Polycyclic aromatic hydrocarbons in house dust and surface soil in major urban regions of Nepal: Implication on source apportionment and toxicological effect Ishwar Chandra Yadav a,c, ⁎, Ningombam Linthoingambi Devi b , Jun Li a , Gan Zhang a a State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China b Centre for Environmental Sciences, Central University of South Bihar, BIT Campus, Patna 800014, Bihar, India c Department of International Environmental and Agricultural Science (IEAS), Tokyo University of Agriculture and Technology (TUAT) 3-5-8, Saiwai-Cho, Fuchu-Shi, Tokyo 1838509, Japan HIGHLIGHTS • Concentration of ∑ 16 PAH in soil was 1.5 times higher than dust. • HMW-PAHs were most abundant than LMW-PAH both in soil and dust. • PAH chemicals both in soil and dust showed weak correlation with TOC/BC. • Source apportionment study found mixed source from pyrogenic and petrogenic release. GRAPHICAL ABSTRACT abstract article info Article history: Received 21 September 2017 Received in revised form 29 October 2017 Accepted 30 October 2017 Available online xxxx Editor: Kevin V. Thomas Urban centers have turned to be the provincial store for resource consumptions and source releases of different types of semi-volatile organic compounds (SVOCs) including polycyclic aromatic hydrocarbons (PAHs), bringing about bound- less environmental pollutions, among different issues. Human prosperity inside urban communities is unambiguously dependent on the status of urban soils and house dusts. However, environmental occurrence and sources of release of these SVOCs are challenging in Nepalese cities, as exceptionally very limited data are accessible. This motivated us to explore the environmental fate, their source/sink susceptibilities and health risk associated with PAHs. In this study, we investigated the contamination level, environmental fate and sources/sink of 16 EPA's priority pollutants in surface soil and house dusts from four major cities of Nepal. Additionally, the toxicological effect of individual PAH was studied to assess the health risk of PAHs. Generally, the concentrations of ∑ 16 PAHs in surface soil were 1.5 times higher than house dust, and ranged 767–6770 ng/g dry weight (dw) (median 1810 ng/g dw), and 747–4910 dw (median 1320 ng/g dw), respectively. High molecular weight-PAHs both in soil and dust were more abundant than low molec- ular weight-PAHs, suggesting the dominance of pyrogenic source. Moderate to weak correlation of TOC and BC with PAHs in soil and dust suggested little or no role of soil organic carbon in sorption of PAHs. Source diagnostic ratio and principal component analysis indicated fossil fuel combustion, traffic/vehicular emissions and combustion of bio- mass are the principal sources of PAHs contamination in Nepalese urban environment. The high average TEQ value of PAHs in soil than dust suggested high risk of soil carcinogenicity compared to dust. © 2017 Elsevier B.V. All rights reserved. Keywords: Persistent organic pollutants Principal component analysis Petrogenic Pyrogenic Biomass combustion Toxicity equivalence quantity Science of the Total Environment 616–617 (2018) 223–235 ⁎ Corresponding author at: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China. E-mail address: icyadav.bhu@gmail.com (I.C. Yadav). https://doi.org/10.1016/j.scitotenv.2017.10.313 0048-9697/© 2017 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv