I can't find an article that treats this well, so I'll just link to the one with the best title:
One article even used the "C word." I'm sure we'll soon have Federal legislation making illegal the snorting of dairy, dairy-like, or smells-like-some-dairy products. Then we'll have a spate of kids grinding up cheap artificially-flavored butterscotch and mainlining it. Then someone else will set up an institute to study "diacetyl's beneficial health aspects" or some such rubbish.
Link: diacetyl on Wikipedia.
Edit: Wow -- an epidemiology blog. The blog is already being Slashdotted about the popcorn/diacetyl issue; one more link won't hurt, right?
