A modeling framework for estimating children's residential exposure and dose to chlorpyrifos via dermal residue contact and nondietary ingestion

To help address the Food Quality Protection Act of 1996;, a physically base d probabilistic model has been developed to quantify and analyze dermal and nondietary ingestion exposure and dose to pesticides. The Residential Stoc hastic Human Exposure and Dose Simulation Model for Pesticides (Residential -SHEDS) simulates the exposures and doses of children contacting residues o n 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 di stributions of measured surface residues and exposure factors, and pharmaco kinetic rate constants. Model outputs include individual profiles and popul ation statistics for daily dermal loading, mass in the blood compartment, i ngested residue via nondietary objects, and mass of eliminated metabolite, as well as contributions from various routes, pathways, and media. To illus trate the capabilities of the model framework, we applied Residential-SHEDS to estimate children's residential exposure and dose to chlorpyrifos for 1 2 exposure scenarios: 2 age groups (0-4 and 5-9 years); 2 indoor pesticide application methods (broadcast and crack and crevice); and 3 postindoor app lication time periods (< 1, 1-7, and 8-30 days). Independent residential tu rf applications (liquid or granular) were included in each of these scenari os. Despite the current data limitations and model assumptions, the case st udy predicts exposure and dose estimates that compare well to measurements in the published literature, and provides insights to the relative importan ce of exposure scenarios and pathways.