As a chemist, my most horrifying compound is Dimethylmercury. It readily passes through protective latex and PVC. Consider Karen Wetterhahn. She spilled a couple of drops onto her gloves, quickly cleaned it up but still ended up dying a rather gruesome death where she persisted for weeks in a state that shifted from comatose to highly agitated before she passed. This was preceded by nearly a year of abdominal pain, weight loss and mental decline. Just a little bit will kill you in a slow, agonizing death and your gloves won't even save you!
What's weird is the metal and inorganic salts of mercury aren't particularly toxic.
The vapor is toxic, one of my college professors said his graduate adviser was suffering from years of exposure to mercury fumes because in the bad old days they used to seal the gas valves in the lab with a little pool of mercury. Poor guy spent 40 years in the lab breathing mercury fumes.
What's weird is the metal and inorganic salts of mercury aren't particularly toxic.
It's not too weird if you think about their physical properties.
Metallic mercury - not that reactive or soluble in water; in fact eating metallic mercury is not that dangerous, it tends to just pass through your body
Mercury salts - Mercury(II) salts are water soluble, but Hg(II) reacts with thiols pretty rapidly (it's chelated by them). That includes all of the sulfur containing amino acids in your body (cysteine and methionine). The problem is it will also bind to important enzymes. Hg(II) salts with trash your kidneys, but don't make it into the brain.
Organic mercury - fat soluble, can penetrate most membranes of the body; that means it gets into the brain and through metabolic transformation results in neuron death
If you can spend 40 years in a lab breathing mercury fumes, maybe it isn't as dangerous as the public perceives it to be? I mean sure, let's stop sealing gas valves with it, a space should be built to be safe to work in for 40 years. But let's not freak out about perorming a couple experiments with it, using a mercury-bulb switch in a thermostat, or the few milliliters released by a broken CFL bulb.
This puts me in mind of one of my favourite cringe-worthy medical paper abstracts: "Fulminant acute colitis following a self-administered hydrofluoric acid enema" (Am J Gastroenterol. 1993 Jan;88(1):122-6):
The phrase "while intoxicated from intranasal cocaine administration" made it into the abstract. One suspects the words "watch this!" were uttered in the immediately preceding moments ...
There was a tragic accident in Japan back in 1982: A dentist mistakenly applied HF solution instead of fluorides to a girl, who subsequently suffered extreme pain and died. Both materials are called フッ素 (fusso, which is actually the name of Fluorine), and there was a fatal miscommunication between dentist's assistant and the distributor. The dentist felt so guilty and stressed out that he died from stroke at the girl's funeral.
For Japanese in my generation, the fear of HF was imprinted by the accident. I couldn't find English reference, but here's Japanese wikipedia page:
Ha! Then we did the same thing today. I was trying the print-on-demand references I found, but those companies seem to have been absorbed by / transformed into ProQuest, who not longer has a print-on-demand service that I could find.
It's fantastic, an alternating mix of dry chemistry and hair-raising lab anecdotes.
For those who haven't read it: in the post-war early rocket period, government chemists could tell from basic stochiochemistry what mixtures might make good rocket fuels. But their other properties had to be tested experimentally. Especially hypergolicity and detonation resistance. There's a long subthread about red fuming nitric acid, which would make a great oxidiser once people could find a way of stopping it eating through stainless steel tanks.
My mother has a story - and some significant scars to back it up, about her time employed in the 70's at Litronix moving wafers from between the stepper, furnace, etching, etc in the era where you could still be in the same room as the wafer.
As this was the 70s, "occupational safety" didn't mean the same thing as it does today, so apparently the etching was done by hand. This involved putting on three layers of heavy gloves and dipping boats of wafers in some type of etching acid. My mother wasn't sure of the contents, but knew it involved extremely concentrated acids, which were shipped in daily because the couldn't be stored more than a few days in the glass bottles (!!!). As she described it, the HCl and HNO3 were easy to identify when you worked with them, because they cause intense burning - and scaring - if you splashed any on your arm.
At least one of the etching steps, though (maybe all? I'm not sure) used concentrated HF.
So this went fine, until my mother took off her gloves one day... and aw bone. Didn't even notice it. She sat with her hand under the DI faucet suggesting someone should probably call an ambulance. The paramedics wanted to amputate her hand immediate (on site). Instead, they were talked into trying to estimate how much acid actually actually made it's way to her hand, and spent the afternoon injecting various things to try to neutralize the HF.
Fortunately, it must have been a very small amount of acid, as she made a full recovery, albeit with a nasty scar on her finger. It wasn't even the worst thing that happened to her - she was a lot more concerned the day she discovered someone had used several full storage shelves (total an entire wall wide, floor to ceiling) to store the "empty" nitric acid bottles that were still full of very-nasty fumes. Shelves, that were a few feet from the (full) liquid O2 tanks. That warranted an immediate call to OSHA... from another building.
Seriously, there are any number of nasty things floating around a wet chemistry lab. Chromerge and piranha solutions (sometimes aqua regia) for cleaning glassware, various super acids and bases, pyrophoric organometallics, stuff that's oxygen or water or shock sensitive… the list goes on. HF is certainly bad, but it tends to get the respect it deserves and so is handled safely. I'm more worried about chronic occupational exposure to "safer" things like chloroform.
Edit: the one that really scares me? Anything solvated with DMSO. It dramatically increases absorption through the skin. I bet every chemist has a secret chemical fear.
Edit 2: oh, and peroxides. One idiot postdoc had a habit of buying THF without stabilizers (no need for him to do so), and storing them in the back of the chemicals cabinet where they were frequently forgotten. At least he had the decency to store them on the bottom shelf. So admittedly I have two fears, but I'll work with HF!
I was kidding. I however do think refusing to work with a uniquely useful substance because of the risks, without considering risk mitigation, is irrational and can impede good science.
cool. thx for replying back - maybe i'm a bit sensitive about this sort of thing but i'm tired of seeing students put in dangerous situations and then if/when something bad happens they're labelled 'professionals' and their supervisor walks off scott free. once i got out of academia and did some real H&S training and assessments I was amazed at how badly I'd been trained over a decade or so of chem.
I think we both agree that occupational health and safety, as it's generally practiced in academia, is an abomination; the sooner academia comes up to industry standards, the better.
Reading in C&EN about completely preventable accidents that happen in the ivory tower is both frustrating and heartbreaking.
Also, working in a biomedical lab studying cancer, we frequently solvate some nasty drugs (e.g DNA repair inhibitors) in DMSO... always gives me pause.
Also generating lentivirus with some nasty payloads (commonly various protein knockdowns/shRNA, which reduces expression of a given protein, some very important to cell stability)
I've seen people applying DMSO to their joints as some kind of arthritis treatment. I can only assume that what these people buy is actually massively cut with water, or they'd have already been poisoned by whatever residue was on the skin at some point.
Yeah, that's when I was the most worried, when I was using stuff meant to muck with cell signaling solvated in DMSO. Be sure you're using the correct gloves! The "sensitive" nitrile and latex gloves typically found in biology labs don't offer good protection against DMSO.
The history of isolating fluorine from HF is pretty scary:
Humphry Davy of England: poisoned, recovered. George and Thomas Knox of Ireland: both poisoned, one bedridden 3 years, recovered. P. Louyet of Belgium: poisoned, died. Jerome Nickels of Nancy, France: poisoned, died. George Gore of England: fluorine / hydrogen explosion, narrowly escaped injury. Henri Moissan of France: poisoned several times, success, but shortened life. For isolating fluorine, Moissan got the Nobel prize, two months before he died.
I think the best one in this series is chlorine trifluoride [1]:
> The compound also a stronger oxidizing agent than oxygen itself, which also puts it into rare territory. That means that it can potentially go on to “burn” things that you would normally consider already burnt to hell and gone, and a practical consequence of that is that it’ll start roaring reactions with things like bricks and asbestos tile.
I'm the opposite of Lowe. I would never touch HF solutions, and am totally OK with HF gas (and I have used HF gas). HF solutions are a weak base - which means that quite a bit of it remains as the diatomic molecule HF, which can penetrate cell membranes and wreak havoc in your body. You can get severely injured without noticing it. If there's any risk of exposure, you need to rub yourself with calcium gluconate cream, ASAP.
HF gas, on the other hand, well, it's dangerous enough that you're going to be taking a ton of precautions around it. Your setup is going to be under negative pressure, and in a fume hood. You're going to wear thick rubber splashguard over your lab coat, you're going to have a checklist of things to do in the procedure, the entire apparatus is teflon, and there's a calcium hydroxide scrubber out the other end, and you'll never work with more than 10 mL at a time.
Lowe's account of a leak is a little bit overwrought. Unless you're working in an (idiotic, but I've seen them) positive pressure setup, the best thing to do is to calmly shut the valve to the HF tank, close the fume hood, and walk away.
> If there's any risk of exposure, you need to rub yourself with calcium gluconate cream, ASAP.
One of the really nasty parts is that an HF solution will penetrate your fingernails, while calcium gluconate will not. You won't like the solution to that problem.
I've heard a suspiciously large number of explanations for HF's toxicity.
1. It eats your bones (BS meter at 99.9% due to stoichiometry)
2. It poisons enzymes (as seen in TFA, passes the BS detector, but begs the question: which ones?). EDIT: "which ones?" answered by [2], but it's focus is on cell biology not toxicology, so it's possibly answering the question "what causes the local burns?" rather than "what kills you dead?".
3. It binds Ca++ in your blood, stopping the power stroke of your heart [1] (my own suspicion, although it's obvious enough that there is a 0% chance of it being "original"). EDIT: [3] pretty much confirms this.
I've lost convenient access to the academic literature, so if there's anyone on here who would be willing to do a quick (ha) dive on my behalf, I'd be much obliged. EDIT: I think I found the answers I wanted, but most of the top results were paywalled, so I'd still appreciate a second look by someone with access to institutional subscriptions.
In safety training at a university, we were instructed that if we were exposed to aqueous HF, we were to immediately slather on calcium gluconate on the burn area, grab an HF MSDS, and demand that the ambulance take us to a specific Level 1 trauma center and insist that the physicians understand that we were exposed to HF and not some generic acid.
I don't know the precise mechanism for toxicity (I thought it was hypocalcemia), but if the tradionally safety-lax academia takes HF that seriously, you know it's the real deal.
Yep, I got the same lecture, I was specifically asking about mechanism because the explanation we were given was "eats your bones" which is patently ridiculous.
Your bones are constantly remodeled, as part of calcium regulation in the body. HF, interfering with that remodeling, may give the appearance of it "eating your bones".
As a mechanism for chronic toxicity? Sure. As a mechanism for acute toxicity? Not a chance.
The "slap on some calgonate and rush to the hospital" protocol (of which you were quick to remind us) was justified by way of the acute toxicity (to me, anyway), not prevention of chronic toxicity, so my remark stands.
The calcium ion depletion version is the correct one, at least from days handling fluorine chemistries. The poisoning risk covers a more diverse range of common fluorine compounds than just hydrofluoric acid. Skin exposure to these compounds is often sufficient for it to enter the bloodstream and there can be a significant delay to the effects as it moves through tissues.
Treatment for fluoride poisoning is intravenous calcium solution, which provides an ion buffer for the calcium ion depleting effects of the fluoride until all the fluoride binds to something that renders it inert.
Once upon a time I did an electrical engineering internship on-site at an oil refinery. Part of my training was to learn about chemicals like HF and how dangerous they were to human life and what to do if exposed.
Then I learned about how basically in large oil refineries pipes are leaking all the time and crews are always coming in to fix the leaks in the pipes (but not often repair). I left that industry pretty quick and never looked back.
Note that he's primarily taking about HF gas, not the aqueous solution. Aqueous hydrofluoric acid is certainly not to be trifled with but I don't think it's in quite the same category as some of the other substances this guy talks about. I used to work in a lab that used large quantities of the stuff and I knew someone who got some on his skin. He went to the hospital but I don't think he suffered any lasting consequences.
The current HN title is bad, since the first paragraph says that he will happily work with "hydroflouric acid", but not with "hydrogen flouride" (i.e. gaseous HF).
It seems stupid to have humans anywhere near this stuff. Robot chemistry labs would make a lot of sense -- doing the same operations over and over, exactly the same way, with limited downside when things go wrong.
I know some of the biochem procedures are moving to "cloud labs" -- using inherently small amounts of chemicals and repeating things many times. Doing similar things in larger scale labs also seems worth it.
I had a professor who worked in a Dupont lab in New Jersey. He studied crystal structures using x-rays, something too cool for me to comprehend. Anyway he said the lab did work with a mixture of acids they called "Liquid Fire". It would pretty much corrode through any container, metal/plastic/glass. He said there were talks to sell it to the military but it would have been too unsafe to get to the battle field. Note didn't read the article, I think I have read this one before.
I think that one of my father's USGS friends inadvertently got himself with some while using a pipette. It must have been thoroughly unpleasant, but the guy was alive and kicking 20 years later.
