Study of Fe, Zn, Cu, Cd, Pb concentrations in liver, kidney and muscle tissue of cow and sheep marketed in Hamedan in 2011

Importance of heavy metals in food safety and detrimental effects of their high concentrations in food stuff is well documented. In this study, concentrations of Fe, Zn, Cu, Cd and Pb in kidney, liver and muscle tissues of cow and sheep at Hamedan retails were evaluated. A total number of 180 samples was assessed for the amount of heavy metals as ppb in wet weight. For this, wet-digestion method was used to determine the concentration of given elements by ICP (Varian ES-710). Results showed that the highest concentration of heavy metals was determined in the liver and kidney samples, while the lowest concentration was found in muscle tissue. Among the heavy metals, Fe in cow’s liver had the highest concentration (25507±879 ppb) and Cd in muscle tissue of sheep has the lowest concentration (192±54 ppb). In overall, accumulation of heavy metals in tissues of cows was higher than sheep. Statistical comparison of accumulated metals concentration in various tissues of these two animal groups showed significant difference (P<0.001). Regarding the maximum acceptable concentration approved by EU, the concentration of heavy metals was lower than the allowed level, except for Cd and Pb. Due to the toxicity of Cd, the concentration of Cd was compared with the maximum acceptable limit of WHO. Results revealed that the concentration of Cd was higher than acceptable level in all tissues except for muscle tissues (P<0.001). Mean concentration of most metals in this study was found higher in cow tissues than sheep. It seems that cows are more tolerant against the accumulation of toxic metals. Moreover, mean concentration of Fe and Cu was higher in liver which is justifiable by the fact that liver is a storage organ. Since kidneys are responsible for the removal of wastes, mean concentration of Cd and Pb was determined highest in kidney.