A teratology study of carbaryl and malathion mixtures in rat

Recently, much controversy has developed in relation to the use of pesticides alone and in mixtures. Mixtures are used as a more efficient method of pest control. Carbaryl and malathion are one of many combinations used today. A limited amount of work has been done with these two pesticides in relation to their teratogenic potential. This study examined the teratological parameters of carbaryl and malathion in combination compared to the effect of the individual insecticides. Formulation grade carbaryl (0, 1, 10, and 100 mg/kg), formulation grade malathion (1 and 50 mg/kg), and a formulation grade mixture of carbaryl/malathion (1/1 and 50/50 mg/kg) were administered daily by gavage for 3 mo prior to and throughout gestation. Dams were sacrificed on d 20 of gestation, and the fetuses were examined for external, skeletal, and visceral malformations. Significant decreases in dam weight gain during pregnancy and a slight decrease in the number of implantations and number of live fetuses per dam were observed with the 100-mg/kg carbaryl group and were further reduced in both combination doses. The combination dose groups showed a significant reduction in placenta weight. No increases were seen in skeletal or visceral anomalies for the individual treatment groups; however, an increase in external hemorrhagic spots was observed with malathion at 50 mg/kg and the high-dosage mixture group.