Flame Retardant Air?

A fairly ubiquitous class of flame retardants—chemicals used to keep products from readily burning—have been showing up in the environment, in animals, and in ourselves. Studies are just beginning to tease out the potential toxicity of one of the more prominent classes of these agents: They're PBDEs, an acronym which stands for a chemical mouthful—polybrominated diphenyl ethers. A new study now reports data suggesting that roughly one-fifth of the exposure of urban residents may come from the air in their homes.

Isn't that a pleasant thought.

Joseph G. Allen of the Boston University School of Public Health and his coworkers installed air-sampling devices in the bedrooms and main living rooms for each of 20 local volunteers. The devices ran for a week whenever the individuals were at home. The researchers also fitted each recruit with a personal air sampler that traveled with him or her around the home. Its intake was clipped to the recruits' shirt collars so that it would sniff the air at roughly nose level. At bedtime, the personal air sniffer was placed at bed height in the bedroom.

What's rather disturbing: The personal air sniffers picked up significantly more PBDEs than did devices just randomly sampling room air. For instance, the average concentration of these chemicals sniffed in the vicinity of the volunteers' heads was ~765 picograms per cubic meter in air—some 300 pg/m³ higher than in bedroom- or living-room air. The findings appear in a paper published online today and due to appear in print soon in Environmental Science & Technology.

The good news: Measured concentrations were low. However, these pollutants are remarkably persistent, meaning they don't readily degrade. So, there's a distinct possibility that exposures could accumulate, leading to a slow buildup of some of these compounds. What there is no question about is that these compounds do make it into our bodies in measurable quantities. Four years ago, university scientists in this country reported that human exposures begin in the womb and is augmented by breastmilk. That's troubling because studies have suggested that at least of few of these PBDEs can trigger subtle toxicity.

Presumably, the relatively high personal readings reflect individuals spending time in close proximity to household items treated with PBDEs. These might include sofas, mattresses, computer cases, electronics, or any of many other products. However, in this study, Allen's team was unable to correlate air readings with the presence of particular products in the tested homes.

Concern over the potential health effects of these agents led to a U.S. phase-out in the production and sale of two of the three common classes of them. The voluntary move by the manufacturers came after discussions with—and presumably more than a little pressure by—the Environmental Protection Agency. At the time, Europe had already instituted a ban on these chemicals. Together, these two classes comprise nearly 200 different PBDEs, although a few particular ones dominate each mix.

The third class, represented primarily by the deca-brominated PBDE, which is known as PBDE-209, remains in commercial use throughout the United States. In the new study, offgassing vapors of all three PBDE classes were detected in indoor air and by the personal-air sniffers (although concentrations of the deca-PBDE were second highest, on average, of the 12 individual PBDEs assayed).

What's the health significance of the new findings? No one knows. However, one recent study reported that fat cells exposed to brominated flame retardants undergo changes that would appear to foster obesity and type 2 diabetes. Another study showed that sunlight can break down some of these flame retardants into unusual members of the dioxin family. And European scientists, working with lab animals, linked PBDE exposures to reproductive and brain problems.

And what the new study reinforces is that our homes are not necessarily havens from these pollutants.