An excellent piece on ‘Pepper Spray’ and the Scoville scale at Berfrois. A brief excerpt, but do look at the whole thing:

We’ve taken to calling it pepper spray, I think, because that makes it sound so much more benign than it really is, like something just a grade or so above what we might mix up in a home kitchen. The description hints maybe at that eye-stinging effect that the cook occasionally experiences when making something like a jalapeno-based salsa, a little burn, nothing too serious.

Until you look it up on the Scoville scale and remember, as toxicologists love to point out, that the dose makes the poison.  That we’re not talking about cookery but a potent blast of chemistry.