Uh, weed has ramifications, like the whole lung thing. Say you eat it, there still has to be ramifications.
Caffeine has the fewest IMO.
Another question:
Let's say there are triplets whose lives are all the same save for one factor:
One is free to smoke a few hits of weed every day
One is free to drink one glass of alcohol (of varying type) every day
One is free to drink a cup of coffee or a couple diet cokes or whatever every day
Who would you guess would die first?
I'm guessing weed guy would die first, then alcohol guy, then caffeine guy would live the longest. But that's just a guess.