THE NIEHS PREDICTIVE-TOXICOLOGY EVALUATION PROJECT

The Predictive-Toxicology Evaluation (PTE) project conducts collaborat ive experiments that subject the performance of predictive-toxicology (PT) methods to rigorous, objective evaluation in a uniquely informati ve manner. Sponsored by the National Institute of Environmental Health Sciences, it takes advantage of the ongoing testing conducted by the U.S. National Toxicology Program (NTP) to estimate the true error of m odels that have been applied to make prospective predictions on previo usly untested, noncongeneric-chemical substances. The PTE project firs t identifies a group of standardized NTP chemical bioassays either sch eduled to be conducted or are ongoing, but not yet complete. The proje ct then announces and advertises the evaluation experiment, disseminat es information about the chemical bioassays, and encourages researcher s from a wide variety of disciplines to publish their predictions in p eer-reviewed journals, using whatever approaches and methods they feel are best. A collection of such papers is published in this Environmen tal Health Perspectives Supplement, providing readers the opportunity to compare and contrast PT approaches and models, within the context o f their prospective application to an actual-use situation. This intro duction to this collection of papers on predictive toxicology summariz es the predictions made and the final results obtained for the 44 chem ical carcinogenesis bioassays of the first PTE experiment (PTE-1) and presents information that identifies the 30 chemical carcinogenesis bi oassays of PTE-2, along with a table of prediction sets that have been published to date. It also provides background about the origin and g oals of the PTE project. outlines the special challenge associated wit h estimating the true error of models that aspire to predict open-syst em behavior, and summarizes what has been learned to date.