Jean,
That name capsacin rang a bell with me. I'd seen or heard it some where before. I was talking to my partner about this and she said that she thought is was sourced from peppers.

Light bulb above my head!

I went down into the basement to check out my bear repellent. Active ingredient: 5% Oleoresin Capsium (.35 capsaicin).

Should I be spraying this on my thumb instead of a bruin?