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FACTORS INFLUENCING TOTAL DIETARY EXPOSURE OF YOUNG CHILDREN
Citation:
Akland, G G., E. D. Pellizzari, Y. Hu, M. Roberds, C. Rohrer, J. Leckie, AND M R. Berry Jr. FACTORS INFLUENCING TOTAL DIETARY EXPOSURE OF YOUNG CHILDREN. JOURNAL OF EXPOSURE ANALYSIS AND ENVIRONMENTAL EPIDEMIOLOGY 10(No. 6, pt. 2):710-722, (2000).
Impact/Purpose:
The objective of this task is to develop state-of-the-art methods for measuring xenobiotic compounds, to include the isolation of the analyte from the appropriate matrix (extraction), preconcentration (typically sorbent-based), and analysis via GC/MS and/or LC/MS. Once established, these methods will be applied in small scale pilot studies or demonstration projects. Particular emphasis will be placed on methods which are readily transferable to other laboratories, including those within the Human Exposure and Atmospheric Sciences Division (HEASD), the National Exposure Research Laboratory (NERL), other EPA Laboratories, Program Offices, Regions, and academic institutions.
Specific objectives of this task include the following:
1) Development of GC/MS and LC/MS methods for the measurement of key xenobiotic compounds and their metabolites (to include the pyrethroid pesticides, perfluorinated organic compounds, and the BFRs) in relevant environmental and biological matrices.
2) Development of efficient low cost methods for the extraction and clean up of these compounds collected from relevant matrices.
3) Determination of xenobiotic compound and metabolite concentrations in samples derived from laboratory and field monitoring studies to help assess exposures and evaluate associated risks.
Description:
A deterministic model was developed to identify critical input parameters to assess dietary intake of young children. The model was used as a framework for understanding important factors in data collection and analysis. Factors incorporated included transfer efficiencies of pesticide from surfaces to food, from surfaces to hands to food, and more accurate microactivity data related to contact frequency for three variables of interest--hands, surfaces and food. Results from range finding measurements of transfer efficiencies using aqueous pesticide solution of a mixture of malathion, diazinon and chlorpyrifos sprayed on surfaces indicate a higher pesticide transfer occurred from hard surfaces to food (hardwood, plastic) with low transfer from soft surfaces (carpet, cloth). Six children under 4 years old were videotaped to obtain realistic contact frequency and times for interaction of hands, surfaces and foods during meals and snacks in their homes or day care centers. Range of eating events varied from 2-55 minutes (avg 20 minutes). Avg. number of contacts between food/hands was 19 for each eating event (range 10-40). Contacts between surface/hand were about the same. Contacts between food/surfaces ranged from 0-32, but only 5 or less were associated with surfaces other than eating utensil. Children's microactivity data collected during eating events with laboratory results from transfer studies were provided as input into a Monte Carlo simulation of dietary ingestion model. Simulation results indicate that children's handling of food could contribute 20-80% of total dietary intake of pesticides. Dietary exposure due to residues in food before handling accounted for 16 and 47% respectively of total mean intake from simulations for a child's consumption of an apple or banana. Results indicate transfer efficiencies for foods on various surfaces as well as hand contacts with food/surfaces are important as determinants of dietary exposure.