You are here:
IMPORTANT EXPOSURE FACTORS FOR CHILDREN AN ANALYSIS OF LABORATORY AND OBSERVATIONAL FIELD DATA CHARACTERIZING CUMULATIVE EXPOSURE TO PESTICIDES
EGEGHY, P. P., L. S. SHELDON, D. M. STOUT, E. A. COHEN-HUBAL, N. S. TULVE, L. J. MELNYK, M. K. MORGAN, R. C. FORTMANN, D. A. WHITAKER, C. W. CROGHAN, P. A. JONES, AND A. COAN. IMPORTANT EXPOSURE FACTORS FOR CHILDREN AN ANALYSIS OF LABORATORY AND OBSERVATIONAL FIELD DATA CHARACTERIZING CUMULATIVE EXPOSURE TO PESTICIDES. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-07/013 (NTIS PB2007-106980), 2007.
Human exposure research progresses through an iterative series of models and measurements: a model is used to identify areas of greatest risk and the greatest uncertainties associated with that risk; innovative methods and protocols are employed in measurement studies in the laboratory and in the field to address these uncertainties; the model is refined and the process repeats. With each iteration, default assumptions are replaced with high quality, real-world data, thereby producing more accurate assessments of exposure and of risk. Uncertainties in estimating exposure for infants and young children are especially large because their activities and behaviors (e.g., crawling, mouthing of objects) lead to exposure by the dermal absorption and non-dietary ingestion routes. These routes are particularly difficult to quantify and reliable data are limited. Limited data force reliance upon default assumptions, and estimating aggregate exposure compounds the uncertainties associated with default assumptions over multiple routes and pathways. The NERL Children's Pesticide Exposure Program has supported numerous laboratory and field studies to address data gaps associated with pesticide use patterns, spatial and temporal distributions of pesticide concentrations, dermal absorption and non-dietary ingestion routes, and activity patterns of young children. In this task, data from those studies are assembled and analyzed across datasets, employing a holistic approach to identify and evaluate important factors affecting children's exposure to pesticides. Exposure algorithms are evaluated using the real-world data from the field studies. In addition, results from the individual studies are consolidated to highlight important findings and to observe consistencies. The results of analyses performed under this task may be used by exposure modelers to develop or improve probabilistic multimedia, multi-pathway human exposure models. Information on exposure factors will be available to NCEA for inclusion in the Child-Specific Exposure Factors Handbook. Most significantly, the results will be shared with OPP, OPPT, and OCHP to enhance the Agency's risk assessment activities by replacing default assumptions with high-quality, real-world data. Fewer default assumptions will lead to more accurate assessments of exposure and of risk and will bolster ensuing risk reducing actions. Furthermore, by examining relationships among application patterns, exposures, and biomarkers for multiple compounds from different classes of pesticides, this task contributes to the development of more reliable approaches for assessing cumulative exposure.
In an effort to facilitate more realistic risk assessments that take into account unique childhood vulnerabilities to environmental toxicants, the U.S. EPA's National Exposure Research Laboratory (NERL) developed a framework for systematically identifying and addressing the most important sources, routes, and pathways of children's exposure to pesticides. Four priority research areas were identified as representing critical data gaps in our understanding of environmental risks to children. Several targeted studies were conducted under NERL's children's exposure research program to specifically address these priority research needs. This document is a comprehensive summary report of data collected in these studies to address the priority research needs and is intended for an audience of exposure scientists, exposure modelers, and risk assessors. The parameters measured and the measurement methods are described. Data on representative organophosphate and pyrethroid pesticides are compared across studies and across compounds with the primary purpose of identifying or evaluating important factors influencing exposures along each relevant pathway. Summary statistics, comparative analyses, and spatial and temporal patterns are presented to address previously identified data gaps. Results are compared across studies in order to identify trends that might provide a better understanding of the factors affecting children's exposures. While highlights of the results of individual studies are presented, the focus is on presenting insights gleaned from the analysis of the aggregated data from several studies. By examining relationships among application patterns, exposures, and biomarkers for multiple compounds from different classes of pesticides, this report strives to help produce more reliable approaches for assessing cumulative exposure.