Developmental toxicity of chlorpropham in mice.

The present studies were designed to evaluate the developmental toxicity of chlorpropham in mice. The first study was conducted to determine administration time, and the second study was designed to evaluate dose-response effects. Chlorpropham was administered to pregnant mice by gavage on Days 8, 8.3, 9, 9.3, 10, and 11 of gestation at a level of 3000 mg/kg bw, and the females were killed on Day 18 of gestation. The administration on Day 8.3 of gestation induced the highest percentage of external malformations with brachyury occurring among more litters than in other groups. Chlorpropham was administered to pregnant mice by gavage at a level of 0 (control), 750, 1500, and 3000 mg/kg bw on Day 8.3 of gestation, and the females were killed on Day 18 of gestation. The total resorption rate was significantly increased in the 3000 mg/kg bw group. The average fetal body weight of each sex was significantly reduced in the 3000 mg/kg treatment group. The total incidence of external malformations was significantly increased in the two highest dose groups in a dose-related manner. Again brachyury was significantly increased in the 3000 mg/kg bw group.