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USE OF MACROACTIVITY APPROACH TO ASSESS DERMAL EXPOSURE
Citation:
Tulve, N S., P. Hore, E A. CohenHubal, N. G. Freeman, P. J. Lioy, AND L S. Sheldon. USE OF MACROACTIVITY APPROACH TO ASSESS DERMAL EXPOSURE. 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:
Currently, data on children's exposures and activities are very limited and insufficient to support quantitative assessments that do not rely heavily on major default assumptions as substitutes for missing information (Cohen Hubal et al. 2000a, b). Cohen Hubal et al. (2000a, b) have identified research needed to reduce this uncertainty, including: collection of activity pattern data for young children required to assess exposure by all routes, and, collection of data on concentrations of environmental contaminants, biomarkers, and transfer coefficients (TCs).
One method being evaluated to assess children's dermal exposure to pesticides is the macroactivity approach. In this approach, a child's dermal exposures to chemicals are estimated for each microenvironment where a child spends time and each macroactivity that the child conducts within that specific microenvironment. The total dermal exposure is then modeled by combining surface residue data with empirically-derived TCs specific to each microenvironment/macroactivity combination.
The Children's Post-Application Pesticide Pilot Study is a collaborative effort between the EPA and the Environmental and Occupational Health Sciences Institute (EOHSI) in New Jersey. Nine families with young children (<5 years old) were recruited to participate in the study. Homes were monitored for 28 days following a pesticide application. Four-hour videotape segments, time-activity diaries and questionnaires, cotton dosimeters, dermal wipes, and transferable residue loadings were collected during the study. Specific microenvironment and macroactivity combinations for these children were determined from the videotape segments and the time-activity diaries and questionnaires. Transferable residue loadings from the surfaces on which the children spent the majority of their time were measured using a surface sampler (i.e., Lioy-Weisel-Wainman quantitative surface sampler or alcohol wipes). Cotton socks or pajama bottoms were used to calculate potential exposure to pesticide residues through the feet, knees, legs, and bottom. Dermal wipe concentrations, including hands and knees, were also measured. Transferable residues and cotton dosimeter measurements were used to calculate Tcs.
TCs were found to depend on the activity level of the child, as well as the surfaces contacted. TC values ranged from 2100 cm2/hr (bottom, quiet play, standing) to 84000 cm2/hr (socks, active play). The lower value is similar to defaults used by EPA's Office of Pesticide Programs: 2600 cm2/hr (intermediate-term) and 5200 cm2/hr (short-term) for 1 to 6 year old children.
This work has been funded in part by the United States Environmental Protection Agency under an EPA Technical Services Contract (Contract No. 0D-5227-NAEX) to the Environmental and Occupational Health Sciences Institute. It has been subjected to Agency review and approved for presentation and publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.