| The Children's-Post-Pesticide-Application-Exposure-Study (CPPAES) was conducted to look at the distribution of Chorpyrifos within a home environment for a 2-week period following a crack-and-crevice application, and to assess the amount of the Chorpyrifos that a child may absorb. Ten residential homes with a 2–5-year-old-child in each were selected, and the homes were treated with chlorpyrifos. Pesticide measurements were made from the indoor air/indoor surfaces/gauze pads/plush toys. In addition, dermal rinse/wipe and urine samples were collected from each of the children. The urine samples were analyzed for 3,5,6-trichloropyridinol, the primary metabolite of chlorpyrifos, to determine the children's absorbed dose. Chlorpyrifos levels in the indoor air and surfaces ranged from 2.2–816 ng/m3 and 0.07–25 ng/cm2, respectively, reaching peak levels between days 0–2; subsequently, concentrations decreased throughout the 2-week period. Chlorpyrifos concentrations in/on the gauze pads and plush toys ranged from 2.6–1022 ng/gauze and 7.3–1949 ng/toy, respectively. Concentrations in/on the plush toys increased throughout the 2-week period demonstrating a cumulative trend. The daily average amount of Chorpyrifos absorbed by the CPPAES children post-application ranged from 0.13–1.7 μg/kg/day. Chlorpyrifos absorbed doses for nine of the CPPAES children were greater than the US EPA chlorpyrifos oral reference dose of 0.3 μg/kg/day. The children's body burden levels depended not only on the amount of the pesticide that was present in their surrounding environment, however, also on the activities that they were engaged in.; The CPPAES field-measured data were used to test the performance of MENTOR/SHEDS-Pesticides, a physically based probabilistic model, taking a deterministic approach. For the purposes of this analysis, MENTOR/SHEDS-Pesticides was used to simulate the exposure and the dose profiles for each of the selected CPPAES children for a 2-week post-application period following an indoor crack-and-crevice chlorpyrifos application using input parameters derived from CPPAES data. The results indicated that, in these simulations, the performance of MENTOR/SHEDS-Pesticides in estimating exposures and body burden/elimination of chlorpyrifos was favorable (mostly within a factor of 2). While this research gives us more confidence in the SHEDS algorithms, further evaluation is needed using the methodologies developed in this project. |
