Mutagenicity of hair dye components relative to the carcinogen benzidine in Drosophila melanogaster.

A comparative assay was undertaken in Drosophila melanogaster for the assessment of the mutagenic efficiency of the hair dye components m-toluene-diamine (m-TD) and 4-nitro-o-phenylenediamine (4-NOPD) relative to the aromatic amine human carcinogen benzidine (Bzd). The compounds were injected at equimolar dose ranges (5-20 mM) around the testes of adult males and their mutagenicities were measured separately on the various stages of spermatogenesis. Genetic activity was simultaneously assayed with respect to the overall induction of the X-chromosome recessives (lethals and visibles) relative to the specific effects on rDNA (expressed as bobbed mutations). All compounds exerted decisive mutagenicity both on the X-chromosome and the RNA genes, although their activities on the different genic sites varied between compounds and as a function of cell stage, but not in response to changes in dose, within the investigated molarity range. The mutagenicities and selectivities of the test compounds for rDNA gradually decreased in the order Bzd greater than m-TD greater than 4-NOPD, which correlated with the evidence-so far-about their carcinogenicities.