[Genotoxicity of synthetic dyes in umu test using Salmonella typhimurium TA1535/pSK1002 (1). Results of examination for acid dyes, direct dyes, disperse dyes and reactive dyes].

The umu test system is a newly developed method to evaluate genotoxicities of a wide variety of environmental carcinogens and mutagens (Oda et al., 1985; Nakamura et al., 1987). In the present study, SOS-inducing activity of 142 synthetic dyes was investigated by the umu test using Salmonella typhimurium (TA1535/pSK1002) under the condition of absence and presence of rat liver microsomal fraction. The samples showing a beta-galactosidase activity of more than 1.5 fold over the background level were reexamined and the dose-response curves were prepared at various doses. Then, the samples showing beta-galactosidase activity of more than 1.5-fold of the background level were defined as genotoxic. Among the synthetic dyes examined, 11 compounds induced umu gene expression. The potent genotoxic compounds without metabolic activation were Acid Black 26, Acid Black 50, Acid Brown 2, Disperse Red 73, Disperse Red 145, Disperse Red 157, Disperse Violet 52, Reactive Red 110, Reactive Yellow 13 and Reactive Yellow 75, and in the presence of S9, Reactive Blue 147 was judged to be genotoxic. An evident dose-response relationship was observed between the doses of the dye and umu-gene expression in these 11 dyes.