13-week subchronic oral toxicity study of ammonium sulfate in rats

A 13-week subchronic oral toxicity study of ammonium sulfate was performed in both sexes of F344 rats by feeding them a CRF-1 powder diet containing concentrations of 0%, 0.38%, 0.75%, 1.5%, and 3.0% of the substance. Rats were randomly divided into 5 groups each consisting of 10 males and 10 females. Male animals in the 3% group exhibited diarrhea during the administration period. No changes indicating obvious ammonium sulfate toxicity were observed in the body weights, organ weights, hematological, serum biochemical, or histopathological examinations. Based on these results, the NOEL (no-observed-effect level) of ammonium sulfate for F344 rats was judged to be 1.5% in males (886 mg/kg/day) and 3% in females (1975 mg/kg/day), and the MTD (maximally tolerated dose) for 2-year carcinogenicity studies in F344 rats was concluded to be 3.0% or more in the diet.