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updated 6/30/2011 12:48:54 PM ET 2011-06-30T16:48:54

As public concern has grown over the flame retardant compounds commonly known as PBDEs, researchers have remained uncertain how the chemicals, originally added to furniture foam, carpet pads and electronics, among other things, get from the products into our bodies.

New research now suggests that invisible dust stuck to our hands is a key route of exposure, but the good news is that frequent hand washing can reduce blood levels of PBDEs dramatically.

Polybrominated diphenyl ether compounds, PBDEs, are a group of flame retardant chemicals, one category of which have been associated with thyroid disruption, reduced fertility in women, lower testosterone in men and neurodevelopmental deficits in children.

They are present at levels of 5 to 20 percent by weight in furniture foam, which means there could be pounds of these compounds in many homes.

U.S. manufacturers voluntarily withdrew two categories of PBDEs -- penta PBDEs and octa PBDEs -- from the market in 2004. A third category, deca PBDEs, will be phased out by 2014.

Although the compounds are no longer put into new goods, furniture and electronics can have long lifetimes, so these products will be in office and houses for a long time to come. Meanwhile, researchers also have concerns over the chemicals that are replacing PBDEs.

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While most research has focused on PBDEs in households, the new study surveyed 31 workers, each in an office in one of eight different buildings in Boston. The team measured PBDE levels in dust vacuumed from the floor. They also wiped the workers' hands with large alcohol swabs and measured the PBDEs they recovered in the wipes. And they measured PBDEs in the workers' blood.


The team found PBDEs in the dust of every office. The more PBDEs the researchers found on workers' hands, the higher the workers' blood PBDE levels.

"We know that the indoor environment is thought to be the main source of PBDE exposure but it hasn't really been clear how PBDEs have been getting from air and dust into people," said study lead author Deborah Watkins, a doctoral student at the Boston Unversity School of Public Health.

The new study provides a clue. "The two most notable things are we found this strong association between the levels on hand wipes and the levels in blood. The second is that the levels are affected by hand washing," said Thomas Webster, also of the Boston University School of Public Health and author on the study, published today in Environmental Health Perspectives.

"That doesn't definitely nail the hand-to-mouth behavior, but it strongly indicates it," he said.  

"All morning you've been walking around, getting dust on your hands, from your keyboard and other places. Then you eat your sandwich," Webster said.

The oil on the skin provides a sticky surface for the dust and the oil-loving PBDEs to adhere to. Also, the entire indoor environment is coated with a thin film of organic material -- like a thin film of grease -- that adsorbs PBDE-containing dust, Webster said.

The good news from the study is that workers who reported washing their hands more than four times a day had approximately three times lower blood levels of PBDEs.

That, said Watkins, "suggests that we can decrease exposure to a certain extent just by washing our hands a few times a day."

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The work also confirms that offices are a source of flame retardant exposure, not just homes.

"I think the interesting thing is that handwashing can reduce exposures," said Arlene Blum of the Green Science Policy Institute in Berkeley, Calif.

"We published a paper about a month ago finding high levels of PBDEs and replacements for PBDEs in baby products," Blum said. "Industry said that doesn't prove they are coming out of the product or that they are in homes. This (new work) is an example: They are in the products, they are in the dust, and they are in people."

Blum also criticizes the California fire safety standard, TB-117, that requires high levels of flame-retardants to be used. Californian children have two to nine times more flame-retardants in their bodies than other Americans, and up to 100 times more than Europeans, according to one study. Many products distributed nationally are manufactured to meet the California standard.

Working with a fire safety expert Blum recently presented results comparing treated and untreated furniture and upholstered foam samples and concluded that the TB-117 standard did not "prevent ignition nor reduce the severity of the fire," according to a release about the findings.

Boston requires that all office furniture meet the TB-117 standard.

© 2012 Discovery Channel

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