Teratogenic and embryotoxic effects of orally administered cypermethrin in pregnant albino rats

Lack of consensus in published works regarding cypermethrin's ability to produce teratogenic and embyotoxic effects has led to postulations. The aim of this study was to evaluate the teratogenic and embryotoxic effects of cypermethrin in 5% vegetable oil using albino rats. Acute toxicity study of cypermethrin was evaluated using Probit analysis method. Percentage mortality was calculated and LD50 was determined.  In addition, pregnant female rats in different groups received different oral doses from day 6 to 15 of gestation. Caesarean section was performed on day 20 to examine fetuses because their gestation period is between 21 to 22 days.  Animals given higher doses experienced hyper- salivation, irritability, convulsion, respiratory distress and death, with on an LD50 of 85.1 mg/kg body weight.  Autopsy findings revealed vascular congestion and haemorrhage in different organs. Teratogenic and embryotoxic study revealed reduced fetal weights and with ecchymosis particularly in higher doses. The extent of fetal death and resorptions observed were not statistically significant compared to controls. Histological examination and skeletal staining technique showed no significant abnormalities despite the use of high doses of cypermethrin. The finding of ecchymosis is new, along with low birth weight, which appears to be a consistent effect of cypermethrin.   Key words: Cypermethrin, teratogenicity, embryotoxicity, low birth weight, fetuses, malformation.