Determination of Some Metals in Selected Species of Imported Frozen Fishes Sold in Kano Fish Market

This study aims to evaluate the levels of seven metals (viz:Aluminium, Cadmium, Chromium, Iron, Mercury, Lead and Zinc) in the gills, livers and muscles of seven different imported fish species (viz:Trachurus, Clupea, Scomber, Undulatus, Gadus, Argentine and Oreochromis) sold at the popular Fish market of Kano Line, Kano State Nigeria and to conduct a risk assessment for human consumers. Atomic Absorption Spectrometer (Perkin Elmer PinAAcle 900H) was used to determine the presence of the metals. A 100% metal recovery range for all assayed metals was detected, with the highest concentration recorded in Iron(Fe) (13.33±0.0022mg/kg) and the lowest concentration was found in Cadmium(Cd) (0.001±0.0009mg/kg). The general order of metal bioaccumulation measured in the fish tissues were in the order; Fe > Zn > Hg > Cr > Pb > Al > Cd in the gills, and Fe >Zn >Al > Hg> Cr >Pd >Cd in the livers, and Zn > Fe > Hg > Pb > Al > Cr > Cd in the fish flesh (muscle). The majority of all the metals analyzed in all the tissues of the fish samples were lower than maximum levels by FAO/WHO guidelines except for Mercury (Hg) in the gills and flesh of Oreochromis, and Aluminium (Al) in the livers of all samples and in the gills of Oreochromis and Trachurus. The estimation of the Target Hazard Risk and Hazard Index (noncarcinogenic risk) indicated no adverse health effects from the consumption of the fishes , although, the elevated levels in Oreochromis muscle needs to be closely monitored. The Target Cancer Risk (carcinogenic risk) was also observed to be of low significance, but not ignorable, especially in the Chromium levels of clupea harengus and Oreochromis. The estimated maximum safe consumption (MSC) levels for the metals showed that Mercury (Hg) may cause significant health effects in humans if Oreochromis, Gadus and undulates are consumed in a large amount