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Developing a Tool to Characterize Aggregate Chemical Exposure by Lifestage poster
Citation:
Dai, M., S. Euling, L. Phillips, AND G. Rice. Developing a Tool to Characterize Aggregate Chemical Exposure by Lifestage poster. PEHSU Annual Meeting, Washington, DC, June 03 - 05, 2019.
Impact/Purpose:
This poster will be presented at the Pediatric Environmental Health Specialty Unit (PEHSU) annual meeting being held June 3-5, 2019 in Washington, DC. The goal of ExpoKids is to visually illustrate estimated differences in individuals’ postnatal chemical exposures from different media and across different lifestages.
Description:
Aggregate exposure to environmental chemicals considers the combined exposures from multiple pathways and can be greater among children compared to adults due to differences in behaviors, pathways, and physiology. To explore potential differences in aggregate exposure at various lifestages, an R-based tool was developed using exposure estimates generated by the publicly available US EPA’s Exposure Factors Interactive Resource for Scenarios Tool (ExpoFIRST). ExpoFIRST uses exposure factors derived from the Exposure Factors Handbook, 2011 Edition and user-defined input values for media concentrations. The R-based tool illustrates children’s postnatal and adults’ aggregate oral exposures as average daily dose (ADD) and lifetime average daily dose (LADD) graphs organized by lifestage and by media. To demonstrate the utility of the lifestage aggregate exposure tool, three illustrative case examples were developed for diethylhexyl phthalate (DEHP), manganese, and endosulfan. These examples were used to identify specific media contributions to lifetime exposure (DEHP), to compare exposures to the beneficial dose range of an essential nutrient (manganese), and to examine whether a regulatory policy changed children’s environmental exposures to a pesticide (endosulfan). For DEHP, young infants (under 1 year old), but no other postnatal lifestages, were estimated to exceed the current US EPA reference dose (RfD), and breast milk exposure largely accounted for this dose exceedance. For manganese, exposures during all postnatal lifestages were estimated to be between the National Academy of Medicine’s recommended adequate intake and upper limit. Although ADDs for endosulfan decreased to zero for most food categories after the endosulfan ban, ADDs for vegetables and fruit remained largely unchanged six years later. Together, the case examples illustrate the R-based tool’s ability to assess contributions of specific media and intake characteristics associated with specific lifestages to overall aggregate and lifetime chemical exposure, as well as the tool’s adaptability for answering a diverse set of questions.