The ability of plant genotoxicity assays to predict carcinogenicity

A number of assays have been developed which use higher plants for measuring mutagenic or cytogenetic effects of chemicals, as an indication of carcinogenicity. Plant assays require less extensive equipment, materials and personnel than most other genotoxicity tests, which is a potential advantage, particularly in less developed parts of the world. We have analyzed data on 9 plant genotoxicity assays evaluated by the Gene-Tox program of the U.S. Environmental Protection Agency, using methodologies we have recently developed to assess the capability of assays to predict carcinogenicity and carcinogenic potency. All 9 of the plant assays appear to have high sensitivity (few false negatives). Specificity (rate of true negatives) was more difficult to evaluate because of limited testing on non-carcinogens; however, available data indicate that only the Arabidopsis mutagenicity (ArM) test appears to have high specificity. Based upon their high sensitivity, plant genotoxicity tests are most appropriate for a risk-averse testing program, because although many false positives will be generated, the relatively few negative results will be quite reliable.