Environ. Sci. Technol. 2006, 40, 4400-4405
Occurrence of Polybrominated Biphenyls, Polybrominated Dibenzo-p-dioxins, and Polybrominated Dibenzofurans as Impurities in Commercial Polybrominated Diphenyl Ether Mixtures NOBUYASU HANARI,† K U R U N T H A C H A L A M K A N N A N , * ,‡ YUICHI MIYAKE,† TSUYOSHI OKAZAWA,† PRASADA RAO S. KODAVANTI,§ KENNETH M. ALDOUS,‡ AND NOBUYOSHI YAMASHITA† National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan, 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, and Neurotoxicology Division, NHEERL/ORD, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711
The objective of this study was to determine the concentrations and compositions of polybrominated biphenyls (PBBs), polybrominated dibenzo-p-dioxins (PBDDs), and polybrominated dibenzofurans (PBDFs) as contaminants in the commercial polybrominated diphenyl ether (PBDE) mixtures DE-71, DE-79, and DE-83 and to ascertain the lot-to-lot variations in the proportions of these contaminants. Commercial PBDE mixtures tested in the present study contained both PBBs and PBDFs, as impurities, at concentrations in the range of several tens to several thousands of nanograms per gram. Concentrations of total PBDFs were greater than those of total PBBs in DE-79 and DE-83 mixtures. PBDDs were not detected at levels above the limit of detection. Profiles of PBB and PBDF congeners varied with the degree of bromination of the commercial PBDE mixtures (i.e., more highly brominated mixtures of PBDEs contained heavily brominated homologues of PBBs and PBDFs). On the basis of the production/ usage of commercial PBDE mixtures in 2001, potential global annual emissions of PBBs and PBDFs were calculated to be 40 and 2300 kg, respectively. Results of our study suggest that PBDFs can also be formed during the production of commercial PBDE mixtures, in addition to their formation during pyrolysis of brominated flame retardants.
* Corresponding author e-mail:
[email protected]; phone: 518-474-0015; fax: 518-473-2895. † National Institute of Advanced Industrial Science and Technology (AIST). ‡ Wadsworth Center and SUNY at Albany. § U.S. Environmental Protection Agency. 4400
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ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 40, NO. 14, 2006
Introduction Polybrominated diphenyl ethers (PBDEs) are brominated flame retardants used in textiles, electronic equipment, and plastics to prevent these products from burning (1). PBDEs have been marketed as penta- (e.g., DE-71), octa- (e.g., DE79), and deca-brominated (e.g., DE-83) mixtures. The pentaBDE mixture contains primarily 2,2′,4,4′-tetrabromodiphenyl ether (PBDE 47), 2,2′,4,4′,5-pentabromodiphenyl ether (PBDE 99), and 2,2′,4,4′,6-pentabromodiphenyl ether (PBDE 100) in a ratio of approximately 7:10:2 by mass. The octa-mixture contains primarily 2,2′,3,4,4′,5′,6-heptabromodiphenyl ether (PBDE 183), 2,2′,3,3′,4,4′,5,6′-octabromodiphenyl ether (PBDE 196), 2,2′,3,3′,4,4′,6,6′-octabromodiphenyl ether (PBDE 197), and 2,2′,3,3′,4,4′,5,6,6′-nonabromodiphenyl ether (PBDE 207), in a ratio of approximately 8:3:10:8 by mass. The deca-product is almost entirely composed of decabromodiphenyl ether (PBDE 209), but there are small amounts of 2,2′,3,3′,4,4′,5,5′6nonabromodiphenyl ether (PBDE 206) and PBDE 207. The use of PBDEs has increased over the years, and global annual sales were ∼70 000 metric tons in 2001 (2). Due to their widespread use and potential for bioaccumulation (3), PBDEs have become ubiquitous contaminants in the environment. Similar to PBDEs, polybrominated biphenyls (PBBs) were produced in the early 1970s for use as flame retardants (4, 5). The commercial production of PBBs as Firemaster BP-6 and FF-1 in the United States continued until 1976, with approximately 2500-5000 metric tons of PBBs were produced. In 1973, an accidental contamination of cattle feed by PBBs in Michigan revealed the potential food-chain transfer of this group of chemicals, leading to exposure of humans (6). The congener composition of FireMaster was largely 2,2′,4,4′,5,5′-hexabromobiphenyl (PBB 153), accounting for 50-60% of the total mass, followed by 2,2′,3,4,4′,5,5′heptabromobiphenyl (PBB 180; 10-15%), and 2,2′,3,4,4′,5′hexabromobiphenyl (PBB 138; 5-10%) (7). Combustion of products containing PBDEs and PBBs can release toxic compounds such as polybrominated dibenzop-dioxins (PBDDs) and dibenzofurans (PBDFs) (8-11). Widespread occurrence of PBDEs, PBBs, and PBDDs/DFs in the environment, and ongoing usage of products treated with brominated flame retardants, are causes for concern (6, 12). PBDDs/DFs, in addition to their formation during incineration of PBDE and PBB-containing products, can be found as impurities in commercial PBDE mixtures. Analysis of the composition and content of impurities in commercial mixtures is important if we need to understand the sources of emission, and if we need to estimate global inventories of PBBs and PBDDs/DFs. Furthermore, characterization of impurities in commercial mixtures is essential for accurately evaluating toxic effects of such mixtures observed in laboratory animal studies. For example, two different lots were analyzed for DE-79 and DE-83 to examine lot-to-lot variations in concentrations and compositions, since congener composition of PCB mixtures varied from lot-to-lot (13) and hence resulted in differential biological effects (13, 14). Further, analysis of profiles of PBB and PBDD/DF congeners in commercial PBDE mixtures may also permit fingerprinting of sources of PBBs and PBDDs/DFs in the environment. In this study, we analyzed three commercial PBDE mixtures, DE-71, DE-79, and DE-83, to elucidate congener-specific concentrations and compositions of PBBs and PBDDs/DFs, using a two-dimensional high-performance liquid chromatography (HPLC) cleanup system with porous graphite carbon and pyrenyl ethyl columns, and high-resolution gas chromatography (HRGC)-high-resolution mass spectrometric (HRMS) quantification. Based on the global production levels 10.1021/es060559k CCC: $33.50
2006 American Chemical Society Published on Web 06/20/2006
TABLE 1. Ions Monitored in the Analysis of PBDEs, PBBs, and PBDDs/DFs Using HRMS compound PBDEs tetra-BDE penta-BDE hexa-BDE hepta-BDE octa-BDEa 13C-tetra-BDE 13C-penta-BDE 13C-hexa-BDE 13C-hepta-BDE 13C-octa-BDEa
FIGURE 1. Analytical scheme for the determination of PBBs and PBDFs in commercial PBDE preparations. of commercial PBDE mixtures in 2001, potential annual environmental release of PBBs and PBDD/DFs from these commercial mixtures was estimated.
Materials and Methods Commercial mixtures of PBDEs (DE-71 [lot 1550OI18A], DE79 [lot 1525DD11A and 8525DG01A], DE-83 [lot 0480DL07B and 7480DL10C]) were obtained from Great Lakes Chemical Corporation (West Lafayette, IN). We analyzed two different lots for DE-79 and DE-83 to assess lot-to-lot variability in concentration and composition. According to the manufacturer, the bromine content for DE-71, DE-79, and DE-83 was 69%, 78%, and 82%, respectively. Commercial PBDE mixtures were dissolved in n-hexane (or toluene), and the diluted PBDE mixtures were passed through a porous graphite carbon column (Hypercarb; 100 × 4.6 mm; 7 µm particle size; Thermo Electron, Philadelphia, PA) for fractionation of PBDE congeners from PBDDs/DFs (Figure 1). Details of the fractionation procedure have been described elsewhere (15, 16). The first fraction (15 mL), eluted with 50% dichloromethane (DCM) in n-hexane at a rate of 2.5 mL/min using a Hewlett-Packard series 1100 pump, contained PBBs and most of the PBDE congeners. The Hypercarb column was then reversed and eluted with toluene (45 mL) to collect PBDDs/DFs. The toluene eluate was further fractionated by passage through a Cosmosil 5-PYE column (pyrenyl ethyl group; 250 × 4.6 mm, 5 µm particle size; Alltech Associates Inc., Deerfield, IL). The first and second fractions (0-12 min), eluted with 12 mL of 10% DCM in n-hexane at a rate of 1 mL/min, contained more highly brominated diphenyl ether congeners. The third fraction (12.1-24 min) contained tetra-brominated DDs/DFs and deca-BDE (PBDE 209). The fourth fraction, eluted with 3 mL of 10% DCM in n-hexane and 48 mL of DCM, contained the remaining PBDD and PBDF congeners. This fractionation procedure enabled us to separate PBDFs from PBDEs, which would otherwise coelute in a GC column. Each fraction was concentrated and injected into a HRGC interfaced with a HRMS. A Hewlett-Packard 6890 Series II gas chromatograph interfaced with a Micromass Autospec-Ultima HRMS was used for the determination of tri- to octa-brominated biphenyls, and tetra- to octa-brominated dibenzo-p-dioxins and dibenzofurans. The mass spectrometer was operated in an electron impact (35 eV energy and 500 mA ion current), selected ion monitoring (SIM) mode at a resolution R > 10 000 (10% valley). Ions were monitored at the two most intensive ions of the molecular ion cluster (Table 1). The ion source and interface temperatures were held at 250 °C. Separation of PBDE, PBB, and PBDD/DF congeners was achieved using a DB5 capillary column (15 m length × 0.25 mm i.d. × 0.10 µm film thickness). The column oven temperature was
PBBs tri-BB tetra-BB penta-BB hexa-BB hepta-BB octa-BBb PBDDs/DFs tetra-BDD penta-BDD hexa-BDD hepta-BDD octa-BDD tetra-BDF penta-BDF hexa-BDF hepta-BDF octa-BDF 13C-tetra-BDD 13C-penta-BDD 13C-hexa-BDD 13C-tetra-BDF 13C-penta-BDF 13C-hexa-BDF
(M + 2)+
(M + 4)+
483.7131
485.7111 563.6215 641.5320
495.7533
389.8077
497.6923
481.6974
509.7326 493.7377
497.7513 575.6618 653.5723
391.8057 467.7182 547.6266 625.5371
499.6903 577.6008 655.5113 483.6954 561.6059 639.5164 511.7306 589.6411 667.5515 495.7357 573.6462 651.5566
(M + 6)+
(M + 8)+
565.6195 643.5300 721.4405 799.3510
723.4385 801.3490
577.6598 655.5703 733.4808 811.3912
735.4788 813.3892
469.7162 549.6246 627.5351 705.4456 783.3561
707.4436 785.3541
579.6598 657.5093 735.4198 813.3302
737.4178 815.3282
563.6039 641.5144 719.4248 797.3353
721.4228 799.3333
591.6391 669.5495 575.6442 653.5546
a Octa-BDE ions were used for analysis of deca-BDE. were used for analysis of deca-BB.
b
Octa-BB ions
programmed from 150 °C (2 min) to 300 °C at a rate of 5 °C/min, with a final hold time of 10 min. Internal standards from Cambridge Isotope Laboratories (CIL; Andover, MA) were used (EDF-5071 and EDF-5073; 13Clabeled PBDDs/DFs) to check the recovery through the analytical procedure. Recoveries of 13C-labeled PBDDs/DFs through the analytical procedure varied from 52 to 71% (mean: 60%). Reported concentrations have been corrected for the recoveries of the internal standard. Coefficient of variation between multiple analyses was
