Bioassay of anilazine for possible carcinogenicity (CAS No. 101-05-3).

A bioassay of anilazine for possible carcinogenicity was conducted by administering the test chemical in feed to Fischer 344 rats and B6C3F1 mice. Groups of 50 rats and 50 mice of each sex were administered anilazine at one of two doses, either 500 or 1,000 ppm, for 103 weeks and then observed for 1-6 additional weeks. Matched controls consisted of 25 untreated rats and 25 untreated mice of each sex. All surviving rats were killed at 103-104 weeks; all surviving mice were killed at 107-109 weeks. Administration of the anilazine had no appreciable effect on body weight in the rats and female mice; however, there was a decreased gain in mean body weight in the dosed male mice. Survival also was essentially unaffected. Survival in all groups of dosed and control rats and mice was at least 80% at the end of 90 weeks on study, except for the male control mice; thus, sufficient numbers of animals were at risk in most groups for development of late-appearing tumors. No tumors occurred in dosed rats or mice of either sex at incidences that were significantly higher than those in corresponding controls. Male and female rats and female mice may have been able to tolerate higher doses. It is concluded that under the conditions of this bioassay, anilazine was not carcinogenic for either Fischer 344 rats or B6C3F1 mice.