Human Health Risk Assessment of Heavy Metals in Three Species of Mollusks (Egeria radiata, Limicolaria flammea and Viviparus contectus) from Yenagoa, Bayelsa State, Nigeria

Abstract

Heavy metals pose a threat to human health and their presence in specific matrices is anthropogenic. The work focuses on the penetration of the food chain through the ingestion of mollusk proteins. This study evaluated the composition of heavy metals (Cd, Cr, Mn, Pb and Zn) in three species of mollusks (Limicolaria flammea, Viviparus contectus, Egeria radiata) from Yenagoa, Bayelsa State, Nigeria and the health risk associated with their consumption. Heavy metals concentration was determined by Atomic Absorption Spectrophotometer (AAS). Health risk associated with consumption of the samples were assessed by Estimated Daily Intake (EDI), target Hazard Quotient (THQ) and Carcinogenic Risk (CR). EDI, THQ and CR were done by calculation following standards. Heavy metals concentration range in the samples were: Cd (0.289±0.00 mg/kg - 0.667±0.00 mg/kg), Mn (0.816±0.00 mg/kg - 0.934±0.00 mg/kg), Pb (0.082±0.00 mg/kg - 0.092±0.00 mg/kg) and Zn (4.114±0.00 mg/kg - 8.534±0.00 mg/kg); Cr was not detected in neither of the samples.  EDI of heavy metals through consumption of these samples were within acceptable limits for all heavy metals detected. THQ ranges were as follows: Cd (0.4949-1.1420), Mn (0.000017-0.000019), Pb (0.0401 - 0.0450) and Zn (0.0016 - 0.0066).  THQ values indicate that there is no human risk concern of risk for humans except Cd (in E. radiata). CR values for Cd were as follows: L. flammea (3.8×10-3), E. radiata (4.34×10-4) and V. contectus (1.88×10-4). CR values were within acceptable limits with the exception of Cd in L. flammea. The present study shows that the samples contained detectable levels of heavy metals however their consumption do not pose any form of health risk with the except for Cd in L. flammea, hence the carcinogenic role of L. flammea stands out for its high content of Cd.