"Fire is a significant concern when you're 10,000 feet in the air, but I think it boils down to the question of how effective are these chemicals at retarding fire?" Stapleton said. "The data I've seen recently for use in furniture has not convinced me that they would actually provide significant escape time."
Airliners manufactured by Boeing, Airbus, Canadair Regional, McDonnell Douglas and Embraer were analyzed for flame retardants in the study by scientists from Harvard University, Duke and two other institutions. Dust was vacuumed from the carpet and air return grilles on the wall near the floor of airplanes manufactured between 1986 and 2008.
Concentrations of DecaBDE, a brominated flame retardant known as Deca that is used mostly for electronics, wire and cable insulation and textiles, were "orders of magnitude higher than what is typically found in U.S. homes and offices," the researchers wrote. For example, the average level in airplane dust was 495,000 parts per billion, while in home dust it was 4,500 and in office dust, 4,200.
Deca is being phased out by the end of this year in the United States. Little is known about what, if any, health risk it poses to humans. However, animal studies have linked Deca to damage to the liver, thyroid, reproductive system and developing brain. Based on animal studies, it is classified as a possible human carcinogen by the U.S. Environmental Protection Agency.
After a cross-country flight, the hands of nine flight attendants and one passenger contained high levels of Deca compared to the general public.
A newer flame retardant, HBCD, also was found in airplanes at higher levels than in U.S. homes. Others were found at similar concentrations as homes.
One veteran flight attendant said that she and her colleagues are concerned that they are exposed to many contaminants and other health threats on airplanes. “Of course I'm concerned. I just don’t know what to do other than to quit,” said the flight attendant, who has worked for a major airline for several decades. She asked that her name be withheld. "We get exposed to a lot of stuff...You're sitting in recycled air." On long flights, "by the end of the day that air is really used up."
Research in airplanes is relatively new. The first study to show that concentrations of brominated flame retardants (PBDEs) in dust from airplanes are higher than in homes was published in 2008. More recent studies have supported that finding, showing that PBDEs in cabin air during a flight are higher than in U.S. and U.K. homes and similar to levels found in industrial environments.
Despite the high levels on aircraft, the amount of Deca and other PBDEs in the bodies of airline workers is about the same as the general public. A 2010 study did not find higher average levels of PBDEs in the blood of 30 Dallas-based flight attendants and pilots compared to the U.S. general public, though some individuals did have high levels.
"We found no evidence whatsoever of actual intake into the body above background level," said Arnold Schecter, an environmental epidemiologist at the University of Texas Health Sciences Center in Houston. He said there could be some instances of elevated levels "in pilots, flight attendants, other workers inside of airplanes or even people flying in airplanes,however, it seems to us based on our research to be extremely remote."