HEALTH RISK ASSESSMENT OF TRACE METALS CONTAMINATION IN IMO RIVER, NIGERIA

Levels of seven trace metals (Co, Cd, Fe, Ni, Pd, V and Zn) were quantified in water and Chrysichthys nigrodigitatus (catfish) samples from Imo River, Nigeria, using atomic absorption spectrophotometer (AAS) for both dry and wet seasons. Physicochemical parameters of the water were also quantified using standard methods. The results showed significant differences in levels of the investigated parameters in the analyzed samples between the two seasons. Trace metals have high levels in dry season than wet season. Trace metals in water and catfish ranged from 0.0011 - 0.29 mg/L and 0.0015 - 0.21 mg/kg, respectively. The level of iron was higher than WHO standard of 0.03 mg/L in water. The levels of the trace metals in water and fish in both dry and wet seasons follow the respective trend: Fe ˃ Pb Ni ˃ Zn ˃ Co ˃ V ˃ Cd, Pb ˃ Fe ˃ Ni ˃ Zn ˃ Co ˃ V ˃ Cd and Zn ˃ Fe ˃ Co ˃ Pb ˃ V ˃ Ni ˃ Cd, Zn ˃ Fe ˃ Co ˃ Pb ˃ V ˃ Ni. Transfer factor (TF) showed mixed sources of pollution with anthropogenic source dominating. TF value greater than one means that there is the possibility of transfer of the trace metals from water to fish. Fe, Cd and Zn have higher TF values across all the sampling points in the two seasons. Hazard quotient (HQ) less than one, signify no adverse effect on aquatic organism. Hazard index (HI) for ingestion and dermal contact were greater than one, showing possibility of cumulative effect in aquatic organism. HQ for consumption of Chrysichthys nigrodigitus was less than 1, suggesting no occurrence of adverse effect