Environ. Sci. Technol. 2009, 43, 7350–7356
Polybrominated Dibenzo-p-dioxins/ Dibenzofurans and Polybrominated Diphenyl Ethers in Soil, Vegetation, Workshop-Floor Dust, and Electronic Shredder Residue from an Electronic Waste Recycling Facility and in Soils from a Chemical Industrial Complex in Eastern China J I N G M A , †,‡ R U D O L F A D D I N K , ‡ SEHUN YUN,‡ JINPING CHENG,† WENHUA WANG,† AND K U R U N T H A C H A L A M K A N N A N * ,‡ School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China, Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, New York 12201-0509
Received June 10, 2009. Revised manuscript received August 17, 2009. Accepted August 18, 2009.
The formation and release of polybrominated dibenzo-pdioxins and dibenzofurans (PBDD/Fs) from the incineration of electronic wastes (e-waste) that contain brominated flame retardants (BFRs) are a concern. However, studies on the determination of PBDD/Fs in environmental samples collected from e-waste recycling facilities are scarce. In this study, 11 2,3,7,8-substituted PBDD/Fs and 10 polybrominated diphenyl ether (PBDE) congeners were determined in electronic shredder waste, workshop-floor dust, soil, and leaves (of plants on the grounds of the facility) from a large-scale e-waste recycling facility and in surface soil from a chemicalindustrial complex (comprising a coke-oven plant, a coal-fired power plant, and a chlor-alkali plant) as well as agricultural areas in eastern China. Total PBDD/F concentrations in environmental samples were in the range of 113-818 pg/g dry wt (dw) for leaves, 392-18500 pg/g dw for electronic shredder residues, 716-800000 pg/g dw for soil samples, and 89600143000 pg/g dw for workshop-floor dust from the e-waste recycling facility and in a range from nondetect (ND) to 427 pg/g dw in soil from the chemical-industrial complex. The highest mean concentrations of total PBDD/Fs were found in soil samples and workshop-floor dust from the e-waste recycling facility. The dioxin-like toxic equivalent (measured as TEQ) concentrations of PBDD/Fs were greater than the TEQs of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/ Fs) reported in our previous study for the same set of samples. * Corresponding author. Phone: +518-474-0015. Fax: +518-4732895. E-mail:
[email protected]. † Shanghai Jiao Tong University. ‡ Wadsworth Center and State University of New York at Albany. 7350
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The concentrations of PBDFs were several orders of magnitude higher than the concentrations of PBDDs in samples from the e-waste facility or from soil from the chemical-industrial complex. A significant correlation was found between the concentrations of ΣPBDD/Fs and ΣPBDEs (r ) 0.769, p < 0.01) and between ΣPBDD/Fs and the previously reported ΣPCDD/F concentrations (r ) 0.805, p < 0.01). The estimated daily human intakes of TEQs contributed by PBDD/Fs via soil/dust ingestion and dermal exposures in e-waste recycling facilities were higher than the intakes of TEQs contributed by PCDD/ Fs, calculated in our previous study.
Introduction The growth of the electronic waste (e-waste) recycling industry in developing countries has drawn the world’s attention as a new source of environmental contamination by polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) (1-7). Brominated flame retardants (BFRs) are incorporated into electronic equipment and devices, in particular, printed circuit boards and plastics, to reduce flammability (8-10). The formation and release of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), from thermal treatment of e-wastes that contain BFRs, have received considerable attention (7, 11, 12). The toxicity of the PBDD/Fs has been shown to be similar to that of the corresponding PCDD/Fs (13, 14). Nevertheless, little research has been devoted to the occurrence, fate, and human exposures of PBDD/Fs from low-tech e-waste recycling processes (7, 12, 15, 16). PBDD/Fs have been reported as impurities in technical PBDE mixtures (17). PBDD/Fs are formed during the production and recycling of plastics that have been treated with flame-retardant brominated compounds, especially PBDEs (18). Occurrence of high concentrations of PBDD/Fs in dust collected from the housings of television sets has been reported (19). Fly ash and stack flue gas from municipal solid waste incinerators have been documented to contain elevated concentrations of PBDD/Fs (20, 21). Studies have examined the occurrence of PBDD/Fs in fish and other seafood (22-25), in sediments (15), and in the atmosphere (7, 8, 26, 27) as well as in human adipose samples (28). However, information on the occurrence and emission of PBDD/Fs from e-waste recycling operations is scarce. In this study, we analyzed samples entailing multiple environmental matrices collected from an e-waste recycling facility, to investigate the environmental levels of PBDD/Fs and PBDEs. Electronic shredder waste and workshop-floor dust from the building interiors and soil and leaves from the grounds were collected from a large-scale e-waste recycling facility located in Taizhou in eastern China. For comparison, we also collected soil samples from a chemical industrial complex (including a PVC manufacturing plant and a chloralkali plant) in Shanghai. Additionally, surface agricultural soils collected near seven cities in central and eastern China were analyzed, to enable an understanding of distribution, sources, and profiles of PBDD/F and PBDE contamination in China. Dioxin-like toxic equivalents (TEQs) contributed by PBDD/Fs and human exposures to PBDD/Fs via dust ingestion and dermal sorption were calculated.
Materials and Methods Sample Collection. Three types of sampling location were selected in this study: an e-waste recycling facility, agricultural 10.1021/es901713u CCC: $40.75
2009 American Chemical Society
Published on Web 09/03/2009
land, and a chemical-industrial complex. Multiple matrices, workshop-floor dust (fine particles settled on the concrete floors of workshops), and electronic shredder residues (printed circuit board and plastic materials discarded after the recovery of metals) from the building interiors and leaves from trees and shrubs (camphor tree, Cinnamomum camphora Linn., a large evergreen tree; box, Buxus sp., an evergreen shrub, widely grown as a hedge plant in the study area) and surface soil (0-10 cm depth) from the grounds of the facility were collected at a large scale e-waste recycling facility at Fengjiang town in Taizhou in September 2007. Surface soils (0-10 cm depth) were also collected from a chemical industrial complex at Wujing town in Shanghai in September 2007. Surface agricultural soil samples (0-10 cm depth) were collected from seven locations in China during 2006-2007. Further details of samples and sampling locations are given in our previous study (1). For each location, several samples were pooled, to yield a representative sample. All of the soil samples were collected using a clean stainless steel shovel at a depth of 0-10 cm. All collected samples were wrapped in solvent-cleaned aluminum foil and stored at -20 °C until analysis. Chemical Analysis. PBDE and PBDD/F congeners were analyzed following the method described elsewhere, with some modifications (29, 30). Briefly, 20 g of each air-dried samples was homogenized with anhydrous sodium sulfate and Soxhlet-extracted with dichloromethane and hexane (3: 1; 400 mL) for 24 h. The extracts were rotary-evaporated at 38 °C, and an aliquot (1 mL) from leaf extract was used for the determination of lipid content. 13C12-labeled internal standard (EDF-5071 and ED-5073; tetra-, penta- and hexaBDD/F, Cambridge Isotope Laboratories, Andover, MA) was spiked into the remaining extracts, which were then purified by passage through a multilayer silica gel column with 10 mm inner diameter packed in the following order: 1 g of silica gel, 4 g of 40% acidic-silica gel, 1 g of silica gel, 1 g of Na2SO4 (baked at 400 °C for 6 h) at the top. The column was precleaned by passage of 50 mL of hexane. Sample extracts were then loaded and eluted with 150 mL of 15% dichloromethane in hexane and rotary-evaporated to 10 mL. The extract was then treated with concentrated sulfuric acid (5 mL) and passed through a glass column with 10 mm inner diameter packed with 1 g of silica gel-impregnated carbon (Wako Pure Chemical Industries, Tokyo, Japan). PBDEs were eluted with 150 mL of 15% dichloromethane in hexane (F1); PBDD/Fs were eluted with 150 mL of toluene (F2). Identification and Quantification. Nine PBDE congeners (BDE 28, 47, 66, 100, 99, 85, 154, 153, 138) were determined by gas chromatography-mass spectrometry (GC/MS; Agilent 6890GC and 5973MSD; Agilent Technologies, Foster City, CA). GC separation was accomplished by 30 m Rxi-5MS fused silica capillary column (0.25 mm i.d., 0.25 µm film thickness; Restek, Bellefonte, PA). For the detection of BDE 209, a GC with electron capture detection (GC-ECD; Agilent 6890N and Agilent 7683 autosampler) was used. The GC column used was DB5 (6 m × 0.25 mm i.d. × 0.25 µm film thickness; J&W Scientific, Folsom, CA). Ten PBDD/F congeners were determined by high-resolution gas chromatography (HRGC; Trace GC Ultra; Thermo Electron Corporation, Bremen, Germany) coupled with a high-resolution MAT95XP mass spectrometer (Thermo Electron Corporation, Bremen, Germany) at a resolving power of 9000-10,000 (10% valley). Ion source temperature was kept at 270 °C. The GC column used was Rxi-5MS 15 m × 0.25 mm I.D. × 0.25 µm (Restek). The injector temperature was kept at 270 °C. The GC column oven temperature was programmed from 140 °C (1.5 min) and increased at a rate of 40 °C/min to 200 °C, then at 5 °C/min to 300 °C (4 min hold), and then at 10 °C/min to 320 °C (16 min hold). A GC-MS was used for the detection of octabromodibenzofuran (OBDF), and the results were also
checked with GC-ECD for confirmation (more details about instrument parameters for detection of PBDEs and PBDD/ Fs can be seen in Table S1 in the Supporting Information). All congeners determined by HRGC/HRMS or GC/MS were quantified using the isotope dilution method based on the responses from the corresponding 13C12-labeled congeners. Identification of 10 2,3,7,8-substituted PBDD/F congeners was accomplished by injection of corresponding external standards of each of the congeners (EDF5059; Cambridge Isotope Laboratories). Because 1,2,3,4,7,8-H6BDD and 1,2,3,6,7,8- H6BDD coeluted in this study, values for these two congeners were reported as the sum. Hepta-BDD and octabromodibenzo-p-dioxin (OBDD) were not analyzed in this study. Quality Assurance/Quality Control. Procedural blanks were analyzed with every 10 samples. The reported concentrations in samples have been corrected for blank values, when applicable. The limits of quantification (LOQ) was estimated as 3 times the mean value in the blank (in pg/g dw basis: 3.38 for 2,3,7,8-T4BDD, 2.17 for 1,2,3,7,8-P5BDD, 3.23 for 1,2,3,4,7,8-/1,2,3,6,7,8- H6BDD, 1.09 for 1,2,3,7,8,9H6BDD, 6.01 for 2,3,7,8-T4BDF, 5.74 for 1,2,3,7,8-P5BDF, 5.68 for 2,3,4,7,8-P5BDF, 5.17 for 1,2,3,4,7,8-H6BDF, 40.8 for 1,2,3,4,6,7,8-H7BDF, 420 for OBDF, and 0.005-0.35 ng/g dw for PBDE congeners. For TEQ calculations, concentrations below the LOQ were assigned a value of one-half of the LOQ, and the nondetects were set to zero. Because international toxic equivalency factors (TEFs) are not available for PBDD/ Fs, relative potencies (REPs) derived from a chemically activated luciferase gene expression (CALUX) cell bioassay (EC20) were used for the calculation of TEQs (13). When CALUX REP EC20 values for PBDD/Fs were not available, EC20 values for the corresponding chlorinated dioxins/furans or WHO-TEFs (31) were used (Table 2). For PBDEs, REPs derived from a dioxin-responsive-CALUX bioassay (EC5TCDD) were used for the calculation of PBDE-TEQs (Table 1) (32). Recoveries of 13C12-labeled standards spiked into individual samples were 97 ( 24% (mean ( standard deviation) for 13 C12-2,3,4,7,8-P5BDF; 88 ( 25% for 13C12-BDE 28, 88 ( 26% for 13C12-BDE 47, 91 ( 26% for 13C12-BDE 100, 92 ( 28% for 13 C12-BDE 99, 93 ( 28% for 13C12-BDE 154, and 92 ( 29% for 13 C12-BDE 153. Quality control standards for PBDD/Fs were analyzed after every five samples, to monitor instrument stability. All of the concentrations are presented on a dry weight (dw) basis. Total PBDD/Fs represents the sum of the 11 2,3,7,8-substituted congeners analyzed in this study. Total PBDEs represents the sum of 10 BDE congeners: 28, 47, 66, 85, 99, 100, 138, 153, 154, and 209. Statistical analyses were performed using SPSS version 15.0 software.
Results and Discussion PBDEs. Table 1 presents the mean and range of concentrations of 10 PBDE congeners and total PBDEs in multiple environmental samples from the e-waste recycling facility and soils from the chemical-industrial complex and other reference locations. The mean concentration of total PBDEs in soil from the e-waste facility was approximately 2 orders of magnitude higher than the concentrations in soils from the chemical industry complex and approximately 3 orders of magnitude higher than the concentrations in agricultural soil (p < 0.05), suggesting that a major emission source of PBDEs is the low-tech e-waste recycling facilities (Figure S4A). It has been estimated that the recent production of PBDEs was two or three times higher than that in the 1970s, over half of which were used in electronics - computers, TVs, printers, fax machines, cell phones, cables, and power sources as well as in circuit boards (33). Elevated contamination by PBDEs in environmental matrices from an e-waste recycling facility in China has been reported previously (6, 34, 35). VOL. 43, NO. 19, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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0.005 0.08 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.35
5280 (1.26-21100) 8880 (5.88-30600) 5510 (1.05-19800) 1050 (0.87-3990) 16100 (8.45-61500) 1220 (ND-4900) 758 (ND-3150) 2890 (ND-12500) 519 (ND-3150) 3260 (977-6390) 45500 (997-163000) 92.4 (15.6-253)
2.06 (1.39-3.23) 6.62 (3.99-8.93) 2.33 (1.32-3.44) 0.78 (0.63-1.13) 5.00 (3.52-7.27) 0.21 (ND-0.39) 0.35 (ND-0.72) 1.00 (ND-2.32) ND 12.3 (1.45-40.3) 30.6 (17.1-64.2) 0.22 (0.03-0.80)
leaf n ) 6 85.1 (10.6-172) 310 (69.8-531) 109 (15.5-212) 29.3 (15.3-41.6) 272 (24.2-511) 18 (6.55-28.9) 18.4 (11.7-27.6) 64.9 (22.8-107) 2.09 (ND-10.5) 29800 (5560-80600) 30700 (6300-82200) 478 (89.2-1290)
dust n ) 5
e-waste facility
8.12 (0.13-35.4) 26.5 (0.61-165) 7.34 (0.21-39.9) 5.09 (0.09-25.0) 45.6 (0.66-225) 2.27 (ND-10.7) 3.31 (ND-11.6) 8.69 (ND-25.9) 0.86 (ND-3.02) 1800 (69.9-5530) 1910 (71.6-5710) 28.9 (1.12-88.8)
soil n ) 10 ND 0.03 (
