Citation:

Egeghy, P. In-depth methods for systemic exposure predictions. Cosmetics Europe Long-Range Science Strategy Workshop, Brussels, Belgium, Brussels, BELGIUM, September 21, 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:

Exposure to a wide range of chemicals is ubiquitous and largely unavoidable within modern society. The potential for human exposure, however, has not been quantified for the vast majority of chemicals with wide commercial use. Creative advances in exposure science are needed to support efficient and effective evaluation and management of chemical risks, particularly for chemicals in consumer products. The U.S. Environmental Protection Agency Office of Research and Development is collaborating in the development of scientifically-defensible methods for making quantitative or semi-quantitative exposurepredictions. These novel modeling approaches for evaluating chemicals based on their potential for biologically relevant human exposures will inform toxicity testing and prioritization for chemical risk assessment. The Exposure Prioritization (Ex Priori) model is a simplified, quantitative visual dashboard that provides a rank-ordered internalized dose metric to explore exposures within all chemical space simultaneously (not chemical by chemical). Diverse data streams are integrated within the interface such that different exposure scenarios for “individual,” “population,” or “occupational” time-use profilescan be tailored to quantitatively explore multi-chemical signatures of exposure, internalized dose (uptake), body burden, and elimination. The Risk Assessment IDentification And Ranking - Indoor and Consumer Exposures (RAIDAR-ICE) model affords complementary insight into exposure and potential risks to humans from chemicals applied directly to the body. The model employs a unit emission rate approach for addressing uncertainty in the actual product application or chemical release rates. The development of RAIDAR-ICE involved a comprehensive review of dermal permeation data and models and the development of a new database of skin permeation data for organic chemicals. Recognizing the sensitivity of absorbed dose estimates to dermal absorption modeling assumptions, a more recent effort has focused on estimating “time-to-steady state” to refine current exposure estimates. This overview shares lessons learned from these research efforts that support of chemical risk assessment.

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