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ExpoCast Framework for Rapid Exposure Forecasts (ISES ExpoDat symposium presentation)
Citation:
Wambaugh, J. ExpoCast Framework for Rapid Exposure Forecasts (ISES ExpoDat symposium presentation). Presented at International Society of Exposure Science Annual Meeting, Cincinnati, OH, October 12 - 14, 2014. https://doi.org/10.23645/epacomptox.5082472
Impact/Purpose:
This presentation is part of a symposium at the International Society of Exposure Science annual meeting on the ExpoDat research initiative. Session title: The ExpoDat Initiative: Exposure-Informed Chemical Safety Assessment for High Throughput Prioritization. Session abstract: In 2012, the ExpoDat Initiative was begun to evaluate approaches to consider exposure for targeted testing and risk assessment across a broad range of chemicals. A June 2012 workshop gathered international experts in exposure science from governmental agencies, academia, and industry to explore exposure determinants in high-throughput exposure assessment. The workshop objectives were two-fold: (1) identify and prioritize determinants for near-field and far-field exposures of the general population to chemicals; and (2) consider near-term priorities for assimilation and/or development of relevant data to inform these determinants. A case study approach was used to address the immediate needs for rapid exposure assessment, i.e. approaches that maximize use of available information to efficiently provide estimates of exposure potential. The case study was specifically designed to evaluate a tiered approach for generating exposure estimates for a large group of chemicals that have little or no exposure measurement data and to test this approach using oral equivalent dose data for a subset of the ToxCast™ Phase II chemicals. The workshop results were presented at the 2012 ISES meeting. A November 2013 working meeting among exposure experts reviewed results from ongoing work on the case study that used exposure modeling approaches from three researchers funded by the Long-Range Research Initiative of American Chemistry Council. Other tools for estimating exposures that could be incorporated into a tiered approach were discussed. This proposed symposium will 1) highlight the results from the recent ExpoDat efforts, 2) present other related high-throughput exposure prediction methods, and 3) discuss priority data needs that support the various high-throughput approaches. The value of identifying additional information that could reduce uncertainty in exposure estimates was recognized as a key focus for the ExpoDat Initiative. Recommendations developed during the 2012 workshop will continue to be explored through additional case studies and other approaches.
Description:
The U.S. E.P.A. ExpoCast project uses high throughput exposure models (simulation) and any easily-obtained exposure heuristics to generate forward predictions of potential exposures from chemical properties. By comparison with exposures inferred via reverse pharmacokinetic modeling from monitoring data from CDC NHANES and other sources, we translate the specific predictions of the forward models into probabilistic forecasts of human exposure. This goal of this framework is to minimize the well-known pitfalls of mathematical modeling by both integrating the predictions of multiple models and systematically evaluating performance over as many chemicals as possible. For the thousands of chemicals with no other data on human exposure, the glass could be considered half full since easily obtained heuristics of exposure can explain more than half the variability in parent chemical exposures inferred from CDC NHANES biomonitoring data. However, the glass is also half empty in that the remaining variance appears to be associated with the well documented differences in exposures between various demographic groups. Additional biomonitoring is needed to develop empirical exposure heuristics for these chemicals. Ultimately, the ability to apply knowledge gained from the extant monitoring data to thousands of chemicals with no other source of information is critical information for determining the human health risk posed by environmental chemicals. (This abstract does not necessarily reflect EPA policy).
URLs/Downloads:
DOI: ExpoCast Framework for Rapid Exposure Forecasts (ISES ExpoDat symposium presentation)