Characterization of 209 polychlorinated biphenyls in street dust from northern Vietnam: Contamination status, potential sources, and risk assessment
Science of the Total Environment 652 (2019) 345–355 Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv Characterization of 209 polychlorinated biphenyls in street dust from northern Vietnam: Contamination status, potential sources, and risk assessment Hoang Quoc Anh a,b,c, Isao Watanabe a, Keidai Tomioka a, Tu Binh Minh c, Shin Takahashi a,⁎ a b c Center of Advanced Technology for the Environment (CATE), Graduate School of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama 790-8566, Japan The United Graduate School of Agricultural Sciences (UGAS-EU), Ehime University, 3-5-7 Tarumi, Matsuyama 790-8566, Japan Faculty of Chemistry, VNU University of Science, Vietnam National University, 19 Le Thanh Tong, Hanoi, Viet Nam H I G H L I G H T S G R A P H I C A L A B S T R A C T • Concentrations of 209 PCBs were determined in street dusts from northern Vietnam • PCB levels in industrial and urban samples were significantly higher than rural ones • Street dusts exhibited different patterns of PCBs between study areas • PCB-11 was among the most abundant congeners in all the street dust samples • Street dusts contributed about 2% to total DI of PCBs by occupationally exposed groups a r t i c l e i n f o Article history: Received 12 September 2018 Received in revised form 11 October 2018 Accepted 17 October 2018 Available online 18 October 2018 Editor: Adrian Covaci Keywords: PCBs PCB-11 Street dust Human exposure Northern Vietnam a b s t r a c t A full congener-specific determination of polychlorinated biphenyls (PCBs) was conducted for street dusts in some areas in northern Vietnam Total 209 PCB concentrations (median and range) of 14 (2.2–120), 11 (6.6–32), and 0.25 (0.10–0.97) ng g−1 were measured in the street dusts from an industrial park, an urban area, and a rural commune, respectively, suggesting environmental loads of PCBs related to industrialization and urbanization in northern Vietnam PCB patterns of street dusts from the industrial park were dominated by lightly chlorinated homologs (tri- and tetra-CBs), while more highly chlorinated homologs (penta- and hexa-CBs) were the major contributors to total PCBs in the urban samples, indicating different emission sources Linear correlations of log-transformed sum of indicator congeners with total PCBs and sum of dioxin-like PCBs were observed PCB-11, an inadvertently produced congener of pigment manufacturing processes, was detected in all the samples with more elevated proportions in the urban and rural areas than industrial park Our results have revealed complex emission sources of PCBs in the study areas, including both historical (e.g., the past usage of imported PCB-containing oils and old electric equipment) and current sources such as releases from industrial activities and increasing use of new consumer products Occupationally exposed persons (e.g., street sweepers, street vendors, and traffic policemen) and children in the urban and industrial areas were estimated to receive much higher doses of dust-bound PCBs than general population, suggesting the need for appropriate protection conditions © 2018 Elsevier B.V All rights reserved ⁎ Corresponding author E-mail address: takahashi.shin.mu@ehime-u.ac.jp (S Takahashi) https://doi.org/10.1016/j.scitotenv.2018.10.240 0048-9697/© 2018 Elsevier B.V All rights reserved 346 H.Q Anh et al / Science of the Total Environment 652 (2019) 345–355 Introduction The term polychlorinated biphenyls (PCBs) refers to a class of 209 chlorinated biphenyl isomers that were commercially synthesized and widely used in numerous industrial applications from 1929 to the late 1970s Because of outstanding features such as chemical stability, fire resistance, high thermal conductivity, and electrical insulation properties, the most common uses of PCBs were additives in dielectric fluids in transformers and capacitors, and heat transfer fluids and hydraulic fluids in partially closed-industrial systems (UNEP, 1999; WHO, 2000) PCBs have been also used as additives in lubricants, casting waxes, surface coatings, adhesives, plasticizers, inks, and other open applications (Erickson and Kaley II, 2011; UNEP, 1999) Moreover, PCBs can be unintentionally produced during combustion, chlorination of water, and different industrial production processes (Erickson, 1997) PCBs are extremely persistent in the environment and they have been detected in various environmental media in virtually all parts of the world (Stringer and Johnston, 2001; UNEP, 1999; WHO, 2000) Unfortunately, PCBs can enter the ecosystem, then bioaccumulate and cause a variety of adverse effects on humans, including both carcinogenic risk and non-carcinogenic effects such as acute toxicity, endocrine disruption, developmental toxicity, and neurotoxicity (ATSDR, 2000; Stringer and Johnston, 2001; WHO, 2000) In 2001, PCBs were identified as one of the ‘dirty dozen’ persistent organic pollutants (POPs) and listed under Annex A (elimination) and Annex C (unintentional production) of the Stockholm Convention (UNEP, 2001) In Vietnam, PCBs have been detected in different environmental media such as ambient air (Tue et al., 2013; Wang et al., 2016), indoor dust (Takahashi et al., 2017; Tue et al., 2013), soil and freshwater sediment (Carvalho et al., 2009; Hoai et al., 2010; Romano et al., 2013; Toan and Quy, 2015; Toan et al., 2007), and marine sediment (Hong et al., 2008; Tri et al., 2016) Several studies focusing on the residue levels of PCBs in biological samples and foodstuffs from Vietnam have been also published since the 1990s (Carvalho et al., 2008, 2009; Kannan et al., 1992, 1995; Minh et al., 2006; Nhan et al., 1999, 2001; Ramu et al., 2007; Schecter et al., 1990) Furthermore, PCBs have been found in Vietnamese human tissues such as breast milk (Minh et al., 2004; Schecter et al., 1989; Tue et al., 2010a) and blood (Eguchi et al., 2015; Hansen et al., 2009, Schecter et al., 1992, 1993) The relatively high concentrations of PCBs in soils and foodstuffs from southern Vietnam in the 1990s probably resulted from the operation of the US chemical weapons during the Second Indochina War (Kannan et al., 1992, 1995; Thao et al., 1993a, 1993b) In a more recent study, Wang et al (2016) reported that atmospheric PCB levels in Vietnam were higher than those observed in some other countries in Asia (Jaward et al., 2005) and Europe (Jaward et al., 2004), even though Vietnam has never produced PCBs Several studies have revealed the contribution of current emission sources of PCBs in Vietnam such as the leakages of PCBs from old electrical equipment (Hoai et al., 2010), traffic-related activities (Toan et al., 2007), industrial activities (Hue et al., 2016), and primitive waste processing and recycling activities (Anh et al., 2018b; Eguchi et al., 2015; Takahashi et al., 2017; Tue et al., 2013) Street dust is a complex mixture of particulate materials such as soil, construction matter, vehicular emission, and atmospheric deposition (Cao et al., 2017; Klees et al., 2015; Shi et al., 2014) Street dust has been considered as a sink of heavy metals (Phi et al., 2017; Xu et al., 2015; Zhao et al., 2016); and organic contaminants such as organochlorine pesticides (OCPs) (Shi et al., 2013; Sohail et al., 2018), polycyclic aromatic hydrocarbons (PAHs) and their derivatives (Shi et al., 2013; Tuyen et al., 2014a, 2014b), brominated flame retardants (BFRs) (Anh et al., 2018a; Cao et al., 2017), organophosphorus esters (He et al., 2017; Khan et al., 2016), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) (Klees et al., 2015), and PCBs (Chakraborty et al., 2016; Klees et al., 2015, 2017; Sohail et al., 2018; Wang et al., 2013) Pollutants associated with street dust can also pose a risk to human health, especially for occupationally exposed persons (e.g., professional street sweepers, street vendors, and traffic policemen) and children (Anh et al., 2018a; Cao et al., 2017) Street dust samples have been collected from some areas in northern Vietnam to examine the occurrence of heavy metals and organic pollutants Phi et al (2017) reported that concentrations of lead and zinc in street dusts in Hanoi varied between different functional zones, with the highest levels detected in downtown areas Levels of PAHs and their methylated derivatives and aryl hydrocarbon receptor agonists in street dusts collected from an urban area of Hanoi were higher than those found in a rural village in northern Vietnam, as well as two metropolitan cities in India (Tuyen et al., 2014b) Anh et al (2018a) suggested that street dust can act as an indicator of outdoor contamination by polybrominated diphenyl ethers (PBDEs) and novel BFRs in northern Vietnam To our knowledge, so far there is no study that investigates the occurrence of PCBs, a typical class of persistent toxic substances, in Vietnamese street dusts In the present study, we collected street dust samples from some representative areas in northern Vietnam, characterized by the land use types, population densities, and traffic densities, to determine concentrations of 209 PCB congeners Results of this study may provide basic information on the current pollution status and spatial distribution of PCBs in Vietnamese street dusts, revealing environmental loads of PCBs related to industrialization and urbanization in some areas in northern parts of this developing country Full congener and homolog profiles of PCBs in the street dusts were characterized, providing a comprehensive evaluation of their emission sources Chronical daily intake doses and potential health risks caused by ingestion of dust-bound PCBs were also estimated for individuals in the study areas Material and methods 2.1 Study areas and sample collection A total of 32 street dust samples were collected during August and September 2016 in three areas in northern Vietnam, including an inner urban zone of Hanoi (n = 16), an industrial park in Thai Nguyen province (n = 10), and a rural commune in Bac Giang province (n = 6) Hanoi capital city is the country's second biggest city with an area of 3358.9 km2 and a population of approximately 7.7 million inhabitants in the year 2017 The urban area of Hanoi consists of twelve districts, which covers only 9% of total municipal area of this city but supports N50% of total population This area is characterized by high population density and mixed land use combining residential, institutional, commercial, and light industrial uses Sixteen samples were obtained from the main streets with high traffic density in seven inner districts of Hanoi, including Ba Dinh, Cau Giay, Dong Da, Hai Ba Trung, Hoan Kiem, Long Bien, and Thanh Xuan Song Cong I industrial park is situated in Song Cong city, Thai Nguyen province Established in 1999, Song Cong I is the first industrial park of Thai Nguyen province, comprising a production area of 2.2 km2 The major industrial sectors are metallurgy, ore refining, automotive and machinery part manufacturing, construction materials, plastics, garments, and electronics Ten samples were taken along October Revolution street and its branch roads in Song Cong city Mai Dinh, a rural commune in Hiep Hoa district, Bac Giang province, was chosen as the control site of this study This commune covers an area of nearly 9.1 km2 with mixed agricultural/residential land uses Six samples were collected from narrow paths of low traffic density, next to rice fields Sample names and further description about the sampling sites are provided in Table S1 of Supporting Information At each sampling location, a composite sample of five sub-samples was collected by sweeping street surface using non-plastic brush and pan Each sub-sample of 40–50 g street dust was obtained on an area of about m2 along the road, within 0.5 m adjacent to the curb The composite samples were thoroughly mixed, transferred into paper bags, and sealed in PE zip-lock bags At laboratory, the samples were H.Q Anh et al / Science of the Total Environment 652 (2019) 345–355 dried at room temperature and sieved through a 100-μm stainless steel sieve The homogenized samples were wrapped in solvent-washed aluminum foil, sealed in PE zip-lock bags, and stored at −20 °C until chemical analysis 2.2 Chemical analysis The street dust samples were treated according to our method for POP analysis previously described by Anh et al (2018a) In brief, about g homogenized dust sample was weighted into a 50-mL glass tube and subsequently extracted with 10 mL of acetone and 10 mL of acetone/hexane mixture (1:1, v/v) using a focused ultrasonic processor (VCX 130, 130 W, 20 kHz; Sonic & Materials, Inc.) After extraction, the sample tube was centrifuged at 3000 rpm for 10 The supernatants were combined, evaporated, and solvent-exchanged into hexane A portion of the crude extract corresponding to g dust was used for PCB analyses and the remaining portion will be used for other target analyses and bioassays The crude extract was spiked with surrogate standards (1 ng of each congener, 13C12-PCB-1, -3, -4, -8, -15, -19, -28, -52, -54, -70, -77, -81, -95, -101, -104, -105, -114, -118, -123, -126, -138, -153, -155, -157, -167, -169, -170, -180, -188, -189, -202, -205, -208, and -209; Wellington Laboratories) and successively purified by treating with concentrated sulfuric acid and passing through an activated silica gel column (Wakogel® S-1, activated at 130 °C for h) The target compounds were eluted from the silica gel column by using 80 mL of dichloromethane/hexane mixture (5:95, v/v) The eluate was concentrated, solvent-exchanged into decane, and spiked with internal standards (1 ng of each congener, 13C12-PCB-9, -37, -79, -111, -162, -194, and -206; Wellington Laboratories) before GC/MS quantification Chemicals and solvents used in this study were reagent grade for the determination of PCBs and purchased from Wako Pure Chemical Industries, Ltd PCBs (209 mono- to decachlorinated congeners) were quantified using a 6890 N gas chromatograph (Agilent Technologies) connected to a JMS-800D high resolution mass spectrometer (JEOL) The separation was performed on a HT8-PCB capillary column (60 m length × 0.25 mm internal diameter × 0.25 μm film thickness, Kanto Chemical) Helium was used as carrier gas at a constant flow of mL min−1 Inlet temperature was 280 °C A sample volume of μL was injected in splitless injection mode Column oven temperature was programmed from 120 °C, increased to 180 °C (20 °C min−1), to 260 °C (2 °C min−1), and ramped to 300 °C (5 °C min−1, hold min) Mass spectrometer was operated in positive electron ionization (EI) mode at a resolution of ≥10,000 at 10% valley Ionization energy was 38 eV and acceleration voltage was 10 kV Temperature of interface and ion source was 280 °C Data were acquired in selected ion monitoring (SIM) mode using two molecular ions for each native and 13C12-PCB congener Further descriptions about our quantification method are provided in Table S2 347 glassware was washed with detergent and tap water, baked at 450 °C for at least h, rinsed with solvents (i.e., acetone, toluene, and hexane), and covered by aluminum foil before using Procedural blanks (n = 6) were analyzed with real samples of each batch to control any contamination during chemical analysis Levels of almost all PCB congeners in the blanks were lower than the MDLs Peak areas of the target compounds were subtracted by identical peaks in the blanks when these were found to be significant Average recoveries (±SD) of 13C12-PCBs ranged from 68 ± 5% to 93 ± 7% (Table S6) 2.4 Risk assessment of PCBs associated with street dust Chronical daily intake doses (ID – ng kg−1 d−1) of PCBs via street dust ingestion were estimated using Eq (1) CID ¼ ðC IR FT EF EDÞ=ðBW ATÞ ð1Þ where C is the concentration of total PCBs in street dust (ng g−1) At the urban and industrial areas, high-end dust ingestion rates (IR) of 0.2 g d−1 and 0.05 g d−1 were assigned for children and adults, respectively; whereas medium IRs of 0.05 g d−1 and 0.02 g d−1 were assigned for children and adults at the rural site, respectively (Anh et al., 2018a; Jones-Otazo et al., 2005) An IR of 0.16 g per working day was applied for occupationally exposed persons, including street sweepers, street salesmen, and traffic policemen (Anh et al., 2018a; Cao et al., 2017) An absorption efficiency of 100% was assumed Fraction of time (FT) for traveling on the streets was 3/24 for all individuals An additional FT of working time of 8/24 was accounted for occupational group Exposure frequency (EF) was 365 d year−1 for traveling and 240 d year−1 for working Exposure duration (ED) of children and adults were years and 30 years, implying average time (AT) of 1825 days and 10,950 days, respectively Average body weights (BW) were 60 and 15 kg for adults and children, respectively Non-carcinogenic hazard quotient (HQ) and lifetime cancer risk (CR) due to the ingestion of PCBs associated with street dust were estimated by Eqs (2) and (3), respectively HQ ẳ CID=RfD 2ị CR ẳ C IR FT EF ED 10−6 CSF =ðBW LTÞ ð3Þ A reference dose (RfD) of 20 ng kg−1 d−1 of total PCBs was used (ATSDR, 2000) The cancer slope factor (CSF) of (mg kg−1 d−1)−1 was proposed by US EPA (2017) Mass unit conversion factor was 10−6 Lifetime (LT) was estimated as 25,550 days, corresponding to 70 years 2.3 Quality assurance and quality control (QA/QC) 2.5 Statistical analysis The analytical method validation was performed by triplicate analyses of solid matrix (i.e., sodium sulfate) spiked with native standards of PCBs (1 ng of each congener, 62 mono- to deca-CBs) and Standard Reference Material® 2585 (NIST, Gaithersburg, MD, US) Analytical results of the spiked samples and SRM samples are tabulated in Tables S3 and S4, respectively, indicating acceptable levels of precision and accuracy of our procedure Concentrations of the analytes were reported to two significant figures because relative standard deviations (RSD) of triplicate analyses of above validation samples were up to 15% for some congeners Instrument detection limits (IDLs) were estimated as times of standard deviations (SD) from replicate analyses (n = 5) of the lowest concentration standard (0.5 ng mL−1 of each native congener) Method detection limits (MDLs) were estimated from the IDLs with a sample weight of g and a final volume of 200 μL The MDLs of PCBs ranged from 0.0030 to 0.030 ng g−1 (Table S5) To reduce blank levels, Statistical analysis was performed using Microsoft Excel (Microsoft Office 2010) and Minitab 16® Statistical Software (Minitab Inc.) Mann-Whitney U test at a confidence level of 95% was used to assess the differences of contamination levels between study locations After logarithmic transformation, the dataset was subjected to Pearson's correlation analysis, regression analysis, and principal component analysis (PCA) to evaluate possible relations among PCB congeners For the PCA analysis, the component matrix was rotated using a varimax rotation Homolog compositions of PCBs in the street dusts and selected technical mixtures were analyzed by hierarchical cluster analysis using Ward linkage method and Euclidean distance measure to identify original formulations of PCBs Level of statistical significance was set at p b 0.05 A summary of results of correlation and regression analysis is presented in Table S7, while those of cluster and PCA analysis are shown in Figs S1 and S2, respectively 348 H.Q Anh et al / Science of the Total Environment 652 (2019) 345–355 Results and discussion 3.1 Concentrations of total PCBs PCBs were found in all the street dust samples of our study The concentrations of total 209 PCBs (Σ209PCBs), 10 homologs, and selected congeners are presented in Table Concentrations (median and range) of Σ209PCBs in street dusts from industrial, urban and rural areas were 14 (2.2–120), 11 (6.6–32) and 0.25 (0.10–0.97) ng g−1, respectively The total PCB levels in samples from industrial and urban areas were significantly higher than those from rural sites (p b 0.01) However, there was no statistical difference between industrial and urban areas (p N 0.05), probably due to the large variation in PCB concentrations in the Thai Nguyen samples (RSD = 137%), as compared with those from Hanoi (RSD = 52%) In the industrial area, the highest PCB levels were found in samples collected near a diesel engine manufacturing company and in samples from the central area of the industrial park, comprising numerous factories in different sectors (e.g., TN-01, -02, -08, and -10) In Hanoi, the most contaminated sample was obtained along a main gateway to the city center with several automotive repair shops (HN-01), followed by a sample collected from a key road of the southeastern part of the city, crossing a busy and chaotic bus station (HN-26) Street dusts from the rural area showed the lowest contamination levels with little variation The decreasing order of PCB levels in street dusts from industrial, urban, and rural areas of our study was consistent with those reported for outdoor dusts in Guangzhou and Hong Kong, China (Wang et al., 2013), and the Indus river basin, Pakistan (Sohail et al., 2018) A comparison of PCB concentrations in outdoor dusts between different study locations are shown in Table Levels of total PCBs in street dusts from the industrial and urban areas in northern Vietnam were within the ranges reported for outdoor dusts from an urban area of Hong Kong (Wang et al., 2013) and several sites along the Indus (Sohail et al., 2018) Total PCB concentrations in the Thai Nguyen and Hanoi samples were generally higher than those detected in dusts from nearby highways in the urban center and suburban industrial roadsides of Chennai, India (Chakraborty et al., 2016), but still lower than urban outdoor dusts in Guangzhou, China (Wang et al., 2013) Extremely high PCB concentrations were recorded in street dusts in the surroundings of an e-waste recycling facility (760–16,000 ng g−1; Klees et al., 2017) and some industrial sites (3600–63,000 ng g−1; Klees et al., 2015) in North Rhine-Westphalia, Germany, that were several orders of magnitude higher than our detected levels Concentrations of PCBs in the rural street dusts from Bac Giang were also significantly smaller than those found in some rural sites in western Germany (Klees et al., 2015) As information about the contamination Table Concentrations of PCBs (ng g−1) in street dust from northern Vietnam Industrial area, Thai Nguyen PCB-1 PCB-2 PCB-3 Mono-CBs PCB-11 PCB-15 Di-CBs PCB-18 PCB-28 PCB-37 Tri-CBs PCB-52 PCB-70 PCB-77 PCB-81 Tetra-CBs PCB-101 PCB-110 PCB-105 PCB-114 PCB-118 PCB-123 PCB-126 Penta-CBs PCB-138 PCB-153 PCB-156 PCB-157 PCB-167 PCB-169 Hexa-CBs PCB-170 PCB-180 PCB-189 Hepta-CBs Octa-CBs Nona-CBs Deca-CB Σ7in-PCBsb Σdl-PCBsc Σ209PCBs a b c Urban area, Hanoi Rural area, Bac Giang Median Min Max Median Min Max Median Min Max n.d.a 0.0093 0.012 0.024 0.22 0.27 0.77 0.19 0.72 0.70 3.2 0.30 0.69 0.16 n.d 5.3 0.27 0.36 0.32 0.015 0.48 0.0056 0.0078 2.3 0.36 0.23 0.056 n.d 0.018 n.d 1.2 0.075 0.15 n.d 0.35 0.045 n.d n.d 3.0 1.1 14 n.d n.d n.d n.d 0.15 0.030 0.24 0.050 0.10 0.052 0.44 0.035 0.064 0.023 n.d 0.51 n.d 0.073 0.072 n.d 0.10 n.d n.d 0.40 0.11 0.086 n.d n.d n.d n.d 0.39 n.d 0.069 n.d 0.15 n.d n.d n.d 0.54 0.21 2.2 0.012 0.026 0.020 0.047 0.51 3.0 6.0 3.9 14 6.8 53 3.2 6.0 1.2 0.057 50 1.1 1.2 1.1 0.061 1.7 0.042 0.021 9.0 0.97 0.84 0.14 0.038 0.067 n.d 4.2 0.26 0.53 0.012 1.5 0.29 0.035 0.016 22 4.4 120 n.d n.d 0.015 0.020 0.71 0.026 0.77 0.034 0.096 0.067 0.42 0.14 0.25 0.080 n.d 1.3 0.42 0.55 0.44 0.023 0.81 0.0061 0.012 3.3 0.77 0.62 0.11 0.025 0.049 n.d 3.1 0.15 0.26 n.d 0.77 0.094 n.d n.d 3.4 1.5 11 n.d n.d n.d n.d 0.35 n.d 0.42 n.d 0.062 0.048 0.26 0.096 0.15 0.048 n.d 0.88 0.27 0.39 0.31 n.d 0.57 n.d n.d 2.5 0.50 0.35 0.077 n.d n.d n.d 1.8 n.d 0.15 n.d 0.39 0.030 n.d n.d 2.1 1.1 6.6 n.d 0.021 0.027 0.041 1.5 0.092 1.5 0.21 0.26 0.21 1.4 0.72 0.79 0.26 0.013 4.8 1.8 2.0 1.5 0.099 2.9 0.054 0.034 15 2.1 1.7 0.35 0.084 0.12 n.d 9.2 0.26 0.75 0.020 2.2 0.40 0.035 0.035 9.7 5.2 32 n.d n.d n.d n.d 0.10 n.d 0.10 n.d n.d n.d 0.011 n.d n.d n.d n.d 0.0073 n.d 0.012 0.0091 n.d n.d n.d n.d 0.069 0.015 0.018 n.d n.d n.d n.d 0.039 n.d n.d n.d n.d n.d n.d n.d 0.055 0.018 0.25 n.d n.d n.d n.d 0.059 n.d 0.059 n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d 0.010 n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d 0.0070 n.d 0.10 n.d n.d n.d n.d 0.12 n.d 0.13 n.d n.d n.d 0.024 0.012 0.023 n.d n.d 0.13 0.034 0.037 0.035 n.d 0.073 n.d n.d 0.29 0.081 0.066 0.011 n.d n.d n.d 0.29 n.d 0.063 n.d 0.12 0.012 n.d n.d 0.33 0.12 0.97 Not detected Total of indicator PCBs (PCB-28, -52, -101, -118, -138, -153, and -180) Total of 12 dl-PCBs (PCB-77, -81, -126, -169, -105, -114, -118, -123, -156, -157, -167, and -189) 349 H.Q Anh et al / Science of the Total Environment 652 (2019) 345–355 Table Comparison of PCB concentrations (ng g−1) and TEQs of dl-PCBs (pg WHO-TEQ g−1) in outdoor dusts from different study locations Location Type Year Na nb ΣPCBsc TEQsc Reference Vietnam, Thai Nguyen Industrial area 2016 209 10 Urban area 2016 209 16 Vietnam, Bac Giang Rural area 2016 209 India, Chennai Nearby highways, urban area 2014 26 Suburban industrial area 2014 26 18 Different functional areas 2013 31 0.82 (0.0079–2.3) 1.2 (0.036–3.6) 0.00030 (n.d.d–0.0036) 30 (0.0007–100) (n.d.–30) 1.87 (0.9–34.5)e 0.12 (0.07–0.25)f 82 (16–560) 210 (n.d.–830) 6.7 (1.4–59) 6.8 (3.7–17) 6.5 (4.7–8.3) 2.61 (0.22–131) 9.78 (1.98–50.6) This study Vietnam, Hanoi 14 (2.2–120) 11 (6.6–32) 0.25 (0.10–0.97) 2.6 (0.2–7) 2.5 (0.1–9) 10.3 (0.95–125) 6300 (760–16,000) 10,000 (3600–63,000) 210 (85–950) 350 (140–800) 150 (100–190) 38.9 (4.02–228) 27.7 (7.75–114) Pakistan, Indus river basin Germany, North-Rhine Westphalia 110 g E-waste recycling area 2014 Total Industrial area 2011 Total Industrial/urban area 2011 Total Urban area 2011 Total Rural area 2011 Total China, Guangzhou Urban area 2010 37 90 China, Hong Kong Urban area 2010 37 30 a b c d e f g This study This study Chakraborty et al., 2016 Sohail et al., 2018 Klees et al., 2017 Klees et al., 2015 Wang et al., 2013 Number of PCB congeners Number of samples Mean and range for data from Chakraborty et al (2016), median and range for other studies Not detected TEQs for non-ortho dl-PCBs (PCB-77, -126, and -169) TEQs for mono-ortho dl-PCBs (PCB-105, -114, -118, and -156) Total PCBs estimated as five times of Σ6PCBs (PCB-28, -52, -101, -138, -153, and -180) of street dusts by PCBs in Vietnam is limited, we included data of surface soils to facilitate the comparison The literature shows that the PCB levels in agricultural soils in northern Vietnam not exhibit a large variation over time (Thao et al., 1993a; Toan et al., 2007, Toan and Quy, 2015) and are generally lower than levels in urban and industrial soils (Hue et al., 2016; Toan et al., 2007) Besides the similar spatial distribution affected by land use types, PCB levels in the street dusts of urban and industrial areas of this study were in line with levels detected in urban soils from Hanoi (15–190 ng g−1; Toan et al., 2007) and industrial soils from Thai Nguyen (18–104 ng g−1; Hue et al., 2016) A similar contamination level of PCBs was reported for house dusts from urban (median 10, range 5.6–85 ng g−1) and suburban (5.6, 3.6–20 ng g−1) areas of Hanoi (Tue et al., 2013) The degree of PCB contamination in street dusts of our study were much lower than the hazardous waste threshold of 5000 ng g−1 proposed by the Vietnam Ministry of Natural Resources and Environment (MONRE, 2009) Also, our detected levels of PCBs in Vietnamese road dust were still lower than soil quality guidelines issued by the Canadian Council of Ministers of the Environment (500; 1300; and 33,000 ng g−1 for agricultural, residential, and industrial land use; CCME, 1999) The composition of PCB homologs in street dusts from northern Vietnam are presented in Fig Interestingly, samples from the industrial, urban, and rural areas exhibited quite different PCB accumulation profiles Concentrations of tri- and tetra-CBs in the industrial samples were significantly higher than those detected in the urban and rural sites, whereas the urban samples were more heavily contaminated by higher chlorinated homologs (e.g., penta- to octa-CBs) In the industrial park, tetra-CBs (33.6 ± 8.4%) and tri-CBs (28.3 ± 8.6%) were the most predominant homologs, followed by penta-CBs (16.1 ± 5.9%), hexaCBs (11.2 ± 5.7%), di-CBs (6.2 ± 2.9%), and hepta-CBs (3.7 ± 2.2%) The PCB patterns in street dusts from the industrial area of this study were similar to those detected in surface soils and sediments from Thi Nai lagoon, central Vietnam, that has been affected by rapid industrialization (Romano et al., 2013) The prevalence of tetra-CBs was also found in street dusts of Mambakkam, an already established industrial zone in Chennai, India (Chakraborty et al., 2016) The homolog patterns of PCBs in street dusts from Thai Nguyen were quite similar to those detected in street dusts from the surrounding of an e-waste recycling enterprise in Essen-Kray, Germany, implying a near-source emission of low-molecular-weight PCBs (Klees et al., 2017) The urban samples showed a decreasing order as follows: penta-CBs (37.0 ± 6.5%) N hexa-CBs (28.8 ± 2.6%) N tetra-CBs (13.4 ± 2.2%) N hepta-CBs (7.4 ± 3.9%) ≈ di-CBs (7.4 ± 3.1%) N tri-CBs (4.5 ± 2.4%) The dominance of penta- and hexa-CBs was detected in indoor dusts from Hanoi urban and suburban areas and some informal waste recycling sites in northern Vietnam (Takahashi et al., 2017; Tue et al., 2013) Characterization of 209 polychlorinated biphenyls in street dust from northern Vietnam: Contamination status, potential sources, and risk assessment Fig Compositions of PCB homologs in street dusts from northern Vietnam 350 H.Q Anh et al / Science of the Total Environment 652 (2019) 345–355 Penta- and hexa-CBs were found as the major homologs in street dusts from traffic area of Guangzhou, China (Wang et al., 2013) Di-CBs were the largest contributors to total PCBs in the rural street dusts (45.4 ± 25.4%), followed by penta-CBs (22.9 ± 11.6%), hexa-CBs (15.8 ± 12.6%), tetra-CBs (8.6 ± 9.4%), tri-CBs (3.6 ± 4.2%), and hepta-CBs (3.5 ± 4.9%) This unusual profile was largely due to the presence of congener 3,3′-dichlorobiphenyl (PCB-11), which will be discussed in detail in Section 3.2 Minor proportions of the remaining homologs (i.e., mono- and octa- to deca-CBs) were observed in all the samples Concentrations of in-PCBs in the street dusts from Hanoi and Thai Nguyen were comparable to levels reported for surface soils from agricultural areas, but slightly lower than those from industrial and urban areas of Hanoi (Toan et al., 2007; Toan and Quy, 2015) Levels of Σ7inPCBs detected in this study were generally lower than a threshold of 277 ng g−1 specified for freshwater sediment (MONRE, 2012) A linear regression relationship (R = 0.97, p b 0.0001) between logtransformed Σ7in-PCBs and Σ209PCBs established for the whole dataset is presented by Eq (4): 3.2 Concentrations of 3,3′-dichlorobiphenyl (PCB-11) logΣ209PCBs ẳ 0:6230:023ị ỵ 0:8800:028ị log7inPCBs 4ị The congener PCB-11 has been considered as an inadvertent byproduct of pigment manufacturing processes and detected in a variety of commercial paint pigments and consumer products (Anezaki and Nakano, 2014; Guo et al., 2014; Hu and Hornbuckle, 2010; Shang et al., 2014) As reviewed by Vorkamp (2016), PCB-11 has been found in ambient air, wastewater, storm water, receiving waters, snow, ice, sediment, soil, plants, animals, and humans The high abundance of this congener has been demonstrated in the atmosphere of different parts of the world such as the US (Du et al., 2009; Hu et al., 2008), Japan (Anezaki and Nakano, 2014), Korea (Kim et al., 2003), and even in polar regions (Li et al., 2012; Wang et al., 2017) Information about the presence of PCB-11 in Vietnam's environment is still limited Romano et al (2013) reported that PCB-11 was among the most dominant congeners detected in surficial sediments and soils collected from Thi Nai lagoon, central Vietnam, accounting at least 7% of total PCBs To our knowledge, this is the first dataset reporting the occurrence of PCB-11 in outdoor dusts PCB-11 was detected in all the samples of our study, suggesting the widespread distribution of this compound in these areas Levels of PCB-11 were the highest in street dusts from the Hanoi urban area (median 0.71, range 0.35–1.5 ng g−1), followed by the industrial (0.22, 0.15–0.51 ng g−1) and rural samples (0.10, 0.059–0.12 ng g−1) PCB-11 accounted for 3.8 to 13.9%, with an average of 7.0% of total PCB concentrations in the urban samples that is significantly higher than those recorded in the industrial sites (average 3.1%, range 0.3–8.7%) Although levels of PCB-11 were the lowest in Bac Giang, this congener exhibited the largest contributions to total PCBs in the rural samples (44.5%, 11.1–84.6%), probably due to the low abundance of other congeners, which mainly derived from technical PCB mixtures Levels of PCB-11 correlated highly with total PCBs (Pearson's r = 0.657, p b 0.001), indicating the prevalence of this congener in the urban and rural road dusts However, there is no significant association between PCB-11 and other individual congeners, suggesting the unique sources of PCB-11 Concentrations of PCB-11 in street dusts of this study were comparable with those detected in sediments (median 0.25, maximum 0.61 ng g−1) and soils (median 0.30, maximum 1.31 ng g−1) collected from Thi Nai lagoon and its mainland (Romano et al., 2013) The full congener-specific measurements of PCBs are timeconsuming and costly, so multiplying the sum of certain indicator congeners by a multiplication factor is a simplified way to estimate the total PCB concentrations Klees et al (2017) have derived total PCB levels in plants and dusts by multiplying Σ6in-PCBs (Σ7in-PCBs excluding PCB-118) by a factor of five Four times of Σ7in-PCBs have been used to calculate total PCB levels in sediment (Hoai et al., 2010) and fish (Froescheis et al., 2000) Based on our measured data, a general multiplication factors of can also be applied to extrapolate total PCB concentrations from Σ7in-PCBs in the street dusts from northern Vietnam However, the conversion factors derived for the samples in Thai Nguyen industrial park (4.7 ± 0.9) were higher than those estimated for the Hanoi urban samples (3.2 ± 0.2) This difference probably reflects original formulations of PCBs dominating in the Thai Nguyen and Hanoi road dusts For a simple comparison, the proportions of Σ7in-PCBs in total PCBs are about 16 and 31% in Aroclor 1248 and 1254, respectively, that correspond to the conversion factors of and as described above (Frame et al., 1996) A more detailed estimation of origins of PCBs in our road dust samples will be discussed in Section 3.5 Proportions of seven indicator congeners in total PCB concentrations were the highest in Hanoi samples (31.4 ± 2.2%), followed by industrial (22.0 ± 3.9%), and rural ones (20.2 ± 10.4%) A high prevalence of penta- and hexachlorinated congeners (i.e., PCB-101, -118, -138, and -153) was detected in samples from the Hanoi urban area, which was consistent with congener patterns in other environmental media such as indoor dust, soil, and sediment collected from the same areas (Hoai et al., 2010; Toan and Quy, 2015; Tue et al., 2013) Whereas, tri- and tetrachlorinated congeners such as PCB-28 and PCB-52 were significantly more abundant in the industrial street dusts from Thai Nguyen PCB-28 was also identified as the most predominant indicator congener in outdoor dusts from Guangzhou and Hong Kong, China (Wang et al., 2013) It is noteworthy that lightly chlorinated congeners are less persistent and more volatile than heavily chlorinated congeners, and thus, these compounds were not detected or found at low levels in soils and sediments from some areas in northern Vietnam (Hoai et al., 2010; Toan and Quy, 2015) The abundance of PCB-28 and PCB-52 in the samples from Thai Nguyen reveals a near-source and ongoing emission of PCBs in this industrial area, and emphasizes the feature of street dusts as an indicator of current pollution status of PCBs and other organic pollutants as well (Klees et al., 2015, 2017; Sohail et al., 2018) The samples from Bac Giang showed a variegated pattern of seven inPCBs, possibly due to relatively low detection rates and concentrations of these congeners in this rural area 3.3 Concentrations of seven indicator PCBs (in-PCBs) The term indicator PCBs refers to a group of two mono-ortho (i.e., PCB-28 and -118) and five di-ortho (i.e., PCB-52, -101, -138, -153, and -180) substituted congeners, that dominated the PCB patterns in technical mixtures as well as environmental samples and foodstuffs (Babut et al., 2009; Capel et al., 1985; Kim et al., 2004) Concentrations of Σ7in-PCBs (median and range) in the street dusts from Thai Nguyen, Hanoi, and Bac Giang were 3.0 (0.54–22), 3.4 (2.1–9.7), and 0.055 (0.0070–0.33) ng g−1, respectively Similar to the trend observed for Σ209PCBs, levels of Σ7in-PCBs in the rural samples were the lowest, and the difference between the industrial and urban samples was insignificant The contamination degree of seven in-PCBs in our samples was much lower than those of six in-PCBs (excluding PCB-118) detected in street dusts from different functional areas (e.g., rural, urban, industrially influenced urban, and industrial sites) in North Rhine-Westphalia, Germany (median 59, range 17–12,600 ng g−1; Klees et al., 2015) 3.4 Concentrations of dioxin-like PCBs (dl-PCBs) Concentrations of dl-PCBs and toxic equivalent quantity (WHOTEQ) derived for dl-PCBs in the street dusts from northern Vietnam are shown in Tables and 3, respectively The dl-PCB concentrations and WHO-TEQ levels in the urban samples were a little higher than those from the industrial park, but the difference was not statistically significant Levels of dl-PCBs and WHO-TEQ in our street dust samples were lower than those detected in outdoor dusts from other countries such as China (Wang et al., 2013), Germany (Klees et al., 2015, 2017), 351 H.Q Anh et al / Science of the Total Environment 652 (2019) 345–355 Table TEQ concentrations of dl-PCBs (pg WHO-TEQ g−1) in street dust from northern Vietnam Industrial area, Thai Nguyen Congener TEFa Urban area, Hanoi Rural area, Bac Giang Median Min Max Median Min Max Median Min Max Non-ortho substituted congeners PCB-77 0.0001 PCB-81 0.0003 PCB-126 0.1 PCB-169 0.03 0.016 n.d.b 0.78 n.d 0.0023 n.d n.d n.d 0.12 0.017 2.1 n.d 0.0080 n.d 1.2 n.d 0.0048 n.d n.d n.d 0.026 0.0038 3.4 n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d Mono-ortho substituted congeners PCB-105 0.00003 PCB-114 0.00003 PCB-118 0.00003 PCB-123 0.00003 PCB-156 0.00003 PCB-157 0.00003 PCB-167 0.00003 PCB-189 0.00003 WHO-TEQs 0.0097 n.d 0.014 n.d 0.0017 n.d 0.0010 n.d 0.82 0.0022 n.d 0.0030 n.d n.d n.d n.d n.d 0.0079 0.033 0.0018 0.050 0.0013 0.0042 0.0011 0.0020 0.0010 2.3 0.013 0.0010 0.024 n.d 0.0033 0.0010 0.0010 n.d 1.2 0.0094 n.d 0.017 n.d 0.0023 n.d n.d n.d 0.036 0.045 0.0030 0.086 0.0016 0.010 0.0025 0.0037 0.0010 3.6 0.00030 n.d n.d n.d n.d n.d n.d n.d 0.00030 n.d n.d n.d n.d n.d n.d n.d n.d n.d 0.0011 n.d 0.0021 n.d 0.00030 n.d n.d n.d 0.0036 a b Toxic equivalency factors WHO 2005 TEF (Van den Berg et al., 2006) Not detected India (Chakraborty et al., 2016), and Pakistan (Sohail et al., 2018) Concentrations of dl-PCBs in the Hanoi street dusts (median 1.5, range 1.1–5.2 ng g−1) were comparable to levels found in soil (3.8, 3.0–5.0 ng g−1) but lower than levels in sediment (11, 9.1–16 ng g−1) collected from surrounding areas of this city such as Kieu Ky agricultural area and Cau Bay river (Toan and Quy, 2015) The proportion (average ± SD) of dl-PCBs in total PCBs in the samples from Hanoi was 16.1 ± 2.7%, that much higher than those from Thai Nguyen (7.9 ± 2.9%) and Bac Giang (7.3 ± 7.2%) The most dominant dl-PCBs were PCB-118, -105, -77, and -156 (Fig 2) The pattern of dl-PCBs in the Hanoi street dusts (PCB-118 N −105 N −156 N −77 N −167) was quite similar to those detected in soil samples from Kieu Ky area (Toan and Quy, 2015) The samples from Thai Nguyen industrial park showed a markedly higher proportion of PCB-77 than those from Hanoi and Bac Giang PCB-77 was clarified as the most important coplanar congener in road dusts from SIPCOT industrial region in Chennai, India with possible emission sources related to the combustion of coal and industrial waste (Chakraborty et al., 2016) Furthermore, the prevalence of PCB-77 in the atmospheric environment around steel and iron industrial complexes in China (Li et al., 2011) and Korea (Choi et al., 2008), suggests the emission of PCB-77 from metallurgical plants in Thai Nguyen Although PCB-126 was detected at minor levels, this congener exhibited the largest contribution to WHO-TEQs in most samples from Hanoi and Thai Nguyen that accounted up to 98.2% of TEQ values Fig Compositions of dl-PCBs and WHO-TEQs in street dusts from northern Vietnam 352 H.Q Anh et al / Science of the Total Environment 652 (2019) 345–355 The contributions of other congeners such as PCB-81, -114, -123, -157, -169, and -189 were insignificant After removing two values of non-detected dl-PCBs in the rural area, log-transformed Σdl-PCBs and Σ7in-PCBs were linearly correlated (R = 0.95, p b 0.0001) (Eq (5)), suggesting their similar emission sources logdlPCBs ẳ 0:3740:031ị ỵ 1:005ð0:046Þ logΣ7in−PCBs ð5Þ As previously discerned, a detailed and accurate determination of dlPCBs is relatively complicated and expensive, and therefore, various inPCB schemes have been evaluated to generate interconversion factors between in-PCBs and dl-PCBs (Gandhi et al., 2015) Linear regression analysis also indicates a moderate relationship between logΣ7in-PCBs and log(dl-PCB-TEQs) in our road dust samples (R = 0.63, p b 0.0001) However, in order to obtain more reliable conversion factors, an intensive investigation with larger sample size under different schemes is needed Similar to those observed for the ratios of Σ7in-PCBs to total PCBs, ratios of Σ7in-PCBs to Σdl-PCBs in the Hanoi and Thai Nguyen road dusts (average 2.3 and 3.2, respectively) were in line with the values reported for mixtures Aroclor 1254 (2.6) and Aroclor 1248 (3.5) (Frame et al., 1996) 3.5 Potential sources of PCBs In order to track the origins of PCBs in the outdoor environment of the investigated areas, we analyzed PCB homolog compositions in street dust samples and in selected technical formulations by hierarchical cluster analysis (Fig S1) Almost all the samples from the industrial park in Thai Nguyen were clustered with lightly chlorinated mixtures such as Aroclor 1016, 1242, and 1248, or Kanechlor 300 and 400 These formulations have been applied as additives in dielectric fluids in capacitors and transformers, heat transfer fluids and hydraulic fluids in industrial systems, and other open applications such as plasticizers, adhesives, and wax extenders (IARC, 2016) The homolog patterns of PCBs in urban street dusts were similar to those existed in more highly chlorinated mixtures such as Aroclor 1254 or Kanechlor 500, which have been extensively used for both closed and partially-closed systems (e.g., dielectric fluids, hydraulic fluids, and lubricants) and open applications (e.g., plasticizers, adhesives, wax extenders, dedusting agents, inks, cutting oils, sealants, and caulking compounds) (IARC, 2016) The patterns of urban samples were also in accordance with the homolog profiles of PCB mixtures from Russia (Sovol) or China (PCB5), that were imported into Vietnam in the 1960–1990 period (Kawano and Thao, 2012; Minh et al., 2008; Toan et al., 2007) Samples from the rural area showed a non-uniform pattern that requires more extensive investigations with larger sample sizes According to the Vietnam National Implementation Plan for the Stockholm Convention on POPs, it has been estimated that there were 7000 tons of potentially PCBcontaining oils in Vietnam as of 2006 Of these, approximately 1400 tons were transformer and capacitor oils belonging to the Vietnam Electricity and other independent power plants through the country However, information about PCB usage in other industrial sectors is still obscure (The World Bank, 2015) Principal component analysis of congener-specific profiles has been considered as a useful way to estimate the potential emission sources of PCBs (Chakraborty et al., 2016; Wang et al., 2016) This multivariate tool was applied for log-transformed concentrations of selected PCB congeners with detection rates over 70% in the whole sample set Four major principal components (PC-1, -2, -3, and -4) were extracted, constituting 48.9, 30.8, 8.5, and 5.6% of total variance, respectively (Fig S2) PC-1 highly correlated with penta- and hexachlorinated congeners, including major components in PCB mixtures such as PCB-95, -99, -101, -110, -138, and -153, and most dl-PCBs (e.g., PCB-105, -114, -118, -123, -156, -157, and -167) The correlation in this PC can be possibly explained by the leakages of PCBs from insulating oils in old electric equipment and lubricating oils in motor vehicles (Hoai et al., 2010; Toan et al., 2007); the outgassing of PCBs from PCB-containing construction materials in buildings, roads, or transport infrastructure (Klees et al., 2015; Shanahan et al., 2015); and the emission due to inappropriate disposal of PCB-containing wastes (Romano et al., 2013) A coplanar congener (i.e., PCB-77) and six lightly chlorinated congeners such as PCB-28, -52, -44, -49, -70, and -74 were loaded with PC-2, suggesting the emissions from metallurgical plants in industrial area (Cetin, 2016; Chakraborty et al., 2016) and the use of PCBs in paints, surface coatings, and plastic additives (Wang et al., 2016) PC-3 is associated with two heptachloro congeners as PCB-170 and PCB-180, that dominated highly chlorinated mixtures (e.g., Aroclor 1260 and Kanechlor 600) and exist in transformer oils, hydraulic fluids, plasticizers, and dedusting agents (IARC, 2016) The last PC showed a high loading with only PCB-126, a typical dioxin-like congener that is unintentionally released during combustion and high temperature processes (Chakraborty et al., 2016) Nevertheless, the ratios of (PCB-126 + PCB-169) / (PCB-77 + PCB-126 + PCB-169) in the samples from Hanoi and Thai Nguyen were 9.5 ± 8.3 and 6.3 ± 7.4%, respectively, and were more similar to those of commercial PCB mixtures than those from pyrogenic sources (Kannan et al., 1987; Sakai et al., 1994) In addition, the strongly correlation between logΣdl-PCBs and logΣ7in-PCBs (Eq (5)) partially confirmed the emission of dl-PCBs from PCB mixtures Our results were consistent with values reported for sediment samples from Hanoi urban area and rural area in Hue city, Vietnam, and urban and suburban areas in Osaka, Japan (Kishida et al., 2010) PCB-11 did not show any significant relationship with other congeners, suggesting its unique emission source PCB-11 can be inadvertently formed during the production of pigments and it has been found as a dominant impurity in different types of commercial pigments and paints such as monoazo yellow, diarylide yellow, bisacetoacetic arylides, and quinophthalone (Anezaki and Nakano, 2014; Hu and Hornbuckle, 2010; Shang et al., 2014) Because of the wide applications of these pigments, PCB-11 has been detected in various consumer products, e.g., cardboard, newspaper, magazine, plastic bag, and printed textiles (Guo et al., 2014; Rodenburg et al., 2010) The associations between environmental levels of PCB-11 and human population densities have been demonstrated elsewhere (Basu et al., 2009) Baek et al (2010) suggested that the source of PCB-11 is located in the residential areas rather than in industrial and semirural areas The omnipresence of PCB-11 in the street dusts from northern Vietnam, especially in the Hanoi urban area, has been likely associated with human activities utilizing pigments, for example, the increasing use of color-printed and dyed consumer products (Hu and Hornbuckle, 2010; Romano et al., 2013) Besides, the emission of PCB-11 from construction materials and decoration and furnishing items of the buildings should be also considered (Baek et al., 2010) It should be noted that PCB-11 is a non-ortho substituted congener, and therefore, it may represent dioxin-like toxicity (Rodenburg et al., 2010) Our findings on the ubiquitous presence of PCB-11 in street dusts suggest an urgent need for further investigations on this unique congener in Vietnam, such as emission source tracking, air pollution monitoring, spatial distribution, and seasonal variation studies 3.6 Human exposure to PCBs via road dust ingestion Daily intake doses of total PCBs and dl-PCB-TEQs, and HQ and CR values of total PCBs in the street dusts from northern Vietnam are summarized in Table S8 The occupationally exposed persons in the industrial and urban areas were estimated to receive the highest PCB doses (4.2 × 10−3 to 2.3 × 10−1 ng kg−1 d−1), that were about one order of magnitude higher than those received by general population (2.3 × 10−4 to 1.3 × 10−2 ng kg−1 d−1) This observation suggests that more consideration should be given to labor protection for some occupational groups, for instance, providing them with dust-proof clothing H.Q Anh et al / Science of the Total Environment 652 (2019) 345–355 such as masks with effective dust filtration and dust-proof glasses and gloves The median daily intake doses of total PCBs of 2.3 × 10−2 and 1.8 × 10−2 ng kg−1 d−1 were estimated for children in industrial and urban areas, respectively, that were comparable to those derived for occupational groups In Vietnam, due to the lack of playgrounds, children have played for hours per day on the pavement and some toddlers have been ‘strolling’ fed, resulting in a higher body burden of contaminated outdoor dusts Residents in the Bac Giang rural area were exposed to markedly lower doses of PCBs in street dusts of 2.6 × 10−5 and 4.2 × 10−4 ng kg−1 d−1 for adults and children, respectively Nevertheless, all the HQ and CR values were several orders of magnitude lower than critical values (HQ b and CR b 10−6), indicating negligible non-cancer and cancer risks of PCBs associated with street dusts in these study areas Furthermore, the daily intakes of dl-PCBTEQs in our study were also smaller than tolerable daily intake range of 1–4 pg TEQ kg−1 d−1 (Van Leeuwen et al., 2010) As compared with the overall daily intake of PCBs (comprising diet, indoor dust ingestion, and inhalation pathways) of 50 ng d−1 previously reported by Tue et al (2013) for Hanoi residents, the contribution of street dust ingestion was insignificant for normal adults but it can contribute about 2% in total PCB intake by occupationally exposed individuals The above results on risk assessment need further confirmation and reconsideration because of some limitations Firstly, we assumed a 100% absorption for dust-bound PCBs because of the absence of bioaccessibility estimation Secondly, we report the ID values estimated only for road dust ingestion, while indoor dust ingestion, air inhalation, and food consumption are major sources of PCBs (Harrad et al., 2009; Tue et al., 2013) Thirdly, dioxin-like activities in dusts should be evaluated by in vitro bioassays combined with chemical analysis of dioxinrelated compounds other than dl-PCBs (Tue et al., 2010b) Therefore, a more comprehensive/detailed risk assessment, comprising multiple exposure pathways, bioaccessibility determination, and questionnaire survey, should be conducted to generate more accurate and meaningful information about human health effects of PCBs in Vietnam, especially for occupationally exposed individuals Conclusions This is the first data set reporting levels and accumulation profiles of 209 PCB congeners in street dust samples collected from northern Vietnam Concentrations of total PCBs in street dusts from the industrial park and urban area were significantly higher than those detected in the rural ones, suggesting their emissions related to rapid industrialization and urbanization The specific patterns of PCBs characterized for street dusts from each study area have revealed the relative contributions of different emission sources and original PCB technical mixtures Beside the historical release from imported PCB-containing oils and old electrical equipment, PCBs have been emitted from other emerging sources such as consumer products, building materials, and vehicle lubricants, especially in urban areas Industrial activities have been also a considerable contributor to total PCB emission in northern Vietnam with a particular pattern dominated by lightly chlorinated homologs PCB-11 has been found as an abundant congener in street dusts from all the study areas, indicating the widely application of consumer products containing it in northern Vietnam Although human health risks associated with PCBs in street dusts of this study were generally low, a more comprehensive evaluation comprising different exposure pathways should be conducted for this typical class of POPs in Vietnam Acknowledgements This study was supported in part by Grants-in-Aid for Scientific Research (B: 16H02963) of the Japan Society for the Promotion of Science (JSPS) and the Environment Research and Technology Development Fund (SII-3-2) of the Environmental Restoration and Conservation Agency of Japan (ERCA); and the Vietnam's National Foundation for 353 Science and Technology Development (NAFOSTED) under grant number 104.04-2017.310 We thank the staff of VNU University of Science, TNU University of Science (Thai Nguyen University, Vietnam), and CATE in sampling activities and sample analysis We wish to thank Prof Alexander Scheeline (University of Illinois at Urbana-Champaign, US) for critical reading of the manuscript Appendix A Supplementary data Supplementary data to this article can be found online at https://doi org/10.1016/j.scitotenv.2018.10.240 References Anezaki, K., Nakano, T., 2014 Concentration levels and congener profiles of polychlorinated biphenyls, pentachlorobenzene, and hexachlorobenzene in commercial pigments Environ Sci Pollut Res 21, 998–1009 Anh, H.Q., Tomioka, K., Tue, N.M., Tri, T.M., Minh, T.B., Takahashi, S., 2018a PBDEs and novel brominated flame retardants in road dust from northern Vietnam: levels, congener profiles, emission sources and implications for human exposure Chemosphere 197, 389–398 Anh, H.Q., Tomioka, K., Tue, N.M., Suzuki, G., Minh, T.B., Viet, P.H., Takahashi, S., 2018b Comprehensive analysis of 942 organic micro-pollutants in settled dusts from northern Vietnam: pollution status and implications for human exposure J Mater Cycles Waste Manag https://doi.org/10.1007/s10163-018-0745-2 ATSDR, 2000 Toxicological Profile for Polychlorinated Biphenyls (PCBs) https://www atsdr.cdc.gov/toxprofiles/tp17.pdf, Accessed date: 30 January 2018 Babut, M., Miege, C., Villeneuve, B., Abarnou, A., Duchemin, J., Marchand, P., Narbonne, J.F., 2009 Correlations between dioxin-like and indicators PCBs: potential consequences for environmental studies involving fish or sediment Environ Pollut 157, 3451–3456 Baek, S.Y., Choi, S.D., Park, H., Kang, J.H., Chang, Y.S., 2010 Spatial and seasonal distribution of polychlorinated biphenyls (PCBs) in the vicinity of an iron and steel making plant Environ Sci Technol 44, 3035–3040 Basu, I., Arnold, K.A., Venier, M., Hites, R.A., 2009 Partial pressures of PCB-11 in air from several Great Lakes sites Environ Sci Technol 43, 6488–6492 Cao, Z., Zhao, L., Kuang, J., Chen, Q., Zhu, G., Zhang, K., Wang, S., Wu, P., Zhang, X., Wang, X., Harrad, S., Sun, J., 2017 Vehicles as outdoor BFR sources: evidence from an investigation of BFR occurrence in road dust Chemosphere 179, 29–36 Capel, P.D., Rapaport, R.A., Eisenreich, S.J., Looney, B.B., 1985 PCBQ: computerized quantification of total PCB and congeners in environmental samples Chemosphere 14, 439–450 Carvalho, F.P., Villeneuve, J.P., Cattini, C., Tolosa, I., Thuan, D.D., Nhan, D.D., 2008 Agrochemical and polychlorobyphenyl (PCB) residues in the Mekong River delta, Vietnam Mar Pollut Bull 56, 1476–1485 Carvalho, F.P., Villeneuve, J.P., Cattini, C., Thuan, D.D., Nhan, D.D., 2009 Polychlorinated biphenyl congeners in the aquatic environment of the Mekong River, south of Vietnam Bull Environ Contam Toxicol 83, 892–898 CCME, 1999 Canadian Soil Quality Guidelines for the Protection of Environmental and Human Health – Polychlorinated Biphenyls (Total) http://ceqg-rcqe.ccme.ca/download/en/274, Accessed date: 11 October 2018 Cetin, B., 2016 Investigation of PAHs, PCBs and PCNs in soils around a heavily industrialized area in Kocaeli, Turkey: concentrations, distributions, sources and toxicological effects Sci Total Environ 560–561, 160–169 Chakraborty, P., Prithiviraj, B., Selvaraj, S., Kumar, B., 2016 Polychlorinated biphenyls in settled dust from informal electronic waste recycling workshops and nearby highways in urban centers and suburban industrial roadsides of Chennai city, India: levels, congener profiles and exposure assessment Sci Total Environ 573, 1413–1421 Choi, S.D., Baek, S.Y., Chang, Y.S., 2008 Atmospheric levels and distribution of dioxin-like polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in the vicinity of an iron and steel making plant Atmos Environ 42, 2479–2488 Du, S., Wall, S.J., Cacia, D., Rodenburg, L.A., 2009 Passive air sampling for polychlorinated biphenyls in the Philadelphia metropolitan area Environ Sci Technol 43, 1287–1292 Eguchi, A., Nomiyama, K., Tue, N.M., Trang, P.T.K., Viet, P.H., Takahashi, S., Tanabe, S., 2015 Residue profiles of organohalogen compounds in human serum from e-waste recycling sites in North Vietnam: association with thyroid hormone levels Environ Res 137, 440–449 Erickson, M.D., 1997 Analytical Chemistry of PCBs second ed CRC Press, Boca Raton Erickson, M., Kaley II, R.G., 2011 Applications of polychlorinated biphenyls Environ Sci Pollut Res 18, 135–151 Frame, G.M., Cochran, J.W., Bowadt, S.S., 1996 Complete PCB congener distributions for 17 Aroclor mixtures determined by HRGC systems optimized for comprehensive, quantitative, congener-specific analysis J High Resolut Chromatogr 19, 657–668 Froescheis, O., Looser, R., Cailliet, G.M., Jarman, W.M., Ballschmiter, K., 2000 The deep-sea as a final global sink of semivolatile persistent organic pollutants? Part I: PCBs in surface and deep-sea dwelling fish of the North and South Atlantic and the Monterey Bay Canyon (California) Chemosphere 40, 651–660 Gandhi, N., Bhavsar, S.P., Reiner, E.J., Chen, T., Morse, D., Arhonditsis, G.B., Drouillard, K.G., 2015 Evaluation and interconversion of various indicator PCB schemes for ΣPCB and dioxin-like PCB toxic equivalent levels in fish Environ Sci Technol 49, 123–131 354 H.Q Anh et al / Science of the Total Environment 652 (2019) 345–355 Guo, J., Capozzi, S.L., Kraeutler, T.M., Rodenburg, L.A., 2014 Global distribution and local impacts of inadvertently generated polychlorinated biphenyls in pigments Environ Sci Technol 48, 8573–8580 Hansen, S., Odland, J.Ø., Phi, D.T., Nieboer, E., Sandanger, T.M., 2009 Maternal levels of organochlorines in two communities in southern Vietnam Sci Total Environ 408, 225–232 Harrad, S., Ibarra, C., Robson, M., Melymuk, L., Zhang, X., Diamond, M., Douwes, J., 2009 Polychlorinated biphenyls in domestic dust from Canada, New Zealand, United Kingdom and United States: implications for human exposure Chemosphere 76, 232–238 He, M.J., Yang, T., Yang, Z.H., Li, Q., Wei, S.Q., 2017 Occurrence and distribution of organophosphate esters in surface soil and street dust from Chongqing, China: implications for human exposure Arch Environ Contam Toxicol 73 (3), 349–361 Hoai, P.M., Ngoc, N.T., Minh, N.H., Viet, P.H., Berg, M., Alder, A.C., Giger, W., 2010 Recent levels of organochlorine pesticides and polychlorinated biphenyls in sediments of the sewer system in Hanoi, Vietnam Environ Pollut 158, 913–920 Hong, S.H., Yim, U.H., Shim, W.J., Oh, J.R., Viet, P.H., Park, P.S., 2008 Persistent organochlorine residues in estuarine and marine sediments from Ha Long Bay, Hai Phong Bay, and Ba Lat Estuary, Vietnam Chemosphere 72, 1193–1202 Hu, D., Hornbuckle, K.C., 2010 Inadvertent polychlorinated biphenyls in commercial paint pigments Environ Sci Technol 44, 2822–2827 Hu, D., Martinez, A., Hornbuckle, K.C., 2008 Discovery of non-aroclor PCB (3,3′dichlorobiphenyl) in Chicago air Environ Sci Technol 42, 7873–7877 Hue, N.T., Thuy, N.T.T., Tung, N.H., 2016 Polychlorobenzenes and polychlorinated biphenyls in ash and soil from several industrial areas in North Vietnam: residue concentrations, profiles and risk assessment Environ Geochem Health 38, 399–411 IARC, 2016 IARC Monographs on the evaluation of carcinogenic risk to humans Volume 107 – polychlorinated biphenyls and polybrominated biphenyls http://monographs iarc.fr/ENG/Monographs/vol107/mono107.pdf, Accessed date: 21 February 2018 Jaward, F.M., Farrar, N.J., Harner, T., Sweetman, A.J., Jones, K.C., 2004 Passive air sampling of PCBs, PBDEs, and organochlorine pesticides across Europe Environ Sci Technol 38, 34–41 Jaward, F.M., Zhang, G., Nam, J.J., Sweetman, A.J., Obbard, J.P., Kobara, Y., Jones, K.C., 2005 Passive air sampling of polychlorinated biphenyls, organochlorine compounds, and polybrominated diphenyl ethers across Asia Environ Sci Technol 39, 8638–8645 Jones-Otazo, H., Clarke, J.P., Diamond, M.L., Archbold, J.A., Ferguson, G., Harner, T., Richardson, G.M., Ryan, J.J., Wilford, B., 2005 Is house dust the missing exposure pathway for PBDEs? An analysis of the urban fate and human exposure to PBDEs Environ Sci Technol 39, 5121–5130 Kannan, K., Tanabe, S., Wakimoto, R., Tatsukawa, R., 1987 Coplanar polychlorinated biphenyls in aroclor and kanechlor mixtures J Assoc Off Anal Chem 70, 451–454 Kannan, K., Tanabe, S., Quynh, H.T., Hue, N.D., Tatsukawa, R., 1992 Residue pattern and dietary intake of persistent organochlorine compounds in food stuffs from Vietnam Arch Environ Contam Toxicol 22, 367–374 Kannan, K., Tanabe, S., Tatsukawa, R., 1995 Geographical distribution and accumulation features of organochlorine residues in fish in tropical Asia and Oceania Environ Sci Technol 29, 2673–2683 Kawano, M., Thao, V.D., 2012 Spatial and temporal trends of persistent organic chemicals in Vietnam soils In: Longanathan, B.G., Lam, P.K.S (Eds.), Global Contamination Trends of Persistent Organic Chemicals CRC Press, Boca Raton, pp 279–303 Khan, M.U., Li, J., Zhang, G., Malik, R.N., 2016 New insight into the levels, distribution and health risk diagnosis of indoor and outdoor dust-bound FRs in colder, rural and industrial zones of Pakistan Environ Pollut 216, 662–674 Kim, K.S., Song, B.J., Kim, J.G., 2003 Analysis of all PCB congeners in air samples by HRGC/ HRMS J Anal Sci Technol 16, 309–319 Kim, M., Kim, S., Yun, S., Lee, M., Cho, B., Park, J., Son, S., Kim, O., 2004 Comparison of seven indicator PCBs and three coplanar PCBs in beef, pork, and chicken fat Chemosphere 54, 1533–1538 Kishida, M., Imamura, K., Takenaka, N., Maeda, Y., Viet, P.H., Kondo, A., Bandow, H., 2010 Characteristics of the abundance of polychlorinated dibenzo-p-dioxin and dibenzofurans, and dioxin-like polychlorinated biphenyls in sediment samples from selected Asian regions in Can Gio, southern Vietnam and Osaka, Japan Chemosphere 78, 127–133 Klees, M., Hiester, E., Bruckmann, P., Schmidt, T.C., 2015 Polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins and dibenzofurans in street dust of North-Rhine Westphalia, Germany Sci Total Environ 511, 72–81 Klees, M., Hombrecher, K., Gladtke, D., 2017 Polychlorinated biphenyls in the surrounding of an e-waste recycling facility in North-Rhine Westphalia: levels in plants and dusts, spatial distribution, homologue pattern and source identification using the combination of plants and wind direction data Sci Total Environ 603–604, 606–615 Li, X., Li, Y., Zhang, Q., Wang, P., Yang, H., Jiang, G., Wei, F., 2011 Evaluation of atmospheric sources of PCDD/Fs, PCBs and PBDEs around a steel industrial complex in northeast China using passive air samplers Chemosphere 84, 957–963 Li, Y., Geng, D., Liu, F., Wang, T., Wang, P., Zhang, Q., Jiang, G., 2012 Study of PCBs and PBDEs in King George Island, Antarctica, using PUF passive air sampling Atmos Environ 51, 140–145 Minh, N.H., Someya, M., Minh, T.B., Kunisue, T., Iwata, H., Watanabe, M., Tanabe, S., Viet, P.H., Tuyen, B.C., 2004 Persistent organochlorine residues in human breast milk from Hanoi and Hochiminh city, Vietnam: contamination, accumulation kinetics and risk assessment for infants Environ Pollut 129, 431–441 Minh, N.H., Minh, T.B., Kajiwara, N., Kunisue, T., Iwata, H., Viet, P.H., Tu, N.P.C., Tuyen, B.C., Tanabe, S., 2006 Contamination by polybrominated ethers and persistent organochlorines in catfish and feed from Mekong River Delta, Vietnam Environ Toxicol Chem 25, 2700–2709 Minh, T.B., Iwata, H., Takahashi, S., Viet, P.H., Tuyen, B.C., Tanabe, S., 2008 Persistent organic pollutants in Vietnam: environmental contamination and human exposure Rev Environ Contam Toxicol 193, 213–290 MONRE, 2009 QCVN 07: 2009/BTNMT – National Technical Regulation on Hazardous Waste Thresholds http://vea.gov.vn/vn/Pages/vbqppl_NoiDung.aspx?vId=8868, Accessed date: 20 February 2018 MONRE, 2012 QCVN 43: 2012/BTNMT – National Technical Regulation on Sediment Quality http://cem.gov.vn/Portals/0/moi/qcvn%2043.pdf, Accessed date: 20 February 2018 Nhan, D.D., Am, N.M., Carvalho, F.P., Villeneuve, J.P., Cattini, C., 1999 Organochlorine pesticides and PCBs along the coast of North Vietnam Sci Total Environ 237–238, 363–371 Nhan, D.D., Carvalho, F.P., Am, N.M., Tuan, N.Q., Yen, N.T.H., Villeneuve, J.P., Cattini, C., 2001 Chlorinated pesticides and PCBs in sediments and molluscs from freshwater canals in the Hanoi region Environ Pollut 112, 311–320 Phi, T.H., Chinh, P.M., Hung, N.T., Ly, L.T.M., Thai, P.K., 2017 Spatial distribution of elemental concentrations in street dust of Hanoi, Vietnam Bull Environ Contam Toxicol 98, 277–282 Ramu, K., Kajiwara, N., Sudaryanto, A., Isobe, T., Takahashi, S., Subramanian, A., Ueno, D., Zheng, G.J., Lam, P.K.S., Takada, H., Zakaria, M.H., Viet, P.H., Prudente, M., Tana, T.S., Tanabe, S., 2007 Asian mussel watch program: contamination status of polybrominated diphenyl ethers and organochlorines in coastal waters of Asian countries Environ Sci Technol 41, 4580–4586 Rodenburg, L.A., Guo, J., Du, S., Cavallo, G.J., 2010 Evidence for unique and ubiquitous environmental sources of 3,3′-dichlorobiphenyl (PCB 11) Environ Sci Technol 44, 2816–2821 Romano, S., Piazza, R., Mugnai, C., Giuliani, S., Bellucci, L.G., Cu, N.H., Vecchiato, M., Zambon, S., Nhon, D.H., Frignani, M., 2013 PBDEs and PCBs in sediments of the Thi Nai Lagoon (Central Vietnam) and soils from its mainland Chemosphere 90, 2396–2402 Sakai, S., Hiraoka, M., Takeda, N., Shiozaki, K., 1994 Formation and emission of non-ortho CBs and mono-ortho CBs in municipal waste incineration Chemosphere 29, 1979–1986 Schecter, A., Furst, P., Kruger, C., Meemken, H.A., Groebel, W., Constable, J.D., 1989 Levels of polychlorinated dibenzofurans, dibenzodioxins, PCBs, DDT and DDE, hexachlorobenzene, dieldrin, hexachlorocyclohexanes and oxychlordane in human breast milk from the United States, Thailand, Vietnam, and Germany Chemosphere 18, 445–454 Schecter, A., Furst, P., Groebel, W., Constable, J.D., Kolesnikov, S., Beim, A., Boldonov, A., Trubitsun, E., Vlasov, B., Cau, H.D., Dai, L.C., Quynh, H.T., 1990 Levels of chlorinated dioxins, dibenzofurans and other chlorinated xenobiotics in food from the Soviet Union and the south of Vietnam Chemosphere 20, 799–806 Schecter, A., McGee, H., Stanley, J., Boggess, K., 1992 Dioxin, dibenzofuran, and PCB, including coplanar PCB levels in the blood of Vietnam veterans in the Michigan Agent Orange Study Chemosphere 25, 205–208 Schecter, A., McGee, H., Stanley, J., Boggess, K., 1993 Chlorinated dioxin, dibenzofuran, coplanar, mono-ortho, and di-ortho substituted PCB congener levels in blood and semen of Michigan Vietnam veterans compared with levels in Vietnamese exposed to agent Orange Chemosphere 27, 241–252 Shanahan, C.E., Spak, S.N., Martinez, A., Hornbuckle, K.C., 2015 Inventory of PCBs in Chicago and opportunities for reduction in airborne emissions and human exposure Environ Sci Technol 49, 13878–13888 Shang, H., Li, Y., Wang, T., Wang, P., Zhang, H., Zhang, Q., Jiang, G., 2014 The presence of polychlorinated biphenyls in yellow pigment products in China with emphasis on 3,3′-dichlorobiphenyl (PCB 11) Chemosphere 96, 44–50 Shi, S., Huang, Y., Zhou, L., Yang, W., Dong, L., Zhang, L., Zhan, X., 2013 A preliminary investigation of BDE-209, OCPs, and PAHs in urban road dust from Yangtze River Delta, China Environ Monit Assess 185, 4887–4896 Shi, S., Dong, L., Yang, W., Zhou, L., Zhang, L., Zhang, X., Huang, Y., 2014 Monitoring of airborne polybrominated diphenyl ethers in the urban area by means of road dust and camphor tree barks Aerosol Air Qual Res 14, 1106–1113 Sohail, M., Eqani, S.A.M.A.S., Podgorski, J., Bhowmik, A.K., Mahmood, A., Ali, N., SaboAttwood, T., Bokhari, H., Shen, H., 2018 Persistent organic pollutant emission via dust deposition throughout Pakistan: spatial patterns, regional cycling and their implication for human health risks Sci Total Environ 618, 829–837 Stringer, R., Johnston, P., 2001 PCBs (polychlorinated biphenyls) In: Stringer, R., Johnston, P (Eds.), Chlorine and the Environment: An Overview of the Chlorine Industry Springer, Dordrecht, pp 277–304 Takahashi, S., Tue, N.M., Takayanagi, C., Tuyen, L.H., Suzuki, G., Matsukami, H., Viet, P.H., Kunisue, T., Tanabe, S., 2017 PCBs, PBDEs and dioxin-related compounds in floor dust from an informal end-of-life vehicle recycling site in northern Vietnam: contamination levels and implications for human exposure J Mater Cycles Waste Manag 19, 1333–1341 Thao, V.D., Kawano, M., Tatsukawa, R., 1993a Persistent organochlorine residues in soils from tropical and sub-tropical Asian countries Environ Pollut 81, 61–71 Thao, V.D., Kawano, M., Matsuda, M., Wakimoto, T., Tatsukawa, R., 1993b Chlorinated hydrocarbon insecticide and polychlorinated biphenyl residues in soils from southern provinces of Vietnam Int J Environ Anal Chem 50, 147–159 The World Bank, 2015 Implementation completion and results report (TF-94744) on a GEF grant in the amount of US$ million to the Socialist Republic of Vietnam for a PCB management project http://documents.worldbank.org/curated/en/640731468195589505/ pdf/ICR3593-ICR-VN-P099460-Box-394830B-PUBLIC-12-30-2015.pdf, Accessed date: 22 February 2018 Toan, V.D., Quy, N.P., 2015 Residues of polychlorinated biphenyls (PCBs) in sediment from CauBay River and their impacts on agricultural soil, human health risk in KieuKy area, Vietnam Bull Environ Contam Toxicol 95, 177–182 Toan, V.D., Thao, V.D., Walder, J., Schmutz, H.R., 2007 Level and distribution of polychlorinated biphenyls (PCBs) in surface soils from Hanoi, Vietnam Bull Environ Contam Toxicol 78, 351–360 Tri, T.M., Anh, H.Q., Tham, T.T., Quy, T.V., Long, N.Q., Nhung, D.T., Nakamura, M., Nishida, M., Maeda, Y., Boi, L.V., Minh, T.B., 2016 Distribution and depth profiles of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in H.Q Anh et al / Science of the Total Environment 652 (2019) 345–355 sediment collected from offshore waters of Central Vietnam Mar Pollut Bull 106, 341–346 Tue, N.M., Sudaryanto, A., Minh, T.B., Isobe, T., Takahashi, S., Viet, P.H., Tanabe, S., 2010a Accumulation of polychlorinated biphenyls and brominated flame retardants in breast milk from women living in Vietnamese e-waste recycling sites Sci Total Environ 408, 2155–2162 Tue, N.M., Suzuki, G., Takahashi, S., Isobe, T., Trang, P.T.K., Viet, P.H., Tanabe, S., 2010b Evaluation of dioxin-like activities in settled house dust from Vietnamese e-waste recycling sites: relevance of polychlorinated/brominated dibenzo-p-dioxin/furans and dioxin-like PCBs Environ Sci Technol 44, 9195–9200 Tue, N.M., Takahashi, S., Suzuki, G., Isobe, T., Viet, P.H., Kobara, Y., Seike, N., Zhang, G., Sudaryanto, A., Tanabe, S., 2013 Contamination of indoor dust and air by polychlorinated biphenyls and brominated flame retardants and relevance of nondietary exposure in Vietnamese informal e-waste recycling sites Environ Int 51, 160–167 Tuyen, L.H., Tue, N.M., Suzuki, G., Misaki, K., Viet, P.H., Takahashi, S., Tanabe, S., 2014a Aryl hydrocarbon receptor mediated activities in road dust from a metropolitan area, Hanoi—Vietnam: contribution of polycyclic aromatic hydrocarbons (PAHs) and human risk assessment Sci Total Environ 491–492, 246–254 Tuyen, L.H., Tue, N.M., Takahashi, S., Suzuki, G., Viet, P.H., Subramanian, A., Bulbule, K.A., Parthasarathy, P., Ramanathan, A., Tanabe, S., 2014b Methylated and unsubstituted polycyclic aromatic hydrocarbons in street dust from Vietnam and India: occurrence, distribution and in vitro toxicity evaluation Environ Pollut 194, 272–280 UNEP, 1999 Guidance for the Identification of PCBs and Materials Containing PCBs http:// www.pops.int/Implementation/IndustrialPOPs/PCBs/Guidance, Accessed date: January 2018 UNEP, 2001 Stockholm Convention on Persistent Organic Pollutants http://chm.pops.int/ Portals/0/Repository/convention_text/UNEP-POPS-COP-CONVTEXT-FULL.English PDF, Accessed date: February 2018 US EPA, 2017 Regional Screening Levels (RSLs) - Generic Tables (November 2017) https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables-november2017, Accessed date: 30 January 2018 Van den Berg, M., Birnbaum, L.S., Denison, M., De Vito, M., Farland, W., Feeley, M., Fiedler, H., Hakansson, H., Hanberg, A., Haws, L., Rose, M., Safe, S., Schrenk, D., Tohyama, C., 355 Tritscher, A., Tuomisto, J., Tysklind, M., Walker, N., Peterson, R.E., 2006 The 2005 World Health Organization reevaluation of human and mammalian toxic equivalency factors for dioxins and dioxin-like compounds Toxicol Sci 3, 223–241 Van Leeuwen, F.X., Feeley, M., Schrenk, D., Larsen, J.C., Farland, W., Younes, M., 2010 Dioxins: WHO's tolerable daily intake (TDI) revisited Chemosphere 40, 1095–1101 Vorkamp, K., 2016 An overlooked environmental issue? A review of the inadvertent formation of PCB-11 and other PCB congeners and their occurrence in consumer products and in the environment Sci Total Environ 541, 1463–1476 Wang, W., Huang, M.J., Zheng, J.S., Cheung, K.C., Wong, M.H., 2013 Exposure assessment and distribution of polychlorinated biphenyls (PCBs) contained in indoor and outdoor dusts and the impacts of particle size and bioaccessibility Sci Total Environ 463–464, 1201–1209 Wang, W., Wang, Y., Zhang, R., Wang, S., Wei, C., Chaemfa, C., Li, J., Zhang, G., Yu, K., 2016 Seasonal characteristics and current sources of OCPs and PCBs and enantiomeric signatures of chiral OCPs in the atmosphere of Vietnam Sci Total Environ 542, 777–786 Wang, P., Li, Y., Zhang, Q., Yang, Q., Zhang, L., Liu, F., Fu, J., Meng, W., Wang, D., Sun, H., Zheng, S., Hao, Y., Liang, Y., Jiang, G., 2017 Three-year monitoring of atmospheric PCBs and PBDEs at the Chinese Great Wall Station, West Antarctica: levels, chiral signature, environmental behaviors and source implication Atmos Environ 150, 407–416 WHO, 2000 Chapter 5.10 polychlorinated biphenyls (PCBs) http://www.euro.who.int/ data/assets/pdf_file/0016/123064/AQG2ndEd_5_10PCBs.PDF, Accessed date: 20 December 2017 Xu, F., Liu, Y.C., Wang, J., Zhang, G., Zhang, W., Liu, L., Wang, J., Pan, B., Lin, K., 2015 Characterization of heavy metals and brominated flame retardants in the indoor and outdoor dust of e-waste workshops: implication for on-site human exposure Environ Sci Pollut Res 22, 5469–5480 Zhao, N., Lu, X., Chao, S., 2016 Risk assessment of potentially toxic elements in smaller than 100-μm street dust particles from a valley-city in northwestern China Environ Geochem Health 38, 483–496 ... area of 3358.9 km2 and a population of approximately 7.7 million inhabitants in the year 2017 The urban area of Hanoi consists of twelve districts, which covers only 9% of total municipal area of. .. 2016 Distribution and depth profiles of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in H.Q Anh et al / Science of the Total Environment 652 (2019)... original formulations of PCBs Level of statistical significance was set at p b 0.05 A summary of results of correlation and regression analysis is presented in Table S7, while those of cluster and PCA