Short-term tests in assessment of cancer risks and in primary prevention of occupational cancer.

Screening and testing of chemicals for carcinogenic potency are parts of toxicological test programs and of efforts in primary cancer prevention. At present evidence of carcinogenicity of a chemical can be obtained from epidemiological studies or from long-term bioassays in mammals. Suggestive evidence may derive from results obtained in short-term tests. This is an additional but important information, in some cases it may be the only one we have up to now. Short-term tests do not have in vivo induction of tumors in animals as an endpoint. Their basis are interactions of the chemicals tested (metabolites) with cellular macromolecules. The main types of short-term tests used at present include: Mutagenesis assays with bacteria, mammalian cells, yeasts and moulds, with Drosophila and with whole mammals, transformation assays of cells in vitro, assays of DNA-damage and repair and of cytogenetic damage. Using test-batteries is recommended in order to minimize "false"-negative and/or "false"-positive results. Sensitivity, specificity and prediction value are important criteria of short-term tests. The results obtained may be influenced by metabolic activation/deactivation. Qualitative correlations in the order of 90% or more are being reported between results of at least some short-term tests and results from long-term bioassays. The existence also of quantitative correlations is still under discussion. Short-term tests are applied in different fields of risk assessment and prevention of health hazards. However up to now the conclusive demonstration that a chemical is a carcinogen still requires a significant induction of tumors in vivo.