You are here:
High-Throughput Exposure Potential Prioritization for ToxCast Chemicals
Citation:
WAMBAUGH, J. F. High-Throughput Exposure Potential Prioritization for ToxCast Chemicals. Presented at International Society of Exposure Science 21st Annual Meeting, Baltimore, MD, October 23 - 27, 2011.
Impact/Purpose:
For most of the ToxCast (Phase I and II) chemicals, the descriptors necessary for fate and transport modeling (i.e. model parameters) were not available and had to be predicted based upon structure using Episuite and QikProp. The prioritizations (i.e. rank order) of the two models will be compared with each other as well as ground-truthed with respect to exposures inferred from the Centers for Disease Control National Health and Nutrition Examination Survey (NHANES), pesticide residues, and other similar data sources.
Description:
The U.S. EPA must consider lists of hundreds to thousands of chemicals when prioritizing research resources in order to identify risk to human populations and the environment. High-throughput assays to identify biological activity in vitro have allowed the ToxCastTM program to identify potential chemical hazard, but without similar assessment of potential for exposure, high-throughput risk assessment for chemicals with no other available information cannot be completed. Using models (USEtox and RAIDAR) identified by the EPA Exposure-Based Prioritization Challenge nearly 1000 ToxCast chemicals have been prioritized with respect to far-field exposure potential (e.g. partitioning into environmental media). The ToxCast (Phase I and II) chemicals include industrial compounds, pesticides, and pharmaceuticals that failed in human trials, all of which have been tested in over 500 dose-response assays for potential bioactivity. For most of these chemicals, the descriptors necessary for fate and transport modeling (i.e. model parameters) were not available and had to be predicted based upon structure using Episuite and QikProp (accessed through the Aggregated Computational Toxicology Resource – https://actor.epa.gov). The prioritizations (i.e. rank order) of the two models will be compared with each other as well as ground-truthed with respect to exposures inferred from the Centers for Disease Control National Health and Nutrition Examination Survey (NHANES), pesticide residues, and other similar data sources. [This abstract does not necessarily reflect U.S. EPA policy.]