heavy metal concentrations in muscle tissues of white leg shrimp (litopenaeus vannamei)

aquatic organisms are one of most important human food sources but they can accumulate heavy metals entered aquatic ecosystems in their tissues and organs same time and can be transferred through the food chain to higher food levels and in the most top into the human body. shrimps are of the main groups of sea foods; and because they are benthic species, they can absorb high concentrations of heavy metals from the media. therefore, in this research the concentrations of heavy metals cadmium, nickel, copper and zinc were determined in white leg shrimp (litopenaeus vannamei). samples were randomly purchased from tehran market. the samples were caught from coastal ponds of khuzestan and bushehr provinces. first, length, weight and sex of the samples were determined. then muscle tissues were wet digested and the metal concentrations were determined using atomic absorption spectroscopy (perkin elmer, usa). statistical analysis of data indicated that, there were no correlations between concentrations of metals with morphological variables. no significant differences were observed between the concentrations of metals in two sexes; however, males had higher concentrations of cadmium than females). no significant differences were observed between metals concentrations. the general pattern of metals concentrations were zn> cu> ni> cd. comparison of the metal concentrations with standard values showed that the concentrations of nickel, copper and zinc were lower than fda, who, nhmrc and maff standards but cadmium concentrations were higher than these standards.