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AVAILABLE MICRO-ACTIVITY DATA AND THEIR APPLICABILITY TO AGGREGATE EXPOSURE MODELING
Zartarian, V, J Xue, A H. Ozkaynak, J. Driver, M. Pandian, AND T. Johnson. AVAILABLE MICRO-ACTIVITY DATA AND THEIR APPLICABILITY TO AGGREGATE EXPOSURE MODELING. Presented at Society for Risk Analysis Conference, Baltimore, MD, December 7-10, 2003.
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?
Several human exposure models have been developed in recent years to address children's aggregate and cumulative exposures to pesticides under the Food Quality Protection Act of 1996. These models estimate children's exposures via all significant routes and pathways including ingestion of chemicals from hand-to-mouth and object-to-mouth contact. Equations used to estimate hand-to-mouth and object-to-mouth ingestion exposures use micro-activity data variables such as frequency of hand-to-mouth contact, object-to-mouth contact, and surface areas of hands and objects mouthed. To help compile data for these model input variables, the ILSI Health and Environmental Sciences Institute's (HESI) Risk Assessment Methodologies Technical Committee (RAM Committee), in conjunction with infoscientific.com, Inc., has reviewed public data on frequency of hand-to-mouth behavior events frequencies. These data were evaluated and organized in an electronic database, and will be made publicly available. EPA's Office of Research and Development, National Exposure Research Laboratory, has analyzed these hand-to-mouth frequency data as well as data on fraction of hands mouthed by children, and has estimated probability distributions for variability and uncertainty that could be used in aggregate exposure models. These efforts also provide important opportunities for collaboration and synergy with development of the EPA's Child-Specific Exposure Factors Handbook and regulatory agency exposure assessment methods (e.g., EPA, Office of Pesticide Programs, Standard Operating Procedures for Residential Exposure Assessment).
This work has been funded in part by the United States Environmental Protection Agency. It has been subjected to Agency review and approved for publication