Category → Miscellaneous
(Russ’s post on osmium earlier this week and mine today are both for the “Our favorite toxic chemicals” carnival hosted by Sciencegeist. Go see the collected posts from Monday, Tuesday, and Wednesday. On Twitter, watch #ToxicCarnival.)
In 2005, a California State University, Chico, student died after being forced to drink gallons of water during a fraternity hazing ritual. Four of his fraternity brothers pleaded guilty to charges ranging from involuntary manslaughter to hazing. In 2007, a woman participating in a radio contest to win a Nintendo Wii died after drinking nearly 2 gallons of water without urinating. A jury later awarded $16 million to her family.
Water, H2O. Oxygen, O2. Without either one, we die. But also: With too much H2O, we die. With too much O2, we die. The dose makes the poison.
H2O is essentially the solvent in which all cellular substances are dissolved. Overall, the human body is about 60% H2O, although the amount varies depending on the body part: bone is 22%, brain is 70%, and blood is 83%. H2O is polar, with the oxygen carrying a slight negative and the hydrogens carrying a slight positive charge. That means that H2O tends to form strong interactions with other polar molecules but rebuff nonpolar ones, which is why dispersed oil droplets will gather together in a cup of H2O. At the cellular level, those polar and nonpolar interactions play an important role in things such as membrane formation, protein folding, and protein-protein or protein-substrate binding.
But as the news reports above demonstrate, H2O can also kill, and not just by drowning. Drink more H2O than your kidneys can handle and the fluid builds up in your blood, diluting the sodium concentration–a condition called hyponatremia. H2O then moves into cells to equalize the sodium concentration between the two environments. The influx of H2O causes cells to swell. Some parts of your body have room for that, but your brain does not. “Rapid and severe hyponatremia causes entry of water into brain cells leading to brain swelling, which manifests as seizures, coma, respiratory arrest, brain stem herniation and death,” M. Amin Arnaout, chief of nephrology at Massachusetts General Hospital and Harvard Medical School, told Scientific American.
For its part, O2 is a key player in cellular energy cycles. We breathe in O2, which red blood cells deliver throughout our bodies. Mitochondria in other cells turn that O2, sugar, and adenosine diphosphate into H2O, CO2, and adenosine triphosphate (ATP). ATP then serves as the energy source for a multitude of other cellular activities involved in being alive. One molecule of glucose produces 36-38 molecules of ATP.
But human bodies evolved to breathe in O2 as about 20% of air. Breathing higher concentrations can lead to hyperoxia, or higher-than-normal concentrations of oxygen in body tissues. Increasing the percentage of oxygen to about 50% can cause damage to the lungs and eyes. Increasing the pressure as well, such as in hyperbaric chambers, can be toxic to the central nervous system.
Water and oxygen. H2O and O2. Necessary for life. But there can, in fact, be too much of a good thing.
Osmium is the densest of all natural elements and certainly one of the rarest, with worldwide production of about 545 kilograms annually. It’s incredibly expensive stuff, and yet, look at all the varied uses! Osmium is used by itself or as an alloy for fingerprint detection and in fountain pen tips, pacemakers, light filaments, and jewelry. And it’s reacted with oxygen to form osmium tetroxide.
The word osmium actually comes from the Greek word “osme,” or odor, for the unique acrid odor given off by OsO4. Osmium tetroxide is incredibly toxic and has an OSHA permissible exposure limit (PEL) of 0.002 mg/m3. For comparison, elemental mercury vapor has a PEL of 0.1 mg/m3. Osmium tetroxide might even be considered a perfect component of a terrorist “dirty bomb,” but it’s simply too expensive to buy enough to make that practical.
A primary use for OsO4 is for tissue fixation in electron microscopy. Hundreds of hospitals use it in their clinical labs, and when the solution is spent, it needs to be disposed safely. My experience with OsO4 stems primarily from efforts to recycle the spent compound. Ironically, despite its obvious toxicity, OsO4 isn’t regulated as hazardous waste. While it is certainly toxic to humans, it breaks down fairly readily in the environment, (apparently) isn’t toxic to aquatic or marine life, and isn’t mobile enough to be considered a threat to drinking water. That means that theoretically one could take this non-regulated waste and sell it for a handsome sum to a refiner who could recover and resell the metal.
However, here is a lesson in making sure you know the hazardous waste regulations thoroughly! It turns out that one of the several buffers that labs use with OsO4 is cacodylic acid, which has the formula (CH3)2As(O)OH. Therein lies the rub. While EPA decided that osmium isn’t hazardous to the environment, arsenic is. So, any refiner recovering osmium from the spent solution also containing that particular buffer must have a full-blown EPA hazardous waste treatment, storage, and disposal facility permit! Use a different buffer and you’re fine.
It only took me stops at five hospitals to find out the popularity of the cacodylic acid buffer, thus ruining my plans for an early retirement.
For more on osmium, check out this essay on the metal from C&EN’s 80th anniversary special issue on the periodic table and this video from the Periodic Table of Videos:
A quick note on something else in the magazine this week: A story by Beth Halford on a new way to make diazomethane in situ, without distillation. As Beth notes, diazomethane is both explosive and toxic, and the common alternative trimethylsilyldiazomethane is less explosive but probably NOT less toxic–two chemists died in 2008 from trimethylsilyldiazomethane exposure. Anything that makes the reagents safer to handle seems like a definite plus. Go read.
Courtesy of the Periodic Table of Videos, faculty and staff at the University of Nottingham discuss the most dangerous chemicals they’ve handled:
- cyclopentadienyl nickel nitrosyl, (C5H5)NiNO
- tert-butyllithium, (CH3)3CLi (yes, the same chemical that Sheri Sangji used)
- sulfur trioxide, SO3
What about you, Safety Zone readers? What do you think is most dangerous chemical you’ve handled?
Update on Wednesday, March 14: The question got a lot of responses! I collected the ones on Twitter into this Storify; blog comments are down at the bottom.
Chemical health and safety news from the past week:
- John at Its the Rheo Thing posted about Rubber gloves – They’re not all the same
- Chemical security program stalls: DHS works to fix troubled antiterrorism initiative
- The Charleston, W.Va. Gazette, revealed more details of the Monsanto dioxin class-action settlement
Fires and explosions:
- Twenty gallons of isopropanol spilled and ignited at National Composite Center in Ohio, no one was injured
Leaks, spills, and other exposures:
- Hydrofluoric acid leaked in the alkylation unit of a Citgo refinery in Corpus Christi, Texas; the Chemical Safety Board was still investigating a 2009 fire and HF release at the same refinery and sent a team to look into the new one
- At StanChem in Connecticut, “chemicals were mixed, resulting in an aggressive reaction” and a spill of 200 gallons of…whatever it was
- Mercury spilled at an elementary school in Maryland, a high school in Indiana, and in the food in the cafeteria of a New York medical center (the state police and FBI are looking into the last one)
Not covered: meth labs; ammonia leaks; incidents involving floor sealants, cleaning solutions, or pool chemicals; transportation spills; and fires from oil, natural gas, or other fuels.
And yours truly is now off to Orlando for Pittcon! I’ll be speaking about lab safety on Sunday, in a symposium on “Looking Ahead to a New Era of Analytical Chemistry Education.” James Kaufman of the Laboratory Safety Institute will also facilitate a networking session on lab safety that day. On Tuesday, Just Another Electron Pusher blogger Christine Herman will facilitate a session on “Chemistry Careers Beyond the Bench,” and one of the panelists is C&EN Senior Editor Celia Arnaud.
For your Monday morning entertainment, here’s a video from the talented folks at the Periodic Table of Videos and the University of Nottingham. Safety points of note: wearing gloves to handle toxic chromium trioxide, pouring a small amount of ethanol into a beaker rather than using the stock bottle, using flame-proof gloves to do the reaction, and everything confined within blast shields. But chemistry professor and department safety officer Martyn Poliakoff makes one mistake…
‘Tis the season…for Organic Process Research & Development‘s annual “Safety Of Chemical Processes” section. The issue contains literature highlights, summarized as Safety Notables, as well as original papers.
I recently reviewed a batch record for a simple process (add reagents, heat, monitor until complete, cool, quench, filter, and dry) and was surprised at the length of the document—over 300 pages. There was no doubt that the document was extremely comprehensive, but the question I ask is, Was it likely to be read by the process operator in the amount of detail that was provided? It was extremely complex, and I felt that any safety messages would have been lost in all the detail. In fact, with a document of such complexity I suspected that the operator would be more likely to make mistakes through having misunderstood what he was supposed to do. Surely these batch records can be simplified so that the operator’s instructions are clear. I must admit that I found it difficult to read the entire document and to find the information that I wanted.
I’m late to the game on posting this, but this year CENtral Science is participating in the Donors Choose Science Blogging for Students campaign to help raise money for public school science resources. Naturally, we focused on chemistry-related projects, including one to provide lab coats to an AP Chemistry class in California. The campaign ends at midnight Eastern on Saturday, and right now you can get some extra bang for your buck–the DonorosChoose.org Board of Directors is matching donations made between now and the end of the drive.
And that’s it for me today–C&EN’s annual Advisory Board meeting was this week and we’ve got a staff meeting today before I fly home to California. The round-up will return next week. Have a great weekend, everyone!
I’m in Seattle this week at a U.S. Pharmacopeia meeting. In lieu of a mid-week Safety Zone post, please go check out all the posts collected for the “Your favorite reaction” blog carnival. I’m glad that I’m not judging them–I’d have a very hard time choosing!
Also, via @biochembelle and @geernst, here’s a Piled Higher & Deeper comic on fume hoods as “really expensive storage closet[s]“. If your hood looks like that, your charge for the week is to clean it up! Send me before and after photos and I’ll post them here to inspire others.
We’ll take a brief break from chemical safety today in order to participate in the “favorite reaction” blog carnival.
I first recall learning about the Belousov–Zhabotinsky reaction several years ago when I was working on a story about photos of chemical reactions on display at the University of Wisconsin, Madison. It’s quite possible that I’d learned and forgotten about the BZ reaction before, but this time it stuck. We tend to think of reactions as proceeding to completion or reaching some sort of equilibrium, but they can also oscillate: In simplest form, the products of one reaction become the reactants of another that regenerates the original reactants.
The actual mechanisms of oscillating reactions can be quite complex, however. The classic BZ reaction involves potassium bromate, cerium(IV) sulfate, and propanedioic acid (aka malonic acid) in dilute sulfuric acid. Ten equations (shown) make up the overall reaction. The color changes are due to the oscillating oxidation state of cerium–Ce(IV) is yellow and Ce(III) is colorless. If ferroin is used in place of cerium, the color switches between blue and red. According to a Journal of Chemical Education article by Purdue University chemistry professor Arthur T. Winfree, Russian chemist Boris P. Belousov (1893-1970) first observed his namesake reaction when working in the Laboratory of Biophysics at the USSR Ministry of Health, but he couldn’t get it published. Moscow State University graduate student Anatol Zhabotinsky (1938-2008) followed up on and extended the work. Richard J. Field and Richard M. Noyes of the University of Oregon, along with Endre Körös of Hungary’s L. Eötvös University, published the mechanism in 1972.
Feedback loops along the lines of what happens in BZ or other oscillating reactions are common in biology. My college p-chem textbook tells me that oscillating reactions are the source of heartbeat rhythms, for example. Others point to the interplay of predator and prey populations. Seeing oscillations happen in real time in a dish or beaker is, for me, a lovely example of the wonder and power of chemistry.