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Except for Mercury, the mean concentration of the metals was above the maximum permissible limits recommended by relevant bodies and organizations. Hence, there is need for regular monitoring of heavy metal concentrations in this water body and the aquatic organism inhabitants because of the long term effects.

Bivalve shellfish is considered as delicious and healthy food items in several dietary regimes in the Niger Delta but the accumulation of hazardous substances tend to undermine the nutritional and health benefits derived from their consumption. Four species of bivalve shellfish: Bloody cockle (Anadara senilis), Donax clam (Donax rugosus), Knife clam (Tagelus adansonaii) and Mangrove oyster (Crassosstra gasar) harvested from the brackish water of Iko estuary were assessed of their safety for human consumption. Standard methods of analysis were employed to assess microbiological hazards and toxic element contaminants. Results of microbiological analysis revealed a total viable counts (TVC) lower than the recommended limit (5.7 log cfu/g) for fresh bivalve molluscs while Vibrio cholerae, Vibrio parahaemolyticus, Salmonella spp, Shigella spp, Listeria monocytogenes and E-coli were far above the stipulated FDA standard for molluscian shellfish. Analysis for toxic elements clearly showed differential selectivity for the ranged of toxic elements. Lead concentration was within the acceptable limit (1.5mg/kg). Cadmium concentration in bloody cockle, knife clam and mangrove oyster was higher than the acceptable standard recommended by regulatory agencies for shellfish. The accumulation pattern and tissue burden of bivalve shellfish samples indicated that microbiological hazards and toxic element contaminants were higher in bloody cockle and knife clam when compared to donax clam and mangrove oyster. Therefore, bivalves shellfish harvested from the study location is not considered safe for human consumption without any further treatment and proper processing to reduce the levels of hazards which may pose health risk to the consumers.

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