CSI-style tools offer clues about flame retardants in dust Two new papers published in ES&T provide the first evidence that computers, TVs, and other electronic products, as well as textiles, can slowly degrade over time to produce tiny plastic fragments containing relatively high concentrations of bromine. The work is significant because it sheds light on the mystery of how brominated flame retardants get into indoor dust, where humans can be exposed to them. Over the past few years, scientists have amassed data confirming that the brominated flame retardants used in plastic and fabric consumer goods are found in the air and dust in people’s homes, workplaces, and automobiles. At least seven retardants have been documented in indoor air and dust from North America, Europe, and Asia. Researchers have definitively linked the levels of one widely used class of retardants, PBDEs, in homes’ dust with PBDE concentrations found in the residents’ breast milk. Until now, however, no one has been able to explain exactly how the retardants migrate out of the products they are intended to protect and into the dust, says Tom Webster of Boston University’s School of Public Health, lead author of one new ES&T paper (DOI 10.1021/es803139w). “Many people have assumed that volatilization is the main process” responsible for flame retardants escaping into indoor environments, Webster says. Webster’s paper and a second study by Go Suzuki of Ehime University’s Center for Marine Environmental Studies (Japan) and colleagues (DOI: 10.1021/ es802599d) take a new approach by trying to pinpoint where the bromine is actually located in the dust, says Cynthia de Wit of Stockholm University’s Department of Applied Environmental Science. Taken together, the papers represent “a significant step forward“ for
array of sources, including hotels, restaurants, hospitals, and day care centers. Although their research suggests that volatilization plays a role, both groups observed many bromine-rich fragments that were unevenly distributed within the dust samples. In fact, Suzuki says he was surprised to find that “lots of fragments containing high concentrations of bromine exist in indoor dust.” If the main method of distribution of the bromine were volatilization, the element would have been dispersed throughout the dust samples, points out Jochen Mu ¨ ller of the National Research Centre for Environmental Toxicology at the University of Queensland (Australia). When Suzuki and his colleagues analyzed the concentrations of PBDEs in some of the fragments, they discovered that Environmental scanning electron mithe particles also contained brocroscopy shows that the shiny white mine from additional sources. areas in these dust particles from British cars are enriched in bromine. The This suggests the presence of image on the bottom (a close-up of the other brominated retardants or circled area in the top photo) shows a broknown impurities such as tribromine-rich fragment. mophenol or brominated dioxins, Suzuki says. some of the investigative tools Wear and tear can easily exfound in police laboratories. Usplain how automotive upholstery ing scanning electron microsand curtains fragment; why plascopy, Fourier transform infrared tic breaks down is less obvious. microspectrophotometry, and Webster’s coauthor, James R. energy-dispersive X-ray analysis, Millette, a consultant at MVA they analyzed house and autoScientific Consultants and an mobile dust samples with exauthority on dust, explains it tremely high levels ofBDE-209 this way: “Plastics...tend to de(260-2600 micrograms per gram grade just by drying out.” of dust) from the U.S. and the Changes in atmospheric humidU.K. BDE-209 is the main comity will also cause plastics to deponent of the deca-BDE flame teriorate, he says. retardant mixture, a PBDE forTaken together, the two papers mulation widely used in TVs and suggest that people can be exother electronics sold in the U.S. posed to very high concentrations BDE-209 was ideal for this reof brominated flame retardants search because it is highly nonvia these plastic and fiber fragvolatile, Webster says. ments, Webster says. Suzuki and his colleagues used more conventional tools to analyze dust samples from a wider —KELLYN BETTS researchers interested in how peoplesand animalsstake up flame retardants, she says. Webster and his team jokingly call this their CSI paper, in reference to the popular American television show, CSI: Crime Scene Investigation, because they used
2998 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / May 1, 2009
10.1021/es900669w
2009 American Chemical Society
Published on Web 03/18/2009
