In-vivo investigation of dimethoate toxicity on serum enzymes, target organs and intestinal tissues of albino rats

Abstract

Dimethoate is a broad spectrum organophosphate insecticide used to control agricultural, industrial and domestic pests. Despite its benefits, toxicities in non-target organisms have been widely reported. This study investigated acute and sub-chronic toxicities of dimethoate in rats. The arithmetic method of Karbar and a modification of repeated 8-week oral toxicity were adopted for the determination of acute and sub-chronic toxicities of dimethoate, respectively. Symptoms of acute toxicity evaluated include muscular weakness, respiratory distress, convulsion and death. Animals that were used for the sub-chronic toxicity studies were divided into 4 groups of 5. Groups 2, 3 and 4 were fed with feeds containing 200, 500 and 800 mg/kg dimethoate respectively, while group 1 served as the control. The weight of the animals were determined weekly for 8 weeks, and thereafter sacrificed. Blood samples were collected for biochemical tests, and the liver, kidney, lung, intestine and heart were excised and processed for histopathological analysis. The calculated median lethal dose (LD50) was 176 mg/kg. Animals in all groups gained weight progressively. However, a dose-dependent significant rise in alanine transaminase and alkaline phosphatise, but not aspartate transaminase accompanied with significant focal necrosis in liver, eosinphilic casts in kidney and intestinal ulceration in group 3 and 4 in animals. In addition, dimethoate- induced inflammation was observed in the liver, kidney, lung and intestine tissues. The derangement of biochemical parameters and relevant histopathological alterations observed in rats exposed to dimethoate are suggestive of toxicity. Therefore necessary precautionary measures should be taking during handling and use.