The differential clastogenicity of Solvent Yellow 14 and FD & C Yellow No. 6 in vivo in the rodent micronucleus test (observations on species and tissue specificity)

Solvent Yellow 14 is carcinogenic in rats, inducing neoplastic nodules of the liver, but is non-carcinogenic in mice. The present paper shows that Solvent Yellow 14 induces micronuclei in the bone marrow of rats after a single oral dose of 250 mg/kg and above. In mice, however, there was no increased incidence of micronuclei after single oral doses of up to 2000 mg/kg Solvent Yellow 14, thus reflecting the species specific carcinogenic effect of the compound. The structurally related azo dye FD & C Yellow No. 6 is noncarcinogenic to rats and mice and gave a negative result in both rat and mouse bone marrow micronucleus tests after a single oral dose of up to 2000 mg/kg. The rat bone marrow micronucleus test is therefore capable of discrimination between the carcinogenic and the non-carcinogenic azo dye. A negative result was obtained for Solvent Yellow 14 in an in vivo liver unscheduled DNA synthesis assay after oral doses up to 1000 mg/kg. This result demonstrates the inability of the two in vivo assays used to predict target organ specificity seen in the cancer bioassay.