Picarbutrazox (Pesticides)

The Food Safety Commission of Japan (FSCJ) conducted a risk assessment of picarbutrazox (CAS No.500207-04-5), a methyltetrazole-type fungicide, based on results from various studies. Major adverse effects of picarbutrazox were observed as hepatocellular hypertrophy and hypertrophy of follicular epithelial cells in rats. None of neurotoxicity, reproductive toxicity, teratogenicity and genotoxicity were detected in the experiments described above. Picarbutrazox (parent compound only) and its metabolite B were identified as the relevant substance for the residue definition for dietary risk assessment in agricultural products. The lowest no-observed-adverse-effect level (NOAEL) obtained in all studies was 2.34 mg/kg bw/day in a two-year combined chronic toxicity/carcinogenicity study in rats. FSCJ specified an acceptable daily intake (ADI) of 0.023 mg/kg bw/day, applying a safety factor of 100 to the NOAEL. FSCJ judged it unnecessary to specify an acute reference dose (ARfD), since no adverse effects would be likely to be elicited by a single oral administration.