Study links flame retardants in people to house dust

FORT WORTH, Texas – A new study suggests that people are routinely exposed to potentially harmful chemical flame retardants by ingesting household dust laced with the toxic chemicals, a fact that concerns health researchers who fear that children are at greatest risk.

The study, conducted at Boston University’s School of Public Health, is the first to link the presence in people of the chemical flame retardants to exposure to common dust, which can be inhaled or ingested in food.

And because infants tend to crawl on the floor, where dust accumulates, they are likely exposed to higher levels of the toxic substances, which could place them at risk of developing neurological problems, researchers say.

The flame retardants – called polybrominated diphenyl ethers, or PBDEs – have been in widespread use in the United States since the 1970s and are commonly found in carpet padding, television sets, computer wire insulation, mattress stuffing, waterproof jackets and many other products. The chemicals are added to products to help prevent the spread of fire.

But studies have measured the flame retardants in virtually every American tested, at levels that are the highest in the world.

A growing number of researchers suspect that PBDEs can cause reproductive and neurological problems, disrupt hormonal balance and, at high concentrations, increase the risk of cancer.

Researchers tested the breast milk of 46 first-time mothers in the Boston area. Though they only obtained dust samples from 11 of the women’s homes, they found a statistically significant link between the levels of PBDEs found in the breast milk and in the dust collected in their homes.

“I think what our work shows is that the indoor environment is a significant source of exposure to PBDEs,” said Tom Webster, an epidemiologist at Boston University who led the study.

Webster said researchers aren’t certain how the chemical flame retardants get into the environment. He said he suspects that the chemicals may turn into a gas and attach themselves to dust particles as they waft through the air.

Chemical manufacturers maintain that the flame retardants save lives and that there’s no definitive link between the PBDEs commonly measured in people and health problems.

But some government and industry leaders are moving to phase them out.

The Legislature in Washington state is moving forward on a bill that would ban the three most commonly used PBDEs. It would be the first state to adopt such legislation, which could receive final approval as early as this month.

U.S. manufacturers have agreed to voluntarily halt production of two of the most toxic brominated flame retardants, but not the one in widespread commercial use today. Many companies that sell products containing PBDEs, including Ford, Dell and IBM, have found alternatives.

The federal Environmental Protection Agency recently unveiled draft risk assessments of four common PBDEs. The draft assessments were conducted by a panel of scientists who are trying to establish a safe level of daily exposure to PBDEs, above which health problems might occur. The safe levels in the draft assessments are very low.

Some researchers fear that people are routinely exposed to PBDE levels near the threshold where the EPA draft assessments suggest that health problems could occur.

That’s especially true of children, who crawl and put virtually everything they touch into their mouths, said Heather Stapleton, an environmental chemist at Duke University who has done extensive research on the issue.

“It almost seems like this (PBDEs) could be the next version of lead coming through,” she said. “We don’t know as much about the toxicity of these compounds as we do of lead. But we definitely find very high levels in indoor dust that are going to be an exposure route for children.”

If that’s true, and PBDEs are a health concern, that should be enough to persuade regulators to demand alternatives to the PBDEs, Webster said.

“Flame retardants are useful because stopping fires is good,” he said. “But we probably want to have ones that are not toxic.”