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STUDY TO TEST THE FEASIBILITY OF USING THE MACROACTIVITY APPROACH TO ASSESS DERMAL EXPOSURE
Citation:
CohenHubal, E A., L S. Sheldon, G G. Akland, D. Whitaker, AND J. H. Raymer. STUDY TO TEST THE FEASIBILITY OF USING THE MACROACTIVITY APPROACH TO ASSESS DERMAL EXPOSURE. Presented at Society for Risk Analysis 2000 Annual Meeting, Arlington, VA, December 3-6, 2000.
Impact/Purpose:
1. To identify those pesticides, pathways, and activities that represent the highest potential exposures to children;
2. To determine the factors that influence pesticide exposures to children;
3. To develop methods for measuring multimedia exposures to children, including methods that account for important activities that take place in home, school, and day care settings;
4. To generate data on multimedia pesticide concentrations, pesticide biomarkers, and exposure factors that can be used as inputs to aggregate exposure models for children.
Description:
In the macroactivity approach, dermal exposure is estimated using empirically-derived transfer coefficients to aggregate the mass transfer associated with a series of contacts with a contaminated medium. The macroactivity approach affords the possibility of developing screening level exposure assessments in a shorter time frame and with fewer resources than would be required for the microactivity approach (in which dermal exposure is explicitly modeled as a series of discrete transfers resulting from each contact with a contaminated medium). However, the macroactivity approach was developed to assess occupational exposure in an agricultural setting where workers are engaged in similar activities and are exposed to relatively homogeneous environmental concentrations of pesticides. The macroactivity approach will only be useful for assessing dermal exposure in a residential setting if exposure can be adequately quantified by lumping children's activities into a relatively small number of macroactivities.
To assess the feasibility of using the macroactivity approach for assessing children's exposure to pesticides, a screening-level study was conducted with young children in a daycare center where a known pesticide application had occurred. Four or five children from each of two different age groups were monitored for short time periods while involved in selected macroactivities (e.g., storytime, playtime indoors). To measure dermal loading or exposure, the children were clothed in full-body dosimeters. To measure the pesticide concentration in the exposure medium, transferable residues were sampled in the areas where the children spent time during each monitoring event. In addition, videotaping was conducted to verify the children's activity levels and location during exposure monitoring. The dermal loading and transferable residue measurements were then used to calculate dermal transfer coefficients for each monitoring event. The results of this study demonstrate the variability of dermal loading (and associated transfer coefficients) for children of a given age group performing varying macroactivities. In addition, these data will be used to evaluate the default assumptions currently used in USEPA's Office of Pesticide Programs to assess children's residential exposure to pesticides.
This work has been funded wholly or in part by the United States Environmental Protection Agency under contract no. 68-D-99-012 to Research Triangle Institute. It has been subjected to Agency review and approved for publication.