What I find disturbing is that I read all this, but the 3 people I know that smoke are useless and actually have become unstable, so where is the info on that? its hard for me to agree with all this when ive SEEN it ruin 3 of my friends (im talking about smoking 2-3 a day).
Our brains function optimal based on the way its evolved, I don't buy into the notion of adding "smoke" which will affect your lungs and furthermore change the way the receptors behave in the brain whilst you are high.
We need long term double blind studies which in turn need to be reviewed by a body of other labs, this has to be done several times. All these tests coming out now i'd take with a grain of salt, we need solid long term studies and only "time" can bring them to fruition.
Look at Cancer for example, if we today find a cure, it could take up to 20 years before they could release it. Many studies, short, medium and long term have to be applied.