Assessment of the level of some heavy metals in commonly consumed local fish species displayed for sale in Port Harcourt, Nigeria
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Abstract
Background: The incessant crude oil spillage into the water bodies of the Niger delta region of Nigeria has raised fears that the fish caught in the water bodies would be heavily contaminated with heavy metals. This study tested five commonly consumed local fish species for their lead, cadmium, mercury, and arsenic content.
Methods: Samples of dark tilapia (Sarothendon gallelacus), light tilapia (Oreochronis niloticus), two‑fin catfish (Clarias gariepinus), “Zeghe” (Hydrocynus forskahlii) and three‑fin catfish (Auchenoglanis occidentalis) bought from three fish markets (Creek Road, Mile One and Iwofe) were used for the study. The levels of the heavy metals in the fish samples were assessed in an accredited laboratory, while the human health implications of the contaminants were determined using the relevant international regulatory standards.
Results: The fish samples contained detectable levels of the assessed metals. The mean concentration of cadmium in the fish samples was 0.29mg/kg; while the mean concentration of arsenic was of 1.85mg/kg. The average concentrations of lead and mercury in the fish samples were below the regulatory limits, whereas the mean concentration of cadmium was three times the WHO permissible limit of 0.1mg/kg. The concentrations of cadmium were highest in the light tilapia, and in the fish bought from the Mile One market, and lowest in the three‑fin catfish, bought from the Creek Road market.
Conclusion: The levels of the assessed heavy metals were significantly less than expectation. The levels of cadmium in the samples were however high enough to cause severe adverse health effects, hence the need for a more comprehensive public health response in managing crude oil spills.
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