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Valerie G. Zartarian,¹ Halûk Özkaynak,¹ Janet M. Burke,¹ Maria J. Zufall,¹ Marc L. Rigas,² and Edwin J. Furtaw, Jr.²

¹National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
²National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Las Vegas, Nevada, USA

Abstract

To help address the Food Quality Protection Act of 1996, a physically based probabilistic model has been developed to quantify and analyze dermal and nondietary ingestion exposure and dose to pesticides. The Residential Stochastic Human Exposure and Dose Simulation Model for Pesticides (Residential-SHEDS) simulates the exposures and doses of children contacting residues on surfaces in treated residences and on turf in treated residential yards. The simulations combine sequential time-location-activity information from children's diaries with microlevel videotaped activity data, probability distributions of measured surface residues and exposure factors, and pharmacokinetic rate constants. Model outputs include individual profiles and population statistics for daily dermal loading, mass in the blood compartment, ingested residue via nondietary objects, and mass of eliminated metabolite, as well as contributions from various routes, pathways, and media. To illustrate the capabilities of the model framework, we applied Residential-SHEDS to estimate children's residential exposure and dose to chlorpyrifos for 12 exposure scenarios: 2 age groups (0-4 and 5-9 years) ; 2 indoor pesticide application methods (broadcast and crack and crevice) ; and 3 postindoor application time periods (< 1, 1-7, and 8-30 days) . Independent residential turf applications (liquid or granular) were included in each of these scenarios. Despite the current data limitations and model assumptions, the case study predicts exposure and dose estimates that compare well to measurements in the published literature, and provides insights to the relative importance of exposure scenarios and pathways. Key words: aggregate exposure, children, chlorpyrifos, exposure model, dermal, Food Quality Protection Act, nondietary ingestion, pesticides. Environ Health Perspect 108:505-514 (2000) . [Online 13 April 2000]

http://ehpnet1.niehs.nih.gov/docs/2000/108p505-514zartarian/ abstract.html

Address correspondence to V. Zartarian, U.S. Environmental Protection Agency, 12201 Sunrise Valley Drive, 555 National Center, Reston, VA 20192 USA. Telephone: (703) 648-5538. Fax: (703) 648-4290. E-mail: zartarian.valerie@epamail.epa.gov

We thank D. Smegal for technical input and review of our results. We also acknowledge the technical assistance of J. Xue and G. Glen in developing the computer code for the Residential-SHEDS model.

This paper has been reviewed in accordance with the U.S. Environmental Protection Agency peer and administrative review policies and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

Received 3 September 1999 ; accepted 31 January 2000.