[Pharmwaste] CSI-style tools offer clues about flame retardants in
dldebiasi at deq.virginia.gov
Thu Mar 19 15:48:29 EDT 2009
CSI-style tools offer clues about flame retardants in dust
Environ. Sci. Technol., Article ASAP
Publication Date (Web): March 18, 2009
Copyright © 2009 American Chemical Society
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, which humans can inhale.
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.
In their work, Webster and Go Suzuki of Ehime University’s Center for Marine Environmental Studies (Japan) and colleagues 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 researchers interested in how peopleand animalstake 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 some of the investigative tools found in police laboratories. Using scanning electron microscopy, Fourier transform infrared microspectrophotometry, and energy-dispersive X-ray analysis, they analyzed house and automobile dust samples with extremely high levels of BDE-209 (260−2600 micrograms per gram of dust) from the U.S. and the U.K. BDE-209 is the main component of the deca-BDE flame retardant mixture, a PBDE formulation widely used in TVs and other electronics sold in the U.S. BDE-209 was ideal for this research because it is highly nonvolatile, Webster says.
Suzuki and his colleagues used more conventional tools to analyze dust samples from a wider 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 was volatilization, the element would have been dispersed throughout the dust samples, points out Jochen Mller 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 the particles also contained bromine from additional sources. This suggests the presence of other brominated retardants or known impurities such as tribromophenol or brominated dioxins, Suzuki says.
Wear and tear can easily explain how automotive upholstery and curtains fragment; why plastic breaks down is less obvious. Webster’s coauthor, James R. Millette, a consultant at MVA Scientific Consultants and an authority on dust, explains it this way: “Plastics...tend to degrade just by drying out.” Changes in atmospheric humidity will also cause plastic[s] to deteriorate, he says, adding that different plastics have different rates of decay.
Taken together, the two papers suggest that people can be exposed to very high concentrations of brominated flame retardants via these plastic and fiber fragments, Webster says. He says that the new findings merit further study because people’s ability to bioaccumulate PBDE retardants has been amply documented. Animal research has linked PBDEs to a number of health effects and has shown that deca-BDE is readily bioavailable in dust, Webster adds.
Environmental scanning electron microscopy shows that the shiny white areas in these dust particles from British cars are enriched in bromine. The image on the bottom (a close-up of the circled area in the top photo) shows a bromine-rich fragment.
Deborah L. DeBiasi
Email: dldebiasi at deq.virginia.gov
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