Bioassay of a Mixture of 1, 2, 3, 6, 7, 8-Hexachlorodibenzo-p-Dioxin and 1, 2, 3, 7, 8, 9-Hexachlorodibenzo-p-Dioxin (Gavage) for Possible Carcinogenicity

摘要

A bioassay of a mixture of 1,2,3,6,7,8- and 1,2,3,7,8,9-hexachlorodibenzo-p-dioxins (HCDD) for possible carcinogenicity was conducted by administering the test material by gavage to Osborne-Mendel rats and B6C3F1 mice for 104 weeks. Fifty rats and 50 mice of each sex were administered HCDD suspended in a vehicle of 9:1 corn oil-acetone 2 days per week for 104 weeks at doses of 1.25, 2.5, or 5 micrograms/kg/wk for rats and male mice and 2.5, 5, or 10 micrograms/kg/wk for female mice. Seventy-five rats and 75 mice of each sex served as vehicle controls. 25 untreated animals of each sex and species were present in the treatment room, and in the vehicle-control room. In male rats, hepatocellular carcinomas or neoplastic nodules occurred at low incidences that were dose related but were not deemed statistically significant. In female rats, however, hepatocellular carcinomas, adenomas, or neoplastic nodules occurred at incidences that were dose related and statistically significant. In male and female mice, hepatocellular carcinomas or adenomas occurred at incidences that were dose related and statistically significant. Complex nonneoplastic toxic liver lesions were seen in all dosed groups of rats and mice. Compound-associated hyperplastic lesions of the lung were also found in both male and female rats. Under the conditions of this bioassay, HCDD administered by gavage was carcinogenic, causing increased incidences of hepatocellular carcinomas or neoplastic nodules in female Osborne-Mendel rats and inducing hepatocellular carcinomas and adenomas in male and female B6C3F1 mice. HCDD was not demonstrated to be carcinogenic for male rats.