooctanesulfonic acid: Findings from per- and polyfluoroalkyl substance concentrations in 1999–2018 NHANES

The disparities in exposure to environmental hazards have fueled the environmental justice movement, which has garnered increasing attention and momentum over the past few decades. However, research addressing exposure disparities pertaining to chemicals remains notably limited. Here, leveraging data from the National Health and Nutrition Examination Survey spanning the period from 1999 to 2018, we unveiled that the perfluorooctanesulfonic acid (PFOS) exhibited the highest concentration in human biomonitoring in general U.S. population, with a mean value of 14.54 ± 19.59 ng/ml. Subsequently, the mean concentrations of Perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) were 3.33 ± 3.19, 2.29 ± 3.13, 1.07 ± 1.30, and 0.34 ± 0.71, respectively. Meanwhile, although females or Non-hispanic White exhibited relatively higher levels for most per- and polyfluoroalkyl substances (PFASs) compared to other groups. The individuals with higher household incomes demonstrated elevated exposure to PFASs. Interestingly, despite lower exposure burdens were observed in Non-Hispanic Black individuals, females, and individuals with low family income, we identified relatively higher exposure disparities in these populations. In particular, exposure disparities for general U.S. population exposure to PFOS exhibited an approximate 50 % increase from 1999 to 2018, despite a concurrent decline of 84 % in biomonitoring levels. Meanwhile, the population aging has led to an exacerbation of human exposure to PFOS by 12.4 %. Our findings underscore the necessity of ensuring equitable protection from PFAS exposure for all populations, although further investigation is required to understand the underlying mechanisms driving these disparities.