CARCINOGENICITY OF DINITROPYRENES IN THE WEANLING FEMALE CD RAT

The carcinogenicities of 1-nitropyrene and 1,3-, 1,6- and 1,8-dinitropyrene were assessed in weanling female CD rats. The animals were administered one of the compounds at 10-mu-mol/kg body wt through intraperitoneal or intragastric administration three times a week for 4 weeks. The total cumulative dose averaged 16-mu-mol/animal. The experiment was ended 78 weeks following the first administration. The average survival period for the animals in the 1,6- and 1,8-dinitropyrene i.p. treated groups, due to the occurrence of life-threatening peritoneal malignant fibrous histiocytomas (MFHs) in nearly all of the animals, were 19 and 38 weeks respectively. 1,3-Dinitropyrene induced only a few MFHs. 1,8-Dinitropyrene also induced a significant incidence of leukemia. A significant increase of the incidence of mammary tumors was observed in the groups of rats treated i.p. with 1-nitropyrene, or 1,3- or 1,8-dinitropyrene, and those treated i.g. with 1,8-dinitropyrene. These results demonstrate that nitropyrenes are capable of inducing MFH, mammary tumors and leukemia in the rat.