Current status of the Gene-Tox Program.

The U.S. Environmental Protection Agency's Gene-Tox Program is a multiphased effort to review and evaluate the existing literature in assay systems available in the field of genetic toxicology. The first phase of the Gene-Tox Program selected assay systems for evaluation, generated expert panel reviews of the data from the scientific literature, and recommended testing protocols for the systems. Phase II established and evaluated the database of chemical genetic toxicity data for its relevance to identifying human health hazards. The ongoing phase III continues reviewing and updating chemical data in selected assay systems. Currently, data exist on over 4000 chemicals in 27 assay systems; two additional assay systems will be included in phase III. The review data are published in the scientific literature and are also publicly available through the National Library of Medicine TOXNET system. The review and analysis components of Gene-Tox comprise 45 published papers, and several others are in preparation. Differences that have been observed between Gene-Tox and National Toxicology Program databases relative to the sensitivity, specificity, accuracy, and predictivity of genetic toxicity data compared to carcinogenesis data are ascribable to differences between the two databases in chemical selection criteria, testing protocols, and chemical class distributions.