Measuring Hazards of Heavy Metals Residues On Fish

Abstract

Fish is an important food source for the human body.. Despite its nutritive value consumption fish brings many times a potential hazard concern for the human consumers However, fish are relatively situated at the top of the aquatic food chain; therefore, they normally can accumulate heavy metals from food, water and sediments which can counteract their beneficial effects; several adverse effects of heavy metals to human health have been known for long time.This work had been done in two different states in Sudan by taking 30 tissue samples from the dorsal muscles of two different Spp from two different geographical locations and different lengths and weights, for measuring The concentrations of heavy metals for. ( Cd, Cr and Pb) for two types of fish Spp Orechromis niloticus (Bulti ) and Labeo niloticus (Dabsa), by taking 10 samples Bulti Spp from white Nile Khartoum State and twenty samples 10 of which is from Bulti Spp and the other 10 is from Dabsa Spp Wadi Halfa Nubian lake North State. the thirty fish species were collected from two main landing areas (Halfa, and White Nile) and were analyzed to measure--- the concentrations of these elements in fish (mg/Kg DW) by using atomic absorption spectrometry. The ranges of the measured concentrations Cd, Cr and Pb (mg/kg) in the total samples were all less than the permissible range . Therefore, the study results revealed that the White Nile river Khartoum state and lake Nubian Northern state might be considered as not polluted with the these heavy metal . The levels of the concentration of these heavy metals varied among fish species, weight and length . These differences were discussed for the contribution of potential factors that affected metals' uptake, like age, geographical distribution and species') specific factors(. Generally, recorded metal concentrations were within the permissible or below the levels in similar species from global studies. The concentration of metals in the present fish tissue were accepted by the international legislation limits and are safe for human consumption. Three common heavy metals were measured cadmium (Cd) was ranged between 0.011- 0.019, chromium (Cr) ranged between 0022- 0.019 and lead( Pb) between 0.014-0.068 mg/kg(Bulti fish) in White Nile as for lake Nubian were Three common heavy metals were measured cadmium (Cd) was ranged between 0.017-0.066 , chromium (Cr) ranged between 0.035-0.465 and lead( Pb) between 0.130-0.485 mg/kg in (Bulti fish) and that for Dabsa Spp.the cadmium (Cd) was ranged between 0.021-0.285 , chromium (Cr) ranged between 0.065-0.260 and lead( Pb) between 0.075-550 mg/kg .The obtained results showed also the correlation between the heavy metals depending on the weight and length of the fish samples and the geographical location which also showed no significant result.In the conclusion, this results in this study demonstrated that fish species caught in the White Nile River and Nubian were not contaminated with heavy metals. Although the concentrations of heavy metals in the fish were not detected, the potential for metal toxicity danger may appear in the future depending upon the extent of industrial and domestic wastewater influx and human activities in the adjacent areas to Nile and the lake. To develop a healthy freshwater fishing industry and to prevent heavy metal risks to human health in the River, the water standards and concentrations of heavy metals in the water column and fish should be monitored regularly. In addition to types of heavy metals and characteristics of rivers in Sudan should highly considered in selection of different types of fishes including Red Sea fish for heavy metals analysis.