Assessment of Heavy Metals Concentrations in Selected Crustaceans and Their Potential Health Risk at Qua Iboe Estuary, Ibeno

Abstract

This study was conducted to assess the accumulation of some metals (Pb, Cu, Zn, Cd, and Mn) in the tissues of Procambarus clarkii and Callinectes amnicola, in Qua Iboe Estuary, Ibeno. Four locations were selected, three within Qua Iboe Estuary– Mkpenak, Ukpenekang, and Iwo-Okpom, while the fourth, Ifiayong, served as control.Water and Sediment samples were also collected from the same locations. Standard procedures were employed insample preparation and elemental analysis was carried outusing Atomic Absorption Spectrophotometer (AAS).The results obtained showed that the various concentrations of the metals in water was in the order Mn>Cu>Zn>Cd>Pb at all study locations, and that concentrations of Cd (0.058±0.01mg/l)and Mn (1.086±0.81mg/l) were found to be higher than WHO permissible range, while others (Pb, Cu,and Zn) were withinthe range.In sediments, all concentrations of metals were higher than their values in the overlaying waterand were within the allowable range except for Mn (80.805 ± 6.80mg/kg).Also, concentrations of Cu and Zn in crustacean tissues were lower than the international permissible levels. However, Pb, Cd and Mn exceeded the allowable limits given by FAO/WHO. From calculations, the estimated weekly intake (EWI) for all metals were considerably below the provisional tolerable weekly intake based on the FAO/WHO standards.The Hazard index (HI) for the studied metals in P. clarkii and C. amnicolawere0.474 and 0.370 respectively, showing the absence of potential significant health risk through the ingestion of the crustaceans.The cancer risk factors for Pb (3.2 í— 10^-7 and 2.7 í— 10^-7 in crabs and crayfish respectively) were below the acceptable lifetime carcinogenic risk (10^-5). Relative to the permissible limits for metals in seafood, there was an absence of sufficient accumulation of any of the investigated metals in the crustacean samples to indicate a potential significant health hazard from their consumption. The results of this study revealed a safe level of Pb, Cu, Cd, Zn, and Mn contents in the crustaceans consumed by the population.