maneb and Fetal-Resorption

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.

Topics: Abnormalities, Drug-Induced; Animals; Atmosphere Exposure Chambers; Body Weight; Female; Fetal Resorption; Fetus; Maneb; Maternal-Fetal Exchange; Particle Size; Pregnancy; Rats; Teratogens; Zineb

Oral administration of high dosages of the dithiocarbamate pesticides maneb and mancozeb was teratogenic in rats but not in mice. The malformations, severe limb and craniofacial defects, were pronounced after maneb treatment but less so after mancozeb and propineb, zinc-containing compounds. The teratogenic effect of maneb was progressively reduced by simultaneously administering increasing amounts of zinc acetate. The mechanism of the teratogenic effect may involve the compounds being chelating agents, trapping zinc required for many important enzyme systems.

Topics: Abnormalities, Drug-Induced; Acetates; Animals; Female; Fetal Resorption; Maneb; Mice; Pregnancy; Rats; Thiocarbamates; Zinc; Zineb