Investigation of the Concentration of some Metals in Blood Cockle (Senilia senilis) and Oyster (Crassostrea gasar) from Bonny Estuary and Assessment of the Human Health Risk Associated with their Consumption

There is a growing concerns over the health risk of consuming seafood contaminated with poisonous metals from human activities.  This study examined the concentration and human health risk of Pb, Cd, Cr, Ni, Co, Zn, V and Hg associated with the consumption of blood cockle (Senilia senilis) and oyster (Crassostrea gasar) from Bonny Estuary, Rivers state Nigeria by analyzing the levels of the selected metals using Atomic Absorption Spectrometer Model A 200 AA. Data were used to calculate the non-carcinogenic health risk using Daily Intake Rate (DIR) Target Hazard Quotient (THQ) and Hazard Index (HI). The results showed variations in the concentration of the different heavy metals in the two shellfish. The trend of the metal concentrations in decreasing order was: Crassostrea gasar > Senilia senilis. Levels of metals in Senilia senilis, were all below the WHO and FAO permissible limit for fish. Also, all metals except Pb were below the WHO maximum permissible limit in Crassostrea gasar. The DIR (9.4684E-06 - 0.00281); THQ (8.286E-07 – 1.842E-04) and HI (2.519E-05 -2.595E-04) for all metals were below one indicating no risk for non-carcinogenic effects individually and collectively.  The shell fish analyzed from the Bonny Estuary are free from potential human health hazards from heavy metals. However, continuous monitoring of levels of metals in fish from the estuary is recommended

Trace Metals in Water, Fish and Sediments from Elechi Creek, Port Harcourt, Rivers State, Nigeria

The concentration of trace metals: Cadmium (Cd), Lead (Pb), magnesium (Mn), Nickel (Ni) and Zinc (Zn) were determined in water, sediment and in the tissues of Sarontheron melanotheron, Tympanotonus fuscatus and Tilapia guineensis collected from Elechi creek in Port Harcourt, Nigeria. In sediments, the order of concentration was Cd=Ni<Mn<Pb<Zn while the order in water was Mn<Cd=Zn<Ni<Pd. The mean concentrations of the trace metals (mg/kg dry weight) in fin and shell fish samples ranged from 0.003–0.18 (Cd), <0.001 –2.3 (Pb), 0.004 -1.21 (Mn), 0.16-0.70 (Ni) and 0.09 –7.04 (Zn). Tympanotonus fuscatus recorded the lowest concentration of all the metals. The Pearson product moment correlation among the metals in water, fish and sediment samples showed that all metals positively correlated well (p<0.05). Fishes from Elechi creek were not heavily burdened with these trace metals, but aquatic environment should be monitored periodically to avoid excessive intake of trace metals by human.Keywords: Trace metals, Elechi creek, shell and fin fishes, Sediment