For years now, scientists have known that US and Canadian residents have elevated levels of PBDEs—a flame retardant known to impair development in lab animals—in their bodies, compared with European and Asian counterparts. (See, for example, our own study of PBDEs in northwesterners.)

The problem is that nobody’s been sure of how the compounds get into us. Some speculated that food was the main exposure route—and pointed to studies that found the compounds in common foods taken from grocery store shelves. Others suspected that housedust was the real culprit—and that people were inhaling dust containing traces of PBDEs that had been sloughed off from degrading furniture foams or other consumer items.

Now, one research team claims to have an answer to the food v. dust controversy. Their conclusion: most of the PBDEs in people’s bodies comes from house dust.

As far as I can tell, this is based on a computer model; but the model is based on actual measurements of PBDEs both in foods and house dust.

Still, it’s probably too soon to call this definitive. But to me, it certainly suggests that—in addition to banning the compounds outright—there ought to be more efforts directed at getting PBDE-laden products out of people’s homes.