Exploring the Long-Term Human Exposure to Short-, Medium-, and Long-Chain Chlorinated Paraffins under Variant Environmental Release Trends and Patterns

Releases of chlorinated paraffins (CPs) have led to long-term human exposure globally. Differences in CP use patterns (indoors vs outdoors) and temporal release trends in different regions may be reflected in differences in the extent and pathways of long-term exposure to CPs between human populations. We used the dynamic mechanistic model PROTEX to simulate releases and environmental fates of CPs in China, Canada, and Europe from 1930 to 2020 and contrast the resultant exposures for different birth cohorts. Predicted environmental and human body concentrations agree with measurements from the three regions. Far-field exposure pathways dominate for all cohorts even in China where CP indoor use is high. Longitudinal exposure trends differ between generations and regions due to the divergent release trends. Perinatal exposure causes high body concentrations in infants and children born in years with peak releases. Due to human elimination half-lives that are short relative to the period of release, cross-sectional concentration-age trends have similar shapes regardless of release trend and sampling time. These results imply that whereas use patterns and release trends add to the influence of physicochemical properties on relative exposure pathway importance and cross-sectional concentration-age trends, the release trends are the main factors shaping longitudinal exposure trends.