Measurment and assessment of concentration of heavy metal (Hg, Cd, Pb) in canned tuna fish distributed in Mazandaran province of Iran in 2014-2015

     Introduction: Heavy metals are one of the pollutants which are found in minor amounts in natural water and high concentration in industry waste water. Heavy metals poisoning effects are increasing in marine organisms especially fishes due to disposal of industrial wastes to marine environment and their bio accumulation. The aim of this study is to determine of mercury, cadmium and lead levels in canned fish sold in Mazandaran province of Iran.      Materials and Methods: This descriptive-cross sectional study was done on 12 types of canned tuna distributed, 3 numbers of each type and overall 36 sample. The concentration of 3 type heavy metals assessed with standard method by Atomic Absorption and then expressed based on µg/g of wet weight. The results were compared with WHO and Iran National Standard Organization.      Results: The results show that, minimum and maximum of mercury level in 36 samples of canned tuna fish was 0.01 and 0.5 µg/g, cadmium 0.001 and 0.05 and lead 0.001 and 0.3 respectively. According to replicates experiments, the mean concentration of mercury in 12 such samples of canned tuna fish was from 0.106 to 0.31, cadmium from 0.006 to 0.022 and lead from 0.03 to 0.15µg/g.  that there was a significant difference in samples(p