@Butrflynet,
Because all things cause all symptoms at all time? There are five or six studies including one from VA that shows pot smokers have significantly less bladder cancer than those who don't. I have bladder cancer, a tobacco tied cancer, that kind of information is of interest to at least me.
But I agree. Medicine should not likely bring on a further different harm. For example: men who use Statins are significantly of higher risk to require Viagra or Cealis.
Pot shouldn't be smoked in public. But wouldn't pot-pubs be acceptable?