in reply to the original post i would say probably, i would try my hardest though in stopping them from starting on tobacco as that really is a very expensive and damaging life long habit for most people.
http://www.badscience.net/2007/03/reefer-badness/
should clear up misconceptions about modern weed being 25x stronger,
http://www.badscience.net/2007/07/blah-blah-cannabis-blah-blah-blah/
this one is about psychosis.
Dr Ben Goldacre for those of you that have not heard of him is a very sensible sounding chap that likes to dispel all sorts of nonsense usually spouted by the media. He has many many entries on a very wide variety of subjects.
