Safety Assessment of Heavy metals in Tilapia zilli (Tilapia fish) and Chrysichthys nigrodigitatus (catfish) obtained from Epe Lagoon, Lagos, Nigeria

Abstract

Epe Lagoon in Lagos State, Nigeria, is a notable lagoon in the country that provides important ecosystem and economic services such as fishing,  agriculture, transportation, and water for domestic use, among others. However, the lagoon regularly receives municipal, agricultural, and industrial  waste, which may compromise the suitability of aquatic organisms in the lagoon for consumption. This study determined the safety of the lagoon's fish  for consumption with the aim of providing information for effective pollution control and management. Samples of Tilapia zilli (tilapia fish) and  Chrysichthys nigrodigitatus (catfish) from the lagoon were treated and analysed for copper, chromium, cadmium, lead, and nickel using atomic  absorption spectroscopy. The estimated daily intake (EDI), hazard quotient (HQ), target hazard quotient (THQ), and carcinogenic risks (CR) of the heavy  metals were also calculated. On average, the levels of lead, nickel, chromium, and copper in the various tissues of the two fish species exceeded  permissible limits recommended by the World Health Organization (WHO), with the intestine being the most contaminated, followed by the trunk, head,  and tail, respectively. The EDI, HQ, THQ, and CR of the majority of the heavy metals in the two fish species exceeded the threshold limits. The Tilapia zilli  samples were more contaminated than Chrysichthys nigrodigitatus, suggesting that the former poses more risk. From these results, it can be inferred  that the two fish species may not be ideal for consumption. Heavy metal remediation and periodic monitoring need to be implemented in the lagoon.