Factors influencing total dietary exposures of young children

A deterministic model was developed to identify the critical input paramete rs needed to assess dietary intakes of young children. The model was used a s a framework for understanding the important factors in data collection an d data analysis. Factors incorporated into the model included transfer effi ciencies of pesticide from surfaces to food, transfer efficiencies of pesti cide from surfaces to hands to food, and more accurate microactivity data r elated to contact frequency for the three variables of interest - hands, su rfaces, and food. Results from range - finding measurements of transfer eff iciencies using an aqueous pesticide solution of a mixture of malathion, di azinon, and chlorpyrifos sprayed on the surfaces indicate that a higher pes ticide transfer occurred from hard surfaces to food (hardwood, plastic), wi th low transfer from soft surfaces (carpet, cloth). Six children, all less than 4 years old, were videotaped to obtain realistic contact frequency and times for the interaction of hands, surfaces, and foods during eating meal s and snacks while in their homes or day care centers. The time range of ea ting events varied from about 2 to 55 min, with an average of about 20 min. The average number of contact frequencies between food and hands was 19 ti mes for each eating event. with a range of 10-40. Contacts between the surf ace and hand were about the same as the food and hands. Contacts between fo ods and surfaces ranged from 0 to 32, but only five or less of the contacts per eating event were associated with surfaces other than eating utensil. The children's microactivity data collected during the eating events, toget her with the laboratory results from the transfer studies, were provided as input into a Monte Carlo simulation of the dietary ingestion model. Simula tion results indicate that children's handling of the food could contribute 20-80% of the total dietary intake of pesticides. Dietary exposure due to residues in the food before handling accounted for 16% and 47%, respectivel y, of the total mean intake from simulations for a child's consumption of a n apple or banana. These results indicated that transfer efficiencies for f oods on various surfaces typically found in homes as well as children's han d contacts with the food and surfaces are important as determinants of diet ary exposure.