3-D images show flame retardants can mimic estrogens

August 19, 2013
The brominated flame retardant TBBPA is shown, in this 3-D image, binding to the active site of an estrogen metabolizing enzyme (pink), interfering with the body's natural release of estrogen (transparent grey). Credit: NIEHS

By determining the three-dimensional structure of proteins at the atomic level, researchers at the National Institutes of Health have discovered how some commonly used flame retardants, called brominated flame retardants (BFRs), can mimic estrogen hormones and possibly disrupt the body's endocrine system. BFRs are chemicals added or applied to materials to slow or prevent the start or growth of fire.

"We're beginning to have a better understanding of flame retardants and their effect on human health. This particular study helps us literally see what do when they get in the body—they interfere with the body's natural hormones," said Linda Birnbaum, Ph.D., director of the National Institute of Environmental Health Sciences (NIEHS), part of NIH, and National Toxicology Program (NTP). "Using the 3-D imaging capabilities, we can see the flame retardants binding, or attaching, to proteins like estrogens do."

Birnbaum is an author on the new study which appears online in Environmental Health Perspectives. She and her fellow researchers conducted the study in a facility jointly supported by several NIH institutes.

Birnbaum, a leading researcher on flame retardants, joined with biologists and a to look more closely at one of the most widely used BFRs, tetrabromobisphenol A (TBBPA). Earlier this year, NTP released data from a two-year bioassay study, showing that TBBPA caused tumors in rats and mice.

"Having chemicals act like estrogen or other hormones disrupts how the works," said Birnbaum. "In this case, the ability of flame retardants to bind to and inhibit an enzyme that metabolizes estrogen, called estrogen sulfotransferase, could result in the body having too much estrogen."

The endocrine system is one of the body's main and is responsible for controlling and coordinating numerous functions, including growth and development, reproduction, response to stress, and energy levels.

There are hundreds of different flame retardants. They are often broken into categories based on chemical structure and properties. BFRs, such as TBBPA, are used in many types of consumer goods, including electronics, furniture, building materials, and automobiles. Flame retardants are being studied, because of their pervasiveness and concerns about possible adverse effects on the endocrine, immune, reproductive, and nervous systems.

For this study, the researchers used X-ray crystallography to build a 3-D model of the protein binding to flame retardants. Crystallography allows researchers to look at proteins at the . They examined how TBBPA and a metabolite, or derivative, of another flame retardant called tetrabromodiphenyl ether, or BDE-47, compared with binding of estradiol, a naturally occurring estrogen, to the estrogen sulfotransferase.

Although many flame retardants, including BDE-47, are no longer produced in the United States, some BFRs are slow to break down and can persist in the environment. People can be exposed to flame retardants through a variety of ways, including diet; consumer products in the home, car, and workplace; and house dust.

"Using crystallography allows us to visualize exactly how these compounds can interact with the body's enzymes," said Lars Pedersen, Ph.D., Collaborative X-ray Crystallography Group leader at NIEHS. "Our results revealed TBBPA binding to the estrogen sulfotransferase at the same position and in a similar manner as estradiol binds."

"Although there is much more to be learned about how these chemicals and their metabolites impact different systems in the body, every piece of the puzzle helps increase our understanding of the effects they may have." Researchers, like Pedersen and Birnbaum, hope the findings will be used by companies to develop safer alternatives to current .

Explore further: Non-harmful flame retardants with no additional cost

More information: Gosavi RA, Knudsen GA, Birnbaum, LS, Pedersen LC. Mimicking of estradiol binding by flame retardants and their metabolites: a crystallographic analysis. Environ Health Perspect; DOI: 10.1289/ehp.1306902 [online August 19, 2013]

National Toxicology Program. 2013. Tetrabromobisphenol A. Available: ntp.niehs.nih.gov/go/TS-M200033 [accessed August 12, 2013].

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1 / 5 (6) Aug 19, 2013
Shortly after my wife & I were married while I still had my Environmental Engineering business, a paper came to my attention concerning the dangers of flame retardants. We checked all the mattresses in our house to determine what year they were manufactured. State laws in most of the U.S. by the year 2001 required that all bedding material be treated with flame retardants. We checked the laws for our state & sure enough, we were one of the affected states. Some of our bedding was purchased just before the effective date for our state & was cleared for flame retardants from sampling I sent to a lab I was already doing business with, & found the bedding for the kids was polluted with the poison, and that included the baby's bedding, you know, like the baby is at risk of falling asleep with a cigarette in it's mouth creating a fire hazard.

We burned the kids mattresses, mattress covers,& pillows & replaced all of it from a source in a neighboring state that did not implement the law.
1 / 5 (6) Aug 19, 2013
.......cont'd: We replaced the pillows with virgin wool fill only pillows. All our blankets with fiber fill in them were replaced. As a result, I have healthy kids with no asthma problems, unlike at least third of their classmates in school who suffer from varying degrees of it.

Politicians are brilliant aren't they? Shove pollution prevention laws down our throats & move the same chemicals into our bedrooms under the guise: "We know what's best for you". It pleases me I'm so much smarter than the government Statists who consider themselves such cultural elitists while at the same time they are killing their own family members with their idiocy.
not rated yet Aug 19, 2013
Sounds like that rant was brewing for a while Benni.

I think hindsight can stoke political frustrations. But there will always be an angle one can take to demonize one side or another. If they didn't regulate household furniture then there would be ranting about that. I think there will always be an ever-evolving regulatory environment, so personally, I think it's key to be flexible, change guidelines as new information is found and not simply keep the status quo for the sake of it.

There are plenty of areas where the supposed cure for one thing becomes a future problem. Like aspartame vs high sugar/calorie soda or adding fluoride to drinking water to prevent tooth decay.
1 / 5 (5) Aug 19, 2013
Sounds like that rant was brewing for a while Benni.

There are plenty of areas where the supposed cure for one thing becomes a future problem. Like aspartame vs high sugar/calorie soda or adding fluoride to drinking water to prevent tooth decay.

Sounds like a your own version of a "rant" if you ask me Topher........You work for what government agency? Rest assured I'm all too familiar with this less than tactful language, especially when you are someone who may very well have your own bad decisions to defend.

By the way, there is no fluoride or chlorine in my water & the kids don't have tooth decay, I have a well drawing water from a pristine vein; no soda allowed in my house ever. The best cure for anything is to never have started using chemicals in the first place, whether in your bedding or processed foodstuffs, or farm animals raised shot up with hormones. But I gather you're all for this stuff, have a happy painful life.
1 / 5 (1) Aug 20, 2013
"Using the 3-D imaging capabilities, we can see the flame retardants binding, or attaching, to proteins like estrogens do."
Technically, what you are 'seeing' is a cartoon. Unless the physics in the computer simulation is far more sophisticated than what supercomputers were using last week (and I'm NOT seeing evidence of that) all that has been generated here is an attractive poster.
1 / 5 (1) Aug 20, 2013
"Having chemicals act like estrogen or other hormones disrupts how the endocrine system works," said Birnbaum.
I hope Birnbaum is not relying on the 'results' of the June 1996 Tulane study on endocrine disruptors, occasioned by the publication in March 1996 of the popular press book "Our Stolen Future." That study was retracted by the authors in July 1997 after Science printed a letter from scientists at the U.S.National Institute of Environmental Health Sciences, Texas A&M University and Duke University reporting the Tulane results could not be replicated and Nature published results from British researchers who also could not replicate the Tulane findings.
1 / 5 (5) Aug 20, 2013
How about that, Tadchem & Open think it is appalling that I made lifestyle choices that protects my family from the degrading effects of pollutants they proudly tuck their family members (if they have any) into bed with every night. Goes to show what goes for meaningful science in their lives.

You one star raters are not all that embarrassed to admit what your agenda on a science website really is are you? ..........The disseminating of false, and yes, even deceitful information to protect ..............something.

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