Title: Assessment of Heavy metal contents in commercial fishes consumed in Umuahia and their associated human health risks

Abstract

This study evaluated the heavy metal contents in commercial fishes consumed in Umuahia, Nigeria and their associated health consequences. Trachurus symmetricus, Clupea pallasii, Micropogonias undulatus, Ictalumus punctatus, Scomber japonicus, Merluccius paradoxus, Pomatomus saltatrix and Oreochromis niloticus were fishes used for the study. The digestion of fish samples, heavy metal analyses and health risk aassessment were carried out using standard methods and models. The heavy metals analyses of the fishes show that chromium was not detected in all the fishes while lead was found to be significantly (P<0.05) higher than its permissible limit in all the fishes. With exception of T. symmetricus, M. paradoxus, C. pallasii and S. japonicus that showed detectable levels of Cd, Cu and Co respectively above their permissible limits. Mn and Ni concentrations detected in the fishes were significantly (P<0.05) lower than their respective permissible limits. The concentration of Fe detected in most of the fishes was significantly (P<0.05) higher than its permissible limit. Daily intakes of heavy metals were below their oral reference daily intake except for I. punctatus with daily intake of Fe above its oral reference daily dose. Target hazard quotients (THQ < 1) were observed in all the fishes except I. punctatus with THQ > 1 for Fe. The hazardous index in I. punctatus, M. paradoxus and P. saltatrix were greater than 1. The carcinogenic risks due to Pb, Cd and Nickel were within the acceptable range of predicted lifetime risks for carcinogens. The total cancer risks of carcinogenic metals in C. pallasii, I. punctatus and M. paradoxus are above the minimum acceptable range of predicted lifetime cancer risk for carcinogens while every other fishes have total cancer risks within the minimum range. The findings of this study show that commercial fishes consumed in Umuahia contain high heavy metals at varying concentrations across fish species with the concentration of same been unsafe for consumption with increased risks of both carcinogenic and non-carcinogenic health risks.