Using a Calendar Method to Assess Exposure to Pesticides Applied in the Home at Different Times. S. H. Youngren, C. Walls, L. M. Barraj, and B. M. Polakoff, Novigen Sciences, Inc., Washington, DC
The Food Quality Protection Act of 1996 included a requirement to assess the risk from all potential residential exposures to pesticides. The EPA has translated this requirement into additional emphasis on assessment of non-dietary, residential exposures, particularly for children. The Agency developed Standard Operating Procedures (SOPs) designed "to provide standard default methods for developing residential exposure assessments for both handler and post-application exposures...[for use] in the absence of, or as a supplement to, chemical- and/or site-specific data" (US EPA 1997). The SOPs are high-end scenarios utilizing upper-percentile assumptions. Use of these defaults for multiple exposures results in an assumption that all treatments occur simultaneously. The following paper presents an evaluation of the impact of using a method that incorporates not only conservative assumptions on use, but also includes application periods, the length of the active exposure periods and residue degradation functions. This method, which incorporates distributions of data for use in a Monte Carlo-type analysis, can be used to assess exposure for short-term, intermediate-term and chronic periods. The resulting exposure estimates provide information on the total distribution of exposure for the given time-period. This method allows the user to determine the significant sources, as well as time periods, of exposure for further analysis if necessary.
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