These studies were supported in part by funds from the Comprehensive Environmental Response, Compensation, and Liability Act trust fund (Superfund) by an interagency agreement with the Agency for Toxic Substances and Disease Registry, U.S. Public Health Service.
Toxicity studies were conducted by administering D&C Yellow No. 11 (approximately 99% pure) in feed at dietary concentrations of up to 50,000 ppm to groups of F344/N rats and B6C3F1 mice of each sex for 14 days or 13 weeks. A separate study was conducted to determine the effects of feeding diets containing D&C Yellow No. 11 to female rats during a reproductive cycle and to their offspring.
Although the estimated intake of D&C Yellow No. 11 by mice was more than twice that by rats, the results of the 14-day and 13-week studies were similar for both rats and mice. In both species, D&C Yellow No. 11 caused no deaths (5 animals per group in the 14-day studies and 10 per group in the 13-week studies) but did reduce body weight gain slightly in rats of each sex exposed to 17,000 or 50,000 ppm. Liver weights were increased in dosed rats and mice. There was minimal-to-mild degeneration of the periportal portion of the liver lobules of rats at dietary concentrations of 1,700 ppm and higher and of mice at 5,000 ppm and higher. A dose-related yellow-brown pigment was observed in hepatocytes, Kupffer cells, and biliary epithelium of the liver of each sex and species and in the tubular epithelium of the kidney of rats of each sex. Hepatocellular degeneration progressed slightly in severity with increased time of exposure (i.e., 14 days to 13 weeks) in rats but not in mice. The number and size of hyaline droplets in the tubular epithelium of the cortex and outer medulla of the kidney were increased in all dosed groups of male rats.
In a perinatal toxicity study, body weight gain of rat dams given diets containing as much as 50,000 ppm D&C Yellow No. 11 for 4 weeks before mating to unexposed males was similar to that of controls at the time of mating but was lower at parturition and weaning. However, fertility, gestation length, litter size, and pup birth weights were unaffected by exposure. At weaning, body weights of pups from all dosed dams (5,000, 17,000, and 50,000 ppm) were lower than weights of pups from the controls. After exposure to DC Yellow No. 11 for 4 weeks through the milk and to feed containing the same dietary concentrations that the dams received, weights of the 5,000-ppm pups were similar to those of the controls, but weights of the 17,000- and 50,000-ppm dose groups remained depressed. Microscopic evaluation showed lesions in the pups in all dosed groups; these lesions were similar to those described in the liver and kidney of rats in the 14-day and 13-week studies, including the male rat kidney cytoplasmic alterations.
The results of these studies indicate that compound-related effects occurred at all dietary concentrations of DC Yellow No. 11; i.e., liver weights were increased in dosed rats and mice, and there was an increase in the number and size of hyaline droplets in all dosed groups of male rats.