Heavy Metals Body Burden and Evaluation of Human Health Risks in African Catfish (Clarias Gariepinus) from Imo River, Nigeria

Author(s): Joseph O. Osakwe, Pereware Adowei and Michael Horsfall Jr.

The purposes of this paper is to describe the body burden of heavy metals in the African Catfish (Clarias gariepinus) obtained from the Imo River in Nigeria and assess the potential non-carcinogenic health risk that might be caused by consuming this seafood. A questionnaire-based survey on dietary consumption rates of protein sources among residents of the area showed that catfish-fresh or dried accounted for 58% of total protein consumed, and over 90% of catfish sold in the area were caught in the local region of the river. The non-carcinogenic health risk from individual heavy metal and combined heavy metals due to dietary intake were evaluated by calculating the target hazard quotients (THQs), and hazard index (HI). The concentrations (mean ± sem in μg/g on dry weight basis) of heavy metals determined using AANALYST 400 Perkin- Elmer AAS were: (Cd: 0.125 ± 0.29, Cu: 0.24 ± 0.13, Zn: 2.33 ± 0.14, Ni: 1.12 ± 0.003, Pb: 0.74 ± 0.05, Fe: 4.85 ± 0.54) for edible tissue, (Cd: 0.47 ± 0.13, Cu: 0.13 ± 0.004, Zn: 4.08 ± 0.25, Ni: 1.53 ± 0.12, Pb: 1.24 ± 0.20, Fe: 14.64 ± 0.52) for gills and (Cd: 0.03 ± 0.004, Cu: 0.21 ± 0.009, Zn: 2.65 ± 0.06, Ni: 0.84 ± 0.03, Pb: 0.47 ± 0.007, Fe: 6.89 ± 0.38) for internal organs. The order of heavy metal concentration was; gills > edible tissue > internal organ for Cd, Zn, Ni and Pb; edible tissue > internal organ > gills for Cu and gills > internal organ > edible tissue for Fe. The body burden of heavy metal seems to be highest in gills and lowest in internal organs. Target hazard quotients (THQ) for individual heavy metal and the hazard index (HI) values determined based on the levels of Cd, Cu, Zn, Ni, Pb, and Fe were all less than one, indicating that health risk associated with the intake of a single heavy metal or combined metal through consumption of this catfish for children and adult is relatively low at the moment. However, due to the potential health hazard of heavy metals, the Imo River system requires monitoring and awareness creation to avert possible health risk

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