A little more than 10 years ago, Dr. Arnold Schecter, a public health researcher, started finding traces of chemical flame retardants in the breast milk of American women. It appeared that the compounds were carried into the milk from fat in the mothers' bodies.
"The route wasn't a surprise," Schecter, a professor of environmental health at the University of Texas School of Public Health in Dallas, said. Breast milk is rich in fat, and the compounds he was looking at -- polybrominated diphenyl ethers, or PBDEs -- linger in fat.
The real question was how flame retardants were getting into women's bodies.
One unexpected source turned out to be food. Schecter surveyed Dallas supermarkets and discovered flame retardants in lipid-heavy items like butter and peanut butter, bacon, salmon, chili with beans and sliced lunch meats. They are present in tiny amounts, he emphasized. But that they are there at all raises questions that researchers find increasingly troubling. If flame retardants can be found even in peanut butter, then where else have they spread? And what health risks come with them?
Flame retardants reduce flammability or inhibit the spread of fire in a range of ways, like interfering with fire's ability to consume oxygen and acting as chemical coolants. Use of the chemicals rose greatly in the 1970s as manufacturers increasingly put fast-burning synthetic materials and plastics in their products. Today, about 1.5 million tons of these compounds are used globally every year.
Various formulations of flame retardants are linked to several possible health effects, all being studied. Some seem to be fairly benign; others are suspected carcinogens. Some appear to interfere with the normal operation of hormones, notably thyroid hormones, while some, such as PBDEs, seem to affect brain development.
But to understand and measure these health risks, researchers first must figure out the extent of the contamination in the environment.
The answer is growing clearer: Flame retardants show a remarkable ability to spread everywhere.
"We're exposed in every known environment," said Heather Stapleton, an associate professor of environmental sciences at Duke who has been studying flame retardants for 15 years.
Some of the older chemicals, such as PBDEs, are being phased out in the United States (and have been banned in Europe). But they were designed to be durable, so they persist in our surroundings. And some of their replacements, such as a new generation of organophosphate flame retardants, are also showing up in unwanted places. Flame retardants have been found in Antarctic penguins and Arctic orcas; in North American kestrels and barn owls; in bird eggs in Spain, fish in Canada and, indirectly, in bees -- honey from Brazil, Morocco, Spain and Portugal has been found tainted with flame retardants.
These chemicals have also been discovered in homes and offices, subways and trains, cars and airplanes. Stapleton worked on a recent study showing that airplane cabins contain startlingly high levels, leaching from seats, bins and even that curtain dividing first class and coach. She has found the compounds in baby products. Recently, she published a study examining flame retardants in tents.
"If a camper sets up a tent in very hot area, it looks like the chemicals come off the fabric," Stapleton said.
Human activities help spread the flame retardants, but the larger drift of them over the planet derives from their longtime use in homes and businesses. The compounds are often sprayed into fabrics and foams used in furniture, bedding and clothing, rather than chemically bonded to the material. So they are gradually shed.
Often, they attach to dust particles, which not only settle onto floors and shelves but also waft outside through open doors and windows and air-conditioning systems. Once outside, they can be transported anywhere by water and wind.
"We know this from other long-lasting materials like DDT," Stapleton said. "It's called the grasshopper effect."
Of course, not all of it hops away -- plenty stays right in the room. A 2012 study concluded that most U.S. households contained dust tainted by flame retardants. A recent survey of 40 day care centers in California found a wide range of flame retardants, including PBDEs, in every one of the dust samples.
Flame retardants are regulated in the United States primarily under the 1976 Toxic Substances Control Act, which does not require studies of toxicity or long-term health effects for most industrial compounds before they are marketed. Although several efforts have been made to update that legislation, none has gained enough congressional support.
There is not much you can do to limit exposure. Bradman recommends frequent hand washing and vacuuming, particularly where children may be exposed, and looking for products labeled free of flame retardants.
ActiveStyle on 07/14/2014