Polychlorinated biphenyls (PCBs) in air, soil, and cereal crops along the two tributaries of River Chenab, Pakistan: Concentrations, distribution, and screening level risk assessment Adeel Mahmood a , Jabir Hussain Syed a , Riffat Naseem Malik b, ⁎, Qian Zheng c , Zhineng Cheng c , Jun Li c , Gan Zhang c a Environmental Biology Laboratory, Department of Plant Sciences, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad 45320, Pakistan b Environmental Biology and Ecotoxicology Laboratory, Department of Environmental Sciences, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad 45320, Pakistan c State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China HIGHLIGHTS • First study to report PCB in food crops from Pakistan • Tri and teta-CBs were the dominant PCB homologs. • Urban/industrial sites were classified as potential sources of PCB in the study area. • Lower TEQ values were calculated as compared to the previously published data. abstract article info Article history: Received 14 October 2013 Received in revised form 16 February 2014 Accepted 16 February 2014 Available online 12 March 2014 Keywords: PCBs Cereal crops Air Soil Risk assessment River Chenab This study reports the first systematic data on PCB levels and their risk assessments by consumption of cereal food crops from Pakistan. Polychlorinated biphenyls (PCB) including dioxin-like PCBs (dl-PCBs) were analyzed in wheat (n = 28), rice (n = 28), air (n = 6), and soil (n = 28) samples to assess the levels, spatial distribution pattern, and their risk assessments along with the two tributaries of River Chenab, Pakistan. ∑ 33 PCB concentra- tions ranged between 0.15–2.22 ng g -1 dW, 0.05–9.21 ng g -1 dW, 0.70–30.5 ng g -1 dW and 41–299 pg m -3 in the wheat, rice, soil, and air samples, respectively. In the current study, comparatively lower dioxin toxicity equivalency (TEQ) values were calculated from the previously reported data. Hazardous ratio (HR) for human health risk assessment allied to non-cancer was found lower than integrity. © 2014 Elsevier B.V. All rights reserved. 1. Introduction The ecological behavior and toxicological effects of polychlorinated biphenyls (PCB) are of global concern because these compounds have detrimental properties; persistence, toxicity, and bio-accumulation are harmful to ecological integrity, wildlife, and humans (Guo et al., 2008; Eqani et al., 2012). Human exposure of PCB may lead to severe effects such as carcinogenic, reproductive, neurological, and immunological (Kalyoncu et al., 2009). In recent years, concerns about PCB contamina- tion have increased because these chemicals have been also identified as hormone disruptors that alter the functioning of reproductive and endocrine systems in the wildlife and human (Guo et al., 2008; Wang et al., 2008; Eqani et al., 2013). According to the World Health Organization (WHO), about 1.2 million metric tons of PCBs were produced worldwide during 1929–1977 (WHO, 1993). Thus, the leakage of transformer oil during repair, transportation, and storage of old transformers to industries are the reasons for PCB contamination (Eqani et al., 2013). PCBs, which are similar in structure and properties to dioxins and furans, are called dioxin-like PCBs. Four coplanar PCBs (co-PCBs: CB-77, -81, -126, -169) and eight mono-ortho-PCBs (CB-105, -114, -118, -123, -156, -157, -167, -189) share a common toxic mechanism similar to those of seven polychlorinated dibenzodioxins (PCDD) and ten polychlorinated dibenzofurans (PCDF) (Van den Berg et al., 2006). Science of the Total Environment 481 (2014) 596–604 ⁎ Corresponding author. Tel./fax: +92 5190643017 E-mail address: n_malik2000@yahoo.co.uk (R.N. Malik). http://dx.doi.org/10.1016/j.scitotenv.2014.02.074 0048-9697/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv