Effects of cypermethrin, a synthetic pyrethroid insecticide having a fast-acting neurotoxin that causes free radical-mediated tissue damage in animals, on the body, liver and kidney weights as well as changes in the histopathology of hepatic and renal tissues in the Swiss albino mice Mus musculus L. have been assessed. Twenty five adult male albino mice of 2-3 weeks of age were divided equally into five groups where each 20g mice received the following treatments: distilled water only (T0, served as control); 0.10ml cypermethrin (T1); 0.15ml cypermethrin (T2); 0.20ml cypermethrin (T3); and 0.25ml cypermethrin (T4). Treatments were accomplished intraperitoneally each week for four consecutive weeks. During the experimental period, there were significant decreases between the initial and final body weights in the cypermethrin-treated mice but no abnormalities were observed in the control group. At the end of the 4th week, all the mice were sacrificed; their kidneys and liver were dissected out, weighed and preserved in 70% ethanol. The samples of liver and kidneys were processed for histological studies. Cypermethrin treatment exhibited severe histopathological changes in the hepatic and renal tissues accompanied by weight loss of the organs. Salient manifestations such as haemosiderin in hepatocytes, epithelial and Kupffer cells, dilated sinusoids, haemorrhage and vacuolation, necrotic hepatocytes and congested central and portal veins, inflammatory cell infiltration and increased number of mononuclear cells were diagnosed in liver sections. In kidney sections, on the other hand, oedema, congested or degenerated glomeruli, widened urinary spaces, dilated or vacuolated tubules, degenerated or eroded walls of Bowman’s capsules, haemorrhages and inflammatory cell infiltrations, hyalinized areas and increased numbers of podocytes and mesangial cells were notable features. From these findings, it is postulated that cypermethrin and other synthetic pyrethroids might cause hazardous effects on mammals including human beings, and therefore, judicious applications of this insecticide should be assured while using them at agricultural field and household purposes
