Human Risk Assessment of Consuming Farm Raised Fish in Uyo, Nigeria

Background: Fish farms are usually established in other to achieve self sufficiency in fish production, and to also supplement capture fishery production. This study was carried out to ascertain the risks or otherwise of consuming farm raised fish in Uyo, Akwa Ibom State.

Methods: The fish species collected from these farms was Clarias gariepinus. The fish feeds (multifeed and coppen) as well as the water samples from the ponds were also analysed. All samples were collected from two commercial fish farms located at different areas in Uyo. These samples were digested and analyzed for the level of six trace metals namely lead (Pb), nickel (Ni), cadmium (Cd), chromium (Cr), cobalt (Co) and zinc (Zn) using atomic absorption spectrophotometer. Target hazard quotient as well as hazard index were calculated for the analysed trace metals. Physicochemical properties of the water samples collected were analysed using standard methods.

Results: In general, the highest concentrations of trace metals were present in the feeds except zinc while the lowest concentrations were observed in all the water samples. From the results, it was observed that lead, cadmium and chromium exceeded the maximum permissible limits set by WHO and other international regulatory agencies in water while cobalt and chromium was above permissible limits in fish and feed. From the results, it was revealed that the target hazard quotients (THQ) for individual trace metals and hazard index (HI) values based on Ni, Pb, Cd, Cr and Zn were all less than 1. The physical parameters of the water samples obtained from the ponds indicated that all the parameters were within permissible limits except for pH and conductivity.

Conclusion: From the results obtained from the target hazard quotients and hazard index calculations, the study established that health risk associated with the intake of these metals via consumption of these fishes was insignificant. However, continuous monitoring of farm raised fishes as well as the feeds given to these fishes is necessary in other to reduce or completely avoid contamination by trace metals.