TOXICOLOGICAL EVALUATION OF HEAVY METALS IN TISSUES OF FRESHWATER FISH OREOCHROMIS NILOTICUS COLLECTED FROM LAKES OF COIMBATORE DISTRICT, TAMILNADU, INDIA

Abstract

The aquatic ecosystem has received considerable attention due to their heavy metals toxicity which are dangerous to aquatic biotas as it can be bio- accumulated in them through food chain. Pollutants mainly that enter the inland water bodies may extensively be contaminated with heavy metals released through atmospheric deposition, erosion, due to anthropogenic activities, mixing of untreated industrial effluents, draining of domestic sewage, dumping of mining wastes, hospital wastes and temple wastes from adjacent places in and around the selected study sites. Heavy metals, even at quite low concentrations can cause devastating effects on recipient environment and especially on fish which occupies the higher level in food chain. And these heavy metals get transferred through food web into human beings creating public health problems. As man is the major consumer it is important to determine the bioaccumulation level by edible fishes to assess the potential risk. So, heavy metals (cadmium, copper, zinc, nickel and lead) concentrations were determined in Muscle, Gill and Liver tissues of fish Oreochromis niloticus from lakes in and around Coimbatore district. Fish samples were collected from five stations (Perur, Kurichi, Sulur, Koolipalayam and Orathupalayam). Heavy metal concentrations in the fish samples were analyzed using an atomic absorption spectrophotometer. Heavy metal concentration in the fish samples were decreased in the following order Zn>Cu>Pb>Ni>Cd. Heavy metal concentrations were high in liver and gill tissue while muscle tissue had low concentration. Cd,Zn and Pd had higher concentrations in fish samples than recommended benchmarks of FAO and WHO an indication of risk to human health. So, there is need for a constant monitoring of the heavy metals concentrations in fresh the water ecosystem.