4,4'-Diamino-2,2'-stilbenedisulfonic acid, disodium salt, is used in the synthesis of dyes and optical brighteners or fluorescent whitening agents. Toxicology and carcinogenesis studies were conducted by administering the chemical (approximately 14% water, 6% sodium chloride, 4% impurities, and 76% 4,4'-diamino-2,2'-stilbenedisulfonic acid) in feed to groups of F344/N rats and B6C3F1 mice of each sex for 14 days, 13 weeks, and 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium and Chinese hamster ovary cells.
Groups of five rats and five mice of each sex were given 0, 6,250, 12,500, 25,000, 50,000, or 100,000 ppm 4,4'-diamino-2,2'-stilbenedisulfonic acid, disodium salt, in feed for 14 days. All rats and mice survived to the end of the studies. The mean body weight gain of male rats receiving 50,000 or 100,000 ppm and of female rats and male and female mice receiving 100,000 ppm was significantly lower than those of the respective controls. Clinical findings included diarrhea in the rats and mice receiving 100,000 ppm. There were no chemical-related changes in absolute or relative organ weights in rats or mice. There were no gross or microscopic lesions related to chemical administration in rats or mice.
Groups of 10 rats and 10 mice of each sex were given 0, 6,250, 12,500, 25,000, 50,000, or 100,000 ppm 4,4'-diamino-2,2'-stilbenedisulfonic acid, disodium salt, in feed for 13 weeks. One female rat, six male mice, and one female mouse in the 100,000 ppm dose groups died during the studies. Mean body weight gain was significantly decreased in male rats and female mice receiving 50,000 or 100,000 ppm, in male mice receiving 25,000, 50,000, or 100,000 ppm, and in female rats receiving 100,000 ppm. Clinical findings in rats that received 50,000 or 100,000 ppm and in mice that received 100,000 ppm included diarrhea, emaciation, and hyperemia of the perineum. There were no biologically significant changes in absolute or relative organ weights or clinical pathology results in rats or mice. Histopathologic lesions present in rats receiving 100,000 ppm were bone marrow hypercellularity and chronic inflammation of the anus and rectum. Ulcerative inflammation of the anus and rectum was observed in mice receiving 25,000 ppm and above. Female mice in the 6,250, 12,500, 25,000, and 50,000 ppm dose groups had increased incidences of cystic endometrial hyperplasia.
Doses selected for the 2-year studies were based on mortality, decreased body weight gains, and the presence of diarrhea and chronic inflammation of the anus/rectum in rats and mice during the 13-week studies. Groups of 60 rats of each sex were given 0, 12,500 or 25,000 ppm and groups of 60 mice of each sex were given 0, 6,250, or 12,500 ppm 4,4'-diamino-2,2'-stilbenedisulfonic acid, disodium salt, in feed for up to 103 weeks. Interim evaluations were performed on 10 rats and 10 mice from each dose group at 15 months. There were no biologically significant absolute or relative organ weight, clinical pathology, or histopathology findings in rats or mice administered 4,4'-diamino-2,2'-stilbenedisulfonic acid, disodium salt, in feed for 15 months.
Body Weight, Feed Consumption, Survival, and Clinical Findings in the 2-Year Studies
Mean body weights were marginally decreased for high-dose male and female rats and female mice. Feed consumption by dosed rats and mice was similar to feed consumption by the controls throughout the studies. Survival was similar among control and treated groups of rats and mice. No clinical findings related to chemical administration were observed in rats or mice.
Nonneoplastic and Neoplastic Effects in the 2-Year Studies
There were no chemical-related increased incidences of neoplasms at any site in rats. Ulcers of the forestomach or glandular stomach occurred in dosed rats (males: 1/50, 5/50, 4/50; females: 0/50, 1/50, 4/50), and may have been related to the administration of 4,4'-diamino-2,2'-stilbenedisulfonic acid, disodium salt. There were no chemical-related incidences of neoplasms, nonneoplastic lesions, or other toxic effects in mice in the 2-year studies. Although the animals might have been able to tolerate slightly higher doses, results of the 13-week studies indicate that a doubling of the highest doses could not have been tolerated.
4,4'-Diamino-2,2'-stilbenedisulfonic acid was not mutagenic in Salmonella typhimurium strains TA100, TA1535, TA1537, or TA98 with or without S9 metabolic activation. 4,4'-Diamino-2,2'-stilbenedisulfonic acid did not induce sister chromatid exchanges or chromosomal aberrations in Chinese hamster ovary cells in the presence or absence of S9.
Under the conditions of these 2-year feed studies, there was no evidence of carcinogenic activity of 4,4'-diamino-2,2'-stilbenedisulfonic acid, disodium salt, in male or female F344/N rats receiving 12,500 or 25,000 ppm. There was no evidence of carcinogenic activity of 4,4'-diamino-2,2'-stilbenedisulfonic acid, disodium salt, in male or female B6C3F1 mice receiving 6,250 or 12,500 ppm.