Determination of Median Lethal Dose of Combination of Endosulfan and Cypermethrin in Wistar Rat

The present study was designed to determine the lethal dose 50 (LD50) of combination of cypermethrin, a pyrethroid, and endosulfan, an organochlorine compound in Wistar rats. LD50 is the amount (dose) of a chemical, calculated as per the concentration of chemicals that produces death in 50% of a population of test animals to which it is administered by any of a variety of methods. A single oral dose of combination of cypermethrin and endosulfan were dissolved in dimethyl sulfoxide (DMSO) in a ratio of 1:1 and administered orally at the concentration of 165 mg/kg body weight (b.w), 330 mg/kg b.w, 660 mg/kg b.w, and 1320 mg/kg b.w to experimental animals. LD50 was calculated according to the method described by Miller and Tainter (1994) and was observed as 691.83 mg/kg b.w for this combination. Single dose of test article at 165 mg/kg b.w did not reveal any toxic signs or behavioral alterations, hence considered as No observed Adverse Effect level (NOAEL).