Distribution of heavy metals and potential human health risk in fish species from Komadugu River Basin, Yobe State, Nigeria

Abstract

Fish samples (Clarias anguillaris, Synodontis budgetti and Heterotis niloticus) were collected during the rainy and dry season from Komadugu river basin, Yobe State, Nigeria and identified by a fisheries scientist for the determination of some heavy metals. The concentrations of heavy metals were determined using Atomic Absorption Spectroscopy (AAS) and X-Ray Fluorescence (XRF).Fish samples of uniform size and weight were collected and dissected to remove the flesh, liver, intestine and gills and prepared according to standard method. Heterotis niloticus were observed to show the highest total concentration of the heavy metals studied with a value of 2.19E+03 mg/kg, while Clarias anguillaris shows the lowest concentration with a value of 0.03 mg/kg. The accumulation of heavy metals in the tissues of fish samples were observed to be in the order of gills>liver>intestine>flesh in both methods. The concentrations of all heavy metals were significantly higher using XRF method when compared with AAS. Fe shows the highest average daily intake (ADI) value of 1.53E+00 mg/kg/day in Clarias anguillaris, while Synodontis budgetti shows the lowest value of ADI value of 8.23E-01 mg/kg/day among all the four species of fish samples studied. From the results obtained, the hazard quotient (HQ) values of some of the heavy metals in the fish samples during the rainy season were all above one (1). The lowest HQ value of 9.00E-08 in all the fish samples study was lower than 1, while the highest HQ of 1.50E+01 is greater than one (1). The highest and lowest cancer risks chances for the studied fish species were computed as 5.10E-02 and 5.40E-07 respectively. These risk values indicate that consumption of fish from the study area would result in an excess of 5 cancer cases per 1,000,000 people.