Preventing Fires, Igniting Questions

From: Robina Suwol
Date: 18 Apr 2004
Time: 17:52:58
Remote Name:


"Even as PBDEs became ubiquitous, they escaped close scrutiny. The 1976 law
that banned PCBs required that all new chemicals be reviewed for safety, but
existing chemicals like PBDEs were presumed safe until proved harmful."
Science & Society
Preventing fires, igniting questions
By Karen F. Schmidt
Laura Gerber volunteered to have her breast milk tested for traces of flame-retardant chemicals out of curiosity. But the results turned her into an activist. The Seattle resident and new mother found out recently that her milk contained the substances at roughly three times the average concentration in the United States and 60 times the level in Europe. "I think it's shameful that babies born to American women are exposed to such high levels of these chemicals," says Gerber, who marched on the state capital calling for action.
Gerber is part of a rising tide of alarm over PBDEs--polybrominated diphenyl ethers. No one knows whether these compounds, added to everything from foam cushions to fabrics to plastics, pose a threat to people. But they have unsettling similarities to known chemical villains and are building up fast in the environment and in adults. The average concentration in Americans' tissues doubles every five years and is now approaching levels that harm laboratory animals. "Someone needs to show us that this kind of increase is not harmful,"
says Kim Hooper, a researcher at California's Environmental Protection Agency.
Such concerns have prompted steps to phase out the compounds in California, Maine, and Gerber's state, Washington. More legislation is in the works. But no one knows how long PBDEs will seep out of old products or sit in the environment--or whether substitutes will prove safe or be as effective at preventing fires.
Rogues' gallery. In the 1970s, a series of chlorine- and bromine-containing flame retardants were found to be toxic and were banned. Tris, a compound added to clothing such as children's pajamas, was linked to cancer risk and kidney damage. PBBs, common in plastics, caused accidental poi- sonings in Michigan and Japan. And PCBs, used in electrical equipment, impaired brain development in lab animals and children born to exposed mothers.
But although PBDEs are chemically related, little was known about their safety. Demand grew rapidly as product safety standards tightened. Each year the United States and Canada now consume about 70 million pounds of the compounds in three forms, called penta, octa, and deca for the number of bromine atoms each contains. Added to polyurethane foam, carpet padding, mattresses, computer and hair dryer casings, insulation, drapery, paints, and car parts, they permeate our environment--and have saved countless lives.
Even as PBDEs became ubiquitous, they escaped close scrutiny. The 1976 law that banned PCBs required that all new chemicals be reviewed for safety, but existing chemicals like PBDEs were presumed safe until proved harmful. Yet some toxicologists say there were good reasons to be wary. "If you look at the chemical structures of PBDEs, you can see that they, too, will be persistent and could be toxic--it's just a no-brainer," says Joel Baker, an environmental chemist at the University of Maryland.
In 1998, Swedish researchers discovered that PBDE levels were rising fast in women's breast milk. They also saw hints of toxicity: Giving low doses of penta and other PBDEs to 10-day-old mice caused permanent defects in their ability to learn and remember.
The findings persuaded Sweden to ban penta and octa, and the European Union began scrutinizing them. That got the attention of Hooper and his colleagues, whose California lab decided to analyze fat tissue--where PBDEs accumulate--from women in the San Francisco Bay area. The women had levels 6 to 10 times as high as women in Europe, where the compounds are used more
sparingly. Other studies have found levels 20 times as high.
Researchers are only now figuring out how most PBDEs move out of products and into people. Miriam Diamond and her colleagues at the University of Toronto took samples of grime coating windows and found the highest concentrations indoors, in the city. She thinks PBDEs waft out of plastics and furniture indoors and stick to dust particles that people breathe and swallow. Several studies, the latest coming out this month from the Environmental Working Group, have found high concentrations in house dust. "It raises questions
about babies crawling around engaging in hand-to-mouth activities," says EWG's Sonya Lunder, an environmental analyst. PBDEs also migrate outdoors, ending up in waterways and in some fish.
Meanwhile, other worrisome hints have emerged from the lab. "We've seen that the commercial penta mix delays puberty and affects the developing testes in rats," says Linda Birnbaum, a toxicologist at the Environmental Protection Agency's National Health and Environmental Effects Research Lab in North Carolina.
Last year, state governments began taking action against penta and octa. And in November, the Great Lakes Chemical Corp. of West Lafayette, Ind., the largest U.S. maker of the two chemicals, said it would end production. That leaves deca, which has been promoted as the safest PBDE--unlikely to escape from products or get taken up by organisms because its molecules are bulky. "Deca does not pose a risk to human health," says Peter O'Toole of the Bromine Science and Environmental Forum, which represents makers of flame retardants.
Yet Arnold Schecter and his colleagues at the University of Texas recently found this PBDE in breast milk and in foods from supermarkets. "It appears to have been a mistake to think that deca couldn't get into the body," he says. Swedish researchers reported in August that deca, too, can affect brain development in mice. And new studies show that deca can break down in the environment to form penta and octa, as well as other toxic byproducts.
Last month, Washington State lawmakers decided to err on the side of safety and approved the first steps to phase out all three PBDEs. Maine followed suit this month, and California will decide this spring whether to add deca to its ban. Europe may extend its general ban on penta and octa, which will begin this summer, to include all products containing deca.
Still, it's unclear how effective these steps will be in bringing down exposure. Optimists point to Sweden, where PBDE levels in breast milk have already begun to decline. But in the United States and Canada, says Diamond, "there could be a huge lag time for concentrations to come down because of the replacement time for all our gizmos." And PBDEs could still find their way onto the market in imported products.
Industry is at work on substitutes, but the troubled history of chemical flame retardants has convinced some critics that it's time to try making products safe without such additives. One is Clark Williams-Derry, research director for Northwest Environment Watch, the Seattle-based group that tested Laura Gerber. He points to a growing list of companies--Ikea, Motorola, Ericsson, Intel--that have redesigned their products, often using less flammable materials, to eliminate the need to add PBDEs. Says Williams-Derry, "I think
we're underestimating our ability to solve this problem through ingenuity."


Last changed: March 14, 2006