Developmental Toxicity of Dinitroaniline Herbicides in Rats and Rabbits

The potential developmental toxicity of trifluralin was evaluatedin rats and rabbits. Pregnant rats and rabbits were dosed oncedaily by gavage on Gestation Days 6–15 and 6–18,respectively. Doses for rats were 0, 100, 225, 475, or 1000mg/kg; doses for rabbits were 0, 100, 225, or 500 mg/kg. Cesareansections were performed on rats and rabbits on Gestation Days20 and 28, respectively. In rats, maternal toxicity was indicatedin the 475 and 1000 mg/kg treatment groups by depression ofbody weights and food consumption. Fetal viability and morphologywere not adversely affected at any dose level. Developmentaltoxicity was indicated at the 1000-mg/kg dose level by depressionof fetal weight. The NOAEL for maternal toxicity in the ratwas 225 mg/kg the NOAEL for developmental toxicity in the ratwas 475 mg/kg. In rabbits, maternal toxicity was indicated atthe 225 and 500 mg/kg dose levels by abortions and/or deathsin conjunction with anorexia and cachexia. Developmental toxicitywas indicated at the 500 mg/kg dose level by depressed fetalviability and weight. Fetal morphology was not adversely affectedat any dose level. The NOAELs for maternal and developmentaltoxicity in the rabbit were 100 and 225 mg/kg, respectively.Based on these data, trifluralin did not exhibit selective toxicitytoward the developing conceptus.