Estimation of metal residues in Oreochromis niloticus and Mugil cephalus intended for human consumption in Egypt: a health risk assessment study with some reduction trials

Abstract

Fish, including tilapia (Oreochromis niloticus) and mullet (Mugil cephalus), is a major source of essential amino acids, omega-3 fatty acids, vitamins and minerals. However, fish as aquatic organism is highly exposed to environmental pollutants such as heavy metals. This study investigated the residual concentrations of lead (Pb) and cadmium (Cd) as toxic metals, and copper (Cu) and zinc (Zn) as essential trace elements in tilapia and mullet intended for human consumption in six major cities in Egypt. Correlation analysis between metal content and fish biometrics was done. Fish is heat-treated before consumption in Egypt; therefore, the effect of heat treatment, either alone or in combination with ascorbic acid 2%, on the residual content of heavy metals in tilapia was investigated. Dietary intake and health risk assessment for the measured metals were calculated. The achieved results indicated higher contents of Pb and Cd in the examined fish compared to the established maximum residual concentrations. Immersion of tilapia in ascorbic acid 2% followed by pan-frying significantly reduced metal load in the fish muscle; however, grilling of fish increased the metal content, probably due to water evaporation and concentration of metals in the fish muscle. Estimation of dietary intakes of such metals through fish consumption indicated potential exposure of Egyptians to the adverse effects of Pb and Cd. At the same time, tilapia and mullet can partially provide humans with their needs of the essential trace elements (Cu and Zn). In conclusion, consumption of contaminated fish with Pb and Cd may constitute potential health hazards for people heavily consuming such fish. Immersion of fish in ascorbic acid 2% for 30 min followed by pan-frying is recommended for reduction of metal load in the fish. Continuous monitoring programs for toxic metal contents in fish are highly recommended.