Flame retardants are a controversial subject. Many fire departments and chemical industry sources praise retardants for reducing fire damage and saving lives. Critics say they do more harm than good and should be banned; they are concerned about the spread of manmade chemicals in the environment and the harm they do or might do to human health. Both sides have an agenda. As with other controversial subjects like circumcision and marijuana, it’s hard to find information that is free of bias and emotion.

The history of flame retardants

Note: my source for this section is an article from the New York Times website written in 2015

In the 1970s, Tris, or Tris(2,3-dibromopropyl) phosphate, was used as a flame retardant in children’s pajamas. When Tris was found to be a mutagen, the Consumer Product Safety Commission prohibited its use in sleepwear. The ban was struck down by the courts, but manufacturers voluntarily agreed not to use it in their products. A newer version, chlorinated Tris, was also voluntarily kept out of sleepwear; but it was widely used, along with other chlorinated and brominated flame retardants, in furniture. A California regulation, Technical Bulletin 117, required upholstery foam to withstand a small open flame for 12 seconds, and the same standards were adopted nationwide. Researchers found that the standard was unrealistic: the fabric covering catches fire first, and its flames can overwhelm the flame retardants in the foam.

There were increasing concerns about health. The retardants are not chemically bonded to the foam and they can escape into the environment and contaminate everything from household dust to rivers to mothers’ breast milk. Small children may be particularly vulnerable because they put almost anything into their mouths, and their nervous and reproductive systems are still developing. Studies found lower IQs in children exposed to flame retardants.

After flame retardants were introduced, the number of home fires declined by 50%, but this could have been partly due to the decline in smoking, the introduction of self-extinguishing cigarettes, changes in building codes, and the prevalence of smoke alarms. In 2012, the Chicago Tribune published a series of alarmist articles alleging that manufacturers had waged deceptive campaigns leading to the proliferation of toxic chemicals that don’t even work as promised. Shortly thereafter, California amended its standards, requiring furniture to resist, not an open flame, but a smoldering cigarette. With the new standards, some furniture is now retardant-free.

A new generation of chemicals, PFAS (poly- and perfluoroalkyl substances) that are found in many consumer products, are considered safe by the chemical industry, but environmental researchers are concerned, saying:

It’s likely they’re going to have some health effects, it just may take us a while to figure out what that is.

Those are not the words of a good scientist. Scientists ask if there are any health effects; they don’t decide ahead of time that it is likely that there are and then go out and try to identify them.

Under the Toxic Substances Control Act of 1976, the government can only act after a substance’s potential for harm has been demonstrated. No flame retardant has ever been banned outright by the government; but some have been voluntarily phased out by industry.

There is no scientific consensus that the levels encountered in homes have any impact on human health, but critics say that is only because these substances have not been adequately tested by independent researchers.

Opinions vary

The criticism of flame retardants is exemplified by an alarmist Mercola webpage: “Flame Retardants Do More Harm Than Good, Research Shows.” He claims they have been linked to infertility, birth defects, neurodevelopmental delays, reduced IQ and behavioral problems in children, hormone disruptions, and cancer. He says they “do not work,” and they actually release toxic fumes that are more likely to kill you than the fire itself. He says these chemicals are also poisoning pets and wildlife. He suggests that flame retardants are responsible for cancers in firefighters, even while acknowledging that firefighters are exposed to hundreds of other toxic, carcinogenic chemicals during all phases of firefighting. His references include rat studies, popular publications like newspapers, and unreliable source like Rodale. He talks about studies that show associations as if they showed definitive proof of causation.

The Cleveland Clinic warns that PBDEs, polybrominated diphenyl ethers, the most commonly used fire-retardant chemicals, have been linked to numerous health problems including thyroid disruption, early onset of puberty, cognitive problems, and delayed mental and physical development. While they acknowledge that flame retardants are associated with decreased burn injuries in children, they are concerned that the long-term effects of using these chemicals in pajamas, furniture, and other products has not been adequately studied. They recommend fire prevention as the best protection for your children, and of course that is true; but there is no way to guarantee that a fire won’t happen despite the best precautions, and to my mind protection with the safer kinds of fire retardants is valuable insurance.

Pro-retardant websites are full of video arguments by chemistry professors. They tell us we each have a 1/3 probability of having a fire in our house some time during our lifetime. Flashover occurs in 3 minutes; with flame retardants, heat release is reduced and flashover is delayed, giving you up to 10-15 minutes to get out after a fire starts. There is plenty of evidence supporting those facts, and many studies that were done by independent researchers rather than by industry. Anecdotes abound. In a recent Air France crash off the end of the runway, the plane was completely destroyed by fire, but all 353 people aboard had time to escape without injury because the plane interior was treated with flame retardants. When a school bus caught on fire in North Carolina, it was totally destroyed, but all 64 children had time to escape out the rear exit without injury. (Of course, we have no way of knowing for sure how many would have died in those cases without flame retardants.) They argue that flame retardants demonstrably save lives. They say if we stopped using them, more people would die. That may be true, but I’d feel better about it if we had better studies with good controls.

Our modern lifestyle depends on polymers and other flammable materials. Water comes in plastic bottles rather than glass. Your furniture is plastic rather than wood. You can sit on a comfortable cushion instead of a hard surface. Your car is plastic. Plastics are made of carbon, hydrogen and oxygen, and the bonds are weaker than in the materials they replace; they burn far more easily. Electrical and electronic equipment and composite materials also increase the risk. Flame retardants are widely used in furniture, transportation, homes, and offices to decrease the risk. A couch without flame retardants can burn down a house in 3 minutes. People worry about toxicity, but the toxicity of a couch without flame retardants may be much worse.

A government-commissioned study in the UK reported: “Both the number and lethality of furniture and furnishing fires rose before the introduction of the regulations and fell afterwards.” It also notes, “The reduction in the rate and lethality of furniture and furnishing fires was estimated to equate to 54 lives saved per year, 780 fewer casualties per year and 1065 fewer fires per year in the period 2003-2007.” This sounds compelling, but can we entirely rule out a post hoc ergo propter hoc fallacy? The numbers declined after the regulations were in place, but how can we know if they declined solely because of the regulations?

Mercola claims that the government is not conducting chemical testing to make sure flame retardants are safe before they are marketed. In reality, the EPA must approve the marketing of flame retardant chemicals. A few compounds have been identified as hazardous, but during a recent review, the EPA identified 50 flame retardants that they concluded were unlikely to pose a risk to humans.

The evidence

What biased people say about the evidence is often misleading. In the first place, flame retardants include a diverse group of chemicals, some more toxic and some more effective than others, and they can’t all be lumped together; we must specify which one we’re talking about and how it is used in products.

One study found 4-point decrements in IQ in children whose mothers showed exposure to one flame retardant, polybrominated diphenyl ethers (PBDEs). That particular compound is no longer used, but it can still be found in older furniture and in dust in the home. Scientific American reported that study and said it was in line with other studies but they pointed out that none of the studies had demonstrated a definitive cause-and-effect link in humans. Correlation is not causation, and confounding factors might have skewed the data.

Flame retardants unquestionably can reduce the risk of fires starting and of fires spreading, as demonstrated in video tests comparing the results of exposing products with and without flame retardants to an open flame. For instance these, on the American Chemistry Council website. Admittedly, this is a pro- industry organization that supports companies and fights government regulation. But I couldn’t find any non-industry videos showing anything that contradicted their findings.

Whose version can we trust?

The person I have come to trust the most on questions like these is Dr. Joe Schwarcz, chemistry professor at McGill University and director of its Office for Science and Society. He understands the chemistry, knows how to interpret the published evidence, is not influenced by anything but science and reason, and has the good judgment to put risks into proper perspective. In his book Monkeys, Myths, and Molecules, which I reviewed for SBM, he has a chapter on flame retardants. He reports that researchers have linked PBDEs to problems in the development of the nervous system, disruptions of the endocrine system, fertility issues, behavior problems, and decreased birth weight; but they only showed associations that were not sufficient to prove cause and effect, and as he points out:

No adverse effects have been noted in foam or electronic equipment recyclers or in carpet installers, despite these workers having higher blood levels of flame retardants than the average population.

A New Zealand study compared exposures in cars to the amounts shown to be risky in animal studies and concluded that flame retardants in car seats were not likely to cause adverse health effects. Gymnasts are exposed to high levels from the foam mats and pits in the gym. In one small study, gymnasts were found to have three times the blood levels of brominated flame retardants as the general population, but no actual health effects have been found in gymnasts.

The new test standard, for smoldering rather than open flame, has been opposed by the flame retardant industry. They claim that it will erode safety. Dr. Joe comments:

That’s debatable, as is whether a decrease in exposure to a few compounds with possible hormonal effects will have an impact on our health in a world where exposure to thousands of both synthetic and natural hormone mimics is common. Hopefully with the elimination of brominated flame retardants we won’t be going from that proverbial frying pan into the fire.

Conclusion: No clear answers

We simply don’t have clear-cut, compelling scientific evidence to guide us at this point. We know flame retardants retard flame, delay flashover, and allow more time for people to escape in laboratory demonstrations; but we don’t really know how much impact widespread flame retardant use and regulations will have on real-world fires. We have concerns about possible health effects, but as yet no compelling evidence that humans are actually being harmed. In the absence of good data, some people tend to invoke the precautionary principle and say we should avoid any chemicals that “might” be harmful. I tend to invoke “the poison is in the dose” principle. We are unavoidably exposed to low levels of a host of chemicals, both natural and manmade; and our body has evolved mechanisms for coping with them. Our laboratories have become good enough to detect the tiniest amounts of all sorts of chemicals in our blood, alarming us about levels that may have no significance for health. For instance, they have found tiny amounts of uranium in our blood; the amounts are too small to worry about, they are negligible in comparison to the higher exposure to background radiation we get from living in Denver or in a brick house. I prefer to wait for clearer evidence before I worry too much about potential harms from low levels of environmental contaminants that may or may not turn out to be significant hazards for human health. Of course, we should continue studying these issues and adapt our regulations and practices as new evidence becomes available.

Posted by Harriet Hall

Harriet Hall, MD also known as The SkepDoc, is a retired family physician who writes about pseudoscience and questionable medical practices. She received her BA and MD from the University of Washington, did her internship in the Air Force (the second female ever to do so),  and was the first female graduate of the Air Force family practice residency at Eglin Air Force Base. During a long career as an Air Force physician, she held various positions from flight surgeon to DBMS (Director of Base Medical Services) and did everything from delivering babies to taking the controls of a B-52. She retired with the rank of Colonel.  In 2008 she published her memoirs, Women Aren't Supposed to Fly.