Heather M. Stapleton
National Institute of Standards and Technology
Analytical Chemistry Division, Organic Analytical Methods Group
Building 227, Room A127, Mailstop 8392
Telephone: (301) 975-8578; Fax: (301) 977-0685
Over the past twenty years the use of brominated flame retardants (BFRs) has increased in industrial and commercial applications. BFRs are chemical additives which are liberally applied to many types of electronic equipment including TVs, computers, and circuit boards, and they are also applied to many textiles and furniture products. These compounds are well suited as flame retardants because at high temperatures, bromide ions are liberated which quench and slow down the oxidative combustion reactions in fire. Polybrominated diphenyl ethers (PBDEs) are a specific class of BFRs, and there are three different mixtures of PBDEs used commercially which vary by their degree of bromination. Recently, the European Union and the state of California issued bans on the use of two of the three commercial mixtures (pentaBDE and octaBDE) due to their persistent and bioaccumulative nature. However, the third commercial mixture, decaBDE, is still being used quite heavily, and in 1999, the market demand for decaBDE in North America was listed at 24,300 metric tons (www.bsef.com).
Recent studies have shown that 2,2’,3,3’,4,4’,5,5’,6,6’-decabromodiphenyl ether (BDE 209, see Figure), the dominant compound in the decaBDE commercial mixture, can debrominate both biotically and abiotically (Stapleton et al., 2004; Söderstrom et al., 2004). Debromination of this highly brominated congener can lead to the formation of numerous less brominated diphenyl ether isomers. Toxicokinetic studies on PBDEs have observed increasing risks of toxicity and increased bioaccumulation with decreasing degree of bromination (Burreau et al., 1997;Meerts et al., 2001). Therefore, debromination of BDE 209 in the environment may lead to increased exposure to toxic and bioaccumulative compounds.
BDE 209, the fully brominated diphenyl ether, has often been difficult to accurately measure in environmental samples due to its instability at high temperatures. A method was developed to quantify BDE 209 using GC/ECNI-MS with on-column injection. This method provides a more accurate and precise method for quantifying BDE 209 than more common methods employing split/splitless injections onto a gas chromatograph capillary column. Using this method we quantified PBDEs in candidate Standard Reference Material (SRM) 2585, household dust, to examine the levels and distribution of BDE congeners. Our results found very significant levels of PBDEs that are common components of both the pentaBDE and the decaBDE commercial mixtures. The BDE 209 concentration in this material was 3145 ± 233 µg/kg dry mass, and is higher than levels reported in dust collected immediately following the collapse of the world trade center (Lioy et al., 2002) We also detected the presence of other BDE congeners in this material which are not found in the commercial mixtures. This may suggest that debromination of PBDEs may be occurring in households.