Submitted to: Environmental Protection Agency
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2002
Publication Date: 8/30/2002
Citation: CLEWELL, H., FREEMAN, N., HATTIS, D., HEERINGA, S., KISSELL, J., MACDONALD, P., PORTIER, K., POTTER, T.L., POWELL, S., ROBERTS, S. STOCHASTIC HUMAN EXPOSURE AND DOSE SIMULATION MODEL: REVIEW OF A SCENARIO SPECIFIC MODEL TO ESTIMATE CHILDREN'S EXPOSURE AND DOSE TO WOOD PRESERVATIVES FROM TREATED PLAYSETS AND RESIDENTIAL DECKS. ENVIRONMENTAL PROTECTION AGENCY. AVAILABLE FROM: http://www.epa.gov/scipoly/sap/2002/august30/agenda.htm. 2002. Interpretive Summary: The 1996 Food Quality Protection Act (FQPA) requires that residues in food and drinking water and impacts of residential use be combined when estimating potential pesticide exposures. Toxic effects of all pesticides with a common mode of action must also be summed. To aid the Environmental Protection Agency (EPA) in this complex task, EPA Scientists developed a model and software package, Stochastic Human Exposure and Dose Simulation Model (SHEDS). It is one of several models being considered by the agency for pesticide exposure assessment. EPA Office of Pesticide Programs convened an expert panel to review a SHEDS module designed to estimate children's exposure and dose to wood preservatives from treated playsets and residential decks. The panel concluded that several improvements were needed. Significant uncertainty in parameters which govern the magnitude of exposure estimates was identified. The need to consider exposures of high-risk subpopulations, such as down's-syndrome children was also emphasized. Incorporation of these recommendations is expected to improve the accuracy of exposure assessments. This will benefit all stakeholders including the public, pesticide users, industry, and government agencies responsible for pesticide regulation.
Technical Abstract: U.S.Environmental Protection Agency (EPA) scientists developed a module for the agency's Stochastic Human Exposure and Dose Simulation Model (SHEDS) model to estimate children's exposure to wood preservatives from contact with playsets and residential decks. EPA Office of Pesticide Programs convened an expert panel to review the module's underlying science, computational approaches and its ease of use within in the SHEDS model structure. This report describes recommendations made by the panel to improve model accuracy and transparency, computational speed, and output format. The panel emphasized the need to develop more accurate estimates of key exposure factors and their distributions. High uncertainty was identified in wood surface to skin transfer coefficients and rates of dermal transfer in general. The need to incorporate a potentially important behavioral exposure factor, direct wood surface to mouth contact, in the model, and to examine subpopulations that may be at high risk was also emphasized.