Assessment of heavy metal content in imported and local fish and crustacean species obtained within Lagos Metropolis

Abstract

Fishes are known for their abilities to concentrate heavy metals in their muscles and since they play important role in human nutrition, they need to be carefully screened to ensure that unnecessary high level of some toxic trace metals are not being transfer to man through their consumption. The study was to evaluate heavy metals (chromium, lead, iron and cadmium) in imported and local species of shrimps, crabs and fish using Atomic Absorption Spectroscopy. The selected imported species were horse mackerelkote fish (Trachurus trachurus), mackerel - titus (Scomber scrombus), croaker (Pseudotolithus typus), smooth swim crab (Portunus validus) and pink shrimp (Farfantepenaeus notialis) while the local species used were; Sole fish (Cynoglossus senegalensis), Tilapia (Oreochromis niloticus), brackish water catfish (Chrysichthys nigrodigitatus), freshwater catfish (Clarias gariepinus), lagoon crab (Callinectes amnicola) and freshwater prawn (Macrobrachium macrobrachion). It was observed that there was no significant difference in the metals (Cd, Pb and Cr) between the imported and local fish species and between imported and local crustacean species. However, these metals concentrated more in the local fish species, O. niloticus (1.846 ± 1.00 mg/100g). The mean heavy metals concentration occurred in the following decreasing order: Fe > Cd > Pb > Cr for all the samples. The mean concentrations of the analyzed heavy metals in the samples were below the maximum permissible limits as recommended by the International Atomic Energy Agency (IAEA), United Nations Environment Program (UNEP) and Federal Environmental Protection Agency (FEPA) for heavy metals in fish.

Keywords: Fish, Shrimp, Crab, Heavy metal, Chromium, Lead, Iron