title: Bioassay of 2-aminoanthraquinone for possible carcinogenicity.
abstract: A bioassay of 2-aminoanthraquinone for possible carcinogenicity was conducted using Fischer 344 rats and B6C3F1 mice. 2-Aminoanthraquinone was administered in the feed, at either of two concentrations (except for female rats), to groups of 50 male and 50 female animals of each species. The time-weighted average dietary concentrations used in the chronic bioassay were 0.69 and 0.35 percent for high and low dose male rats, respectively, 0.2 percent for the treated female rats, and 1.0 and 0.5 percent, respectively, for high and low dose mice of both sexes. After a 78-week period of chemical administration (80 weeks for high dose mice), observation of the rats continued for up to an additional 32, weeks and observation of the mice continued for up to an additional 16 weeks. In both species adequate numbers of animals in all groups, except the treated female rats, survived sufficiently long to be at risk from late-developing tumors. The survival among treated female rats was poor and, as a result, no conclusions could be made regarding the carcinogenicity of the compound in these animals. When male rats having either hepatocellular carcinomas or neoplastic nodules of the liver were combined and the resulting tumor incidences were analyzed statistically, there was a significant positive association between dosage and the incidences of these combined neoplasms. Hepatocellular carcinomas were observed at significantly higher incidences when dosed mice were compared to controls. There was a significantly higher incidence of malignant hematopoietic lymphomas in high dose female mice when compared to controls. Under the conditions of this bioassay, dietary administration of 2-aminoanthraquinone was carcinogenic in male Fischer 344 rats, causing a combination of hepatocellular carcinomas and neoplastic nodules of the liver. The compound was also carcinogenic in B6C3F1 mice, causing hepatocellular carcinomas in both sexes and malignant hematopoietic lymphomas in females.