Assessment of some toxic elements in aquatic bioindicator (Clarias gariepinus) sold in Katcha and Minna, Niger State Nigeria: Major threats to food safety

The major problems in human diets are the presence of toxic materials in consumable foods. Fishes have been used for many years as indicators of environmental pollution status, and, thus, they are regarded as good indicators of metal pollution in marine environments. This study aimed to assess some toxic elements in Clarias gariepinus (Cat fish) sold in Minna, Niger State Nigeria and the health risk associated with their consumption. The fishes used for the study were purchased from Katcha market and Minna fish market from different sellers and these were done in triplicates. The level of some trace metals such as Arsenic (As), Cadmium (Cd), Chromium (Cr), Lead (Pb), and Mercury (Hg), were investigated using Atomic Absorption Spectroscopy (AAS). The Bioaccumulation factor and health risk (daily intake, health risk index and hazard index) from the consumption of these fishes was assessed using standard methods and formula. Fish samples were digested using a modified procedure from the Association of Official Analytical Chemists (AOAC) and were subsequently analyzed using AAS. The results showed that trace metals in fishes sold in Minna town were higher than the WHO/FAO permissible limit of metal in fishes. There is significant different (P<0.05) between the fishes sold in Minna and that of Katcha. Total hazard index of all metals in C.gariepinus from Katcha market and Minna fish market were 0.37 and 1.25 respectively. This concludes that fish in Minna market are contaminated with heavy metals (HMs) with deleterious effect on consumption and also bioaccumulate in the fish. The risk assessment shows that fish in Minna are contaminated with potentially toxic elements and could pose health risk from heavy metal contamination when consume via food chain.