Assessment and validation of US EPA's OncoLogic® expert system and analysis of its modulating factors for structural alerts.

OncoLogic® is a software program able to screen chemical compounds for toxicological effects. The software predicts the potential carcinogenicity of chemicals by applying rules of structure activity relationship (SAR) analysis. To validate the predictivity of OncoLogic® (Version 7.0), 123 compounds tested with the long-term carcinogenicity bioassay on rodents were extracted from the ISSCAN database and were analyzed. The concordance between the OncoLogic® SAR analysis and the bioassay results was high. To better understand the strength of the SAR science in OncoLogic®, we investigated the influence of a select group of modulating factors on the predictions by the structural alerts.