A carcinogenesis bioassay was conducted using groups of 50 male and 50 female F344 rats and B6C3F1 mice which were fed diets containing 12,500 or 25,000 ppm FD & C Yellow No. 6, a widely used food colorant, for 103 weeks. Groups of 90 male and 90 female rats and 50 male and 50 female mice served as undosed controls.
Throughout the study, mean body weights of high-dose female rats and all low-dose groups were comparable with those of the controls, but mean body weights of high-dose male rats and high-dose male and female mice were slightly lower (10% or less) than those of the controls.
No compound-related neoplastic or nonneoplastic lesions were observed in the rats.
The incidence of hepatocellular carcinomas in low-dose male mice was significantly higher than that in the controls, but the lack of a significant increase in high-dose males and the variability of liver tumors in B6C3F1 male mice precluded clearly relating the occurrence of these tumors to the administration of FD & C Yellow No.< >6.
Under the conditions of this bioassay, there was no clear evidence of the carcinogenicity of FD & C Yellow No. 6 in F344 rats or B6C3F1 mice of either sex.