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Development and Evaluation of an ADME-informed High Throughput Exposure Estimation Tool
Citation:
Hubbard, H., C. Henning, T. Hong, D. Vallero, AND P. Egeghy. Development and Evaluation of an ADME-informed High Throughput Exposure Estimation Tool. ISES Annual Meeting, Henderson, NV, Henderson, NV, October 18 - 23, 2015.
Impact/Purpose:
The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
EPA’s Chemical Safety for Sustainability (CSS) research program has been developing new ways to prioritize chemicals used in consumer products and articles. Using a risk-based methodology to account for both toxicity and exposure offers a comprehensive and systematic approach toward prioritization. The purpose of this prioritization initially is to identify those chemicals for which typical product usage rates may lead to undesirable exposures, and ultimately to identify potentially problematic chemicals before they even reach the marketplace. We developed a flexible dashboard-type chemical prioritization tool that ranks exposures from consumer products accounting for product formulation and use; physical-chemical properties (e.g., partitioning coefficients); and user exposure factors, activity patterns, and product use profiles. Additionally, the tool incorporates route- and chemical-specific internal dose predictions that consider absorption, distribution, metabolism, and excretion (ADME) processes allowing for better comparison of toxicity and exposure estimates. The tool indicates products likely to be in specific microenvironments, along with the ways people will contact chemicals in these products, thus allowing better screening and ranking of exposure in a high throughput environment. Currently, the tool considers seven pathways of exposure for 451 chemicals present in 946 separate consumer products with the ability to add more chemicals and products as information becomes available. In this presentation, the tool is evaluated by comparing the predicted rank order of chemical exposures based on internal dose against biomonitoring data from National Health and Nutrition Examination Survey (NHANES) and the rank order based on intake as compared to other existing high throughput screening models. The views expressed here are those of the authors and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency.
