Evidence mapping and exposure estimate meta-analysis for human exposure pathways to per- and polyfluoroalkyl substances (PFAS)
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Human exposure to per- and polyfluoroalkyl substances (PFAS) has been primarily attributed to contaminated food and drinking water, but there is information indicating other sources and pathways of exposure. Here we conducted a systematic search of the literature to increase understanding of the relative importance of human exposure pathways to PFAS, identify data gaps, and inform research priorities. Eight well-studied PFAS chemicals (PFOA, PFOS, PFBA, PFBS, PFDA, PFHxA, PFHxS, and PFNA) and their occurrences in human matrices and exposure media (outdoor and indoor air, house dust, drinking water, food, food packaging, household articles, consumer products, and soil) were targeted in the literature search and screening process. Included studies (632) were categorized by matrix and chemical species, and additional study characteristics were extracted to aid in evidence mapping. Evidence maps showed that PFOA and PFOS were the most frequently studied chemicals in the literature, and concordant exposure media and human biomonitoring data were mainly reported for diet and drinking water pathways. Then, a subset of literature (7) that reported PFAS in concordant residential media (indoor air, house dust, food packaging, household articles, and consumer products) and biomonitoring measurements were identified for meta-analysis. The meta-analysis used exposure intake estimates and pharmacokinetic calculations to investigate relative source contribution from exposure pathways other than drinking water and diet. Literature was particularly scarce for this effort and most residential media with concordant biomonitoring measurements were house dust measurements. Results of this analysis for children showed that up to 31.7% (PFOA), 10.3% (PFOS), 15.2% (PFNA), and 54.8% (PFHxS) of serum concentrations could be attributed to exposure from contaminated house dust. For adults, up to 27.6% (PFOA), 15.5% (PFOS), 9.5% (PFNA), and 41.9% (PFHxS) of serum concentrations could be attributed to exposure from contaminated house dust. The lack of concordant data from exposure pathways other than diet and drinking water identifies a research gap that will be critical to interpretation of PFAS biomonitoring data and future policy decisions for these chemicals.