Assessment of Metal Contamination in Oreochromis niloticus from Ekiti State’s Major Dams, Southwest, Nigeria and its Human Health Implications

Abstract

Agricultural and domestic activities around dams in Nigeria involve the use of agrochemicals and insecticides to boost production and combat insect pests respectively. The study aimed to ascertain metals contents and assess the hazards associated with heavy metals in Oreochromis niloticus in three major dams in Ekiti State. Fish samples were collected for 24 months. Metal concentrations in fish samples were determined using spectrometry. The metals concentrations in the tissues were at lower concentrations compared to the maximum acceptable limits in food by Food and Agricultural Organization (FAO) and World Health Organization (WHO). Metals accumulation pattern revealed that the accumulation of the essential metals were higher than those of the non-essential metals in the fish tissues. There were significant seasonal variations in the concentrations of metal in fish tissues within the dam and among the dams. Significant relationships existed at P < 0.05 or P < 0.01 between some of the metals and the fish body weight and body length in the different dams while in others the relationships were not significant. Human health risk assessment showed no significant non-carcinogenic adverse health risk. Carcinogenic health assessment indicates that the utilization of the species as a protein source does not currently pose public health risk to consumers. However, the discovery of cadmium and lead in fish muscle is of great concern because of their toxic effects on human. Therefore, there is a need for close monitoring of these toxic metals contamination to prevent their excessive accumulation in the human food chain.