Immunotoxic responses of cypermethrin, a synthetic pyrethroid insecticide in rats.

The study was undertaken to evaluate immunotoxic effects of cypermethrin administered orally (in ground nut oil) to male albino rats at dose levels (mg/kg) of 0 (control), 5, 10, 20 and 40 once daily for 90 days. Cypermethrin administration produced a significant leucopenia at 40 mg/kg on day 90. A dose dependent decrease (P greater than 0.05) in delayed type hypersensitivity reaction was noticed on day 61 post treatment. Humoral response as evidenced by serum haemagglutinin and haemolysin titres did not show any definite pattern on day 90. However, a significant decrease in spleen weights and significant increase in adrenal weights was recorded in rats receiving the highest test level. Total body weights and liver weights did not show any significant change with any of the dose level studied. Results of the study reveal that low doses (5 and 10 mg/kg) did not have any adverse effect on the immuno-competence of rats.