Human health aspects of the metals zinc and copper in tissue of the African sharp tooth catfish, Clarias gariepinus, kept in treated sewage emuent and in the Krugersdrift Dam

Bioaccumulation and health risks of the metals zinc and copper were studied in the liver, kidney and muscle tissues of the African sharptooth catfish, Clarias gariepinus, kept in treated sewage effluent and in the Krugersdrift Dam, Bloemfontein, South Africa. Metal concentrations were also studied in the water and sediment of the mentioned localities. Marked differences in the bioconcentrations of Zn and eu were measured in the different types of tissue, Concentrations of the selected trace elements were noticeably higher in the livers and kidneys than in the muscle tissue. However, no set seasonal patterns could be established regarding the incidence of these elements in both localities. The occurrence of Zn and eu in the water of both localities was very low and therefore it would oot be considered harmful ortoxic to aquaculture. The Cu and Zo concentrations found in the muscles of C. goriepinus, kept in domestic effluent from abiofilter plant, are not considered to be a health hazard to consumers. Gutted fish only would be recommended for intake due to the Cu and Zn concentrations found in the kidney and liver tissue. A diet containing fish would contribute to the daily requirement of 4 to 10 mg for Zn and approximately 3 mg for Cu.