Negative results of carcinogenicity bioassay of methyl carbazate in rats: significance for the toxicological evaluation of carbadox.

Methyl carbazate, a metabolite of carbadox in the rat, was administered orally to rats for 2 years. The compound was mixed in the diet at concentrations corresponding to dose levels of 0, 2.5, 5 and 10 mg/kg body wt/day. There was no evidence of any treatment-related toxicity or, in particular, of carcinogenicity.