title: Bioassay of 1-nitronaphthalene for possible carcinogenicity.
abstract: A bioassay of technical-grade 1-nitronaphthalene for possible carcinogenicity was conducted using Fischer 344 rats and B6C3F1 mice. 1-Nitronaphthalene was administered in the feed, at either of two concentrations, to groups of 50 male and 50 female animals of each species. The high and low time-weighted average concentrations used in the chronic study were, respectively, 0.18 and 0.06 percent for rats and 0.12 and 0.06 percent for mice. After a 78-week period of chemical administration, the rats were observed for an additional period of up to 31 weeks and the mice for an additional period of up to 20 weeks. For rats 50 animals of each sex were placed on test as controls for the low dose groups and 25 of each sex for the high dose groups. For mice 50 animals of each sex were placed on test as controls for each dosed group. In both species adequate numbers of animals in all groups survived sufficiently long for the development of late-appearing tumors; however, no compound-related increase in the incidence of neoplasms, nonneoplastic lesions, or other toxic effects was evident. Under the conditions of this bioassay 1-nitronaphthalene was not demonstrated to be carcinogenic in Fischer 344 rats or B6C3F1 mice.