Predicting mammalian mutagenesis by submammalian assays: an application of database GEN.

A database containing qualitative information on the genotoxic activity of about 3000 chemicals is described. The initial aim for the construction of the database was to develop an instrument for comparing the performance of different genotoxicity assay systems. One application of the database is the prediction of expected results in any genotoxicity assay for chemicals that were tested in a small number of genotoxicity assays. The Bayesian prediction is calculated based on the sensitivities and specificities between any predictive test and the target test for which the prediction is to be determined. The predictivity of the system for in vivo mammalian assays is at present (with the exception of the micronucleus assay and the in vivo sister chromatid exchanges) limited, in particular because of the limited number of chemicals tested in the expensive in vivo assays and, in addition, due to the lack of sufficient information on negative compounds. A continued updating of the database will possibly help to overcome some of the present difficulties.