Heavy metal residues in some Manzala Lake fishes

Abstract

This study aimed to determine the content of heavy metals as lead, mercury, cadmium and arsenic in edible muscles of three common freshwater fishes like Nile tilapia, Flathead grey mullet and African catfish. A total of 300 freshly caught fish samples (100 each) of different weights collected from Manzala Lake, Egypt during both summer and winter seasons of 2012 have been analyzed using air acetylene flame atomic absorption spectrophotometer. The obtained results revealed that the presence of lead, mercury, cadmium and arsenic in all (100%) examined samples by means of 0.704 μg/g, 0.635 μg/g and 0.64 μg/g for Pb, 0.045 μg/g, 0.0145 μg/g and 0.017 μg/g for Hg, 0.025 μg/g, 0.006 μg/g and 0.020 μg/g for Cd and 0.511 μg/g, 0.621 μg/g and 0.568 μg/g for As in Nile tilapia, Flathead grey mullet and African catfish , respectively. Heavy metal concentrations were significantly varied within and between the studied fishes. However, a significant correlation among heavy metals was observed. This study indicated that various concentrations of heavy metals exist in sampled fish species and most of those levels are within the maximum permissible limits proposed by the Egyptian standards except for Pb, its level exceeded the permissible limits in the majority of tested samples. Therefore, fish caught from Manzala Lake can be considered unsafe for human consumption.