Assessment of bio–concentrated heavy metals in commonly consumed fish in Sapele Delta State

Abstract

Heavy metal contamination in aquatic environments poses significant risks to both ecosystems and human health. Fish, as a major protein source, can accumulate toxic metals, making it essential to monitor their safety for consumption. This study assesses the concentration of six heavy metals, lead (Pb), chromium (Cr), nickel (Ni), cadmium (Cd), mercury (Hg), and barium (Ba) in the liver, kidney, and tissue of three selected fish species (Oreochromis niloticus, Puntius brevis, and Electrophorus electricus) from Sapele Markets, Delta State, Nigeria. The analyses focused on six heavy metals: lead (Pb), chromium (Cr), nickel (Ni), cadmium (Cd), mercury (Hg), and barium (Ba) in the liver, kidney, and tissue of the fish..For all the sampled fish species ,most metals were below WHO limits, except for cadmium, which has already reached a level of great concern. Barium, chromium, and mercury were negligible across all species. Additionally, the length-weight relationship indicated negative allometric growth pattern in the three fish species, with condition factors (k) less than 1, suggesting the fish were in poor health. Stomach content analyses revealed that O. niloticus is herbivorous, P. brevis is carnivorous, and E. electricus is a bottom feeder. These findings suggest that while most heavy metal concentrations are within safe limits, the slightly elevated cadmium levels in O. niloticus tissue pose a potential health risk, emphasizing the need for regular monitoring and intervention to safeguard public health.