I’ve often heard stories of substances being able to kill humans within seconds, even at terribly low amounts. How do these substances work, and how do they become effective so fast?
Obviously, this question covers a lot of substances, and not all work in the same way, but take for example hydrogen cyanide. Does this attack the brain? The lungs? Something else?
Cyanide kills by inhibiting the cells production of ATP. Specifically, it blocks the action of cytochrome c oxidase, which normally transfers electrons from cytochrome c to molecular oxygen. Unable to use oxygen, the cells die as quickly as does a person who holds their breath too long.
In other words, not the instananeous death of spy movie fame?
It depends on how stubborn you are.
A person loses consciousness after 10 seconds or so of complete oxygen deprivation to the brain cells. The brain uses an enormous amount of blood, so it stands to reason that the brain would be hit very hard by any toxins in the blood. Therefore, the brain would suffer a great deal of the effects of cyanide. The victim loses consciousness and brain function, and death comes quickly thereafter.
Do a google search for accounts of the Nazi death camp gas chambers. The victims often struggled for many, many minutes (up to a half hour, IIRC). Of course, I imagine all that would depend on the concentraion of cyanide in the air, body mass, general health, etc.
After reading Sebastian Jankowski’s account of what a drowning death might feel like, I give you that certain processes, while becoming disjointed, migh still continue on in disparate fashion. However, I’m going to need some convincing after hearing the bodies hit from the Trade Center that a person who just flew from a building to the sidewalk below still has any semblance of cognizant thought or realization of pain.
After reading Sebastian Junger’s account of what a drowning death might feel like, I give you that certain processes, while becoming disjointed, migh still continue on in disparate fashion. However, I’m going to need some convincing after hearing the bodies hit from the Trade Center that a person who just flew from a building to the sidewalk below still has any semblance of cognizant thought or realization of pain.
I don’t have handy cites on cyanide that is eaten or injected. But I do have one on the gas chamber.
From Panati’s Extraordinary Endings Of Practically Everything And Everybody
Does it feel like missing a field goal?
Some years ago I read about a cyanide compound being used to treat sickle cell anemia. Does anyone, esp. Squink, know anything about this and its present status?
No. You wish you’d drowned, especially if your last name is Scott “Wide Right” Norwood.
Saying that is true of all the real life incidents is simply wrong through and through. It may be true of some, and neither you nor I knowwhat proportion, but you can not possibly say all or even most.
A person who has had the top of thier skull removed and their brains scattred along a 100 yard stretch of highway will not be requiring an EMT to tell lies about their final period of pain. Any EMT who told you that is incompetent. The same goes for other less gory massive head or heart injuries. Their are jurisdictions on this planet where a finding of instantaneous death by a coroner means just that: instantaneous death’.
But then I notice that youhave been banned after 3 posts. Maybe that tells us something.
Where’s Lekatt when you need him?
Quick point that cyanide poisoning is not irreversible. Amyl nitrite, if delivered promptly, can prevent death.
Well, I hadn’t heard that one. However, a little digging will set that right.
it turns out that eating Cassava, a food rich in cyanide/cyanates, offers some protection from sickling. The ingested cyanates react with blood hemoglobin to form protein-carbamates.
While unmodified sickle cell hemoglobin readily polymerizes (sickles) when it’s in the unoxygenated state, the carbamyl-hemoglobin does not.
Why not then treat sickle cell crises with cyanate pills ? Well the therapy turned out to have a serious toxic downside:
There doesn’t appear to be any serious ongoing research into the use of these compounds. However, cyanate therapy is still promoted by scammers..
Yeah, but was he banned instantly, or did he suffer?
Only one post is listed when checking their post history (even though it says 3). One would think the SDMB coroner would render a decision of instantaneous death.
Actually some poisons can kill prety quickly. Here it says:
Another poison that works similiarly to Cyanide (by binding more strongly than oxygen to the Fe3+ ion in cytochrome a3) and is also highly toxic is Hydrogen Sulfide. The tricky part about Hydrogen Sulfide is that it can be detected by smell at levels of several ppb (parts per billion). It gives off a really strong smell of rotten eggs. Anyone who has been to Yellowstone knows the smell. But at levels above about 50 ppm (parts per million) it actually kills the sense of smell, and above about 500 ppm it is fatal in a very short period of time. For more information, see
The favourite poison of mystery writers, curare, also has some interesting effects, which are described here.
Either that, or perhaps a verdict of [sub]TOO STUPID TO LIVE[/SUB]
Cytochrome a3, the third and final active site of the cytochrome c oxidase complex, actually contains both iron and copper (as Fe(II) and Cu(I) in the reduced, ‘resting’ complex and Fe(III) and Cu(II) in the oxidized complex). In normal activity, this binding site is geometrically optimal for a molecule of O2 to slide into the gap between the iron atom (which is bound by a large, planar heme-a ligand) and the copper atom (bound to three histidine residues from the protein it’s contained in, if you want to know…). The oxygen molecule binds to both the Fe and the Cu, and then undergoes the final reaction of “cellular respiration”:
O2 + 8 H+ + 4 e- --> 2 H2O + 4 H+
The significance is that those four protons on the right side are in a different place than the ones on the left – they’ve been transported across the mitochondrial membrane, and they can now be used to synthesize ATP.
Cyanide works by binding to cytochrome a3, as Mycroft explained. It does so much better than O2 can – it’s exactly the right size, and its electronic properties are much better for binding (for reasons I won’t get into…) than oxygen is. (Incidentally, the carbon atom is closer to the iron atom, and the nitrogen closer to the copper; the binding is linear.) The binding is irreversible, and so ATP synthesis rapidly stops. This doesn’t just kill by preventing the heart from beating; it also prevents nerves from functioning. I expect that cyanide poisoning, with sufficient concentration, causes rapid loss of consciousness. If ‘death’ is defined as the cessation of ATP synthesis, then cyanide poisoning would be one of the most rapid mechanisms of causing death.
Amyl nitrite (or any alkyl nitrite) has to be given immediately after exposure to cyanide, since it doesn’t reverse the effects of cyanide poisoning. It works by oxidizing the Fe(II) in hemoglobin to Fe(III) to form methemoglobin; cyanide reacts with methemoglobin to form cyanomethemoglobin, which is not capable of transporting oxygen but not toxic either. (I was also told that it oxidizes cyanide to cyanate, but that’s not what the monograph (PDF) for sodium nitrite says.
Some other poisons:
Carbon monoxide binds irreversibly to hemoglobin to form carboxyhemoglobin; it would kill more slowly than CN, because it doesn’t act as directly.
Arsenic is most toxic as arsenite, As(III). Arsenic poisoning is typical heavy-metal poisoning; generally chronic exposure is required to kill (though massive doses can kill quickly), which is why it’s such a good mystery-novel poison. It works by binding to the -SH (sulfhydryl) groups of cysteine residues in proteins. Hair contains a lot of these, which is why arsenic poisoning can be detected from hair samples. It also subsitutes for phosphorus in bones. Mercury also has a high affinity for sulfur and works much the same way as arsenic. Mercury metal is not toxic, but its vapor is dangerous, and all compounds of mercury are dangerous, some in milligram quantities.
Acetylcholinergic poisons: Curare is an antagonist (blocker)at the nicotinic acetylcholine receptor, which is important for skeletal muscle function. I assume that it paralyzes the victim, but leaves their brain functioning until they lose consciousness due to heart failure. Sarin, Tabun, VX, and similar nerve gases do the opposite – they overload acetylcholine receptors by blocking the enzyme that breaks the neurotransmitter down. (I suppose that curare, in small doses, could work like atropine as an antidote for these agents…) Strychnine acts at a different site, the glycine receptor, also as an antagonist.