Considering the growing population and increasing demand for protein intake, the need for more resources to supply protein is a subject of interest 1 . The proteins with marine origin have a significant degree of importance due to their higher protein and omega 3 fatty acid contents 2 . With population growth, we witnessed the industrial development and as a result the increasing problem of environmental pollution and food conta- mination to heavy metals were brought about which require major focus 3 . Meanwhile, fish due to aquatic pollution are exposed to different levels of these elements depending on fish size and age and these heavy metals can accumulate in fish tissue at different significant levels. Some large species of fish such as thunnus SPP due to having a special diet that is known as biomagnifications have high concentrations of mercury in their body tissue. Since mercury, arsenic, cadmium and lead, are toxic for humans even at a very small amounts, their exact measurement and identification is important. Biotransformation of mercury changes it into a toxic known as methyl mercury; also, an increase in the nickel intake increases the risk of lung, larynx and prostate cancer 4-7 . NOTE Determination of Mercury, Cadmium, Tin and Nickel in Three Canned Tuna in Iran AFSHIN MOTAGHIFAR 1 , KHORSHID HOSSEINZADEH 2 , HOOMAN SHAFIPOUR 1 , POLIN SHOHRE 3 , DAVOUD NASIRI 4 and ABBAS TAVAKOLI VASKAS 5,* 1 Department of Aquatic Animal's Health and Disease, Science and Research Branch, Islamic Azad University, Tehran, Iran 2 Department of Food Technology, Agricultural Sciences & Natural Resources University of Gorgan, Gorgan, Iran 3 Department of Aquatic Animal's Health and Disease, University of Tehran, Tehran, Iran 4 Department of Veterinary Sciences, Naghadeh Branch, Islamic Azad University, Naghadeh, Iran 5 Department of Food Science and Technology, Ayatolah Amoli Branch, Islamic Azad University, Amol, Iran *Corresponding author: E-mail: dr_tavakolli@yahoo.com (Received: 17 October 2012; Accepted: 15 April 2013) AJC-13243 Considering the importance of fish and its related products to meet the needs of the people to protein and other minerals as well as the impact of infected aquatic ecosystems on the fish infestation are the subject of interest. The presence of heavy metals as the result of industrial pumping and environmental contamination in sea food products such as tuna, measuring the existing heavy metals levels in the aquatic environment can serve as a suitable indicator of water pollution and the quality of these food and the risks of their being poisoned with heavy metals can be considered accordingly. This research was conducted on 21 samples of canned tuna selected randomly from the three factories producing canned tuna namely Shilton, Teihou and Telaji in 2011. After transferring the samples to the laboratory and digesting them, they were analyzed for heavy metals including mercury, tin, cadmium and nickel through atomic absorption technique. The highest and lowest amount of mercury and nickel were observed in the manufacturing factories of Telaji and Shilton, respectively and the highest and lowest amounts of cadmium and tin were related to the manufacturing factories of Teihou and Shilton, respectively. The results showed that the amount of the given heavy metals in the products of these factories were lower than the standards set by FDA, EPA, FAO/WHO and are not detrimental to human's health. Key Words: Heavy metals, Mercury, Cadmium, Tin, Nickel, Canned tuna, Iran. Asian Journal of Chemistry; Vol. 25, No. 10 (2013), 5501-5502 The cadmium causes poisoning and iron deficiency and the tin, which is not a toxic element can, cause corrosion of cans due to its high application in the manufacture of cans for painting the cans. Since the south waters of Iran, providing the main source of canned tuna are exposed to various contami- nants due to passing tanker and sewage disposal, therefore, the fish caught from these areas can be exposed to such conta- mination. As a result, measurement and evaluation of heavy metals to determine the health quality of the canned products for human consumption and compare them with some standards to assess of risk factors appear to be crucial. Twenty one samples of canned tuna produced by Telaji, Teihou and Shilton factories were randomly selected (7 samples from each factory) and were transferred to the Amol central laboratory of food quality control. All the samples for each factory (7 samples from each factory) were separately combined and homogenized. In order to chemically digest and prepare the samples, AOAC (Association of official Analytic chemist) reference technique was used. For mercury measure- ment, approximately 2 g of the sample (with measurement http://dx.doi.org/10.14233/ajchem.2013.14714