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DEVELOPMENT AND EVALUATION OF AN AGGREGATE SURFACE SAMPLING METHOD FOR USE IN ASSESSING DERMAL EXPOSURES OF YOUNG CHILDREN
Citation:
CohenHubal, E A., G G. Akland, J. H. Raymer, E. D. Pellizzari, AND L S. Sheldon. DEVELOPMENT AND EVALUATION OF AN AGGREGATE SURFACE SAMPLING METHOD FOR USE IN ASSESSING DERMAL EXPOSURES OF YOUNG CHILDREN. Presented at 11th Annual Meeting of the International Society of Exposure Analysis, Charleston, SC, November 4-8, 2001.
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). Current techniques for applying pesticides indoors at homes and schools, such as along walls, doors, and sinks, result in a nonuniform distribution of pesticide. To use the macroactivity approach a representative measure of surface contaminant loading is required.
As part of a larger study to test the feasibility of applying the macroactivity approach to estimate children's residential exposures to pesticide contaminated surfaces, we are developing and testing a method for collecting an aggregate measure of surface loading. The following approach was used to develop and test an aggregate-surface-loading measurement method. Daycare centers were recruited and one classroom from each was selected for surface sampling following a known pesticide application. Ten sampling points were selected to include the types of surfaces and locations that children contact during their normal activities. Individual C-18 press samples were collected at each location. In addition, two aggregate samples were collected using one C-18 disk for each of five locations, and one aggregate sample collected using one C-18 disk at all ten locations. In three of the sampling locations, a PUF roller sample and wipe sample were also collected to facilitate development of an empirical database for method comparison and modeling. Using the database, the surface concentration distribution was modeled using a geo-statistical model, and an average estimated surface concentration developed. The resulting data will form the basis for constructing a protocol for obtaining a spatial average of the transferable residue across the classroom. Results obtained from sampling in eight different daycare centers and for different pesticides will be presented.
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.