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More than one-third of all couches in the United States are thought to contain potential toxins that can be dangerous for humans to inhale as furniture foam disintegrates into dust, according to a Duke University and University of California-Berkeley study.

The study, published today in Environmental Science & Technology, found that 85 percent of the couches tested are treated with chemical flame retardants, which can be toxic or lack adequate health information.

Of the 104 couches tested, researchers found that 41 percent contained chlorinated tris, (or TDCPP). Another 17 percent contained pentaBDE, which has been banned around the world.

"In the 70s, tris was brought up when companies were using it in baby clothes and pajamas for very young children," James Klaunig, environmental health professor at the Indiana University School of Public Health, told ABC News. "There was concern about the toxicity. It was removed from the products."

The American Home Furnishings Alliance, whose members include furniture manufacturers, said the industry has been squeezed between competing demands to make fire-resistant products that are free of toxic chemicals.

Its successful efforts to reduce household fires involving upholstered furniture has resulted in increased use of flame-retardant chemicals, the group said today in a statement.

"Throughout nearly four decades of debate over how best to reduce the number of residential fires that involve upholstered furniture, AHFA has steadfastly maintained the position that product modifications should be made only as they are proven safe, effective and affordable for the greatest number of consumers," according to the statement.

"AHFA has advocated against increasing chemical risks to its customers and its employees as a solution to fires caused by 'small open flame' ignition sources."

The Duke-U.C. study noted that many of the flame retardants found in the couches are "associated with hormone disruption, neurological and reproductive toxicity and/or cancer in hundreds of animal studies and a number of human studies."

The study says the furniture foam turns into dust and lingers, a potential problem for small children who might be close to the floor and put their hands in their mouths.

But Klaunig said more tests need to be done before drawing any definitive conclusions about toxin levels and health ramifications.

"Basically, these compounds are toxic and have been shown to cause cancer in rodents. What needs to be defined is how much actual individuals are accumulating in their system from the use of these materials," said Klaunig, who was not involved in the study. "How much do we actually get in our blood system or body system from using the couches?"

Because of a California flammability standard, known as TB117, many furniture manufacturers treat polyurethane foam with flame retardants. TB117 requires furniture sold in the state to withstand a 12-second flame exposure without igniting. Most states have now mandated similar laws.

"Some of the chemicals in the flame-retardant group are stronger than others and last longer in our bodies," Dr. Marcel Casavant, medical director of the Central Ohio Poison Center at Nationwide Children's Hospital in Columbus, said.

"There's really very limited data on whether these chemicals actually cause trouble to humans. They do accumulate in humans. We do absorb them and store them in our tissues, but we don't know the real effect curve."

Casavant, who was not involved in the study, said the most important thing is for manufacturers to choose flame retardants that are less toxic than others.

"People die in fires all the time, so it's important to have that preventative action," Casavant said. "But if manufactures have a choice in which ones they use, obviously, the less dangerous ones are favored."