Jordan
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Cyanide Care Sheet
Given what happened to me in the scenario described in this thread:
https://www.sciencemadness.org/whisper/viewthread.php?tid=68...
...I thought I would post some of my research post-exposure about this chemical, in particular the cautions and biological hazards. I'm hardly a
cyanide expert but my exposure got me heavily into CN research, especially the safety and exposure aspects, and I thought I would pass this info along
to the internet community. There's some stuff I didn't know about it which may be of use to future generations, or whoever. 
This MSDS link gives the rundown of HCN and its hazards, which I will combine with my experience report:
http://www.raesystems.com/sites/default/files/content/resour...
Summary of my experience of low level exposure:
Between the time that I could smell something toxic to the time that I was lying in bed with dyspnea, ataxia, and tachycardia was about 30-45 seconds.
I did not lose consciousness but anytime I tried to move I started to feel like I might pass out, so I laid perfectly still. This indicates to me that
the ppm HCN in the air was not that high, otherwise I would've passed out at my lab site. As the link above indicates, the oxygen % lso determines
severity of symptoms.
My first immediate physical symptom was light headedness, and an unpleasant chemical taste and irritation in the back of my throat. I immediately
started seeing stars and felt light headed. I was in denial for a moment, maybe thinking I got too much sun, or had been crouched over the reaction
for too long, but denial is quickly dispelled by how fast toxicity sets in. The sense of panic comes and goes depending on oxygen intake. I've learned
that even a mild sense of asphyxiation and anxiety go hand in hand. For me, initial recovery time beyond the acute stage took 30 minutes, full
recovery took 3-5 hours. The first 30 minutes were hell. My hands and feet went numb and my fingers, toes and face turned red. I was clammy and any
time I tried to move a muscle I started seeing stars again. The only way to not increase oxygen burden was to just stay put. After about 30 minutes I
could move again, but I didn't feel right for a good few hours.
Do not attempt cyanide experiments if:
1) Inadequate ventilation. Even if outdoors, a windy day or a calm day could make the difference between life and death if accidentally inhaled. A
fume hood is a must.
2) Inadequate safety gear: must use compatible respirator as a BACKUP, and not as primary protection. (This was the mistake I made, and I also had the
wrong class of respirator.) Respirators have efficiency ratings and if their filtration media are used up, they may not completely work. Cover all
skin and eyes, as cyanide can absorb through both these routes.
3) Inadequate experience with the safety culture of chemistry, which can only be gained with lab experience.
4) Low hemoglobin. Makes the body more sensitive to oxygen deprivation events. Cyanide does not bind to hemoglobin specifically but low hemoglobin
decreases the overall oxygen perfusion rate of cells, which in turn increases cellular burden during a toxic event.
5) You're in a hot or sweaty environment. This causes the blood vessels of the skin to dilate and pores to open, allowing easier absorption of cyanide
into the blood stream via the skin.
6) You have already had a recent exposure, no matter how low. Thiosulfate, the detox mechanism for cyanide in the body which converts cyanide to
harmless thiocyanate, is limited and slow acting. It takes the kidneys several days to excrete thiocyanate from an acute poisoning, and it takes the
same amount of time to replenish thiosulfate levels to endure another potential event. If you've already been exposed then your survival margin will
be less with an additional exposure soon after.
7) You have hypothyroidism. Thiocyanate prevents the uptake of iodine into the thyroid and will decrease thyroid function further. Whether or not this
suppression is permanent is uncertain. On the plus side, it's more common in chronic exposure than acute.
Procedural notes and warnings:
1) If your cynaide reaction is meant to be in an open vessel, do not at any point in the experiment place a lid on your reaction vessel without a
system in place to collect the gas (like a condenser), even if the reaction seems complete. This will concentrate any HCN to lethal levels. This was
how I got poisoned.
2) Similar to above, if you need to pause the experiment and save the reactants for later, either store the solution in a well ventilated area with
the lid slightly loose so gas can escape, or otherwise do not resume the experiment until you can open the sealed container under a fume hood. (In
fact, just use a fume hood anyway. Though I know some people create cyanide salts in BBQs and what not.)
3) Do not assume that your nitrile gloves and other protections are foolproof. If you have a splash incident, no matter how minor, you should change
your gloves or attire before continuing.
4) Assume that lethal HCN gas will be present at every point in the experiment, regardless of what your calculations account for. Even 4ppm of HCN can
have deleterious effects.
5) Have a plan in place in case you suffer exposure: leave a note explaining what you were doing, have your phone home screen unlocked with 911 ready
to dial, do not perform cyanide experiments alone in case you need to be dragged away from the area of exposure. Leave the door to your lab/home
unlocked in case emergency services need rapid access. Let a friend know what you're doing. Have hydroxycobalamin, amyl nitrite or thiosulfate ready
to go (these can be purchased individually or as a kit for cyanide exposure, depending on your region).
6) If you live in a populated area and you're not using a fume hood / scrubber, then at the very least you should locate your experiment outdoors and
far away enough from people that poisonous gas would be heavily diluted by air travel. Conduct your experiment during times when neighbors are
unlikely to be home (i.e. during work / school days), or better yet just don't bother doing it without total containment.
7) Get a shower after your experiment is complete, and especially if you suffered a toxic exposure. Place all experiment materials in a hypochlorite
solution for a day or so to convert cyanide to cyanate before disposal. (This is for residues and small amounts only. If you wish to dispose of larger
amounts of cyanides you need to use a buffered hypochlorite solution with a sustained PH above 10, otherwise the solution will become acidic and
evolve HCN gas.)
Rescue agents (given by IM or IV):
1) Amyl nitrite (inhaled) -- causes vasodilation and greater oxygen perfusion in the blood. Generally only works for low to moderate level exposures.
Cyanide is a vasoconstrictor and this counter acts that aspect.
2) Sodium thiosulfate -- provides additional detoxing capacity for the body. (IV)
3) Sodium nitrite (IV) -- usually given with thiosulfate to aid the process.
4) Hydroxycobalamin - a form of B12 that will bond with cyanide to form harmless cyanocobalamin. Most sources claim this is the most fast acting,
non-toxic, and thorough. 5g will bind 100mg cyanide so it is best done by IV, but even smaller amounts administered before an experiment or after
exposure may provide some protection.
General Notes:
Cyanide is detoxed in the body through the thiosulfate pathway, and is then gradually excreted by the kidneys over the course of several days. The
body's thiosulfate supply is small, meant for detoxing native cyanide that is a byproduct of metabolic reactions. Assuming the ratio of thiosulfate to
cyanide is available, cyanide's half life in the body is ~2-3 hours. Once the supply of thiosulfate is exhausted, anymore cyanide will be retained in
the body and will cause impairment and potential damage until it can be detoxed. Thiocyanate prevents the uptake of iodine into the thyroid, so
hypothyroidism can be an unfortunate side effect of even low level exposures. Usually this is due to chronic exposure, but hypothyroidism from acute
exposure has also been recorded.
Cyanide will target the areas of the body where oxygen demand is highest, such as the cerebral cortex of the brain, and the heart. The heart can
usually take a bigger hit of cyanide than the brain before it stops functioning. The cognitive neurological damage of cyanide may not be known until
several weeks or months after exposure. People who don't lose consciousness normally don't suffer permanent brain damage because they did not
experience sufficient loss of oxygen. That doesn't necessarily mean they got off scott free. The most common noticeable impairments relate to short
term memory or cerebellar functions (like balance and motor coordination), and will be noticed within the initial weeks following toxicity. There may
also be personality changes, like depression or confusion. Whether or not the impairments are permanent depends on severity and duration of exposure.
If you did not lose consciousness, you're usually OK. People who lapse into temporary comas due to cyanide and survive usually suffer brain lesions
and permanent debility. A severe consequence of cyanide exposure is pseudo-parkinson's.
In addition to blocking oxygen metabolism in the cytochrome oxidase pathway of a cell's mitochondria, it also prompts biogenic amine release in the
body which causes vasoconstriction of the heart and lungs. It also stimulates the release of NMDA which is what contributes to its seizure potential.
Down-regulation of the NMDA receptors in the pre-frontal cortex from this bombardment is one of reasons why cyanide indirectly damages short term
memory.
If you don't lose consciousness in the first 5-10 minutes and you're safety relocated away from the contaminated area, then chances are you will be
OK. Lay flat, don't move, wait a while. If there is someone else nearby who can help you, ask them to open windows to maximize fresh air. Remove
restrictive clothing. If the body's thiosulfate is depleted and there is still cyanide present in your system, you may continue to deteriorate over
the course of 30 minutes. The signs will be obvious. You will get worse, not better. You should call 911 immediately. Of course, calling 911 at any
point is advisable, but for those of us who don't want to get in trouble for doing cyanide experiments, some may choose to wait. (Crazy, I know.)
Feel free to add any other stories, anecdotes, or education to this thread. Cyanide is an intriguing compound that is eventually vital to most
experiments. It should not be viewed with fear but with respectful caution. I post this here so that people don't make the same mistakes I did.
Cheers.
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nezza
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Just a question about relative toxicities. I have read that azides are about as toxic as cyanides. Working in a lab in the 80's we regularly made up
reagents and used sodium azide as a bacteriostat. Apart from having kilograms of the stuff about we used to weigh out 10's of grams of it with little
attention to safety and nobody ever noted any symptoms of poisoning from it. Fortunately we had plastic drainage pipes because the hazards of heavy
metal azides were appreciated.
If you're not part of the solution, you're part of the precipitate.
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Melgar
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I work in the jewelry industry, where cyanide is a necessity for gold and silverplating, and I have to say, you're exaggerating the dangers to a
nearly ridiculous proportion, because of what seemed to be a freak accident that happened specifically to you. It's good to be cautious, but bad to
be hyperbolic in your safety statements. Now, if I was doing that, I would have gone over to the pan, lifted the lid and held my breath, stepped back
and waited a few seconds, then cautiously approached the pan, checking to see if I could smell cyanide, then if the smell were particularly strong,
I'd add KOH or something.
INDOORS, hydrogen cyanide can be deadly, but outdoors, it dissipates rather quickly, since it's lighter than nitrogen, oxygen, and CO2, which make up
essentially all of our atmosphere. Like I said earlier, they tried using HCN as a chemical weapon during WWI, but it didn't work, because it's
lighter than air and dissipated too quickly. Also, rebreathers are a bad idea if you're outdoors, or pretty much anywhere where you can get to a safe
area quickly. They're meant for use in mines and sewers and such, where you can hit a pocket of gas that's too large to quickly escape from. If
you're using the wrong kind of rebreather, or it malfunctions, and it traps cyanide gas in the air that you're breathing, then your flight instincts
are worthless. (I just had a mental image of that one scene with Nick Cage in The Wicker Man. lol)
Really, the cardinal rule with cyanide salts is "don't add acids" (the AAA rule wasn't meant for cyanide salts!). If you can just remember that one
rule, you're probably good. If you absolutely know what you're doing, and are adding an acid or acidic salt anyway, do it dropwise, stir after every
drop, and stop adding if gas bubbles form, or you smell cyanide significantly more strongly than the faint odor that the salt gives off as it absorbs
CO2. Generally, you never want to add any acid to cyanide directly, but instead add an acidic salt, which the cyanide will then complex with.
Examples are silver nitrate, silver chloride, and various iron salts if you're trying to make Prussian blue.
Also, if you're outdoors using it, and get a strong whiff of it, run away a few steps crouching, then drop to the ground.
My disagreement here, is mainly that if an accident happens, don't pile more safety equipment ontop of the excessive amount of safety equipment you
already have. That's why these 1970s nuclear reactors are so accident-prone; they'd add more safety mechanisms, which would create a more complex
system where more could go wrong. Instead, read as much as you can regarding gold extraction safety literature, which is meant for workers who will
be around cyanide constantly. They're the real experts, and they have an excellent track record.
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Cryolite.
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I agree mostly with Melgar above, but I want to add another small thing: the mechanism you have for how nitrites help with cyanide exposure is totally
incorrect. Cyanide is toxic because it has a strong affinity for iron, and will thus bind to the iron in the heme centers found in cytochrome
oxidases. This causes the enzyme to stop working, halting respiration. Nitrite limits the damage of cyanide by oxidizing some of the heme iron found
in hemoglobin to ferric iron. This destroys the ability of the hemoglobin to transfer oxygen (indeed, an overdose of nitrite can induce
methemoglobemia by this mechanism), but now there is a large pool of heme iron capable of adding cyanide competing for the remaining cyanide with the
cytochrome oxidases. This causes almost all of the remaining cyanide to harmlessly bind to the oxidized hemoglobin, stopping the damage from
progressing.
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