Abstract
Food Safety Commission of Japan (FSCJ) conducted a risk assessment of pyridachlometyl (CAS No.1358061-55-8), a pyridazine fungicide, based on results from various studies. The data used in the assessment include the fate in plants (wheat, sugar beet and others), residues in crops, fate in livestock (goats and chickens), residues in livestock, fate in animals (rats), and tests of subacute toxicity (rats, mice and dogs), chronic toxicity (dogs), combined chronic toxicity/carcinogenicity (rats), carcinogenicity (mice), two-generation reproductive toxicity (rats), developmental toxicity (rats and rabbits), genotoxicity and others. The major adverse effects of pyridachlometyl in experimental animals were observed in body weight (suppressed body weight gain), thyroid (increased weight, hypertrophy of follicular epithelial cell: rats and mice) and liver (increased weight, hepatocellar hypertrophy). No adverse effects were observed in the tests of fertility, teratogenicity or genotoxicity. The lowest no-observed-adverse-effect level (NOAEL) obtained from all the studies was 8 mg/kg bw per day in a two-year combined chronic toxicity/carcinogenicity study in rats. FSCJ specified an acceptable daily intake (ADI) of 0.08 mg/kg bw per day by applying a safety factor of 100 to the NOAEL. It is unnecessary to specify an acute reference dose (ARfD) because of adverse effects not expected to occur via a single administration of pyridacholometyl.