Presence of Polycyclic Aromatic Hydrocarbons (PAHs) in Water and Sediment from Owo River and Ologe Lagoon: A Focus on Distribution, Source Apportionment, Human and Ecological Risk Assessment

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are pollutants of concern due to their toxic, persistent and long-term adverse effects to the aquatic life. This study was undertaken to assess the human health and ecological risk of 16 PAHs in water and sediments. 16 PAHs were analyzed in a total of 6 water and sediment samples. The results obtained indicate the prevalence of high molecular weight PAHs in all the samples. PAHs concentrations in water and sediment samples from all the sampling sites were in the range of 182.53–218.02 ng/L and 9626.00–9885.67 ng/kg, respectively. The toxic equivalent quantity (TEQ) value of all PAHs in sediments in the range of 3.05–3.54 μg/kg was lower than the safe level (600 μg/kg). The mean effects range median quotient (M-ERM-Q) for Owo river and Ologe lagoon sediments were 1.19 × 10−2 and 1.40 × 10−2 indicating low probability (<10% incidence) of acute toxicity caused by PAHs in the sediment. Health risk assessment was conducted using incremental life time cancer risk (ILCR) models coupled with benzo[a]pyrene toxic equivalent method. The exposure pathways considered in this study were direct water ingestion and dermal contact under residential scenario. The cancer risk was predominantly contributed (greater than 98%) by dermal exposure rather than the oral in both adults and children. The total ILCR is found to be greater than the low safety risk of 1-in-10,000. The results of the study will be useful for the regulatory policy makers in understanding the actual impact of the contamination on the end users.