I just looked at the relative risk of heavily smoking cannabis vs tobacco. I'd try to post links on this later. What I'm noticing is the relative risk of both seems pretty proportional to carbon monoxide exposure. That is somthing any good vaporizer eliminates. The big remaining factors for cannaabis include tar and ammonia. A vaportizer plus a water pipe might help with both of those. I've seen a previous poster showing how a water prime reduces ammonia exposure of you lungs. Anyhow, I wanted to get a discussion going here.