Retarding Flame Retardants

I have previously written about flame retardants and how the practice of incorporating brominated flame retardants (BFRs) into materials is used to improve public safety by slowing down, or retarding, the spread and growth of a fire, thus increasing the time it takes to reach flashover. Several national agencies set flammability requirements for plastic foam insulation and other building materials, as measures to help prevent loss of life and minimize physical damage. To meet these performance requirements, BFRs (and other types of flame retardant chemicals) are added to the material. While these BFRs have been found in the environment and in people, their use has always been defended based on the fact that they improve public safety and save lives. However, these improved public safety claims have recently come under fire.

The issue was first drawn to the public’s attention with the excellent investigative journalism series by the Chicago Tribune titled Playing With Fire. Below is the introductory video, but do yourself a favor and read the entire series.

The fiery debate regarding the efficacy and necessity of the incorporation of flame retardant chemicals into furniture foams heats up, as claims by industry go up in smoke.

One of the findings presented in the series, was from a report by the Consumer Product Safety Commission (CPSC) which found that “fire-retardant foams did not offer a practically significantly greater level of open-flame safety than did the untreated foams (p.23).” The report further noted that a fire barrier (composed of fiberglass, modacrylic, and polyester) between the upholstery fabric and the foam provided a markedly increase in the overall fire safety of the furniture. A similar report by Underwriters Laboratories (UL) also reached the conclusion that barriers (often called interliners) offer significant fire-safety advantages, while flame retardants in foam do not. When called before the US Senate Committee on Environment & Public Works, Marshall Moore, spokesperson the flame retardant producing company Chemtura, defended his companies products noting “Scientific data show the relative risk associated with our flame retardants is extremely low and is far outweighed by the societal benefits of an innovation that reduces the number and severity of fires that can threaten lives and property.” This claim was disputed by scientists, and the lead author on the paper cited by Moore, in the Tribune series.

The above studies indicate that the incorporation of flame retardant chemicals furniture foam, has no significant effect on fire safety, and in fact, more improvements in fire safety are achieved with the use of design and technological interventions, such as barriers. While this holds true for upholstered furniture, there had been some questions as to whether this held true in other products for which flame retardants are added, such as building materials. Recently, a report found that flame retardants routinely added to foam insulation make no difference to the prevention of fire in buildings where a fire-safe thermal barrier already exists. As with the furniture case, the authors found that when a code-mandated thermal barrier was in place, the flame retardants (in this case HBCD and TDCPP) did not provide additional benefit to reducing fire hazard. They further comment that during fires, flame retardants are liberated and can actually make fires more deadly! It was recently found that halogenated flame retardants increased the amount of carbon monoxide and hydrogen cyanide released during combustion, increasing the acute toxicity of those exposed. As well, when products with BFRs incorporated into them burn at high temperatures, they can produce polybrominated dibenzo-p-dioxins and dibenzofurans, which have chronic health effects for those exposed, particularly fire fighters.

The few examples above prove that chemical intervention is not the only option for improving fire safety, and in fact it may not do much to improve it at all. Given that the role of flame retardants is to increase public safety, it is time that we took a serious look at whether they are causing more harm than good, and begin to retard their usage.

Flashover

As a follow-up to yesterdays post, today I wanted to discuss what flame retardants do, and why they are beneficial and controversial. Before you read this post, it might be helpful to watch the movie Backdraft, or the first season of Rescue Me, as they each do a great job of depicting what it is like inside a fire, and highlight the very real danger they present (in a pinch you could watch Ladder 49, or Third Watch, I just don’t find them to be as good). As mentioned yesterday, flame retardants act to slow the spread of fire, mainly they increase the time to flashover. Flashover is the point at which temperatures get so hot that everything in the room bursts into flames. The incorporation of flame retardants increases the time to flashover, by some estimates up to 8 minutes.

Progression of a fire without flame retardants (red) and with flame retardants (blue).

While that may not seem like a lot of time, in a fire every second counts, and those extra minutes might be the difference between life and death. In fact after the August 2nd, 2005 plane crash at Toronto’s Pearson Airport, where an AirFrance airbus carrying 309 passengers, burst into flames, yet everyone managed to escape, flame retardants were credited with giving the flight crew the few extra minutes needed to ensure everyone got off the plane safely.

In addition to their use in the transportation sector, flame retardants are also heavily used in the household. In the United States, a total of 3 010 civilian fire related deaths occurred in 2009, 85% of which were in the home. Continue reading

Fire Chemistry

What better way to kick off the week than with a discussion of chemistry! And in keeping with the fire theme from last week I though it would be good to talk about the chemistry behind fire, and try to answer the question, what is fire?. The question has been asked throughout history. Aristotle considered fire one of the major elements of the universe, along with water, earth and air. Alchemists and early chemists, namely Johann Joachim Becher, believed fire was caused by the liberation of a substance called phlogiston. The phlogiston theory posited that all flammable materials contain phlogiston, a massless, odorless, colorless, tasteless substance that is liberated upon burning. The idea of phlogiston was eluded to in the Star Trek The Next Generation episode, Thine Own Self, where Data crash lands on a planet and loses his memory and is forced relearn everything from this pre-industrial society, which has an Aristotelian view of the universe. Data shoots down that theory quite nicely.  Just as Data was able to poke holes in that theory, so too was Antoine-Laurent Lavoisier able to poke holes in the phlogiston theory. In 1777, Lavoisier demonstrated that burning is a process that involves the combination of a substance with an element in the air, which he named oxygen (previously described as “dephlogisticated air” by Joseph Priestly). Lavoisier explained combustion not as the removal of phlogiston, but rather as the addition of oxygen, a process called oxidation. When oxidation reactions occur at high temperatures, and in the presence of fuel, fire is produced. Thus, fire is the visible, tangible side effect of matter changing form as part of a chemical reaction that releases heat and light.

Myself, deep in thought next to the camp-'side effect of matter changing form as part of a chemical reaction', in Algonquin Park

In the combustion process the following steps happen; First an energy source (heat, incandescent material or a small flame) acts as the initial ignition source. The energy is transmitted by the ignition source to the material (wood, polymer etc.), where pyrolysis takes place. Pyrolysis is a process that degrades the long-chain molecules in the material into smaller hydrocarbon molecules, which in turn release into the gas phase. In the condensed phase, the result is an inert carbonised material called char. It is in the gas phase where the combustible gases released from the pyrolysis reaction combine with oxygen, producing an exothermic chemical reaction (flame), which  involves high-energy free radicals (H• and OH•). Incomplete combustion products are emitted as smoke, and the energy emitted during the exothermic reactions is transmitted back onto the material and reinforces pyrolysis. As you can tell from its cyclical nature, that left unchecked this chemical reaction has potential for great destruction. And that is where flame retardants come into play! Continue reading

This Post is on Fire

Saturday posts are going to be about music, and I hope to draw attention to some great artists, particularly independent Canadian artists. The artist that I am featuring today is Pat LePoidevin, Pat has a great voice, and uses a loop pedal to create some really amazing songs, and is definitely worth checking out live if you ever get the chance. He played a show in Guelph a couple of years ago, and at one point he started a song, then realized he left a guitar in his car, so he kept the loop going, and ran out to his car and got it and was back to finish the song like nothing had happened. It was really keen. One of my favorite songs of his is Fire. One lyric in the song that stands out for me is “Fire, teach us both how to dance in the forest”. It really reminds me of the importance fire has played in shaping human history. While it is not really known when early hominds began controlling fire, estimates range around the 1.4 million years ago mark, this achievement likely coincides with the emergence of modern Homo sapiens. The control of fire gave early hominds many advantages that would ultimately shape human evolution. Keeping a fire at a campsite would keep predators at bay, allow for the cooking of food, and even create a community, which may have been the beginnings of a society. This whole notion is wonderfully depicted/parodied in the short video Tadufeu.

Screen grab from the video "Tadufeu", while it starts off fun and light, it take a turn for the morid at the end.

Cooking food not only makes it easier to chew and digest, it also allows for more energy to be released for use in the body. This increase in available energy has been suggested as the reason why our brains have grown to their relatively large size compared to our ancestor australopithecines. Cooking food may also be responsible for our increasing waistlines. A study by Rachel Carmody from the Department of Human Evolutionary Biology at Harvard’s Graduate School of Arts and Sciences examined the role of cooking on foods’ caloric content. She found that cooking food boosts the amount of energy your body can get from it compared to raw food. This has implications for nutrition labels, which list the same number of calories for ingredients whether they are raw or cooked. So just as fire and cooking food led our ancestors to energetically “trade guts for brains”, we are now in the process of trading back for our guts. Just some food for thought (sorry I couldn’t help it).