ABSTRACT
D&C Red No. 36, a drug and cosmetic dye commonly used for coloring lipsticks, was evaluated for its carcinogenic potential in male and female Wistar rats. This dye has been shown to exhibit mutagenic activity towards Salmonella typhimurium TA 98 in the presence of S9 mix. In the present study, 50 male and 50 female rats in each group were given diets containing D&C Red No. 36 at 2 different concentrations, 1,000 ppm and 2,000 ppm, for 78 weeks and sacrificed at week 98. It was found that dye treatment had no significant effect on the survival of either male or female animals as well as the body weight gain in males. However, body weight gain of treated females was slightly lower than that of the control group. Histopathological assessment demonstrated a number of benign and malignant tumors to have developed in various organs of both dye treated and control groups. In male rats, benign liver tumors were found at incidences of 16.7% and 18.8% of the low (1,000 ppm) and high (2,000 ppm) dose groups, respectively, similar to the 20% for the control group. Malignant tumors of the thyroid gland were observed only in the low dose and control groups, at 4.2% and 2%, respectively. In the high dose group, the incidences of lung, liver, urinary bladder and soft tissue cancers were 4.2%, 2.1%, 2.1% and 2.1%, respectively, only one soft tissue cancer being observed in a control group animal. In females, benign tumors were observed in the liver and mammary glands. The incidences of liver tumors in the low and high dose groups were 12.8% and 16%, respectively, and 6% in the control group. Values for mammary gland tumors were 10.6%, 10%, and 18% respectively. Malignant tumors were also observed in various other organs, including the uterus, lung, kidney, thyroid, thymus and salivary gland, but the incidences were very low (about 2-4%) and in dye treated male and female rats were not statistically different from those in the control animals. The results of the present study thus demonstrated that D&C Red No. 36 at the concentrations of 1,000 ppm and 2,000 ppm in the diet is not carcinogenic either to male or female Wistar rats. While the occurrence of benign liver tumors in female rats may be related to dye treatment, the lack of any apparent dose-dependence or any statistically significant difference from the control group (P = 0.06) suggests that this is unlikely.
