Dust is unsightly, a sign of poor housekeeping, perhaps. But toxic? Unfortunately, yes.

In 2003, researchers from Massachusetts-based Silent Spring Institute sampled dust from 120 homes on Cape Cod looking for hormone-like chemicals known as endocrine disruptors. They followed that up with a study of 50 homes in California. In both cases, they found what they were looking for.

One of the chemicals they found in high levels was a banned flame retardant called PBDE. So they went back, again, to look for other flame retardants in those California homes. And, again, they found what they were looking for in abundance. One class of flame retardants, known as chlorinated Tris compounds, made up as much as 0.1% of dust. That's a lot for a single chemical.

California is home to a fire safety law that requires foam used in household furniture to be impregnated with flame retardants. And exposure to flame retardants is higher in California than elsewhere. But this is far from an isolated problem. At least 80% of furniture on the market now is made with flame-retardant-treated foam.

While that sounds like a good thing, there's evidence that the levels of flame retardants currently being used may not provide any significant fire safety benefit. On the other hand, they may be having negative health impacts. The chemicals in question have been linked to thyroid dysfunction and cancer.

The potential risks of widespread flame retardant use has become a hot topic in the scientific world in recent years. A New York Times Magazine profile of Arlene Blum, a leading researcher and activist in the field, has also put the issue into the public spotlight this fall. The new study from Silent Spring Institute adds an important new layer to his complex story.