Assessment of Polycyclic Aromatic Hydrocarbons in Water and Fish and the Associated Human Health Risk at Porto-Novo Lagoon, Benin Republic

The Porto-Novo and Cotonou Lagoon complex serve as a trade route for goods and petroleum in both Nigeria and Benin Republic. The complex geographic location also makes it a sink for a large portion of pollutants coming from the city and surrounding areas, as well as from the Ouémé River, which receives pollutants from the north to the south of the country. In order to assess the level of polycyclic aromatic hydrocarbons (PAHs) contamination and the associated health risks, sixteen PAHs in Sarotherodon melanotheron and water from Porto-Novo Lagoon were evaluated. PAHs were extracted from fish and water from four locations and quantified by gas chromatography analysis. PAH concentrations in the water ranged from not detected (ND) to 64.65 mg/l and from ND to 46.24 mg/kg in fish. The PAH of the highest concentration was Benzo(b)fluoranthene while Naphthalene and Acenaphthene were the lowest. The total PAH concentrations ranged between 43.07 and 128.12 mg/L with a mean value of 89.30 ± 20.34 mg/L in water and 67.83 to 97.43 mg/kg with a mean value of 78.35 mg/kg in fish. Spatial distribution showed the highest total concentration in Djassin. Five rings PAHs predominated in water and fish. The hazard quotients (HQs) and hazard index (HI) were < 1.0 indicating that non-carcinogenic risk through water dermal absorption or fish consumption was low. The carcinogenic risk determined was high for Porto-Novo Lagoon water contact by the skin. Porto-Novo Lagoon fish consumption could result in a carcinogenic effect based on carcinogenic toxic equivalent (TEQ) values recorded (TEQ > screen value). The predominance of high-weight molecules (HMW) indicate that PAHs are mainly from pyrolytic sources.