Hugh, glad you didn't leave the statement that cigarettes kill but marijuana doesn't.
I meet the teenage marijuana users at AA and NA meetings. They are generally more desperately troubled and at a younger age than we dinosaur AAers who passed up the weed in the 60s.
I know this is anecdotal - but it isn't a good sign. At least alcoholics and smokers either had lives which we lost or losing or attempting to save. The younger folks (marijuana, etc) never even acquire a life it seems. Oh, and they do have kids --- until they are taken away.