Toxicity of increasing concentration of an organophosphorus pesticide on blood chemistry of Indian catfish Clarias batrachus

Pesticides are much overused in the environment despite the fact that they are toxic and hazardous to our health and environment. Enough studies have been done to prove that the use of pesticides is futile and probably does more harm than good in the long run. To know the impact of pesticides in the present investigation, male and female Clarias batrachus fish, which are air breathing in nature, were exposed to different test concentrations (2 ppm, 4 ppm, 6 ppm, 8 ppm) of an organophosphorus pesticide, parathion. Increase in the level of blood urea whereas gradual fall in the plasma protein were observed in all the test concentrations of parathion. Parathion toxicity showed an increase in the level of blood glucose upto 6 ppm and thereafter significant fall in its level at 8 ppm. There was a significant rise of blood cholesterol level in initial dose of the pesticide and significant fall in 6 ppm and 8 ppm. Gradual fall in the protein level and increased values of urea might be due to hyperactivity of adrenocorticoides and impaired functions of the kidney of the fish respectively. The rise in the level of blood glucose from control condition upto 6 ppm might be due to secretion of glucagon hormone under stress condition. A significant fall in the blood glucose level at 8 ppm might be attributed to the utilization of glucose by the tissues of extremely active fish at higher dose of the pesticide. A significant rise in the serum cholesterol at lower concentration of parathion is attributed to the stimulation of adrenal gland whereas at higher level, the rise in the blood cholesterol value might be due to increased breakdown of fats into cholesterol and free fatty acids in the fish.