ASSESSMENT OF HUMAN HEALTH RISK FOR Pb, Cd, V, Cr, Ni, Fe AND Zn IN Tillapia zilli COLLECTED FROM QUA IBOE RIVER ESTUARY, SOUTH-SOUTH, NIGERIA

The concentration of some trace metals in the muscles of Tillapia zilli from Qua Iboe system was quantified using standard procedures and USEPA models were used to estimate the target hazard quotient (THQ) and hazard indices induced by the consumption of the above fish. The range for different trace metals investigated in the dry season was as follows: Pb (0.10 – 0.42 mg/kg), Cd (0.01 – 0.35 mg/kg), V (0.01 – 0.03 mg/kg), Cr (0.03 -0.12 mg/kg), Ni ((0.11 - 0.29 mg/kg), Fe (22.84 – 38.79 mg/kg), Zn (0.19 – 0.37 mg/kg). The result for the wet season was: Pb (0.01 - 0.04 mg/kg), Cd (0.005 - 0.02 mg/kg), V (0.003 – 0.015 mg/kg), Cr (0.02 – 0.08 mg/kg), Ni (0.06 - 0.43 mg/kg), Fe (6.76 – 13.18 mg/kg). The results further revealed that the concentrations of lead and iron measured were significantly higher (P<0.05) for fish sampled in the dry season than for the wet season. Concentrations of all the determined trace metals were below WHO standard except Cadmium at Ukpenekang. The order of decrease in THQ for the metals was Cd>Pb>Fe>Cr>V>Ni>Zn> while the decrease for the average daily intake (ADI) was Fe>Zn>Ni>Cr>Cd>Pb>V. The highest percentage contribution was from cadmium while the least value was recorded for zinc. The result reveals dominant risk contributions from Cd, Pb and Fe in the dry season and dominant contributions from Cr, Cd, Ni and Fe in the wet season. From the human health risk point of view, the study reveals that the intake of Tillapia zilli may not pose any adverse health risk to the consumers. However, regular monitoring of trace metals level in Tillapia zilli is advocated due to possible bioaccumulation and biomagnification.