Toxicology and Carcinogenesis Studies of HC Yellow 4 (CAS No. 59820-43-8)in F344Rats and B6C3F1 Mice (Feed Studies)
Chemical Formula: C10H14N2O5
HC Yellow 4 is used in semipermanent hair dyes. Toxicology andcarcinogenesisstudies were conducted by administering HC Yellow 4 (greater than 93%pure) infeed to groups of F344/N rats and B6C3F1 mice of each sex for 14 days, 13weeks, and 2 years. Genetic toxicology studies were conducted in Salmonellatyphimurium, cultured Chinese hamster ovary cells, and Drosophilamelanogaster.
Groups of five rats of each sex were given 0, 5,000,10,000,20,000, 40,000, or 80,000 ppm and groups of five mice of each sex weregiven 0,1,250, 2,500, 5,000, 10,000, or 20,000 ppm HC Yellow 4 in feed for 14 days.All animals survived to the end of the studies. Final mean body weights ofmale rats that received 20,000 ppm or more, female rats that received 10,000ppm or more, and female mice that received 20,000 ppm were significantlylowerthan those of the controls. The mean body weights of exposed and controlgroups of male mice were similar. No chemical-related decrease in feedconsumption was observed. No chemical-related clinical findings or changesinabsolute or relative organ weights occurred in rats or mice. No gross ormicroscopic changes were related to HC Yellow 4 administration in rats ormice.
Groups of 10 rats of each sex were fed dietscontaining 0,2,500, 5,000, 10,000, 20,000, or 40,000 ppm and groups of 10 mice of eachsexwere fed diets containing 0, 5,000, 10,000, 20,000, 40,000, or 80,000 ppm HCYellow 4 for 13 weeks. All rats survived to study termination.Chemical-related deaths occurred at the two highest dose levels in male andfemale mice. Final mean body weights of male rats that received 10,000 ppmorgreater, female rats that received 20,000 or 40,000 ppm, and mice thatreceived10,000 ppm or greater were significantly lower than those of the controls.There were no biologically significant changes in absolute or relative organweights. Mineralization of the renal papilla occurred in all male rats in the40,000 ppm group. Thyroid pigmentation occurred in rats receiving 40,000ppmand in mice at all dose levels. Uterine atrophy occurred in female rats in the20,000 and 40,000 ppm groups and female mice in the 40,000 and 80,000ppmgroups. Lymphoid depletion and atrophy of the spleen occurred in male micethat received 40,000 or 80,000 ppm and female mice that received 80,000ppm.Atrophy of the thymus occurred in male and female mice that received 40,000or80,000 ppm.
Groups of 70 male rats were fed diets containing 0,2,500, or5,000 ppm and groups of 70 female rats and 70 mice of each sex were feddietscontaining 0, 5,000, or 10,000 ppm HC Yellow 4 for up to 2 years. Interimevaluations were performed on 10 rats and 10 mice from each dose group at6 and15 months. No biologically significant changes in absolute or relative organweight or hematology or clinical chemistry values were found in these rats ormice. No compound-related lesions were seen in exposed rats. In exposedmice,pigmentation of the thyroid gland was observed at the 6-month interimevaluations; pigmentation and hyperplasia of the thyroid gland were seen atthe15-month interim evaluations.
Body Weight, Survival, and Feed Consumption in the 2-Year Studies:
The meanbody weight of female rats that received 10,000 ppm was significantly lowerthan that of the controls. The mean body weights of mice receiving 10,000ppmwere 20% to 30% lower than those of the controls during the second year ofthestudies. The survival of exposed rats and mice was similar to that of thecontrols.
Neoplasms and Nonneoplastic Lesions in the 2-Year Studies:
Pituitarygland parsdistalis adenomas were marginally increased in exposed male rats (0 ppm,17/45;2,500 ppm, 20/49; 5,000 ppm, 28/49), and there was a concomitantdose-relatedincrease in the incidence of hyperplasia (8/45, 13/49, 18/49). There was noincrease in the incidence of pituitary gland adenomas or carcinomas in femalerats (34/49, 35/48, 30/49).
In mice, no neoplasms were considered related to chemicaladministration.However, a dose-related increased incidence of thyroid gland pigmentationandfollicular cell hyperplasia occurred in both sexes of mice.
HC Yellow 4 was mutagenic in Salmonellatyphimuriumstrains TA100, TA1537, and TA98 with and without exogenous metabolicactivation(S9); the response in strain TA1535 without S9 was equivocal. HC Yellow 4induced sister chromatid exchanges in Chinese hamster ovary cells in theabsence but not the presence of S9 activation; no induction of chromosomalaberrations occurred in Chinese hamster ovary cells, with or without S9. HCYellow 4 induced sex-linked recessive lethal mutations in germ cells of adultmale Drosophila melanogaster when administered by injection; results of areciprocal translocation test in D. melanogaster were negative.
Under the conditions of these 2-year feed studies, therewasequivocal evidence of carcinogenic activity of HC Yellow 4 in male F344/N ratsbased on the increased incidence of pituitary gland adenomas andhyperplasia.The male rats may have been able to tolerate a slightly higher dose of thechemical. There was no evidence of carcinogenic activity of HC Yellow 4 infemale F344/N rats given 5,000 or 10,000 ppm. There was no evidence ofcarcinogenic activity of HC Yellow 4 in male or female B6C3F1 mice given5,000or 10,000 ppm.
There was a chemical-related increase in the incidence of thyroid glandpigmentation and follicular cell hyperplasia in mice.
Report Date: June 1992