title: Comparison of modeling approaches to prioritize chemicals based on estimates of exposure and exposure potential.
abstract: While only limited data are available to characterize the potential toxicity of over 8 million commercially available chemical substances, there is even less information available on the exposure and use-scenarios that are required to link potential toxicity to human and ecological health outcomes. Recent improvements and advances such as high throughput data gathering, high performance computational capabilities, and predictive chemical inherency methodology make this an opportune time to develop an exposure-based prioritization approach that can systematically utilize and link the asymmetrical bodies of knowledge for hazard and exposure. In response to the US EPA's need to develop novel approaches and tools for rapidly prioritizing chemicals, a "Challenge" was issued to several exposure model developers to aid the understanding of current systems in a broader sense and to assist the US EPA's effort to develop an approach comparable to other international efforts. A common set of chemicals were prioritized under each current approach. The results are presented herein along with a comparative analysis of the rankings of the chemicals based on metrics of exposure potential or actual exposure estimates. The analysis illustrates the similarities and differences across the domains of information incorporated in each modeling approach. The overall findings indicate a need to reconcile exposures from diffuse, indirect sources (far-field) with exposures from directly, applied chemicals in consumer products or resulting from the presence of a chemical in a microenvironment like a home or vehicle. Additionally, the exposure scenario, including the mode of entry into the environment (i.e. through air, water or sediment) appears to be an important determinant of the level of agreement between modeling approaches.
authors.affiliation: U.S. Environmental Protection Agency, National Exposure Research Laboratory, Research Triangle Park, NC 2771, USA. jade@msu.edu
authors.forename: Jade
authors.initials: J
authors.lastname: Mitchell
authors.forename: Jon A
authors.initials: JA
authors.lastname: Arnot
authors.forename: Olivier
authors.initials: O
authors.lastname: Jolliet
authors.forename: Panos G
authors.initials: PG
authors.lastname: Georgopoulos
authors.forename: Sastry
authors.initials: S
authors.lastname: Isukapalli
authors.forename: Surajit
authors.initials: S
authors.lastname: Dasgupta
authors.forename: Muhilan
authors.initials: M
authors.lastname: Pandian
authors.forename: John
authors.initials: J
authors.lastname: Wambaugh
authors.forename: Peter
authors.initials: P
authors.lastname: Egeghy
authors.forename: Elaine A
authors.initials: EA
authors.lastname: Cohen Hubal
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Vallero
mesh_terms: D062126:Databases, Chemical; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D015386:Hazardous Substances / Q000145:classification* / Q000633:toxicity*; D008962:Models, Theoretical; D014481:United States; D014484:United States Environmental Protection Agency
chemical_list: D015386:Hazardous Substances