On the Perils of Swallowing Liquid Nitrogen
On the subject of swallowing toxic items, have a look at this unnerving account of what happens when you swallow liquid nitrogen:
That may have been the point of no return. I, as is traditionally my role, answered that the nitrogen evaporates at the surface of the table, which provides a cushion of air for the drop to sit on, and thermally insulates the drop to minimize further evaporation. So you see a drop dance around without boiling away, and without interacting with the table and getting slowed down or smeared out. Then, I continued... I mentioned that the same principle makes it possible to dip a wet hand into molten lead, or to drink liquid nitrogen without injury.
I had done the latter several years earlier in a cryogenics lab, and remembered the physics behind how it worked. Naturally, people around me were skeptical. “You can't drink the stuff... it'll freeze your whole body... Remember 'Terminator 2?' ” But I was sure of myself. I had done it before, and I believed in the physics behind it. So, naturally, I poured myself a glass and took a shot.
Simple. Swallow. Blow smoke out nose and mouth and impress everyone at the party. Within about two seconds, I had collapsed to the floor, unable to breathe or feel anything other than intense pain. Ambulance arrives. Police arrive. Trip to hospital. Admission. Try to explain to ER staff exactly how something like this happens. Then I pass out. Wake up next morning connected to many machines, some beeping, others performing more important functions like digesting my food and breathing for me.
Later on he explains what went wrong:
Turns out that, in accordance with popular belief, you really should not drink the stuff. I eventually learned a few things about liquid nitrogen. Like... while you can safely put it in your mouth, and blow neat smoke patterns, you should never ever ever swallow. First off, the closing of the epiglottis prevents the nitrogen gas from escaping, so it is forced into your body instead. Second, your esophagus naturally constricts around anything inside it, so, even if there is a thin protective gas layer, the esophagus will find a way to make contact with the liquid nitrogen.
Also turns out that my memory was flawed. When I had done it six years ago, I put it into my mouth and didn't swallow. Over time, that fine line between parlor trick and near fatal accident must have blurred.
Thanks to Pharyngula for providing the link.