Zakari Mohammed, Joseph C Akan, Lawan I Bukar and Abdullahi M Idi
The occurrence of antibiotics in the marine environment over a long time period can lead to development of Fish (Clarias anguillaris, Tilapia zilli, Synodontis budgetti and Heterotis niloticus) samples from Komadugu river basin of Yobe State, Nigeria were collected on seasonal basis (rainy, dry seasons and harmattan period) for the determination of the levels of seventeen (17) polycyclic aromatic hydrocarbon (PAHs). Risk assessment was conducted to evaluate the risk associated with consumption of fish from the study area. The concentrations of all the PAHs in tissues of fish samples were determined using GC/MS SHIMADZU (Agilent 7890A). The levels of the studied PAHs were observed to be higher in the tissues of Heterotis niloticus with a total value of 4.23E+01 mg/kg, while the lowest concentrations were observed in the tissues of Clarias anguillaris with a total value of 3.95E+01 mg/kg. In all the fish samples studied, the seasonal accumulation were observed to be in the order of rainy>dry>harmattan. In the present study, the highest average daily dose (ADD) value in the fish studied was observed in the liver of Heterotis niloticus with a value of 1.38E-06 mg/kg day-1, while the lowest value was observed in the intestine of Tilapia zilli with a value of 9.93E-13 mg/ kg day-1. These values are less than the tolerable daily dose limit from the daily per capital fish consumption of 7.00E-02 kg for Nigeria. The hazard quotient (HQ) values obtained for all the fish samples studied were all below one (1), this shows that the fish consumption in the study area are found to be free of risk. The highest hazard index (HI) value for PAHs was found in the gills of Tilapia zilli with a value of 2.98E-06, whereas the lowest level was observed in the intestine of Tilapia zilli with a value of 5.16E-14. The (HI) values of all the PAHs in the tissues of fish samples were less than one (1), this is an indication that there is no risk from the intake of these fish from the study area. The cumulative probability distributions of calculated incremental life expectancy cancer risk (ILECR) for different tissues of Clarias anguillaris, Tilapia zilli, Synodontis budgetti and Heterotis niloticus showed that, more than one in one million of the population is prone to cancer risk upon consuming of the fish samples from the study area.
