Fish as a bioindicator of polycyclic aromatic hydrocarbon pollution in aquatic ecosystem of Ogun and Eleyele Rivers, Nigeria, and risk assessment for consumer's health

Abstract

Ogun and Eleyele Rivers in Nigeria are known to be prone to industrial wastes pollution. Therefore, assessing Polyaromatic Hydrocarbon (PAH) contamination in fish tissue harvested from the two rivers is considered highly important. Polycyclic aromatic hydrocarbon (PAH) in the fish tissue was extracted and identified by Gas-Chromatographic Flame Ionization Detector (GC-FID). Health Risk Assessment was done by estimating the Targeted Hazard Quotient (THQ), Daily Intake (EDI), and Carcinogenic Risk (CR) of the PAHs. The diagnostic ratio was used for the determination of source pollution of the PAH.Principal Component Analysis (PCA) was employed for the analysis of PAH distribution in the tissue of the fish species using Minitab Statistical Software. QSAR descriptor was generated with PADEL tool, and the analysis was done on the DTC laboratory. Fourteen PAHs were identified in the tissue of Sarotherodon melanotheron and Clarias gariepinus obtained from the two rivers. Benzo[a]pyrene concentration in most of the fish tissue exceeded 2 µg/g set by the European union. PCA showed mixed distribution of low and high molecular weight PAHs in the tissues of fish. The diagnostic ratio showed that the PAH are majorly of petrochemical and minor pyrogenic source. The EDI for naphthalene exceeded the set limit in the fish tissue. The incremental lifetime cancer risk exceeds 10−4 indicating possible cancer risk to the consumers. The QSAR analysis resulted in the generation of highly predictive and robust model with VR2-Dzs, VR1-Dt and SPMin7_Bhi descriptors serving as the major structural attributes contributing to the acute toxicity of the identified PAH. Our result showed that consumption of fish obtained from the study sites pose some health concerns, therefore necessary governmental interventions are required for pollution control of the Ogun and Eleyele rivers.