Applications of Microexposure Monte Carlo Modeling to Human Health Risk Assessments: A Case Study of Modeling Childhood Lead Exposures. P.E. Goodrum, J. M. Hassett, D. L. Johnson and M. E. Dakins, SUNY-College of Environmental Science and Forestry, Syracuse, NY 13210
The utility of a probabilistic exposure model in human health risk assessments lies in its ability to simulate actual spatial and temporal variability in key exposure parameters such as environmental concentrations and individual activity patterns that contribute to highfiend exposures. Although the use of Monte Carlo analysis in exposure assessment is superior to using conservative point estimates, it tends to overestimate the high-end exposures. This overestimation can lead to the incorrect conclusion that a small number of individuals may receive unacceptable risks. A new modeling technique, called MicroExposure modeling, is suggested for quantifying the distribution of doses received by a population potentially exposed via multiple pathways. Using the MicroExposure model leads to a more accurate characterization of the distribution of exposures through separate event modeling of the dose received during each exposure event throughout an individual's lifetime. A case study of childhood lead exposures demonstrates how the MicroExposure model simulates exposures via multiple exposure pathways (e.g., soil, dust, paint chips, and tap water), and incorporates correlation structures in the selection of values for key exposure parameters. The model utilizes site-specific data regarding lead physical and chemical speciation, bioavailability, age and gender-specific activity patterns, and spatial distribution statistics, to predict the distribution of venous blood lead concentrations. The MicroExposure model is also applied to assess the efficacy of various treatment/ remediation strategies in reducing potential high lead exposures..