Author: Nicole Fahrenfeld
Institution: Johns Hopkins University
Date: April 2005
Why are a group of chemicals proven to save lives in fires feeling the burn from scientists and governments over public health concerns? Brominated flame retardants (BFRs) are added to products like couches and electronics, but are now found in places they shouldn't be, like our food and breast milk. A number of studies about the possible health effects from BFRs have ignited a movement to ban them. As some BFRs are being pulled from the shelves, will a recent plot twist in the BFR story be enough to quell this heated debate?
Experiment (do not try at home): take an American TV set, which, because of fire regulations, contains flame retardants, and an European TV set, which does not. Pour alcohol on the American version, leave the European set alone, and set both on fire. Notice that flames on the American TV only last until the alcohol has burned off. As for the European TV set . . . evacuate the room - it's filled with dark smoke and the fire is spreading.
The website of the Bromine Science and Environment Foundation (BSEF) proudly shows video clips like this and others demonstrating how products that contain flame retardants delay ignition, lessen the amount of toxic gases produced, and slow the spread of flames. All of these add valuable time for people to escape from a fire.
"Two hundred and eighty lives are estimated to be saved thanks to the use of brominated flame retardants alone" in the US in 2000, the BSEF website reports. That same year over 4,000 fire-related deaths occurred, according to BSEF.
Some Chemistry Concerns: How'd They Get There? (Part I)
BFRs are not the only type of flame retardant but they are the most commonly used. BFRs constitute a class of chemicals that contain at least one bromine. Tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), and 3-polybrominated diphenyl ethers (PDBEs) penta-, octa-, and deca-, are the most used. The structures are very similarmostly rings of carbon with several bromines attached. They can comprise up to 30% of the volume of a finished product.
"If you're a chemist and you draw the structure [of PBDEs], they look a lot like PCBs," explains Ronald Hites, an environmental chemist at Indiana University. Hites went on to note that PCBs have a history of being environmentally unfriendly.
A report by the National Science Foundation (NSF) supports Hites. "Brominated Flame Retardants: A Cause for Concern?," the NSF report, individually addresses TBBPA, HBCD, and speaks of PBDEs as a class. All of these BFRs have high octanol-water partition coefficients, symbolized as Kow, which says they have a higher affinity for fat than water. Animals store BFRs in fat, passing the chemicals up the food chain.
As Hites and other chemists would have predicted, scientists are measuring BFRs in the tissues of marine animals- particularly salmon, human breast milk, and sewage sludge among other places.
To Worry or Not to Worry
With a growing number of animals accumulating BFRs, scientists are asking whether or not BFRs are harmful. BSEF is quick to discount the "speculation" about the environmental and health effects of BFRs.
"Those raising questions aren't required to have any particular expertise or to have demonstrated knowledge about the existing database," their website reads. "To date, no human health or environmental effects have been associated with the BFRs detected."
But several peer-reviewed publications have printed health related research papers that suggest otherwise; papers report neurotoxic effects in Environmental Health Perspectives, thyroid disruption in Journal of Clinical Endocrinology, and T-cell inhibition, which hurts the immune system, in Toxicology.
"It's very difficult to say whether people should or should not be worried," says Heather Stapleton, a postdoctoral fellow at the National Institute of Standards & Technology, and lead author of a 2004 study on PDBEs in household dust. "That depends on a person's views of environmental and indoor contamination."
Stapleton found PBDE levels in household dust ranging from 700 to 30,100 nanograms of PBDE per gram of dust. Another study conducted by Professor Miriam Diamond, a University of Toronto scientist, stated that indoor air contains 10 to 20 times the level of PBDES found in outdoor air. Diamond estimates that toddlers, who spend a lot of time close to the PBDE polluted dust on household floors, get 90% of the PBDE exposure from breathing in the dust.
How'd They Get There? (Part II)
If BFRs are harmful, how are they getting into our bodies, wildlife, and dust? One particularly alarming report is that sperm whales, creatures that normally spend their whole lives in the deep sea, have high levels of BFRs in their blubber.
"We still are not confident in the primary [human] exposure routes (i.e. how important is dietary exposure relative to inhalation and exposure in the home)," explains Stapleton. This question, she believes, is something on which research should focus.
Now it's time for the twist: the PBDEs, a class of BFR, found in whales are not just from industrial sources, according to a group working at Woods Hole Oceanographic Institution (WHOI).
"It has been assumed that industrially-produced compounds accumulate in animals, but our results show that natural products do as well," says Emma Teuten, lead author of the whale study and a postdoctoral fellow in the Department of Marine Chemistry and Geochemistry at WHOI. In other words, BFR accumulation might be a natural process.
So are fire retardants off the hook? Probably not quite yet.
"Animals have been exposed to industrial compounds for years," says Teutan. "And having natural compounds of similar chemical structure may help toxicologists explain how and why enzymes have the ability to metabolize compounds like PCBs. Did the whale we studied accumulate these compounds from its diet of squid, and if so, where did the squid get them?"
"No We Didn't Light It, But We Tried to Fight It"
Meanwhile, governments have been banning certain BFR formulas as a precautionary measure. In the US, the Great Lakes Chemical Corporation is voluntarily phasing out two formulas, which is a virtual ban because they were the main producer of these chemicals. Researchers are looking into safer' flame retardants. These include types of BFRs that are considered less prone to bioaccumulate and are more stable.
"There are other BFRs that can be used as replacements for PBDEs [the formulas being banned]," says Stapleton. "However, we don't know much about these "new" BFRs and only time will tell if they follow a similar path."
What will be the next piece of evidence to fan the flames of this heated debate? It is hard to say, but there is a plethora of reading available on the flame retardant issue to piece together a guess. Meanwhile, we are still weighing evidence on whether permitting or banning BFRs is a better way to protect the environment and public health.
Sources and Suggested Reading
Betts, Kellyn. "Research challenges assumptions about flame retardant." (2004) Environmental Science and Technology. 38(1), 8A-9A.
Birnbaum, L. and D. Staskakl. (2004) "Brominated Flame Retardants: A Cause for Concern?" Env Health Perspectives. 112(1): 9-17.
de Boer, J., Wester, P., Klamer, H., Lewis, W.E., and Boon, J. (1998) "Do Flame Retardants Threaten Ocean Life?" Nature. 394, 28-29.
"Flame Retardants in Household Dust." C&E News. 83(2), 34.
Schecter et al. (2004) "Polybrominated Diphenyl Ethers Contamination of United States Food." Env Sci Technol. 38(20), 5306 -5311.
Stapleton, H., Dodder, N., Offenberg, J., Schantz, M., and Wise, S. (2005) "Polybrominated Diphenyl Ethers in House Dust and Clothes Dryer Lint." Environmental Science and Technology. 39(4), 925-931.
Tullo, Alexander. (2003) "Resting easier: The flame-retardant industry is optimistic about its future, thought some products are under fire." C&E News. 81(46), 43-44.