Distribution of heavy metals in tissues and organs of tuna

The occurrence of heavy metals (Copper, Zinc, Cadmium, Lead and Manganese) in fresh edible tissue and organs of three species of Tuna were assessed to determine the concentrations, distribution patterns and affinities of metals to organs and tissues. The fish samples were obtained from fish landing sites in Tema, Ghana, West Africa. Metal concentrations in the samples were determined by the Atomic Absorption Spectrometer after nitric acid digestion. From the results, the edible tissues had the lowest concentrations of metals. The concentrations of metals such as Cu, Mn and Zn which are micronutrients were generally higher than the non-essential ones (Cd and Pb) in all the species analysed. Cadmium was found to largely accumulate in the liver, whiles Mn was found to be higher in the bones. Variations observed in metal accumulation patterns were attributed to varying characteristics and possible affinities of the metals to particular organs.