Dimesulfazet (Pesticides)

Food Safety Commission of Japan (FSCJ) conducted a risk assessment of a sulfonanilide herbicide, dimesulfazet (CAS No. 1215111-77-5), based on results from various studies. The data used in the assessment include the fate in plants (paddy rice), residues in crops, fate in animals (rats), subacute toxicity (rats, mice and dogs), chronic toxicity (dogs), combined chronic toxicity/carcinogenicity (rats), carcinogenicity (mice), acute neurotoxicity (rats), subacute neurotoxicity (rats), two-generation reproductive toxicity (rats), developmental toxicity (rats and rabbits), and genotoxicity. The major adverse effects of dimesulfazet from those test results were observed in body weight (suppressed body weight gain in all test results), kidneys (increased weight in rats) and urinary bladder (urothelial hyperplasia in mice and dogs). None of carcinogenicity, neurotoxicity and genotoxicity were observed. No obvious effects on fertility were detected. The lowest no-observed-adverse-effect level (NOAEL) obtained from all the studies was 0.39 mg/kg bw per day in two-year combined chronic toxicity/carcinogenicity study in rats. On the basis of this value, FSCJ specified an acceptable daily intake (ADI) of 0.0039 mg/kg bw per day after applying a safety factor of 100 to the NOAEL. The lowest NOAEL for potential adverse effects after a single oral administration of dimesulfazet was 15 mg/kg bw per day in the developmental toxicity study in rabbits. FSCJ thus specified an acute reference dose (ARfD) of 0.15 mg/kg bw after applying a safety factor of 100 for women who are pregnant or might be pregnant. For the general population, an ARfD of 0.41 mg/kg bw after applying a safety factor of 300 (additional factor 3 by applying LOAEL of 125 mg/kg bw resulted from acute neurotoxicity study in rats).