A Case Study: Estimating the Aggregate Exposure from Major Uses of Chlorpyrifos. B. A. Shurdut, DowElanco, 9330 Zionsville Road, Indianapolis, IN 46268-1053; and M. Francis, TAS, Inc., 1000 Potomac St. NW, Washington DC 20007
An integrated exposure model is used to determine exposures for multiple uses and for multiple routes of exposure to chlorpyrifos-containing products. Dermal, inhalation and ingestion exposure measurements from studies of termite, lawn, and crack and crevice treatments are combined with personal factors (age, body weight, etc.), exposure factors (residence type, time spent indoors, etc.) and market use data to calculate distributions of absorbed daily doses for each product use. These distributions of exposures are calculated for the day of treatment and succeeding days. The market use data are used to determine the amount of product applied, the location(s) of application in and around the home and the frequency of application. Dietary exposure is added into the model as a distribution of exposures for every day of the year. Integrated exposure results are provided for adult and child populations. This approach may be valuable for the evaluation of potential exposures to multi-use chemicals where multiple routes of exposure are possible. The probabilistic approach used here provides a more realistic alternative method for exposure assessment than methods which simply sum all potential exposures.