Pakistan J. Zool., vol. 46(6), pp. 1521-1527, 2014 Concentration of Metals in Frozen and Canned Fish in Pakistan Sidra Siddique, 1* Amtul Bari Tabinda, 1* Abdullah Yasar 1 and Jaffar Hussain 2 1 Sustainable Development Study Centre, GC University, Katchery Road, Lahore-54000 2 Department of Statistics, GC University, Katchery Road, Lahore-54000 Abstract.- Fish being at the top of the aquatic food chain has the capacity to accumulate significant amount of metals in muscles that may cause health risk for consumers. Therefore, toxic and essential metals concentrations in muscles of frozen (local and imported species of fish and shrimp), canned fish (imported) samples were analyzed by Atomic Absorption Spectrophotometer. Among all frozen fish and shrimp samples analyzed, highest Cu (5.23 μg/g) concentrations were found in fish imported from Malaysia, similarly highest levels (μg/g) of Ni (3.03), Pb (2.95) and Mn (2.10) were detected in fish imported from Thailand. In canned fish samples, highest levels (μg/g) of Pb (2.50), Cu (2.18), Mn (1.62) and Ni (1.33) were detected in sardine skin imported from Thailand. Pb and Ni concentrations in majority of frozen and canned samples were greater than EC and USEPA limits. Key words: Frozen fish, heavy metals, Pb, Cu, Ni, Mn, canned fish. INTRODUCTION Fish and fish products are widely consumed all over the world because it is the important constituent of healthy diet. They are source of high quality protein, valued vitamins, low saturated fat (Clarkson, 2002; Dominogo et al., 2007) and omega 3 fatty acids (Ikem and Egiebor, 2005) known to prevent coronary heart disease (Oomen et al., 2000). It also reduces blood clotting tendency (Ismail, 2005), thrombosis and arrhythmias (Kris-Etherton et al., 2002). Unfortunately, fishes are continually exposed to contaminants and chemicals in polluted water. Metals are categorized into three types as potentially toxic metals (Pb), probably essential metals (Ni) and essential metals (Cu, Mn) (Munoz-Olivas and Camara, 2001). Essential metals are required at low concentrations but at high concentrations they may be toxic (Oehlenschlager, 2002). Over the last few decades, number of chemicals has been increased in the water bodies as a result of industrial, agricultural and domestic waste discharges (Ajani and Ayola, 2007). Pollution due to metals causes the drastic impacts on aquatic ecosystem and humans. Fish accumulates significant amount of metals not only from aquatic pollution but also from ________________________________ * Corresponding author sidrasiddique388@gmail.com - amtulbaritabinda64@yahoo.com 0030-9923/2014/0006-1521 $ 8.00/0 Copyright 2014 Zoological Society of Pakistan food processing and packaging. Copper is an essential metal which is an important part of metalloenzymes. It is also involved in hemoglobin synthesis and metabolic reactions but it becomes toxic in ionic forms. Nickel acts as activator of some enzymes at trace amounts but at higher concentrations it accumulates in lungs and causes bronchial damage. Fish accumulates substantial amount of lead in their muscles and tissues from canning process in addition to its accumulation from relevant polluted waters. It accumulates in humans where it replaces calcium in bones (Ashraf, 2006). Manganese is an essential metal that is present in all living organism at trace amounts. Excess of manganese not only damages central nervous system but also causes liver cirrhosis and Parkinson’s disease (Momtaz, 2002). There is little information regarding status of heavy metals in the frozen and canned fish. The present study aims at determining the concentration of metals in the frozen and imported canned fish in order to evaluate health risk of these products. MATERIALS AND METHODS Sample collection Commercially available frozen and canned fish were purchased during the Oct 2011 to March 2012. Samples were placed in icebox at 4ºC during transportation and stored in the laboratory at -20C (Al-Busaidi et al., 2011).