AbstractFood 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).