| Abstract: |
1- Analytical study:260 fish samples (170 Tilapia species, 50 Cl arias lazera, 20 Mugilcephalus and 20 imported frozen Mackerel) of different sizes were collectedfrom various sites in Egypt. Muscles samples from collected fish weredigested and analyzed by Atomic Absorption Spectrophotometer fordetermination of Hg, Cd, Pb, Cu and Zn concentrations.The obtained results revealed that the overall mean of Hg, Cd, Pb, Cuand Zn concentrations (ug/g wet weight) in fish muscles were: 0.275, 0.119,0.328, 1.171 and 7.406, respectively in Tilapia species; 0.452, 0.168, 0.329,0.467 and 6.64, respectivelyinClarias lazera; 0.196, 0.100, 0.243,1.01 and10.66, respectively in Mugil cephalus; and 0.56, 0.077, 0.208, 0.503 and8.01, respectively in imported frozen Mackerel. Amongst Tilapia species,sh from Nasir Lake found to contain the lowest concentrations of the mostnxic heavy metals (Hg, Cd and Pb).Concerning the permissible limit set in Egypt, 6.5% of TilapiaIpecies, 18% of Clarias lazera and 40% of imported frozen Mackerel werexceeded the Hg limit (0.5 Jlglg wet weight); whereas for Cd, 31.2% ofilapia species, 46% of Clarias lazera, 15% of Mugil cephalus and 20% ofported frozen Mackerel were above the permissible limit (0.1 ug/g weteight). This is not of serious concern because Egyptian standard found toamong the lowest international recommended limits. For Pb, 3.5% of
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