Combined reproductive and developmental toxicity study of pesticide abamectin on male and female Wistar Hannover rats

Abstract

Abamectin is a widely used pesticide and anthelmintic for humans and animals. Previous toxicological studies showed evidence of adverse effects on reproduction, but the findings were inconclusive. Abamectin is known to exhibit teratogenic activity, causing different malformations during developmental stages in rats and rabbits. The present work aims at combining reproductive and developmental toxicological assessments in a single study to evaluate the impact of abamectin on reproductive, fertility, and developmental functions. Abamectin was administered orally to 20 male and 20 female rats at doses of 0, 0.1, 1.0, and 2.0 mg/kg body weight. Abamectin exposure was prolonged for 11 weeks for males and 10 weeks for females before mating. Females were also treated during mating and pregnancy. In this study, treated animals were mated with untreated intact animals to further assess the potential sex sensitivity effect. The results demonstrate that male rats were more susceptible to general toxic effects such as decreased body weight and showed a more toxic effect on reproductive function and fertility at doses of 1.0 and 2.0 mg/kg/day. Furthermore, stages of gametogenesis and early fetal development are the most vulnerable of the reproductive process to endocrine disruptors' action, leading to changes in the estrous cycle in females and sperm quality in males. Abamectin can produce developmental toxicity in rats at a dose of 2 mg/kg/day, which is not a maternally toxic dose. Accordingly, NOAEL for reproductive toxicity and developmental toxicity with fetotoxic effects were established at the dose level of 0.1 mg/kg/day and 1.0 mg/kg/day, respectively.