Atmospheric polychlorinated biphenyls in Indian cities: Levels, emission sources and toxicity equivalents Paromita Chakraborty a, b, * , Gan Zhang a , Sabine Eckhardt c , Jun Li a , Knut Breivik c, d , Paul K.S. Lam e , Shinsuke Tanabe f , Kevin C. Jones g a State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China b SRM Research Institute, SRM University, Kattankulathur, Tamil Nadu, India c Norwegian Institute for Air Research, Box 100, NO-2027 Kjeller, Norway d University of Oslo, Department of Chemistry, Box 1033, NO-0315 Oslo, Norway e State Key Laboratory in Marine Pollution, Department of Biology and Chemistry, City University of Hong Kong, Hong Kong f Centre for Marine Environmental Studies (CMES), Ehime University, Matsuyama 790-8577, Japan g Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK article info Article history: Received 27 April 2013 Received in revised form 13 July 2013 Accepted 17 July 2013 Keywords: Polychlorinated biphenyls Air India FLEXPART HYSPLIT Toxicity equivalents abstract Atmospheric concentration of Polychlorinated biphenyls (PCBs) were measured on diurnal basis by active air sampling during Dec 2006 to Feb 2007 in seven major cities from the northern (New Delhi and Agra), eastern (Kolkata), western (Mumbai and Goa) and southern (Chennai and Bangalore) parts of India. Average concentration of S 25 PCBs in the Indian atmosphere was 4460 (2200) pg/m 3 with a dominance of congeners with 4e7 chlorine atoms. Model results (HYSPLIT, FLEXPART) indicate that the source areas are likely confined to local or regional proximity. Results from the FLEXPART model show that existing emission inventories cannot explain the high concentrations observed for PCB-28. Electronic waste, ship breaking activities and dumped solid waste are attributed as the possible sources of PCBs in India. S 25 PCB concentrations for each city showed significant linear correlation with Toxicity equivalence (TEQ) and Neurotoxic equivalence (NEQ) values. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Tropics have been evidenced with significant emission source regions for polychlorinated biphenyls (PCBs) and associated global atmospheric distribution of PCBs (Iwata et al., 1994; Watanabe et al., 1996). Exposure to PCBs can cause a wide variety of health effects, often at very low exposure levels and are highly toxic compounds with carcinogenic and mutagenic effects (Ruiz et al., 2008). PCBs have been widely used as plasticizers, as coolants and lubricants in transformers and capacitors, and as hydraulic and heat exchange fluids, and may be present in the electronic waste (e- waste) stream (Wong et al., 2007). It has even been hypothesized that there has been a shift in primary emission regions of PCBs on a global scale with high emission continuing in some sub-tropical and tropical regions implicated as recipients of wastes, paralleled by significant reductions in atmospheric burdens within former use regions (Breivik et al., 2011). Furthermore due to the tropical climate in India, PCBs can readily enter the atmosphere from some sources such as volatilization from or incineration of PCB contain- ing materials and products, vaporization from landfills, airewater/ soil exchange, vaporization from contaminated surfaces and sludge dewatering beds contaminated with PCBs (Totten et al., 2004; Biterna and Voutsa, 2005). Inhalation exposure is an important route and is of substantial concern for the urban environment. Very limited data is available on the atmospheric emissions and con- centrations of PCBs in Indian cities although high levels were re- ported in 1994 (Iwata et al., 1994) and recently elevated levels have been reported in our previous work (Zhang et al., 2008) and also by the global atmospheric passive air sampling study from New Delhi in India (Pozo et al., 2008) and from agricultural regions of India (Pozo et al., 2011). An international mandate under the Stockholm Convention (UNEP, 2001) aims to identify and quantify ongoing PCB sources and the continued presence and distribution of these chemicals in the environment. Some dioxin-like PCBs (dl-PCBs) are of particular toxicological concern. 4 coplanar PCBs and 8 mono- * Corresponding author. E-mail addresses: paromita.c@res.srmuniv.ac.in, parochakraborty@gmail.com (P. Chakraborty). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol 0269-7491/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.envpol.2013.07.032 Environmental Pollution 182 (2013) 283e290