He was trying to convince everyone of something basically obvious, the burning heat sensation and pain caused by casual exposure to capsaicin is nothing but a molecular coincidence. It isn’t the result of real damage taking place it just happens to fit the same receptors that would fire if it were. He was apparently so stunned by this discovery that he felt the need to share it - emphatically - (and brought a witty, folksy style with him to the conversation).
In pure form (something millions of times more concentrated than a chili pepper) capsaicin would cause severe skin blistering. I would consider that, by definition, to be tissue damage. Here is one quick cite
“Just one drop of pure capsaicin in 100,000 drops of water would be enough to blister your skin. In fact, capsaicin is so hot that researchers who handle it need to wear protective clothing and gloves, and work in a specially filtered room.”
The link to skin cancer I cited earlier in the thread could also be considered definite tissue damage. But, as even our friend **keintabak **pointed out in his reply to that point, almost everything is ‘linked to cancer’ if you subject yourself to it over and over, repeatedly on an ongoing basis. And who would be stupid enough to do that anyway?
My favorite quote from this entire thread so far has to be:
You can pretty well follow that opener with everything else that he had to say on the subject.
The one time I got some pepper spray in my eye (I was defending myself against an attacker, and he deflected the hand holding the can), the pain was truly awful. The entire left side of my face felt like it was on fire. However, there was no lasting injury. Due to the circumstances of the attack (on an unlit road, far from home and late at night), I could only start to wash off the pepper spray 1/2 hour after the attack, by which time some of the burning sensation, on the face at least, had started to subside. The absence of any lasting damage damage to my eye, I attribute to the fact that I was wearing contact lens. That particular pair of contacts, of course, had to be discarded. And I could not wear the lens again for about 36 hours after the event. But since then (this was in mid-dec 2010) I have not have had any vision problems.
Admittedly, this is a merely anecdotal evidence, and dosage may have been too small to cause any adverse effects. However, in India, several women who regularly work in spice factories (much of the grinding and sorting of chillis is still done by hand) eventually develop a good deal of tolerance to the heat. Thus, it does appear that casual exposure to small amounts of capsaicin (or large amounts of the diluted version?) does not cause any lasting effects. Unless you are naturally allergic to hot chillis, that is.
In lab tests with rats and mice, it was possible to cause lethal toxic reactions from capsaicin.
The dose that caused death in 50% of the test subjects was around 100mg per kg of animal weight, in doses administered orally.
Animals that died showed irritation of the lungs, as well as ulcerations of the esophagus.
The manner of death appears to be suffocation due to inhalation of the toxin causing severe respiratory spasms.
Interestingly, animals that survived showed no ulcerations. The damage and resulting death was NOT caused by capsaicin, it was triggered by the chemical. Capsaicin itself causes the death by causing the animal to kill itself due to the reaction to the exposure.
Because of the fatty nature of the molecule, Capsaicin can directly enter into cells, and probably will reach a toxic level with enough exposure. However in the LD50 tests, toxicity was caused by the self destructive reaction to the exposure, and not the exposure itself.
Sort of like how water can kill you by drowning, you die because you are not getting oxygen, not because of acute toxicity of water.
But Water IS toxic, the ld50 for water is 190g/kg in rats. That is not by drowning, but via acute toxicity, probably by diluting body fluids excessively.
But the point is, capsaicin is about as toxic as caffeine if you manage to inhale it. It is probaby much less toxic than that if you can swallow without inhaling it. It probably can cause a blister, if you leave it in the pure form on the skin for a few hours.
Wow, that’s fascinating – so the lungs and esophagus were irritated and ulcerated because of the thrashing and coughing, or what? What kind of respiratory spasms caused that kind of damage?