Effects of Icon, a pyrethroid insecticide on early pregnancy of rats.

Icon is a water miscible type II synthetic pyrethroid insecticide based on active ingredient lambda cyhalothrin (10% w/w). It is used in Sri Lanka as an adulticidal indoor spray against malaria vector mosquitoes. The goal of this study was to assess the effects of Icon on pregnancy outcome of rats when exposed during early pregnancy (days 1-7). Icon was gavaged daily for 7 consecutive days in three different doses; 63, 83, or 125 mg/kg/day (active ingredient; lambda cyhalothrin; 6.3, 8.3, 12.5 mg/kg/day), respectively. Several parameters of reproduction and pre- and post-natal development were monitored. The results show that Icon is detrimental to pregnancy outcome (in terms of quantal pregnancy, number of uterine implants, implantation index and foetal deaths) but induced no detectable developmental defects. The anti-reproductive effects of Icon were mainly due to increased pre-implantation losses. Enhancement of post-implantation losses played a subsidiary role. These effects resulted from multiple mechanisms: maternal toxicity, stress, uterotropic activity and embryo-foetotoxicity. Further progesterone had a protective effect against Icon induced anti-reproductive actions. Overall, the results suggest that exposure to Icon during early gestation may result in a threat to pregnancy.

Effects of pyrethroid insecticide ICON (lambda cyhalothrin) on reproductive competence of male rats.

AIM: To assess the effect of ICON (trade name of lambda-cyhalothrin) on sexual competence and fertility of male rats. METHODS: Male rats were gavaged daily for 7 consecutive days with different doses of ICON (63 mg/kg and 100 mg/kg) or vehicle (distilled water). Their sexual behaviour and fertility were evaluated at different time points during treatment and post-treatment using receptive females. RESULTS: Treatment had no effect on fertility, but sexual competence was seriously impaired: libido (assessed in terms of pre-coital sexual behaviour, and numbers of mounting, intromission and ejaculation), sexual arousability/motivation (in terms of latencies for mounting, intromission and ejaculation), sexual vigour (judged by frequencies of mounting and intromission or copulatory efficiency). In addition, ICON suppressed intromission ratio, indicating erectile dysfunction. These effects on sexual function had a rapid onset and was reversible. ICON-induced sexual dysfunction was mediated by multiple mechanisms, mainly toxicity, stress, sedation and possibly via GABA and dopaminergic systems. CONCLUSION: Exposure to ICON may cause sexual dysfunction in male rats.