Accumulation of Heavy Metals in Tissues of Long Tail Tuna from Karachi Fish Harbour, Pakistan

Abstract

The present study was conducted to investigate the contamination of Fe, Mn, Cu, Zn, Ni, Pb, Cd, and Cr in the tissues of commercially important fish Thunnus tonggol and to evaluate risks to human health associated with seafood consumption. The results from this study showed that the concentrations of all metals measured except Cr were relatively high in the liver compared to the muscle, gills and gonads. High concentrations of Cr were present in the kidneys. Fe had the highest concentration compared with other metals tested in all tissues of followed by Cu and Zn. The highest mean concentration (µg/g) of Fe 36.43±11.41, Mn 1.29±1.08, Cu 23.35±11.47, Zn 3.89±2.23, Ni 0.35±0.12, Pb 0.27±0.12, Cd 0.71±0.13 and Cr 0.35±0.20 were recorded in the edible muscle tissues of the fish. Overall, the findings from the present study revealed that all metals except Cu and Cd concentrations in the muscle tissues were lower than the maximum permissible limit as recommended by the international regulations. However, the estimated the Provisional Tolerable Weekly Intake (PTWI) of Cu is below the established PTWI. The data indicate that the examined fish were polluted with Cd. It was also found that levels of the metals in other tissues in some samples were higher than the recommended concentrations. However, consumers do not consume the liver, kidney, gills and gonads.