Antigestational effect of Icon ®, a parathyroid insecticide on late pregnancy of rats

Abstract

Icon* is a type II synthetic pyrethroid insecticide based on active ingredient Lambda cyhalothrin (10% w/w) and used as an adulticidal indoor spray against malaria vector mosquitoes in Sri Lanka. The purpose of this study was to review the effects of Icon" on pregnancy outcome oj rats when exposed during late pregnancy (days 15-21). Icon' was orally administered for 7 consecutive days in three different doses 63, 83, or 125 mg/kg/day respectively. Oral exposure to Icon" during late pregnancy was detrimental to pregnancy outcome (in terms of number of viable pups, gestation index, live birth index, pups survival ratio, viability index) and developmental parameters of pups (such as body weight, cranial length, cranial diameter, tail length, cranial - sacral length and viability at postnatal day I) but induced no detectable congenital malformations. Further, there was a significant prolongation of pregnancy. The mechanism of Icon" induced deaths and growth retardation of foetuses appear to be due to Intra Uterine Growth Retardation (IUGR) mediated by a combination of specific and non specific modes of actions such as reduced food consumption, maternal and embryo/foetotoxicity, stress and uterotropic activity.