DETERMINATION OF HEAVY METALS IN IMPORTED FROZEN FISH AND LOCAL FRESH FISH OBTAINED FROM DIFFERENT MARKETS IN LAGOS STATE, NIGERIA

Abstract

Fish is an important source of protein for the human body. Despite its nutritional value, it can also be a potential health hazard for the consumer because heavy metals enter into the aquatic environment and subsequently into the food chain.The aim of this study is to compare the concentrations of heavy metals in local fresh fish with that of imported frozen fish obtained in Lagos State, Nigeria.The study involved ten different species of local fish and six species of imported frozen fish. The fishes were dried, digested and analyzed for heavy metals using the Atomic Absorption Spectrophotometer, (AAS). 

 

The concentrations of heavy metals ranged between 0.00-0.20g/g (lead), 1.00-2.00g/g (copper), 0.00-30.00g/g (nickel), 0.00-39.00g/g (chromium), 0.00-2.00g/g (cadmium) and 0.00-3.00g/g (cobalt) for local fresh fish. For imported frozen fish, the heavy metals ranged between 0.00-0.50g/g (lead), 2.00-2.61g/g (copper), 3.00-310.00g/g (nickel), 0.00-95.15g/g (chromium), 0.00-0.09g/g (cadmium) and 0.00-6.50g/g (cobalt).Lead concentration is significantly higher in imported frozen fish, although in trace amounts which is within safe limits. Nickel is present in high concentrations in imported frozen fish when compared with the local fresh fish. These levels are significantly higher than safe consumption limits of the World Health Organization. Copper and cadmium levels were below the limits and are only present in Sardine and Thread fin fish in trace amounts. Cobalt levels are high in imported frozen fish when compared with local fresh fish but still within safe limits.The presence of high concentrations of nickel in imported frozen fish (which is above safe limits) and traces of chromium in the frozen fish may pose a health risk to the consumers.