In the wake of mounting evidence that brominated flame retardants pose risks to both human and environmental health, researchers at the Second International Workshop on Brominated Flame Retardants held May 14-16 in Stockholm, Sweden, reported that high levels of brominated flame retardants may be commonly found in office dust and even high quality sewage sludge. That documentation is likely to turn more than a few heads, given that the tested dust came from European Parliament buildings and the sludge could be used to grow American vegetables.

Despite growing evidence that brominated flame retardants are bioaccumulating throughout the world, flame retardants are currently much more of a concern in Europe and Japan than in the United States. The penta brominated diphenyl ether (penta-BDE) formulation will be banned in the European Union (EU) in 2003 (Environ. Sci. Technol. 2000, 34 (9), 222-226), and at the Stockholm conference Kjell Larsson, the Swedish Minister of the Environment, vowed to push for all brominated flame retardants to be banned in the EU. The chemicals possess a number of the characteristics of persistent organic pollutants, says Maged Younes of the World Health Organization (WHO), who called on researchers to collect more data on human exposure to the compounds.

There is evidence that at least some brominated flame retardants can be persistent, bioaccumulative, and toxic to both vertebrates and invertebrates, says Linda Birnbaum, director of the Human Studies Division of the U.S. EPA's National Health and Environmental Effects Research Laboratory. They can cause liver and neurodevelopmental toxicity, disrupt hormone systems, and be sensitizers, she says.

In the United States, penta-BDE is used as a flame retardant with the polyurethane foam padding found inside in seat cushions of all kinds, according to Robert Hale of the Virginia Institute of Marine Science at the College of William and Mary in Gloucester Point, VA. Hale looked for penta-BDE and "penta-like" compounds in sewage sludge from different types of treatment plants throughout the United States. Hale's research has yet to be published, but he told conference attendees that he found levels ranging from 1100 to 2290 micrograms/kilogram (µg/kg), which he characterized as being a 40-fold increase over the levels generally found in European sludges, and 10 times higher than the highest levels previously reported in either Europe or Canada. He found lower levels of deca-BDE, another popular formulation that researchers are currently investigating for potential health effects.

Hale believes that the penta-BDEs are getting into U.S. sewage sludge from fragments of polyurethane foam released from old chairs and couches. After the foam is exposed to the environment, it tends to break down and fragment into dust that can be washed down sewers, he says. "It doesn't take a lot of polyurethane foam to contaminate a lot of sludge," he adds. Because polyurethane foams typically contain 10-30% penta-BDE, by weight, if the flame retardants in a foam cushion weighing 1 kg get into a sewage treatment plant, they can contaminate 100,000 kg of sludge at 1000 µg/kg, he says. Hale has found brominated flame retardants in even the highest "EQ" quality sludges.

More investigation would be required to determine whether older polyurethane foam was the source of the brominated flame retardants found in the office dust collected from the European houses of Parliament, according to David Santillo, a research scientist with the University of Exeter's Greenpeace Research Laboratories. But all samples, which were analyzed in conjunction with the Netherlands Institute for Fisheries Research (RIVO), contained "significant levels of brominated flame retardants," Santillo says. The researchers found more than 20 different chemicals associated with brominated flame retardants in the dust they collected with the aid of the cleaning staffs in 13 different European government buildings, Santillo says, noting that deca-BDE was found in the highest concentrations. The Italian and U.K. parliaments had the highest overall levels of brominated flame retardants in their dust, he says.

The Exeter findings, which have yet to be published, call into question whether ingestion may be the main source of exposure to brominated flame retardants, Santillo says. That is important because it is still unclear how these flame retardants are getting into people, Birnbaum says. Recent studies show that although the concentrations of polybrominated diphenyl ethers (PBDEs) in Swedish women's breast milk may have peaked, the amounts are rising in the United States. At the American Chemical Society meeting in March, for example, Myrto Petreas reported the highest levels of PBDEs found in the adipose tissue of any women to date, an average of 85.7 nanograms per gram of fat in a small sample group. —KELLYN BETTS