Chemical flame retardants are used to limit fires, but they've been linked with several health problems. Photo courtesy macwagen, Flickr Creative Commons
Chemical flame retardants are used to limit fires, but they've been linked with several health problems. Photo courtesy macwagen, Flickr Creative Commons

An industry group welcomes a Duke researcher to explain the troubling legacy of chemicals intended to to make materials fire resistant

By Catherine Clabby

Before environmental chemist Heather Stapleton briefed a roomful of textile industry professionals about how people get exposed to potentially harmful flame retardants, she acknowledged the obvious.

“I just want to thank the organization for this invitation to this meeting,” the Duke University assistant professor Thursday told members of the Association of Textile, Apparel & Materials Professionals gathered in Cary for two days this week. “It’s a very different venue and a very different group of people than I normally interact with.”

Heather Stapleton supervises a lab that offers free chemical tests of residential foam. Photo courtesy National Institute of Environmental Health Sciences

“I know this can be a very controversial issue. There are hundreds of different fire retardants on the market. And there is really more of an environmental concern for a handful of them,” she said. “That is where most of my research has fallen.”

With that, Stapleton launched into summaries of a long list of experiments she and the members of her laboratory have conducted in recent years. They’ve been looking at a subset of fire-supressing chemicals that can easily shed potentially toxic small-molecule chemicals inside our homes, directly onto our bodies and even into indoor air.

Long lasting

That’s a concern, Stapleton said, because these chemicals—designed to keep working for years, long enough to deter fire in long-lasting products—don’t break down easily. Some accumulate over time within people, increasing the levels and length of exposure a child or adult experiences over time.

Stapleton has focused much of her research on a flame-retardant mixture called PentaBDE (PBDE), manufacture of which was phased out in the United States in 2004 but remains in many home products, including those containing polyurethane foam. Animal studies indicate it may be toxic to the human liver, the thyroid and impair normal neurological development.

She is also interested in the chemicals developed to replace PBDE since the phase-out, the make-up of which have not always been disclosed for “proprietary” reasons; those include tris (1,3-dichloro-2-propyl) phosphate (TDCPP). Animal studies suggest this new flame retardant harms brain cells, disrupts normal hormone messaging, and hinders normal reproduction.

Through highly technical detective work with sensitive instruments, Stapleton has found flame retardants in car seats, portable crib mattresses, baby carriers, changing table pads, nursing pillows and high chairs. She also has found them in camping tents. Some of the househould discoveries came from samples she and colleagues at Duke have collected and analyzed for free as part of a research project. Her research team has also documented the chemical’s presence in household dust, as well as human blood and the urine of pregnant women.

Contentious issues

Stapleton explained all this near the end of the two-day conference called Shining a Light on Flammability in Textile Applications.

For much of the meeting, which drew participants from multiple states, Central America, South America and Europe, the focus was on less controversial topics, including fire science, new protective clothing for firefighters, and laundering effects on flame retardant materials.

Chemical flame retardants are used to limit fires, but they’ve been linked with multiple health problems. Photo courtesy macwagen, Flickr Creative Commons

Thursday afternoon was reserved for items producing more friction within the industry. In addition to Stapleton’s research, participants heard about stepped up federal regulation of chemicals that could, in time, limit the use of some flame retardants. They also were briefed on court cases brought against manufacturers using California’s Proposition 65, a “right to know” law that requires manufacturers of consumer products to notify consumers when some potentially cancer-causing chemicals are contained in products beyond a certain threshold.

A bill to ban some flame retardants in North Carolina has been introduced several times in recent years without making much progress in the General Assembly.

Bert Truesdale, a senior director at TenCate Protective Fabrics in Georgia and an organizer of the meeting, said Thursday’s talks were vital for a diverse industry that wants to be educated about everything relevant to its practices. “It helps us understand the priorities,” he said.

Making changes in materials used in manufacturing isn’t always simple, stressed Maggie Baumann, a marketing advisor to FRX polymers, based in Massachusetts.

“There is always a trade off when you make change in a formula. It can be difficult to maintain the performance standards in the products,” she said.

FRX has developed a different approach to producing flame retardants, one that embeds that ability into stable polymers instead of using easy-to-escape compounds like those Stapleton studies. Trouble is, they are more expensive.

New regulations may nudge the industry into using these more expensive components, she said.

Away from her presentation, Stapleton said she considers wider potential costs when it comes to the chemicals that she studies. Her research shows that children, particularly infants, have the highest exposure to potentially toxic flame retardants. Infants, she has concluded, are more sensitive to exposure to these chemicals and more research is needed to detect whether their exposures are linked to neurodevelopmental disorders, such as attention deficit, autism and cancer.

But before she stepped away from the podium, Stapleton offered one bit of advice from the research realm to the industry people who listened politely to her technical talk.

Her recommendation was to always think about exposure.

“Risk is a function of exposure and toxicity,” she said. “If there are ways to reduce the emission of these chemicals, that would reduce the risk.”

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Catherine Clabby

Catherine Clabby (senior environmental reporter) is a writer and editor. A former senior editor at American Scientist magazine, Clabby won multiple awards reporting on science, medicine and higher education...

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