I haven’t posted here in a while, but I did some moonlighting for the blog The Starfish. The article is part of an EcoTox series exploring Toxicants in Consumer Products. So far the topics discussed have included, DDT, phthalates, perflourinated compounds, more phthalates, and my article on flame retardants in furniture. The Starfish is a great place to participate in thought provoking dialogue surrounding the themes of science and the environment, biodiversity and conservation, and making a difference. I encourage you to head over there and check out the articles and leave a comment.
As I mentioned in my previous post, I was recently in San Francisco for the 6th International Symposium on Flame Retardants. California is a fitting host for a conference on flame retardants, as their unique flammability standard, TB-117, has likely contributed to the ubiquitous contamination of humans and the environment with brominated flame retardants (BFRs), specifically the polybrominated diphenyl ethers (PBDEs). Research has shown repeatedly that PBDEs are environmentally persistent, capable of bioaccumulating in organisms, and potentially toxic. As a result of these facts, PBDEs have been banned in several jurisdictions, and industry has agreed to a voluntary phase-out. This has led replacement chemicals being used in place of the PBDEs. These replacements are less well studied than traditional BFRs, and given that they can be structurally and functionally very dissimilar there is a need for new measurement methodologies and descriptions of their environmental fate and biological activity. The efficacy of flame retardants, which are designed to increase public safety, has also recently been called to question. At this symposium the most current state of the science for flame retardants was presented, and below I highlight some of the interesting research from the various sessions.
Studying BFRs often comes with certain analytical challenges. BFRs are tricky to analyze, and given their widespread use, they have become ubiquitous, background contaminants, often showing up in blank laboratory samples. One way to minimize background contamination is to automate and contain the entire extraction procedure. Philip Bassignani of Fluid Management Systems, presented Validating multiple matrix analysis of PBDEs using pressurized liquid extraction and multi-column clean-up, where he showcased the available technology for incorporating Pressurized Liquid Extraction (PLE) and automated multi-column Clean-up as a sample prep procedures, thereby reducing many of the problems associated with traditional manual approaches, and saving loads of time. It was a very cool talk, and made me really wish that this type of instrument was available during my research.
Another problem that was touched upon in this session was the lack of analytical standards for many of these emerging flame retardants. Standards are needed so the identity of a compound can be verified. This is particularly tricky when you are not even sure what you are looking for. Such is the case when you are trying to determine what degradation products, metabolites, or unknown compounds may be in a sample. Mehran Alaee of Environment Canada presented the work Post target determination of brominated flame retardants and related compounds in American Eels captured in Eastern Canada, which was somewhat of an environmental detective story, where they were able to deduce the structure of several unknown contaminants in samples of Eel. This is accomplished by gaining an accurate mass for the unknown compound from the time of flight mass spectrometer, and then determining the possible combination of atoms that could result in that mass, then determining whether the mass spectra of that possible combination fits with the observed spectra in the sample. It is like trying to solve a puzzle, without knowing what the picture is supposed to be.
Measurements in Abiotic Media
Once the methods are developed for analyzing these flame retardants (again not an easy task), next you can go out an measure them in real samples. Rob Letcher of Environment Canada presented the paper Comparative photolytic debromination of decabromodiphenyl ether, decabromodiphenyl ethane, and tetradecabromodiphenoxybenzene flame retardants and environmental considerations, in which he highlights some of the measurements of new and relatively huge BFRs, and some of the pathways by which they can be transformed into more toxic compounds.
Measurements in Biota
In addition to measuring flame retardants in environmental samples like, air, dust, water, and sediment, it is also important to monitor these compounds in biota. The uptake of compounds from the environment into biota is known as bioaccumulation, and if the accumulation is great enough, this can result in toxic effects. Roxana Sühring of Helmholtz-Zentrum Geesthacht, Institute of Coastal Research presented work on the accumulation of flame retardants in two different species of eel, throughout their lifecycles, From glass to silver eel – brominated flame retardants and Dechloranes in European and American eels. The work was very interesting, largely in part because of the unique life-history traits of eels (future post), and the varying susceptibility to contaminants and contaminant profile during their life cycle.
One of the reasons for concern over flame retardants is due to their toxicity. Flame retardants tend to not be acutely toxic, but rather demonstrate a chronic toxicity, often mediated through endocrine system, as several flame retardants have structural similarities to hormones, particularly the thyroid hormones. David Volz of the University of South Carolina presented some very compelling evidence Aryl phosphate esters within a major penta-BDE replacement product induce cardiotoxicity in developing zebrafish embryos: potential role of the aryl hydrocarbon receptor, that demonstrated that some flame retardants are exerting their toxicity through the aryl hydrocarbon receptor; the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin is also mediated through this receptor.
Regrettably I missed this session as I was discussing my posters with other researchers over lunch and things went long. However, the talk Associations between maternal serum PBDEs and fetal thyroid hormones: Results from the Chemicals, Health and Pregnancy (CHirP) study, looked really cool.
Before there can be toxicity, there must be exposure. This session showed many ways (mainly dust and food) which we are being exposed to these compounds, but two of the talks were about unique occupational exposures. The first, by Anna Strid of Stockholm University looked at Exposure to brominated flame retardants during maintenance work in aircrafts. Airplanes are loaded with flame retardants, and that is probably a good thing, but continuous workplace exposure can become an issue for pilots, flight attendants, and mechanics. Another interesting and overlooked group in terms of high levels of occupational exposure, are gymnasts. Courtney Carignan of Boston University School of Public Health presented work on Gymnast exposure to flame retardants, given that much of gymnastic equipment is foam, which contains high concentration of flame retardants, levels in the air, dust and gymnasts were elevated. The work presented was just the preliminary findings and there is much more to be done, but this was really cool and will be something to keep an eye on.
The symposium concluded with talks related to how all the research that has been done can change or influence policy. One of the first challenges that will need to be addressed is to get everyone talking the same language. Andreas Rydén of Stockholm University presented A novel abbreviation standard for organobromine, organochlorine and organophosphorus flame retardants, to help get everyone on the same page, which means I will have to change all my references to TBBPA-DBPE, BEHTBP, and EHTeBB in my papers to TBBPA-BDBPE, BEH-TEB, and EH-TBB, respectively. The symposium ended with a panel discussion, which focused on whether there is a need for these flame retardants in various consumer products (e.g., insulation, couches, children’s toys and products), and the current regulatory system for flame retardants which is highly stove-piped (e.g., EPA, California Bureau of Home Furnishings, Department of Toxic Substances Control all have interests and regulations relating to flame retardants) and largely ineffective. There was a comment from the audience that flame retardants (and other chemicals in consumer products, (e.g., PFCs, musks, nanoparticles) should be regulated just as food, drugs, and pesticides are currently. One comment that really struck me is that scientists are spending lots of time and money (often public funds), to just determine what substances are in the products we are exposed to everyday. Recently, there has been lots of excellent work by researches focused on determining what is in our couches, knowledge that industry has, but does not share because of its proprietary nature. This just seems so backwards to me.
Overall it was a great symposium filled with an almost overwhelming amount of interesting research and discourse. Flame retardants are going to be an environmental and human health issue for a long time, and forums like this symposium are crucial for helping researchers gain insights and share ideas.
- Fire Safety without Harm (science.kqed.org)
- Flame retardants, found in many consumer products, ignite health concerns (bangordailynews.com)
- Dear California, You Owe America a New Couch (laurasrules.org)
The Up-Goer Five Challenge was inspired by a xkcd comic titled “Up Goer Five” which sought to describe the design of the Saturn V Rocket, using only the one thousand (or “ten-hundred”) most common English words. AmericanScience: A Team Blog has a great description of the reaction to the comic, and the resulting challenge to scientists to translate their research abstracts using a special web-based text editor to contain only the ten-hundred most common words. The challenge was taken up by many people, including chemists, and a linguist who beautifully describes Saturn, who displayed their efforts on Twitter #upgoerfive, which were collated into a Storify, and a Tumblr was created to showcase the entries.
I thought I would try the challenge as well, using the abstract from my thesis, titled Environmental Fate and Toxicity of Three Brominated Flame Retardants in Mesocosms. Before I start, I fully acknowledge that the abstract (presented below) is full of jargon, acronyms, and not very accessible, but it describes my work in a way that is accepted by my community. Here it is,
Traditional brominated flame retardants (BFRs), namely the polybrominated diphenyl ethers (PBDEs), have persistent, bioaccumulative, and toxic properties that have resulted in the phase out of their production and their being banned in certain jurisdictions. To meet regulatory flame retardancy requirements, non-PBDE BFRs have entered the marketplace. Much remains unknown regarding the environmental fate and toxicity of these emerging BFRs. The objective of this thesis was to use outdoor mesocosms to examine the fate and toxicity of three emerging BFRs; bis(tribromophenoxy)ethane (BTBPE), tetrabromobisphenol A bis(dibromopropyl ether) (TBBPA-DBPE), and BZ-54, which consists of two BFRs, ethylhexyl-tetrabromobenzoate (EHTeBB) and bis(ethylhexyl)tetrabromophthalate (BEHTBP).
While it was difficult to accurately determine degradation rates because of fluctuating concentrations, the estimated half-lives indicated these compounds are persistent (> 60 days in sediments). The partitioning of the compounds between the particulates and the sediment resulted in differential degradation rates (greater in the particulates), and products formed; those formed on the particulates were consistent with photodegradation products.
The effects of these emerging BFRs on Hyalella azteca and the benthic macroinvertebrate community were assessed through the use of in situ exposure and sampling techniques. The in situ Hyalella cages showed a high degree of variability for most endpoints, regardless of their placement (e.g., water column vs. sediment) in the mesocosm. BTBPE accumulated in the H. azteca (0.03 – 1.4 ng/g ww), however this was not associated with any changes in growth or reproduction. There was high variability in abundance and diversity between the mesocosms, which limited the ability to detect statistically significant differences. Interestingly, the BZ-54 treated mesocosms had the greatest abundance, and the least amount of community diversity.
This thesis examined the bioaccumulation potential of these compounds in fathead minnow (Pimephales promelas), as well as the associated effects on growth and development as measured through physical and biochemical endpoints. There was considerable uptake and persistence of BTBPE and TBBPA-DBPE, as well as indication of metabolism of these compounds, but limited physical effects observed. There were indications of increased oxidative stress in the BZ-54 treatment, and increased induction of vitellogenin in fathead minnow from the BTBPE treatment.
I could tell translating this into Up Goer Five language was going to be a difficult challenge, as from the title of my thesis, “and” “of” and “three” were the only words recognized by the Up Goer Five word editor. The description was made more difficult when words like “treatment”, “pond”, and even “fish”, were not allowed. So with a bit of working (e.g., fish = water cats, thanks PETA) here is my translated abstract using only the ten hundred most common words.
Old school fire slowing things are long lasting and bad, so new fire slowing things were made. We don’t know much about the new fire slowing things, like if they are long lasting or bad, so we tried to figure that out using small bodies of water.
While it was hard to find out how long they stick around, the best guess for half-lives says that these new fire slowing things are long lasting (> 60 days in the bottom of water). Where these fire slowing things ended up changed over time, with them liking to go into the bottom of the water. These fire slowing things changed into other things over time, these new things had been seen by other people too.
We wanted to figure out if these new fire slowing things would hurt the little life forms in water. Most of the little life forms were the same in all the bodies of water, no matter what new fire slowing thing was put in the water. One fire slowing thing made its way into some of the little life forms, however this did not change the growing or baby making of the little life forms. There were lots of changes in total number and make up of little life forms between the water bodies. The bodies of water that had one fire slowing thing in them, had the greatest numbers, but the least number of types.
This work also looked into the way the fire slowing things could move into water cats, and if they caused any problems in growing or making babies. Two of the fire slowing things moved into the water cats and stayed there for a long time, and did break down into other, smaller things. There was not much change in the growing, well being, or baby making of the water cats. One of the fire slowing things did look like it was causing some hurt, but only a little bit. Some of the boy water cats that were in the one fire slowing thing water body, had stuff in their blood that should only be found in girl water cats, but not so much that it was really important.
I am not sure that this Up Goer Five version is less jargon filled or any more readable than the original but it certainly illustrates the point about how the language we use, and the restrictions that are placed on that language, to communicate science can have a big difference. AmericanScience notes “what’s at issue is how the language in which we conduct and communicate science—though essential—can be a handicap both to public understanding and to scientists’ own abilities to work out problems together. How much this hits home will depend on the area you’re talking about, of course, but there’s a certain truth to how technical terminology can impede—rather than expedite—collaboration, especially across subfields”. Effective science communication can be tricky, and the Up Goer Five challenge is an interesting way to get people to thinking more carefully about how their word selection impacts readability.
- The Up Goer Five is a rocket, you guys (cubiksrube.wordpress.com)
- Up-Goer Five and Science Communication (skepticblog.org)
- Drug Discovery With the Most Common Words (pipeline.corante.com)
- The Up-Goer Five Text Editor (and how to use it for SEO) (halfblog.net)
- The Up-Goer Five – a thing you can find on a computer (guardian.co.uk)
- The Up Goer Five Text Editor (chronicle.com)
- Hit-Ball and the Best Player Present (thefundamentalsblog.wordpress.com)
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.
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