Studies on the teratogenic effects of deltamethrin in rats.

Deltamethrin is a pyrethroid insecticide used to eradicate external parasites on farm animals. Residues of this pesticide were shown to be present in food from animal origin which encouraged us to investigate the effects of deltamethrin on foetuses of pregnant rats. Literature search shows that previous research was focused on organochlorine and organophosphate pesticides whereas little attention was given to the newer pyrethroid insecticides. Four groups of pregnant rats (20 rats each) were given either the vehicle (control) or doses of 1, 2.5 or 5 mg/kg b. w. of deltamethrin orally from day 6 to day 15 of pregnancy which was terminated by killing the animals on the 19th day for foetal examinations. The incidence of early embryonic deaths was higher in deltamethrin-treated rats than in control females. Deltamethrin caused retardation of growth, hypoplasia of the lungs, dilatation of the renal pelvis and increase in placental weight. No skeletal changes were observed in foetuses recovered from deltamethrin-treated females. Although deltamethrin is relatively safe, however its effects on the foetus should be considered when used on pregnant animals or in environments where pregnant animals and women live.