The genetic toxicity database of the National Toxicology Program: evaluation of the relationships between genetic toxicity and carcinogenicity.

The database of the U.S. National Toxicology Program has been developed over approximately two decades, principally focused on substances evaluated for carcinogenicity in rodent bioassays. These assays generally provide data on the relative toxicity and carcinogenicity of chemicals based upon discrete subchronic (13 week) and chronic (104 week) exposures. A major value of these data are that the assay protocols, rodent strains, and technical methodologies have been generally consistent, thus permitting comparisons between assays and chemicals. The genotoxicity data for many of the same chemicals have been developed also using standardized biological systems and protocols. Data for assays including mutagenicity in Salmonella and mouse lymphoma cells, chromosomal aberrations, and sister chromatid exchange in Chinese hamster ovary cells, transformation of Balb/c 3T3 cells, and in vivo cytogenetic effects in rodents have been compiled for many chemicals. The results of all of these assays provide a substantial database for evaluating chemical effects and for defining the complex relationships between mutagenicity and carcinogenicity.