Flame retardants in house dust match residents' blood levels.

Jul 23, 2010

Johnson, PI, HM Stapleton, A Sjodin and JD Meeker. 2010. Relationships between polybrominated diphenyl ether concentrations in house dust and serumEnvironmental Science & Technology http://dx.doi.org/10.1021/es100697q.

Synopsis by Laura Vandenberg

People who live in houses with higher levels of flame retardant chemicals in the dust have themselves higher levels of the chemicals in their blood, a finding that implicates dust as a major exposure source for the compounds.

The mystery of why some people have higher levels of certain flame retardants in their bodies than others may hinge on simple house dust, according to a recent study by a team of U.S. scientists. Prior studies point to dust and food as major sources of exposure to PBDE chemicals yet questions remained about the importance of dust as a source.

This study clarifies dust's role because it is the first to compare levels of flame retardants in house dust with levels in the people who live in the same house. The scientists report that while some foods do harbor PBDEs, eating and breathing dust seems to be the main source of exposure in the United States. Dust, then, may provide an easy and accurate way to predict exposures in the people who live in the home, the researchers explain.

This is in contrast to some European countries. PBDE levels are remarkably lower in dust samples collected in Europe compared to the United States, possibly because many PBDEs were banned there years ago. For example, in  Belgium and Germany, no associations are found between PBDE levels in dust and in people's blood.

Levels also vary across the United States. The highest levels of PBDEs are measured in Californians. The state has the strictist fire safety standards in the nation, and therefore, flame retardant use is high.

Many consumer products contain PBDEs. During fires, the chemicals slow down burning of the electronics, carpeting, textiles, mattresses and upholstered foam furniture that contain them.

Several PBDEs have been phased out of use in the United States because of concerns for the toxic and hormonal effects of these chemicals. However, older products such as carpets and furniture that contain these types continue to release them as they age. Also, products with these chemicals can still be imported and sold.

In rodents, certain PBDEs can affect brain development and thyroid hormone levels as well as having endocrine disruptor activities. That is, they can act like or prevent the normal action of hormones in those animals. Additional studies in humans indicate that higher levels of some PBDEs in the body can lead to altered hormone levels.

The researchers collected used vacuum cleaner bags from 50 households in Massachusetts and examined the contents for the presence of over 30 PBDEs. At the same time, blood samples from 12 adult couples were collected and tested for several of the PBDE types found in the majority of the house dust samples.

The levels and types measured show that PBDEs are a large component of indoor dust. Total PBDE concentrations averaged 4,742 nanograms per gram (ng/g) and ranged from 980 to 44,546 ng/g. Of those measured, six were not detected in any house, three were found in a small number of houses – less than 30 percent – and the rest were found in the majority of the dust samples. Thirteen PBDEs were detected in every house sampled.

Three of those – BDE 47, 99 and 100 – had related levels in dust and in blood. That is, houses with high levels of these chemicals in dust samples were likely to have occupants with high levels of the chemicals in their blood. Gender had a similar strong association; men with high levels in their blood were likely to live with women who also had high levels in their blood.