Food Safety Commission of Japan (FSCJ) conducted a risk assessment of desmedipham (CAS No. 13684-56-5), a carbanilate herbicides, based on results from various studies. Major adverse effects of desmedipham were suppressed body weight, hemolytic anemia, methemoglobinemia and follicular cell hypertrophy in thyroid. Neither carcinogenicity, reproductive toxicity, nor genotoxicity relevant to human health was observed on desmedipham. Desmedipham, at the dose with maternal toxicity, caused external anomalies such as mandibular malformation and cleft palate, visceral anomalies such as ventricular septum defect, and skeletal anomalies such as defect of sternum and asymmetric alignment of seternebral hemicentres in developmental toxicity studies in rats. No teratogenetic effects were observed in rabbits. The lowest no-observed-effect level (NOAEL) obtained in all studies was 3.2 mg/kg bw/day in a two-year combined chronic toxicity/carcinogenicity in rats. FSCJ specified an acceptable (ADI) of 0.032 mg/kg bw/day, applying a safety factor of 100 to the NOAEL. The lowest NOAEL for adverse effects elicited by a single oral administration of desmedipham was 90 mg/kg bw/day obtained from the developmental toxicity study in rabbits (the 2nd study in the Table 2). Consequently, FSCJ specified an acute reference dose (ARfD) of 0.9 mg/kg bw applying a safety factor of 100 to the NOAEL.
