Toxicology and carcinogenesis studies of di-n-butyl phthalate administered in feed to Sprague Dawley (Hsd:Sprague Dawley SD) rats and B6C3F1/N mice

Di-n-butyl phthalate (DBP) is a phthalate used in the manufacture of consumer products such as plastics and personal care products. Widespread exposure in the population occurs throughout life, including during pregnancy and lactation. Because limited data are available in both animals and humans to evaluate DBP as a human carcinogen, the National Toxicology Program conducted 2-year studies of DBP in rats and mice. Time-mated female Sprague Dawley (Hsd:Sprague Dawley SD) rats were exposed to 0, 300, 1,000, 3,000, or 10,000 ppm DBP in feed during gestation and lactation. Postweaning, F1 offspring consumed diets with the same exposure concentrations as the dam for 2 years (n = 50/sex/exposure group). Male and female adult B6C3F1/N mice were exposed to 0, 1,000, 3,000, or 10,000 ppm DBP in feed for 2 years (n = 50/sex/exposure group). Estimated average chronic chemical consumption was 16-17, 54-57, 152-169, and 510-600 mg DBP/kg body weight/day (mg/kg/day) in rats in the 300, 1,000, 3,000, and 10,000 ppm groups, respectively, and 105-112, 329-347, and 1,306-1,393 mg/kg/day in mice in the 1,000, 3,000, and 10,000 ppm groups, respectively. (Abstract Abridged).