Health risk assessment of polycyclic aromatic hydrocarbons and heavy metals in surface water from Bakana river in southern Nigeria

The level of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in surface water from Bakana River located within the hydrocarbon pollution-prone Niger Delta Region of Nigeria was assessed to evaluate possible human health hazards and other associated risk to seafood. Surface water samples were analyzed for various physicochemical parameters using standard analytical methods. The level of sixteen (16) USEPA-recognized PAH compounds and selected HMs (Zn, Cu, Ni, Pb, Cr and Cd) were investigated. PAHs and HMs were determined using gas chromatography-flame ionization detector (GC-FID) and atomic absorption spectrophotometer (AAS). Analytical results revealed deterioration of surface water from the study location, with significantly (P<0.05) high turbidity (30.00 ± 0.63 NTU), BOD (8.06 ± 0.66mg/l), total hardness (1079.05 ± 10.11mg/l) and nitrite (4.98 ± 0.16mg/l). For HMs, Cd and Pb showed values above WHO permissible limits, recording 0.014±0.001mg/l and 0.132±0.001mg/l respectively. Varying levels of PAH compounds were found to be present in the surface water samples. Naphthalene, acenaphthylene acenaphthene, phenanthrene, fluoranthene and pyrene showed significance presence when values were compared with results for control surface water samples. Health risk evaluation was performed using Estimated Daily Intake (EDI), Target Hazard Quotient (THQ) and Carcinogenic Risk (CR) assessment, and indicated that surface water from Bakana River has potential health risk cancer risk for Cd, Pb, Cr and Ni in adult and children populations. These findings demonstrate that residents of Bakana Community and its environs are exposed to contaminated surface water and the health risks associated with consumption of toxic contaminants in water.