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A MODELING FRAMEWORK FOR ESTIMATING CHILDREN'S RESIDENTIAL EXPOSURE AND DOSE TO CHLORPYRIFOS VIA DERMAL RESIDUE CONTACT AND NON-DIETARY INGESTION
Citation:
Zartarian, V, A H. Ozkaynak, J M. Burke, M J. Zufall, M L. Rigas, AND E J. Furtaw Jr. A MODELING FRAMEWORK FOR ESTIMATING CHILDREN'S RESIDENTIAL EXPOSURE AND DOSE TO CHLORPYRIFOS VIA DERMAL RESIDUE CONTACT AND NON-DIETARY INGESTION. ENVIRONMENTAL HEALTH PERSPECTIVES 108(6):505-514, (2000).
Impact/Purpose:
The primary objective of this research is to produce a documented version of the aggregate SHEDS-Pesticides model for conducting reliable probabilistic population assessments of human exposure and dose to environmental pollutants. SHEDS is being developed to help answer the following questions:
(1) What is the population distribution of exposure for a given cohort for existing scenarios or for proposed exposure reduction scenarios?
(2) What is the intensity, duration, frequency, and timing of exposures from different routes?
(3) What are the most critical media, routes, pathways, and factors contributing to exposures?
(4) What is the uncertainty associated with predictions of exposure for a population?
(5) How do modeled estimates compare to real-world data?
(6) What additional human exposure measurements are needed to reduce uncertainty in population estimates?
Description:
To help address the Food Quality Protection Act of 1996, a physically-based probabilistic model (Residential Stochastic Human Exposure and Dose Simulation Model for Pesticides; Residential-SHEDS) has been developed to quantify and analyze dermal and non-dietary ingestion exposure and dose to pesticides. The model simulates children contacting residues on surfaces in treated residences and turf in treated residential yards by combining sequential time-location-activity information from children's diaries with micro-level 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 non-dietary objects, and mass of eliminated metabolite, as well as contributions from various routes, pathways, and media.
To illustrate the capabilities of the model framework, Residential-SHEDS was applied to estimate children's residential exposure and dose to chlorpyrifos for 12 exposure scenarios: 2 age groups (0 to 4 years, 5 to 9 years); 2 indoor pesticide application methods (broadcast, crack and crevice); and 3 post-indoor application time periods (<1 day, 1 to 7 days, 8 to 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.
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 and commercial products does not constitute endorsement or recommendation for use.