Bioaccumulation and Health Risk Assessment of Lead, Cadmium, Arsenic, and Mercury in Blue Crabs Found in Creeks in Bayelsa State of Niger Delta Region of Nigeria

Abstract

This research investigated the accumulation of four heavy metals: Pb, Cd, As, and Hg in male and female crabs obtained from four creeks in Bayelsa State and the potential health risks associated with their consumption. The heavy metals were analyzed using Micro-Wave Plasma Atomic Emission Spectrophotometer 4200 Agilent. The mean concentrations of Pb (mg/kg) in the male crabs obtained in Nembe, Taylor, Kolo and Nuno creeks were 41.13±0.17, 31.23±0.12, 38.70±0.33 and 11.63±0.37 respectively, whereas those of the female crabs were 45.63±0.25, 32.00±0.24, 40.00 0.08 and 12.20±0.08 respectively. The mean concentrations of Cd (mg/Kg) in the male crabs from the same creeks were 46.77±0.42, 37.23±0.17, 41.83±0.37 and 28.60±0.29 respectively, whereas those of the female crabs were 47.73±0.37, 39.65±0.45, 45.03±0.25 and 29.40±0.08 respectively. The mean concentrations of As (mg/Kg) in the male crabs from the same creeks were 5.067±0.21, 4.83±0.21, 4.73±0.21 and 1.77±0.12 respectively, whereas those of the female crabs were 6.03±0.17, 5.13±0.17, 5.10±0.08 and 2.07±0.12 respectively. The mean concentrations of Hg (mg/Kg) in the male crabs from the same creeks were 7.87±1.37, 5.57±0.16, 6.80±1.14 and 5.93±0.90 respectively, whereas those of the female crabs were 9.20±0.99, 6.40±0.54, 9.23±1.01 and 6.17 ±0.09 respectively. The concentrations of all the heavy metals were generally higher than the permissible level by Food and Agriculture Organization and World Health Organization in seafood. Statistical analysis of the level of the studied metals showed there is a significant difference p< (0.05). The Total Hazard Quotient (THQ) in all the blue crab in all the creeks were less than 1. The Estimated Metal Intake, Health Risk Index,  and Carcinogenic Risk indicated a risk of developing cancer over time due to the ingestion of Pb, Cd, and As. From the results, the health risks associated with exposure to the heavy metals through the consumption of the blue crabs for the inhabitants in the study area are in the order: Pb ˃Cd>Hg>As. Therefore, blue crabs from the creeks under study are considered unsafe for consumption.