Evaluation of dimethoate toxicity on pregnancy in albino mice

We investigated whether dimethoate, an organophosphorus insecticide, causes abortion or fetal resorption in pregnant albino mice. Graded doses of 16, 20, 24, and 28 mg/kg body weight/d were administered orally from days 7 to day 15 of pregnancy. Laparotomy was performed on day 8 of pregnancy to note the number of implantations, and the animals were autopsied on day 19. The results revealed no inhibition of pregnancy in all dimethoate treated mice relative to a suitable control group. Treatment with 24 or 28 mg dimethoate caused a significant decrease in the number of implantations, live fetuses, and corpora lutea, but a decreased percent fetal survival and increased percent post-implantation loss and gestation length were not significant when compared with control mice. In all mice treated with 28 mg dimethoate, a significant decrease occurred in the body weight of the ovaries, uterus, and liver when compared with control mice. Following treatment with 16 or 20 mg dimethoate, however, no significant change was found in body and organ weights or in the number of implantations, live fetuses, and corpora lutea, percent post-implantation loss, and fetal survival, or gestation length compared with the corresponding parameters in control mice. The results of this study clearly indicate that dimethoate does not cause abortion or fetal resorption in pregnant mice. A significant decrease in the number of corpora lutea and percent fetal survival observed at higher doses of dimethoate could be due to a toxic effect on the embryo or to a hormonal imbalance.