The toxic effects of heavy metals particularly mercury, cadmium and lead have been broadly documented as well as levels of heavy metals in fish. Mercury vapor is easily transported in the atmosphere,deposited on land and water, and then, in part released again to the atmosphere. Trace amounts of mercury are soluble in bodies of water, where bacteria can cause chemical changes that transform mercury to methylmercury, a more toxic form. Fish absorb methylmercury from water as it passes over their gills and as they feed on aquatic organisms. Larger predator fish are exposed to higher levels of methylmercury from their prey. Methylmercury binds tightly to the proteins in fish tissue, including muscle and cooking does not appreciably reduce the methyl mercury content of the fish. Over the last few decades, there has been growing interest in determining heavy metal levels in the marine environment and this has also drawn attention to the measurement of contamination levels in public food supplies particularly fish (Kalay, Aly, & Canil, 1999). Several agencies and organizations such as the US Food and Drug Administration (US FDA), Food and Agriculture Organization (FAO), and the World Health Organization (WHO) provide guidelines on the intake of trace elements by humans. The joint FAO/WHO Expert Committee recommended Provisional Tolerable Weekly Intakes (PTWIs) and acceptable daily intakes as guidelines for food additives and certain contaminants in foods The United States uses reference dose while the K/European
Union has adopted tolerable daily intake (TDI) to estimate the amount of a substance that can be ingested daily over a lifetime without appreciable health risk. These safety guidelines represent an intake where there is essentially no risk, as far as it can be
judged from the available scientific evidence (COT, 2004). Canned fish has become very popular in Ghana because it is affordable and convenient as fast food. Several brands have consequently become available on the Ghanaian market manufactured either locally or imported. Owing to the great consumption of this product,the safety issues related to the possibility of heavy metals contamination are of concern to human health. Despite the global concern about the dangers of heavy metal contamination, coupled with numerous publications on heavy metal levels in processed or canned fishes, publications are scanty in Ghana. This study seeks to estimate the levels of mercury, lead and cadmium in canned fish samples purchased in Kumasi. Information on the metal content in canned fish is important to evaluate the exposure of the population to these toxic metals through consumption. Consequently,evaluation of the estimated weekly intakes of these metals by
adults consuming the different species for the purpose of possible human health risks was further undertaken.