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Increased human population and anthropogenic activities around Lake Victoria leads to pollution and health risks to consumers of water and fish. This study was conducted to assess the levels of Mercury (Hg), Cadmium (Cd) and Lead (Pb) in Nile perch muscles, water, and sediment in Lake Victoria in Mwanza, Mara and Kagera in Tanzania. A total of 180 samples were collected from 60 national designated sampling stations. From each region, 20 sampling stations were selected and three samples including water, sediment and Nile perch muscles were collected from each station. The collected samples were analyzed using Graphite Furnace, Flame and Cold Vapour Atomic Absorption Spectrometers techniques. The human health risk due to the consumption of Nile perch was established by calculating the daily exposure rates, hazard quotients and the total hazard indices of the toxic metals. In sediments, the concentration of heavy metals ranged from 0.05 – 2.11, 16.06 – 39.07 and 520.25 – 1086.88 μg/kg for Hg, Cd and Pb, respectively. The corresponding concentrations in the water ranged from 0.0004 – 0.161, 2.34 – 31.06 and 0.13 – 99.54 μg/L for Hg, Cd and Pb, respectively. The concentrations in Nile perch muscles ranged from 0.03 – 0.38, 20.93 – 79.17 and 166.33 – 527.97 μg/kg
for Hg, Cd and Pb, respectively. The highest levels of Hg and Pb were recorded in sediment samples and for Cd in Nile perch muscle samples. The lowest levels of Hg, Cd and Pb were recorded in the water. The total hazard indices of Hg, Cd and Pb indicated no risk outcome from the consumption of the Nile perch from Lake Victoria. Based on the findings of this study, it is concluded that the concentrations of Hg, Cd and Pb were lower compared to the WHO permissible limits; hence the consumption of Nile perch may not pose any significant threat to human health. |
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