Distribution, characterization, and human health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in Ovia River, Southern Nigeria Isioma Tongo & Lawrence Ezemonye & Kingsley Akpeh Received: 12 May 2016 /Accepted: 7 April 2017 # Springer International Publishing Switzerland 2017 Abstract The levels and distribution of polycyclic aro- matic hydrocarbons (PAHs) in surface water, sediment, and fish (Clarias gariepinus) samples from Ovia River, Southern Nigeria, were evaluated, to assess the contami- nation profile, dietary intake, and human health risks associated with exposure. Results showed that naphtha- lene, acenaphthylene, and fluoranthene were the most dominant contaminant in water, sediment, and fish, respec- tively, with mean concentrations (μg/L) of 3.08, 45.4, and 90.7. Spatial distribution showed high occurrence of PAHs in Ekenwan, the downstream station, for all the matrices. Source identification using multivariate analysis revealed mixed patterns of pyrogenic and petrogenic origins. Esti- mated daily intake (EDI) of PAHs through fish consump- tion ranged from 2.18 × 10 −7 to 5.23 × 10 −5 mg/kg/day; values were however lower than the reference dose (RfD) indicating low risk. Estimated values for hazard quotients (HQs) and hazard index (HI) for both non-carcinogenic and carcinogenic risks were below 1 indicating low risk through dietary and non-dietary exposure to water, sedi- ment, and fish from Ovia River. However, estimated HI values for direct ingestion of sediment were above 1, indicating the possibility of non-carcinogenic health risk from exposure. Carcinogenic risk indices also indicated low risk from fish consumption. In spite of the assessed low risk from exposure, continuous monitoring of PAH levels in this water body is imperative to prevent future human health effects. Keywords PAHs . Water . Sediment . Fish . Sources . Health risk Introduction Polycyclic aromatic hydrocarbons (PAHs) are a diverse group of persistent organic compounds (POPs) formed from the combustion of fossil fuels (Doong and Lin 2004). Most PAHs are ubiquitous and are found in different environmental matrices at varying concentra- tions (Ezemonye 2006; Chen and Liao 2006). Accumu- lation of PAHs in the environment is basically as a result of anthropogenic inputs with petrogenic and pyrolytic sources considered to be the most important inputs (Bamforth and Singleton 2005). Pyrolytic PAHs are formed as a result of incomplete combustion, while petrogenic PAHs are mainly from crude oil and its refined products (Qiu et al. 2009; Perra et al. 2009). PAHs are of great health concern due to the highly carcinogenic nature of most of them (Doong and Lin 2004; Simpson et al. 1998; Kim et al. 1999). High concentrations of PAHs have been reported in different environmental matrices along with its associated health hazards (Ravindra et al. 2001; Tsai et al. 2001; Kabzinski et al. 2002; Doong and Lin 2004; Zhang et al. 2004; Anyakora et al. 2005; Ezemonye 2006; Chen and Liao 2006; Shi et al. 2007; Kafilzadeh et al. 2011). Mean PAH concentrations of 0.43 μg/L in Environ Monit Assess (2017) 189:247 DOI 10.1007/s10661-017-5931-5 I. Tongo (*) : L. Ezemonye : K. Akpeh Laboratory of Ecotoxicology and Environmental Forensics, Department of Animal and Environmental Biology, Faculty of Life Sciences, University of Benin, Benin, Nigeria e-mail: isioma.tongo@uniben.edu