Toxicological assessment of fish (Clarias gariepinus) from bitumen-polluted River Oluwa, Nigeria.

Toxicological evaluation of Clarias gariepinus from bitumen-polluted River Oluwa, Nigeria, was carried out in furtherance of studies on the environmental impacts of the bitumen exploration in Ondo State, Nigeria. Samples were taken from three different (two polluted and one as control) sites. The effect of changes in monthly seasonal flow rate was assessed for the sites of study. Blood plasma clinical-chemical parameters (BCCPs) and histological changes/lesions in various organs were evaluated as markers of pollution in the fish blood using standard methods. The result of the physicochemical properties of water from the sampling points revealed some of the values conforming to approved standards while others showed deviation. Significant differences were found in the blood and histological endpoints between the control and the polluted sites as well as between the two seasons evaluated across the sites. The public health implications of consuming this fish are fully discussed.