Chlorpyrifos is considered moderately hazardous to humans by the World Health Organization. Chlorpyrifos exposure may lead to acute toxicity at higher doses, Poisoning from chlorpyrifos may affect the central nervous system, the cardiovascular system, and the respiratory system and also skin and eye irritant. Healthy wistar strain mice of the same age group 100±10 days and weight 75±10 grams were selected as experimental animals for the present study. The organophosphate compound chlorpyrifos provided by Nagarjuna Agri Chem Limited, East Godavari District, Andhra Pradesh, was chosen as the toxic chemical. Acetone was used as the vehicle for administering chlorpyrifos. The route of administration followed was oral intubation method.In the present study the toxicity of chlorpyrifos in Mice was determined, to ascertain the LD50 and subacute doses. The animals were exposed to different concentrations of chlorpyrifos, showed no mortality up to 28 mg/kg body weight, 16.66% mortality at 32 mg/kg body weight, 25% mortality at 42 mg/kg body weight, 33.33% mortality at 52 mg/kg body weight, 50% mortality at 62 mg/kg body weight, 66.66% mortality at 72 mg/kg body weight, 83.33% mortality at 82 mg/kg body weight, 100% mortality at 92 mg/kg body weight and 102 mg/kg body weight observed. The LD50 value obtained from the sigmoid curve is 62 mg/kg body weight for 48 hours.During the present investigation the appearance of signs and symptoms were observed in between 20-150 minutes, except lacrimation, and salivation which were occurred between 10-20 minutes following the chlorpyrifos administration.
