If you bought your couch after 2005, it's most likely full of harmful chemicals.

There's nothing more relaxing than coming home after a long day and flopping on the couch to unwind. That is, until you realize that your couch and the chemicals inside it are doing anything but helping you de-stress—like even causing cancer or reproductive problems. Those chemicals, intended to prevent fires when the foam in your sofa is exposed to an open flame, are cropping up in American homes in vastly increasing numbers, according to new research published in the journal Environmental Science & Technology.

Researchers from Duke University asked people all over the country to send them small samples of foam from their couches with detailed information about where and when the couch was purchased. According to their analysis, 50 percent of American's couches are likely to contain a chemical known to cause cancer.

Here's a short summary of what they found.

If you bought your couch before 2005…
There's a good chance it has a chemical in it called PentaBDE, which was phased out in 2004 due to concerns that it interferes with neurological development in children. Nearly 40 percent of the couches purchased prior to 2005 that were analyzed contained it. But the good news is that while 75 percent of older couches looked at contained flame retardants, 25 percent did not. So there's a small chance your pre-2005 couch is chemical free.

If you bought your couch after 2005…
There's a really good chance that it has chemicals. Around 97 percent of the newer couches analyzed contained flame retardants, and a wide variety of flame quellers, at that. The most common is a cancer-causing chemical known as "Tris" or TDCPP, which was detected in 50 percent of the foam tested. In 2011, it was listed on California's Proposition 65 list of chemicals known to cause cancer, and as a result, the company that makes chemical has announced that as of January 2013 it will no longer sell Tris to furniture and baby-product manufacturers (though it will still be used in automobiles).

The second most common chemical found in post-2005 couches is actually a proprietary blend called Firemaster 550. "That mixture has not been thoroughly tested," says Robin Dodson, ScD, research scientist at the nonprofit Silent Spring Institute, which studies the link between environmental chemicals and cancer. She says that certain components of the blend are similar to other chemicals that are known to cause reproductive damage and developmental problems in children.

In addition to those two chemicals, researchers found five other chemicals or blends of chemicals, some of which were completely new, and all of which were sorely lacking in data on their human health impacts. None of the chemicals used in sofas are required to be identified on sofa tags or in any other form, which makes it extremely difficult to avoid them.

And you inhale them each time you sit down…
In the same issue of Environmental Science & Technology, Dodson published a separate paper on the levels of flame retardants found in household dust in California, and found the same chemicals at levels that would exceed government health guidelines. Her study detected 55 different flame retardant compounds in 32 different dust samples. Some chemicals they found were used alone and others used in combination with others in proprietary blends such as Firemaster 550. Some of the highest concentrations she found were for chemicals like Tris that have been linked to cancer.

"There are pounds of these flame retardants in a typical couch," she says, and couches gradually release them in small amounts over time. As the foam breaks down, the chemicals puff out, bind to dust, and settle on your floor or in your lungs. "It's a constant source of these chemicals in your home. New or old, any couch will be an exposure source." 

And couches aren't even the only source. Dodson says that these compounds are used in curtains, carpets, carpet padding, and building insulation—all of which are made with petroleum-based fibers that are inherently flammable. "Anything in the home that is made from oil will likely have flame retardants in them."

The chemicals are in couches because of a California state law, known as Technical Bulletin (TB) 117, that has become a de facto national law, simply because furniture manufacturers don't want to make different pieces of furniture to sell in different states. The law requires the polyurethane foam used in couches to resist an open flame. As a result—as these two studies show—your couch may contain as much as a pound of these harmful chemicals. 

But the good news is the law is getting a long-overdue revamp. The California government is redrafting TB117 so that it's in line with a proposed federal law that will require the upholstery fabric, not the foam, to be smolder resistant. According to the Consumer Product Safety Commission (CPSC), 85 percent of upholstery fabrics on the market already provide protection against candles and smoldering cigarettes without the addition of chemicals. "We're getting more fire safety and no real health harm," says Arlene Blum, PhD, founder of the Green Science Policy Institute and one of the first chemists to sound an alarm on the dangers of flame-retardant chemicals. California legislators are drafting a new TB117 now, and Blum says she expects a revised law to go into effect next summer.

What you can do
Because of the sheer numbers of products that contain flame retardants, it's impossible to completely eliminate the chemicals from your house. But you can cut back on your exposure with these tips from the Silent Spring Institute:

• Buy natural fibers. When you're shopping for rugs, curtains, and other home textiles, opt for linen and wool, two natural fibers that are inherently fire resistant.

• If it's ripped, fix it. Repairing torn upholstery will prevent a good chunk of flame-retardant-laden dust from migrating out of couches.

• Dust & vacuum. Use a damp mop to pick up dust from furniture and use a HEPA-filter-equipped vacuum cleaner to get toxic dust off floors and out of furniture.

• Wash your hands regularly. You'll reduce the amount of flame retardants entering your body, and not just at home. Flame retardants are used in cars, office furniture, and electronics, and you can get exposed from all those sources.

• Speak up! In addition to the revised TB117 being drafted, the CPSC has been sitting on its proposed law since 2008. Visit greensciencepolicy.org/take-action to find ways to contact your own legislators and urge them to enact the CPSC law.