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CHILDREN'S RESIDENTIAL EXPOSURE TO CHLORPYRIFOS: APPLICATION OF CPPAES FIELD MEASUREMENTS OF CHLORPYRIFOS AND TCPY WITHIN MENTOR/SHEDS PESTICIDES MODEL
Citation:
HORE, P., V. ZARTARIAN, J. XUE, H. A. OZKAYNAK, S. WANG, Y. YANG, P. CHU, L. S. SHELDON, M. ROBSON, L. L. NEEDHAM, D. B. BARR, N. C. FREEMAN, P. G. GEORGOPOULOS, AND P. J. LIOY. CHILDREN'S RESIDENTIAL EXPOSURE TO CHLORPYRIFOS: APPLICATION OF CPPAES FIELD MEASUREMENTS OF CHLORPYRIFOS AND TCPY WITHIN MENTOR/SHEDS PESTICIDES MODEL. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier Science Ltd, New York, NY, 366(1-2):525-537, (2005).
Impact/Purpose:
1. Identify and evaluate the factors that affect children's exposures as a function of age (for age bins proposed by EPA's Risk Assessment Forum).
2. Determine the impact of microenvironment and macroactivity on children's exposure to current-use pesticides and selected phthalates in residences.
3. Determine temporal variability of multimedia concentrations of selected pesticides and phthalates in the residences of very young children (0 to 3 years of age).
4. Perform aggregate exposure estimates for current-use pesticides (soon after application) and phthalates for very young children.
5. Evaluate the relationship between concentrations of biomarkers of exposure measured in urine and aggregate exposure estimates derived from diet and environmental measurements for pesticides and phthalates using the algorithms and approaches specified in the Draft Protocol for Measuring Children's Non-Occupational Exposure to Pesticides by all Relevant Pathways.
6. Evaluate and apportion exposure pathways for pesticides and phthalates.
7. Collect data for selected polybrominated diphenyl ethers (brominated flame retardants) and perfluorinated chemicals (PFOS and PFOA) in the diet and in environmental samples collected in the residences to assess spatial and temporal variability and the potential for children's exposure.
8. Evaluate the utility of the draft standardized protocol for performing exposure assessments for young children.
9. Develop critical inputs for the human exposure models (SHEDS, CARES, Lifeline, Calendex, and others).
10. Collect preliminary data on environmental concentrations of selected metals found in the outdoor residential environment.
11. Evaluate the utility of standardized data collection methods for future large scale studies.
Description:
The comprehensive individual field-measurements on non-dietary exposure collected in the Children's-Post-Pesticide-Application-Exposure-Study (CPPAES) were used within MENTOR/SHEDS-Pesticides, a physically based stochastic human exposure and dose model. In this application, however, the model was run deterministically. The MENTOR/SHEDS-Pesticides employed the CPPAES as input variables to simulate the exposure and the dose profiles for seven children over a 2-week post-application period
following a routine professional indoor crack-and-crevice chlorpyrifos application. The input variables were obtained from a personal activity diary, microenvironmental measurements and personal biomonitoring data obtained from CPPAES samples collected from the individual children and in their homes. Simulation results were compared with CPPAES field measured values obtained from the childrens' homes to assess the utility of the different microenvironmental data collected in CPPAES, i.e. indicator toys and wipe samplers to estimate aggregate exposures that can be result from one or more exposure pathways and routes. The final analyses of the database involved comparisons of the actual data obtained from the individual biomarker samples of a urinary metabolite of chlorpyrifos (TCPy) and the values predicted by MENTOR-SHEDS Pesticides using the CPPAES-derived variables. Because duplicate diet samples were not part of the CPPAES study design, SHEDS-Pesticides simulated dose profiles did not account for the dietary route. The research provided more confidence in the types of data
that can be used in the inhalation and dermal contact modules of MENTOR/SHEDS-Pesticides to predict the pesticide dose received by a child. It was determined that we still need additional understanding about: 1. the types of activities and durations of activities that result in non-dietary ingestion of pesticides and 2. the influence of dietary exposures on the levels of TCPY found in the urine.