Researchers at the Nicholas School of the Environment at Duke University in Durham, N.C., and colleagues at the Boston University School of Public Health and the University of California, Berkeley, collected and analyzed 102 samples of polyurethane foam from residential couches purchased in the United States from 1985 to 2010.
California's furniture flammability standard Technical Bulletin required the phaseout of polybrominated diphenyl ether -- PBDE -- flame retardant mixture PentaBDE in 2005. California has an old fire standard for upholstered furniture exposed to an open flame, but furniture manufacturers use the same fire-retardant-treated foam in all their furniture, not just pieces for California.
In the 41 samples purchased prior to 2005, PBDEs associated with the PentaBDE mixture were the most common flame retardant detected at 39 percent followed by tris1,3-dichloroisopropy1 phosphate at 24 percent, which is a suspected human carcinogen.
In the 61 samples purchased in 2005 or later the most common flame retardants detected were tris (1,3-dichloroisopropyl) phosphate at 52 percent and components associated with the Firemaster550 mixture at 18 percent.
Since the 2005 phaseout of PentaBDE, the use of tris (1,3-dichloroisopropyl) phosphate increased significantly, the study said.
The findings were published in the journal Environmental Science and Technology.