Study of tobacco smoke-induced DNA damage in association with carcinogenicity using multi organ mouse SCG assay.

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We tested the genotoxicity of cigarette smoke in the organs of the mouse using the alkaline single cell gel electrophoresis (SCG, or comet) assay. We also tested the effect of free radical scavengers on the genotoxicity of the smoke. After the animals were exposed to smoke, SSB appeared in the lung, stomach, and liver. Either VC or VE (100 mg/kg/day) pretreatment completely prevented SSB in the lung, stomach, and liver. Thus, the SCG assay detected DNA SSB induced by cigarette smoke in the known target organ, two possible target organs, and none of the non-target organs ; antioxidants could prevent those effects, suggesting that free radicals may have been a source of the damage. Our results suggest the importance of SCG assay as a tool in the studies of genotoxicity and carcinogenicity. 8-OH dG was not detected by HPLC with ECD detector after the inhalation of tobacco smoke. Then, we determined the genotoxicity of synthetic red tar dyes currently used as food color additives in many countries, including Japan. For the preliminary assessment, we treated pregnant mice with amaranth (Food Red No.2), allura red (Food Red No.40), or acid red (Food Red No.106). The assay was positive in the colon after the administration of amaranth and allura red. Acid red did not induce DNA damage in any sample at any sampling time. None of the dyes damaged DNA in other organs or the embryo. Thus, we tested male mice with amaranth, allura red, and new coccine (Food Red No.18). The three dyes induced DNA damage in the colon starting at 10 mg/kg. Because the three azo additives we examined induced colon DNA damage at a very low dose, more extensive assessment of azo additives is warranted.