In the case of OD it's almost always a case of what has NOT been mixed in before you got it. "Bad" batches of any given narcotic are usually in fact particularly pure batches, which haven't been cut in the way you're used to. The result can be fatal, and in most cases you would never know what hit you.

This isn't an unusual problem for smack heads - but I've certainly never heard of anyone OD'ing on a dirty great reefer!

Rob