Abstract: BACKGROUND AND AIM: To study the combined toxic effects of phoxim (Pho) and methomyl (Met) on female reproductive toxicity. MATERIALS AND METHODS: Twenty-four adult female rats were randomly divided into 4 equal groups (including a control and three treated groups). Daily doses of Pho(29.4 mg/kg), Met(0.34 mg/kg) and Pho＋Met(29.4 mg/kg＋0.34 mg/kg) were given to rats by gastric gavage for 30 successive days. 2×2 factorial analysis was used in the experiment. Vaginal smears of rats were taken to determine estrous cycle. Serum 17β-estradiol(E2) and progesterone(P4) concentrations were measured by radioimmunoassay. The activities of superoxidedismutase (SOD) and glutathione- s-transferase(GST), and the levels of malondialdehyde(MDA) ,glutathione(GSH) and BchE in blood and ovary were measured by spectrophotometry. RESULTS: Significant differences were found in estrous cycle changes, and the concentrations of estradiol (E2) and progesterone (P4) in blood of the Met group. There were significant differences in the levels of SOD,GST ,GSH and the content of MDA in blood and ovary of Pho and Met groups. There were interactions between Pho and Met on the levels of SOD ,GST and the content of GSH in blood and ovary and also the content of MDA and P4 in blood. The joint action was characterized as an antagonistic effect. No interaction was noted between Pho and Met on weight gain in rats, estrous cycle changes,ovary and uterus internal organs coefficient, estradiol(E2) and the levels of BchE in blood ;the joint action was characterized as an additive effect. Ovarian histomorphology showed no obvious changes. Uterine pathology revealed that glands were increased and some were distended. CONCLUSION: Pho and Met could disrupt the reproductive functions of female rats. Markedly increased toxic effect of the pesticide mixtures was found in the antioxidant system. Combined exposure of Pho and Met might produce some additive reproductive toxicities in female rats.

Key words: phoxim, methomyl, female reproductive toxicity