Another problem is that there are so many types and growing methods of marijuana that it is virtually impossible to draw any conclusions. Bottom line: It's a plant and should be grown 100% organic, any additives can cause health risks. This applies to everything from carrots to advocados. Lastly, the only way you can be sure what your smoking is to grow it yourself.
I think it definately shows a distinction between soft drugs (Caffeine & Cannabis) and the hard drugs (Heroin, Alcohol, Cocaine and Nicotine).

