Health Risk Assessment of Heavy Metal Concentration in Oyster (Crassostrea gasar) in Woji Creek, Rivers State, Nigeria

Abstract

Aim: A study on the health risk assessment of heavy metal concentration in Oyster (Crassostrea gasar) found along the stretch of Woji creek, Rivers State, Nigeria. Study Design: A cross-sectional randomized study. Place and Duration of Study: Three (3) sampling stations along Woji Creek, Rivers State and the study was conducted from July to December 2024. Methodology: Seventy-five (75) oysters were randomly collected (twenty-five per sampling station), conveyed to the laboratory for identification and analysed for copper, arsenic, nickel, lead, cadmium and chromium using atomic absorption spectrophotometer as well as water samples from Woji creek were analysed for selected physicochemical parameters. Results: The physicochemical parameters indicated that pH of the creek increased progressively from 6.72±3.31 in station 1 to 8.10±2.51 in station 3, biochemical oxygen demand was least in station 2 at 2.54±6.78 and highest at 3.00±2.64 in station 1, dissolved oxygen concentration ranged from 4.39±0.15 in station 1 and 5.46±0.64 in station 3, electrical conductivity was between 34.61±7.92 in station 1 to 42.58±4.83 in station 2, chemical oxygen demand ranged from 10.53±2.05 in station 1 to 15.34±1.76 in station 2, salinity fluctuated between 9.09±1.42 in station 1 to 10.26±1.03 in station 3, temperature values ranged from 28.03±0.94 in station 1 to 29.11±2.45 in station 2 and total dissolved solids ranged from 16.45±2.14 in station 3 to 24.42±4.60 in station 2; the physico-chemical parameters recorded in this study were within the WHO permissible limit. Based on heavy metals analysis, copper ranged from 3.15±1.98 in station 1 to 6.57±1.08 in station 2, Arsenic was highest (0.98±1.00) in station 1 and least (0.37±0.16) in station 3, nickel ranged from 0.01±0.05 in station 1 to 1.00±0.07 in station 2, lead ranged from 0.94±1.00 in station 2 to 1.06±0.41 in station 3, cadmium ranged from 0.21±0.10 in station 1 to 0.53±1.10 in station 2 and chromium ranged from 0.42±1.61 in station 2 to 0.68±0.006 in station 1. EDI values were low in nickel, cadmium and chromium but higher in arsenic, copper and lead while nickel, arsenic, copper, cadmium, lead and chromium all had THQ less than 1 in oyster samples. Conclusion: Existing regulations should be enforced on point and non-point discharges of effluents and wastes around Woji creek to minimize accumulation of heavy metals in aquatic organisms, which cause health complications when consumed by humans.