Levels of Some Essential Heavy Metals in Commercially Important Fish Species Collected from Markets in Monrovia, Liberia

Heavy metal levels in fish are of particular global interest because of the potential risk to humans who consume them. While attention has focused on self-caught fish, most of the fish eaten by the public comes from commercial sources. In this study, sixty samples covering 29 commercial fish species were randomly obtained from major fish markets in and around Monrovia, Liberia and analyzed for copper (Cu), zinc (Zn) and iron (Fe). A mixture of HNO3, HClO4 and H2SO4 was used for complete oxidation of organic tissue. Concentrations of the selected metals were measured using an atomic absorption spectrophotometer. The concentrations of metals (µg g-1 wet weight basis) ranged as follows: Cu 0.101-2.990; Zn 1.783-6.013 and Fe 2.122-6.804. The metal levels in the edible fish muscle tissues were generally below the FAO/WHO maximum permissible limits. On average, the order of metal concentrations in the fish muscle was Zn>Fe>Cu. The study showed that all the tested fish species are safe for human consumption with respect to levels of Cu, Zn and Fe.