Preventing fires, igniting questions
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.
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