Health Risk Assessment of Heavy Metal Accumulation in Fish Species from Coastal Beach Waters South-South Nigeria

Abstract

Heavy metal contamination of fish is a serious public health concern worldwide and Nigeria is not an exception to this. In this study, eight commonly consumed fish species namely; African Cat Fish (Clarias gariepinus), Croacker Fish (Micropogonias undulatus), Sardine Fish (Sardinella maderensis), NileTilapia (Oreochromis niloticus), Tilapia (Tilapia zillii), Bony Tongue Fish (Heterotis niloticus), Cat Fish (Chrysichthys nigrodigitatus) and Elephant Fish (Campylomomyrus rhychophorus) were analyzed for Arsenic (As), Cadmium (Cd), Lead (Pb), Copper (Cu), Chromium (Cr), Zinc (Zn) and Mercury (Hg) using Atomic Absorption Spectrophotometer. The fish samples were collected from fisher men at the beaches. The Estimated Daily Intake, Target Hazard Quotient, Health risk index, Hazard Index, and Carcinogenic/Cancer Risk (CR) were assessed for adults and children.
Heavy metal analysis showed that Pb, Cr, Zn and Cd were observed in all the fish species, Cu in some of the fish species while Hg and As were not observed in any of the fish species. Cd and Pb exceeded the maximum permissible limit. The estimated daily intake (EDI) values for the metals were lower than the recommended dietary allowance for adults for both seasons while Pb exceeded the recommended dietary allowance for children at Tourist beach and Ibeno beach during the wet season, Tourist, Ibeno, Okpoama and Asaba beaches during the dry season. The Target Hazard Quotient (THQ) were <1 for all the fish species in adults and children for both season indicating no apparent health risk from these heavy metals over a life time of exposure.
Health Risk Index (HRI) was <1 in all the fish species in all the adults indicating no apparent health risk from these heavy metals over a life time of exposure while HRI was <1 in children from all the beach waters except Cr in Tourist and Agenobode beaches during the wet and dry season respectively. Hazard Index for all the fish species from beach waters were <1 for both adults and children for both season showing that the non-carcinogenic adverse effect is negligible. The carcinogenic risk for both adults and children, showed all estimated values for Cr, Cd, As and Pb for some of the fish species to be above the tolerable limit. This indicates that excessive consumption over a long time period might cause carcinogenic effect as the Cancer Risk (CR) values were higher than the acceptable guideline value (10−4–10−6) (E−6 and E−4). This indicates that consumption of fish from these beach waters should be of concern to the public that patronize barbecue sellers at the beaches. This calls for periodic monitoring of heavy metals in fish species sold at the beaches as well as sensitization of the beach tourists on the need to check what they consume.