Teratogenic evaluation of mancozeb in the rat following inhalation exposure.

Crl:CD rats were exposed (whole body) to mancozeb by inhalation at 0, 1, 17, 55, 110, 890, or 1890/500 mg/m3 for 6 hr/day from Day 6 through 15 of gestation (sperm-positive vaginal smear considered Day 1). Dams were killed 1 day prior to natural delivery and fetuses were examined externally, viscerally, and skeletally for any alterations. Maternal toxicity, as evidenced by significantly decreased body weight gain, hindlimb paralysis, general debilitation, and death or termination in extremis, was noted among rats exposed to mancozeb at concentrations of 500 to 1890 mg/m3. Dams from the 55 and 110 mg/m3 groups exhibited decreased body weight gain and hindlimb weakness. There was no maternal toxicity for dams exposed at a concentration of 17 mg/m3. Embryofetal toxicity, as evidenced by a significantly increased incidence of totally resorbed litters, external hemorrhage, and wavy ribs, was noted at concentrations of 55 mg/m3 and above. The embryofetal toxicity occurred only at concentrations toxic to the dam. Among the groups exposed to mancozeb, the incidence of major malformations was not dose related. Hence, under the test conditions of this study, mancozeb was not found to be teratogenic and produced no toxicity unique to the conceptus.