PBDEs and novel brominated flame retardants in road dust from northern Vietnam
Accepted Manuscript PBDEs and novel brominated flame retardants in road dust from northern Vietnam: Levels, congener profiles, emission sources and implications for human exposure Hoang Quoc Anh, Keidai Tomioka, Nguyen Minh Tue, Tran Manh Tri, Tu Binh Minh, Shin Takahashi PII: S0045-6535(18)30075-4 DOI: 10.1016/j.chemosphere.2018.01.066 Reference: CHEM 20647 To appear in: ECSN Received Date: 30 October 2017 Revised Date: January 2018 Accepted Date: 14 January 2018 Please cite this article as: Anh, H.Q., Tomioka, K., Tue, N.M., Tri, T.M., Minh, T.B., Takahashi, S., PBDEs and novel brominated flame retardants in road dust from northern Vietnam: Levels, congener profiles, emission sources and implications for human exposure, Chemosphere (2018), doi: 10.1016/ j.chemosphere.2018.01.066 This is a PDF file of an unedited manuscript that has been accepted for publication As a service to our customers we are providing this early version of the manuscript The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain AC C EP TE D M AN U SC RI PT ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT PBDEs and novel brominated flame retardants in road dust from northern Vietnam: levels, congener profiles, emission sources and implications for human exposure Hoang Quoc Anh a, b, c, Keidai Tomioka a, Nguyen Minh Tue d, e, Tran Manh Tri c, Tu Binh Minh c, Shin Takahashi a, * a Ehime University, 3-5-7 Tarumi, Matsuyama 790-8566, Japan b Tarumi, Matsuyama 790-8566, Japan RI PT M AN US C Center of Advanced Technology for the Environment (CATE), Graduate School of Agriculture, The United Graduate School of Agricultural Sciences (UGAS-EU), Ehime Univeristy, 3-5-7 10 c 11 Tong, Hanoi, Vietnam 12 d 13 Matsuyama 790-8577, Japan 14 e 15 of Science, Vietnam National University, 334 Nguyen Trai, Hanoi, Vietnam Faculty of Chemistry, VNU University of Science, Vietnam National University, 19 Le Thanh D Center for Marine Environmental Studies (CMES), Ehime University, 2-5 Bunkyo-cho, 16 EP TE Center for Environmental Technology and Sustainable Development (CETASD), VNU University 17 * 18 Address: Center of Advanced Technology for the Environment, Graduate School of Agriculture, 19 Ehime University, 3-5-7 Tarumi, Matsuyama 790-8566, Japan 20 Email: takahashi.shin.mu@ehime-u.ac.jp (S Takahashi) 21 Tel.: +81 89 946 9907 22 Fax: +81 89 946 9980 23 Submission to: Chemosphere (Elsevier) AC C Corresponding author: 24 ACCEPTED MANUSCRIPT Abstract Polybrominated diphenyl ethers (PBDEs) and selected novel brominated flame retardants 26 (NBFRs) were examined in road dust samples collected from three representative areas in northern 27 Vietnam, including seven inner districts of Hanoi metropolitan area, an industrial park in Thai 28 Nguyen province and a rural commune in Bac Giang province This study aims to provide basic 29 information on the contamination status, potential sources and human exposure to PBDEs and 30 NBFRs associated with road dust in northern Vietnam PBDEs were detected in all the samples at a 31 range of 0.91 to 56 ng g-1 with a median value of 16 ng g-1 PBDE concentrations in road dusts from 32 urban sites were significantly higher than those from industrial zone and rural area, suggesting their 33 environmental load related to urbanization in northern Vietnam BDE-209, major component of 34 deca-BDE technical mixtures, dominated the congener patterns in all samples, accounting for 60.8 35 to 91.9% of total PBDE levels Decabromodiphenyl ethane, an alternative of deca-BDE, was 36 observed in a detection frequency of 100% in urban and industrial areas and at levels comparable to 37 those of BDE-209 Other NBFRs such as pentabromoethylbenzene, hexabromobiphenyl and 1,2- 38 bis-(2,4,6-tribromophenoxy)ethane, were found at trace levels Daily intake doses of PBDEs via 39 road dust ingestion from 2.3 × 10-5 to 0.11 ng kg-bw-1 d-1 were estimated for residents in study 40 areas, indicating a negligible risk with hazard indexes of 10-9 to 10-5 for selected congeners such as 41 BDE-47, 99, 153 and 209 42 Keywords: PBDEs; DBDPE; road dust; human exposure; Hanoi urban area 43 Introduction AC C EP TE D M AN US C RI PT 25 44 Brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs), 45 polybrominated biphenyls (PBBs), hexabromocyclododecanes (HBCDs) and numerous novel BFRs 46 such as decabromodiphenyl ethane (DBDPE), 1,2-bis-(2,4,6-tribromophenoxy)ethane (BTBPE), 47 pentabromoethylbenzene (PBEB) and brominated phthalate esters, have been widely applied in 48 various consumer products to reduce the risk of fire (de Boer et al., 2000; de Wit et al., 2010; Law 49 et al., 2014) Among the most commonly used BFRs, tetra- to hepta-BDEs, deca-BDE, ACCEPTED MANUSCRIPT 50 hexabromobiphenyl and HBCDs are shown as persistent organic pollutants (POPs) under 51 Stockholm Convention because of their toxicity, persistence, bioaccumulation and long-range 52 transport (UNEP, 2013, 2017a, 2017b) In Vietnam, PBDEs have been detected in soil (Eguchi et al., 2013; Li et al., 2016; 54 Matsukami et al., 2015), sediment (Anh et al., 2017; Mai et al., 2015), indoor dust (Anh et al., 2017; 55 Takahashi et al., 2017; Tue et al., 2013), ambient air (Tue et al., 2013), biota (Minh et al., 2006; 56 Ramu et al., 2007) and even in human (Eguchi et al., 2015; Tue et al., 2010) Previous studies 57 indicated municipal waste dumping (Eguchi et al., 2013), primitive electronic waste (e-waste) 58 recycling (Anh et al., 2017; Tue et al., 2013), and end-of-life vehicle (ELV) processing (Takahashi 59 et al., 2017) as potential sources of PBDEs in this country Besides, it has been suggested that 60 PBDE concentrations in the environment strongly correlated with the degree of urbanization (Li et 61 al., 2008; Stapleton et al., 2005; Wu et al., 2015) However, research focusing on the environmental 62 occurrence of PBDEs in urban areas in Vietnam is still scarce The relatively low levels of PBDEs 63 were observed in urban soils and sediments from Vietnam, as compared with samples from other 64 Asian countries such as South Korea, China, Japan and the Philippines (Kwan et al., 2013; Li et al., 65 2016; Mai et al., 2015) Atmospheric levels of PBDEs in Hanoi urban area were – 12 times higher 66 than those measured in suburban site (Tue et al., 2013) PBDE contents in house dusts collected 67 from Hanoi were – orders of magnitude smaller than levels found in e-waste and ELV recycling 68 sites (Anh et al., 2017; Takahashi et al., 2017; Tue et al., 2013) Information about NBFRs in 69 Vietnam is also limited DBDPE was detected at elevated levels next to BDE-209 in house dusts 70 from Hanoi and e-waste sites in northern Vietnam (Tue et al., 2013) AC C EP TE D M AN US C RI PT 53 71 Road dust is comprised of solid materials such as soil, sand, plant matter, construction 72 material, vehicular emissions and other particles from atmospheric deposition Road dust has been 73 considered as a reservoir of not only inorganic contaminants (e.g., heavy metals) but also organic 74 pollutants such as organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic 75 hydrocarbons (PAHs) and their derivatives, and a wide variety of chlorinated, brominated and ACCEPTED MANUSCRIPT phosphorus flame retardants (Cao et al., 2014, 2017; Chakraborty et al., 2016; He et al., 2017; Phi 77 et al., 2017; Shi et al., 2013, 2014; Tang et al., 2016; Tuyen et al., 2014; Zhao et al., 2016) Tuyen 78 et al (2014) reported that concentrations of PAHs and methylated PAHs and aryl hydrocarbon 79 receptor (AhR) agonists in road dusts from Hanoi were higher than those detected in rural control 80 site and two big cities in India, New Delhi and Bangalore, resulting in higher potential cancer risk 81 for Hanoi inhabitants Considering road dust as an important source of organic pollutants, the 82 behaviors and impacts of organic substances other than PAHs, should also be evaluated RI PT 76 To our knowledge, so far there is no investigation on the presence of brominated flame 84 retardants, including PBDEs and NBFRs, in road dust from Vietnam In the present study, road dust 85 samples collected from the urban area of the capital city Hanoi, an industrial zone in Thai Nguyen 86 province and a rural commune in Bac Giang province, northern Vietnam, were examined to 87 elucidate the distribution of PBDEs and other BFRs including 2,2’,4,4’,5,5’-hexabromobiphenyl 88 (BB-153), PBEB, BTBPE and DBDPE This work was conducted to fill the information gap about 89 contamination status of BFRs in road dust from Vietnam Congener profiles of PBDEs and NBFRs 90 were analyzed to trace the potential sources of BFRs Human exposure to these pollutants via road 91 dust ingestion were estimated for residents as well as an occupationally exposed group (e.g., street 92 sweepers, salesmen and traffic policemen) in the investigated areas 93 Material and methods 94 2.1 Sample collection AC C EP TE D M AN US C 83 95 Road dust samples were collected during August and September, 2016 in three representative 96 locations in northern Vietnam, including Hanoi urban area (n = 16), an industrial zone in Thai 97 Nguyen province (n = 10) and a rural commune in Bac Giang province (n = 5) (Fig 1) Hanoi, the 98 capital of Vietnam, is the country’s biggest urban area covering 3323 km2 and the second most 99 populous city of 7.1 million inhabitants in the year 2015 The inner urban zone of Hanoi consists of 100 ten districts, covering an area of 228 km2 with a population of 2.6 million This area is characterized 101 by a mixture of residential and commercial land uses Sixteen samples on the main streets with high ACCEPTED MANUSCRIPT traffic density were obtained in Hanoi inner urban area Situated about 60 km north of Hanoi, Song 103 Cong I industrial park is the first industrial park of Thai Nguyen province The main industrial 104 sectors are metallurgy, ore refining, mechanical engineering, construction materials, garments and 105 electronics Ten samples were collected along a main gateway and its branch roads in this industrial 106 park In addition, Mai Dinh, a rural commune located 50 km northeast of Hanoi, was chosen as the 107 control site of mostly agricultural/residential land uses Five reference samples were taken from the 108 narrow paths with low traffic density, next to the rice fields RI PT 102 Approximately 200 g of each composite sample comprised of five sub-samples was collected 110 by sweeping the road surface using non-plastic brushes and pans Each sub-sample was obtained on 111 an area of about m2 along the road, within 0.5 m adjacent to the curb Composite samples were 112 transferred into paper bags and sealed in PE zip-lock bags At the laboratory, samples were air dried 113 and sieved through a 100- m stainless steel sieve Homogenized samples were wrapped in solvent- 114 washed aluminum foil, sealed in PE zip-lock bags and stored at -20 oC until analysis 115 2.2 Chemical analysis D M AN US C 109 Sample preparation for road dust was carried out according to our method for POP analysis in 117 settled dust previously described by Tue et al (2013) with some modifications on extraction 118 Briefly, an aliquot of g homogenized road dust sample was transferred into a 50-mL tube and 119 subsequently extracted with acetone and a mixture of acetone/hexane (1:1, v/v) using an ultrasonic 120 processor (VCX 130, 130 W, 20 kHz, Sonic & Materials, Inc.) The extraction conditions were as 121 follows: ultrasonic amplitude 50%, solvent volume 10 mL, extraction time 10 at room 122 temperature After extraction, the sample tube was centrifuged at 3000 rpm for 10 The 123 supernatants were combined, rotary evaporated, solvent-exchanged into hexane and spiked with 124 surrogate standards (monofluorinated FBDE-15, 99, 183, 208, AccuStandard; and 125 Wellington Laboratories) Crude extract was successively purified by treating with concentrated 126 sulfuric acid and passing through an activated silica gel column (Wakogel® S-1, activated at 130 oC 127 for h) Target compounds were eluted from silica gel column using a mixture of AC C EP TE 116 13 C12-BDE-209, ACCEPTED MANUSCRIPT dichloromethane/hexane (5:95, v/v) The eluates were concentrated and spiked with internal 129 standard (FBDE-154, AccuStandard) and solvent-exchanged into nonane before injecting into 130 GC/MS for quantification All chemicals and solvents (i.e., dichloromethane and nonane) used in 131 this study were reagent grade for PCB analysis and obtained from Wako Pure Chemical Industries, 132 Ltd Other solvents (i.e., acetone and hexane) were redistilled prior to use RI PT 128 Thirty six PBDEs (di- to decabrominated congeners, including BDE-7, 10, 15, 17, 28, 30, 47, 134 49, 66, 77, 85, 99, 100, 119, 126, 138, 139, 140, 153, 154, 156, 171, 180, 183, 184, 191, 196, 197, 135 201, 203, 204, 205, 206, 207, 208, 209) and four NBFRs (such as PBEB, BB-153, BTBPE, 136 DBDPE) were quantified using a gas chromatograph connected to a quadrupole mass spectrometer 137 (GCMS-QP2010 Ultra, Shimadzu) BFRs were separated on a fused-silica capillary column (DB- 138 5ht, 15 m × 0.25 mm × 0.1 139 Temperature of injection port was 260oC Initial column oven temperature was 135 oC for min, 140 increased to 215 oC (10 oC min-1), to 275 oC (5 oC min-1), to 295 oC (20 oC min-1, held 0.5 min) and 141 finally raised at 20 oC min-1 to 310 oC and held for The mass spectrometer was operated in 142 electron capture negative ionization (ECNI) mode Methane was used as moderating gas The 143 temperature of the interface and ion source was 310 oC and 250 oC, respectively Twelve ions were 144 selectively monitored, including: m/z = 79/81 and 158.8/160.8 (Br- and HBr2-, for all compounds); 145 406.6/408.6 and 486.5/488.5 (C6HBr4O- and C6Br5O-, for hepta- to decaBDEs); 426.5/428.5 146 (C6FBr4O-, for FBDE-208); and 496.6/498.5 (13C6Br5O-, for 147 monitored ions was partially referred to Hites (2008) 148 2.3 Quality assurance and quality control (QA/QC) M AN US C 133 AC C EP TE D m, Agilent Technologies) Helium was used as carrier gas 13 C12-BDE-209) The selection of 149 The results of triplicate analyses of solid matrix spiked with native standards of PBDEs and 150 NBFRs and Standard Reference Material® 2585 (NIST, Gaithersburg, MD, US) are shown in Table 151 S1 and Table S2, respectively, indicating acceptable levels of precision and accuracy of our 152 analytical method Because relative standard deviations of triplicate analysis of spiked samples and 153 SRM samples were up to 20% for some compounds, concentrations of analytes were reported to ACCEPTED MANUSCRIPT two significant figures To reduce blank levels, glasswares were washed with detergent and tap 155 water, rinsed with solvents (i.e., acetone, toluene, hexane) and baked for h at 450 oC Procedural 156 blanks (reagent blanks, n = 5) were analyzed with real samples of each batch to measure the 157 contamination during chemical analysis and the results are given in Table S3 Instrument detection 158 limits (IDLs) were estimated as times of standard deviations (SD) from replicate analysis (n = 5) 159 of the lowest concentration standard Method detection limits (MDLs) were derived from the IDLs 160 with a sample weight of g and a final volume of 200 L MDLs of di- to nona-BDEs and NBFRs 161 ranged from 0.010 to 0.050 ng g-1 MDL of BDE-209 was 0.50 ng g-1 Average recoveries (± SD) of 162 FBDE-15, 99, 183, 208 and 13C12-BDE-209 were 92 ± 17%, 97 ± 11%, 91 ± 6%, 100 ± 19% and 99 163 ± 22%, respectively 164 2.4 Exposure assessment of PBDEs and NBFRs via road dust ingestion M AN US C RI PT 154 The non-dietary exposures of PBDEs and NBFRs via road dust ingestion were estimated by 166 calculating the daily intake doses (ID – ng kg-bw-1 d-1) and non-cancer hazard index (HI), using the 167 following equations: D 165 ID = (C × IR × FT × EF × ED) / (BW × ET) 169 HI = ID / RfD 170 where C is the measured concentration of target compound in dust (ng g-1) High-end dust 171 ingestion rates (IRs) of 0.2 g d-1 and 0.05 g d-1 were found for children and adults at urban and 172 industrial areas, whereas 0.05 g d-1 and 0.02 g d-1 were assigned as medium IRs for children and 173 adults in rural site Besides, an IR of 0.5 g per working day was applied for a special group 174 occupationally exposed to road dust, including street sweepers, street vendors and traffic policemen 175 (Cao et al., 2017) As data on bioaccessibility of BFRs in road dust is lacking, an absorption 176 efficiency of 100% was assumed Fractions of time spent outdoor (FT) were 3/24 for all persons, 177 mostly comprised the time traveling on the street For professional group, an additional fraction of 178 working time of 8/24 was accounted Exposure frequency (EF) was accounted as 365 d year-1 for AC C EP TE 168 ACCEPTED MANUSCRIPT traveling activities and 240 d year-1 for work Exposure duration (ED) of children and adults were 180 years and 30 years, reflecting exposure time (ET) of 1825 d and 10,950 d, respectively Average 181 body weights (BW) of 60 kg and 15 kg were estimated for Vietnamese adults and 5-year-old 182 children, respectively Daily intake doses were further compared with reference doses (RfD) of 183 selected PBDE congeners (RfD = 100, 100, 200 and 7000 ng kg-bw-1 d-1 for chronic oral exposure 184 to BDE-47, 99, 153 and 209, respectively) (US EPA, 1987, 2008) A RfD of 333,333 ng kg bw-1 d-1 185 for DBDPE was also applied in our study (Hardy et al., 2008) 186 2.5 Statistical analysis M AN US C RI PT 179 Statistical analysis was performed using Microsoft Excel (Microsoft Office 2010) and 188 Minitab 16® Statistical Software (Minitab Inc.) Concentrations of non-detected compounds were 189 treated as zero Concentrations of detected compounds were blank corrected but not surrogate 190 recovery corrected The one-way analysis of variance (one-way ANOVA) with Turkey’s 191 comparison tests were used to compare the BFR levels among study areas The Pearson correlation 192 analysis was conducted to find out the relationship between BFRs in road dust samples 193 Results and discussion 194 3.1 Concentrations of BFRs in road dusts EP TE D 187 Concentrations of PBDEs and NBFRs in road dusts collected from northern Vietnam are 196 presented in Table PBDEs were detected in all road dust samples collected from both locations 197 Seven congeners, BDE-15, 17, 28, 47, 49, 206 and 209, were found in almost all the samples 198 analyzed Other most common congeners such as BDE-99, 100, 153, 154 and 183, were detected 199 more frequently in urban and industrial areas than in rural sites Total PBDE concentrations ranged 200 from 0.91 to 56 ng g-1 with a median value of 16 ng g-1 Total PBDE levels were the highest in 201 Hanoi urban districts (median 24; range 16–56 ng g-1), followed by the industrial zone, Thai 202 Nguyen (median 4.9; range 3.4–11 ng g-1) and Bac Giang rural sites (median 1.1; range 0.91–3.6 ng 203 g-1) (Table 1) Concentrations of Σ35PBDEs (sum of di- to nona-BDEs), BDE-209 and total PBDEs AC C 195 ACCEPTED MANUSCRIPT Hazard indexes of some PBDE congeners and DBDPE via road dust ingestion estimated for 386 residents in both study areas were much lower than the critical value However, the markedly higher 387 daily uptakes of BFRs through road dust by professional group than normal population suggest the 388 need for appropriate labor protection conditions (e.g., effective dust mask) Future research on the 389 pollution status of organic contaminants other than BFRs, in road dusts should be performed in 390 Vietnam, particularly in areas under rapid urbanization and industrialization 391 Aknowledgements RI PT 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Vietnam 580 Fig Diagnostic ratios of selected PBDE congeners in road dusts from Hanoi urban area and in 581 widely used technical PBDE mixtures (La Guardia et al., 2006) AC C EP TE D M AN US C RI PT 577 21 ACCEPTED MANUSCRIPT 16 Tables MDLa DNb Median Industrial park, Thai Nguyen (n = 10) Range c RI PT Urban area, Hanoi (n = 16) Rural commune, Bac Giang (n = 5) DN Median Range DN Median Range 0.010 14 0.010 ND - 0.020 0.010 ND - 0.010 0.010 ND - 0.010 BDE-10 0.010 12 0.010 ND - 0.023 ND ND - 0.010 0.010 ND - 0.010 BDE-15 0.010 16 0.059 0.020 - 0.26 10 0.062 0.021 - 0.38 0.028 0.022 - 0.032 0.077 0.030 - 0.27 0.072 0.031 - 0.39 0.047 0.030 - 0.052 Di-BDEs 0.020 16 0.050 0.034 - 0.073 10 0.055 BDE-28 0.020 16 0.058 0.050 - 0.13 10 0.025 BDE-30 0.010 16 0.023 0.010 - 0.032 10 0.14 0.094 - 0.19 0.020 16 0.12 0.081 - 0.19 BDE-49 0.020 16 0.050 0.042 - 0.085 BDE-66 0.010 16 0.020 0.010 - 0.020 BDE-77 0.010 ND ND 0.19 0.13 - 0.28 ND ND Tetra-BDEs BDE-85 0.010 TE BDE-47 D Tri-BDEs 0.049 - 0.074 0.025 0.025 - 0.028 0.020 - 0.025 0.025 0.020 - 0.030 0.028 0.020 - 0.034 0.011 ND - 0.020 0.11 0.094 - 0.13 0.060 0.060 - 0.063 10 0.070 0.042 - 0.33 0.020 ND - 0.020 10 0.045 0.042 - 0.084 0.020 ND - 0.030 ND ND - 0.056 ND ND ND ND ND ND 0.12 0.085 - 0.47 ND ND - 0.040 ND ND - 0.025 ND ND M AN U BDE-17 SC BDE-7 0.020 16 0.15 0.091 - 0.28 10 0.086 0.025 - 0.31 ND ND - 0.025 BDE-100 0.010 16 0.015 0.015 - 0.042 0.015 ND - 0.031 ND ND BDE-119 0.010 14 0.025 ND - 0.025 ND ND - 0.033 ND ND - 0.030 BDE-126 0.020 11 0.025 ND - 0.053 ND ND ND ND 0.11 0.025 - 0.40 ND ND - 0.050 AC C Penta-BDEs EP BDE-99 0.21 0.15 - 0.39 0.020 0.020 - 0.045 10 0.020 0.020 - 0.045 ND ND 0.020 0.010 - 0.081 ND ND ND ND 0.010 ND - 0.067 ND ND - 0.020 ND ND BDE-138 0.020 16 BDE-139 0.010 16 BDE-140 0.010 13 BDE-153 0.020 16 0.080 0.057 - 0.15 10 0.020 0.020 - 0.069 ND ND BDE-154 0.020 16 0.042 0.020 - 0.058 0.020 ND - 0.020 ND ND BDE-156 0.010 0.010 ND - 0.010 ND ND ND ND ACCEPTED MANUSCRIPT Hexa-BDEs 0.17 0.12 - 0.33 0.060 0.060 - 0.12 ND ND 0.020 10 0.040 ND - 0.080 ND ND - 0.040 ND ND BDE-180 0.030 14 0.14 ND - 0.38 ND ND - 0.040 ND ND BDE-183 0.040 16 0.28 0.20 - 0.64 0.040 ND - 0.15 ND ND BDE-184 0.020 14 0.035 ND - 0.093 0.035 ND - 0.035 ND ND BDE-191 0.020 ND ND - 0.030 ND ND - 0.030 ND ND 0.44 0.28 - 1.0 0.13 ND - 0.26 ND ND Hepta-BDEs RI PT BDE-171 0.020 16 0.21 0.16 - 0.41 10 0.065 0.030 - 0.15 ND ND - 0.030 BDE-197 0.020 16 0.16 0.10 - 0.41 10 0.030 0.030 - 0.091 ND ND - 0.030 BDE-201 0.020 16 0.19 0.14 - 0.40 10 0.030 0.030 - 0.13 ND ND - 0.030 BDE-203 0.020 16 0.18 0.11 - 0.42 0.030 ND - 0.096 ND ND - 0.030 BDE-204 0.020 16 0.030 0.027 - 0.14 BDE-205 0.020 13 0.040 ND - 0.082 0.82 0.61 - 1.6 16 1.0 0.67 - 1.9 BDE-207 0.050 16 0.92 0.58 - 1.7 BDE-208 0.050 16 0.54 0.35 - 1.0 Nona-BDEs 2.5 1.6 - 4.5 Σ35PBDEs 4.6 3.4 - 8.2 20 12 - 52 24 16 - 56 0.50 16 Total PBDEs 0.010 16 0.010 BB-153 0.010 16 0.020 BTBPE 0.020 14 DBDPE 0.050 16 Total NBFRs b c ND ND - 0.030 ND ND ND ND - 0.040 ND ND 0.19 0.090 - 0.47 0.090 0.060 - 0.12 0.22 0.17 - 0.42 0.050 0.050 - 0.11 10 10 0.13 0.050 - 0.38 ND ND - 0.050 0.14 ND - 0.24 ND ND 0.48 0.22 - 0.99 0.10 0.10 - 0.16 1.2 0.89 - 2.6 0.36 0.32 - 0.46 3.6 2.2 - 8.6 0.81 0.56 - 3.2 4.9 3.4 - 11 1.1 0.91 - 3.6 10 0.010 - 0.040 10 0.010 0.010 - 0.012 ND ND 0.020 - 0.069 0.010 ND - 0.020 ND ND AC C PBEB EP BDE-209 M AN U 0.050 TE BDE-206 D Octa-BDEs SC BDE-196 0.020 ND - 0.70 ND ND - 0.16 ND ND 14 6.1 - 73 10 2.6 1.1 - 13 ND ND - 0.46 14 6.2 - 74 2.6 1.1 - 13 ND ND - 0.46 17 a 18 Table Concentrations of PBDEs and NBFRs in road dust samples (ng g-1) collected from northern Vietnam Method detection limit; detection number; not detected ACCEPTED MANUSCRIPT Road dust Vietnam, Hanoi Type Main roads, urban area BDE-209 ΣPBDEs Mean Median Range Mean Median Range Mean Median Range 4.9a 4.6 3.4 - 8.2 25 20 12 - 52 29 24 16 - 56 a Main gateway, industrial park 1.5 1.2 0.89 - 2.6 4.1 3.6 Vietnam, Bac Giang Ways next to rice fields 0.38a 0.36 0.32 - 0.46 1.4 0.81 China, Wenling E-waste recycling site 2500b 1870 750 - 6250 3460 3370 China, Wen’an Main route, plastic waste recycling area Roads, emerging industrial cities Main roads, urban area - - - 1430 - 8.67c - NDh - 35.5 322 9.8c 102 This study This study 1640 - 6360 6530 7060 2870 - 9000 Xu et al., 2015 1541 - - 2.67 10,424 4.01 - 1439 - - 3.23 10,640 - Tang et al., 2016 Shi et al., 2014 105 51.6 - 206 111 112 59.1 - 217 Cao et al., 2017 1.03 - 112.5 51.0 - 1.61 - 294.8 73.4 - 6.71 - 342.1 Wu et al., 2015 Industrial, rural and background zones 26.1 3.08 0.69 - 154.5 391.8 254.5 0.33 - 1636 418.0 258.3 1.02 - 1791 Khan et al., 2016 Footpaths, e-waste recycling workshops Footpaths around rice fields - - - 1700 1100 62 – 8200 1900 1200 68 - 9200 Matsukami et al., 2015 - - 1.4 0.46