EVALUATION OF COPPER, ZINC, AND IRON CONTAMINATION IN SELECTED FROZEN FISH SPECIES MARKETED IN ONDO CITY, SOUTHWESTERN NIGERIA

Abstract

This study assessed the levels of concentration of copper (Cu), iron (Fe), and zinc (Zn) in the gill, liver, and muscle tissues of Mackerel (Scomber scombrus), Herring (Clupea harengus), and Hake (Merluccius merluccius), sourced in Ondo City, Southwest, Nigeria, and values were compared with WHO and FEPA regulatory limits. Tissues were digested using aqua regia, a mixture of nitric acid (HNO₃) and hydrochloric acid (HCl) in a 3:1 ratio, and an atomic absorption spectrophotometer (AAS) was used to determine the metal concentration level. The results revealed no significant differences in the levels of Cu, Fe, or Zn among the three fish species across the various tissues (p > 0.05). The trace metal concentration order in the fish was Zn > Fe > Cu. While the concentrations of Cu and Fe in the tissues of all three fish species studied were within the WHO and FEPA-prescribed limits for food fish, the concentrations of Zn in the muscles of Merluccius merluccius (0.262±0.052 ppm), Clupea harengus (0.327±0.099 ppm), and Scomber scombrus (0.362±0.119 ppm) were above the prescribed limit (0.075 ppm) set by FEPA, indicating potential health risks. Regular monitoring of essential metals in fish, along with stricter regulatory enforcement, is necessary to safeguard public health.