Studies on The Protective Effect of Melatonin, Vitamin C and Vitamin E on Lead-Induced Oxidative Stress on Clarias gariepinus

Abstract

During the last 100 years, unrestricted mining, burning of fossil fuels, manufacturing and municipal waste disposal practices have resulted in the addition of large amounts of heavy metals to the biosphere. Such metals can persist indefmitely, posing an ever-increasing threat to aquatic, agriculture and human health .Of particular concern are the highly toxic non­ nutrient metals: mercury, lead, cadmium, silver and chromium. Indeed, the total toxicity of heavy-metal pollutants added to the environment each year now exceeds the total toxicity of all organic and radioactive wastes combined (Nriagu and Pacyna, 1988). Lead is one of the most important metals that pollute the natural environment due to man's impact. As lead cannot be degraded, it accumulates in te atmosphere, water, foods, and in organisms living in contaminated areas (Mahalley, 1977). Environmental accumulation with lead has accelerated due its dose relationship to industrialization and its wide usage in paints and gasoline. Lead and its compounds play a significant role in modern industry; a wide variety of populations were at risk of occupational exposure and lead is suspected to be a human carcinogen (Fracassoal., 2002). Lead has many undesired effects, including neurological (Royce et al., 1990), behavioral (Shafiq-ur-Rehman, 1991), respiratory (Hillam and Ozkan