Environmental Science & Technology
May 5, 2004


By Kellyn Betts

New research provides yet another example of why brominated
flame retardants continue to fascinate scientists interested in
the fate, transport, and bioavailability of chemicals in the
environment. In the paper, Amelie Kierkegaard and her
colleagues at Stockholm University report the first
peer-reviewed data showing that decabromodiphenyl ethane
(DeBDethane) is present in Sweden, where very little of the
compound is believed to be used.

DeBDethane is added to textiles and the plastics used in
electronics products to render them less flammable. It serves
as a replacement for Decabromodiphenyl ether (Deca-BDE), the
most widely used polybrominated diphenyl ether (PBDE) flame
retardant in the world. Germany's dioxin ordinances preclude
the use of Deca-BDE because it produces polybrominated
dibenzo-p-dioxins when burned, a shortcoming that DeBDethane
overcomes. However, the new research indicates that DeBDethane
may not be a suitable replacement for Deca-BDE in Europe, says
Ake Bergman, a colleague of Kierkegaard's at Stockholm
University and an expert on brominated flame retardants.

DeBDethane's manufacturer, Albemarle Corp., has not disclosed
how much of the flame retardant, which it markets as Saytex
8010, it produces. However, Kierkegaard says that the company
claims that it does not export "large amounts" to Sweden.
Nevertheless, she and her group detected the compound in sludge
from 25 of the 50 Swedish sewage plants where they looked for
it. They also identified the compound in the air of a Swedish
electronics dismantling facility, in sediment from The
Netherlands, and in water piping insulation.

Kierkegaard is quick to point out that the researchers detected
very low levels of the DeBDethane, on the order of tens of
nanograms per gram (dry weight) in most cases. The highest
levels she detected were approximately 100 nanograms per gram
in sludge; however, she stresses that the results need to be
regarded as estimated concentrations because the method she
used to detect the DeBDethane was not optimized for the
compound. In all cases, greater amounts of Deca-BDE were found
in the tested samples, she adds. The levels of Deca-BDE were
approximately 1.4 to 50 times higher.

One of the reasons that the findings are notable is because
DeBDethane, like Deca-BDE, was expected not to be an
environmental concern because of its large molecular size and
low water solubility. "We were thinking that [Deca-BDE] will
not enter the biological system and it will not be
bioavailable, but this has been proven wrong," explains Mehran
Alaee, a research scientist with Canada's National Water
Research Institute.

Those assumptions were demolished in the past few years by
research showing that Deca-BDE is indeed bioavailable and that
people can take it up. Most recently, Heather Stapleton of the
University of Maryland has shown that Deca-BDE is unstable in
the environment but persists because it degrades into the more
stable lower-brominated compounds associated with other flame
retardant formulations (Environ. Sci. Technol. 2004, 38,
8A-9A). The same may hold true for DeBDethane, Alaee worries.

Studies with rats indicate that DeBDethane has low oral
toxicity, although some research suggests that may be due to
the compound's poor bioavailability. Both Alaee and Kierkegaard
plan to look for DeBDethane in biota.

DeBDethane is also similar to Deca-BDE in that both are
difficult to analyze in the laboratory. Researchers like
Kierkegaard and Alaee say that the analytical difficulties
inherent in analyzing for the compounds is the main reason why
their presence in the environment wasn't reported previously.
DeBDethane's extremely insoluble nature made it very difficult
to get into a solution, Kierkegaard says; she ended up
succeeding with a combination of acetone, tetrahydrofurane, and
toluene. Kierkegaard also notes that her success in finding the
compound in environmental samples was aided greatly by her
success in obtaining a standard sample from Albemarle.

Kierkegaard plans to determine how likely it is that DeBDethane
debrominates in the environment or in biota. She is currently
gathering sewage sludge samples from around the world to see
how widespread DeBDethane may be.

Copyright 2004 American Chemical Society