A carcinogenesis bioassay of C.I. Solvent Yellow 14 (94.1% pure), a widely used monoazo dye, was conducted by feeding diets containing 250 or 500 ppm of C.I. Solvent Yellow 14 to groups of 50 F344 rats of either sex for 103 weeks. Similar groups of 50 B6C3F1 mice received diets containing 500 or 1,000 ppm of C.I. Solvent Yellow 14 for 103 weeks. Groups of 50 untreated rats and mice of either sex served as controls.
Throughout the bioassay, mean body weights of dosed rats and mice were slightly lower than those of controls. No compound-related clinical signs or effects on survival were observed.
Increases in nonneoplastic lesions included cardiac valve fibrosis for male and female rats, lymphoid hyperplasia of the lung for male rats, and for female rats, bile duct hyperplasia, focal atrophy of the pancreatic acinus, and nephropathy. None of these effects were observed in mice.
Neoplastic nodules of the liver occurred in rats of either sex with a dose-related trend that was significant (male, P<0.001; female, P=0.005), and the incidences in the high-dose groups were significantly higher than those in the controls (male: control, 5/50; low-dose, 10/50; high-dose, 30/50, P<0.001 and female: control, 2/50; low-dose, 3/49; high-dose, 10/48, P=0.011).
Lymphomas or leukemias occurred in low-dose female mice at an incidence significantly (P<0.05) higher than that in the controls (12/50, 23/50, 17/50). Because of the lack of a dose-related trend and because the incidence in the high-dose group was not significant, the association between the increased incidence of hematopoietic tumors in the low-dose group and the administration of C.I. Solvent Yellow 14 is not clearly established. The incidence of lymphomas or leukemias in male mice was higher (not statistically significant) than that in the corresponding controls (5/49, 10/50, 10/50); in both low-and high-dose rats of either sex the incidence was significantly (P<0.001) lower than that in controls.
Under the conditions of this bioassay, C.I. Solvent Yellow 14 was carcinogenic in male and female F344/N rats, as evidenced by increased incidences of neoplastic nodules of the liver. C.I. Solvent Yellow 14 was not carcinogenic for B6C3F1 mice of either sex.