Clarifying temporal trend variability in human biomonitoring of polybrominated diphenyl ethers through mechanistic modeling

Human biomonitoring data collected from individuals of the same age sampled in different years provides within-age temporal trends, which are often employed to evaluate the effectiveness of chemical regulatory policies. For polybrominated diphenyl ethers (PBDEs), this within-age temporal trend has been observed to vary between congeners and age groups. We systematically explore the mechanisms responsible for such variability through simulating human exposure via multiple exposure pathways to PBDEs released from multiple lifecycle stages. Our simulation indicates that, after new use of PBDEs is banned, emissions to the outdoor environment from use and waste disposal outlast those to the indoor environment from the indoor use phase, leading to slower decline rates in contamination of food items sourced from the outdoor environment than that indoors. Compared with indoor exposure pathways, consumption of contaminated food contributes more to the exposure (i) to more hydrophobic, recalcitrant congeners, and (...