There are many resources on marijuana. Its history and evolution are interesting. In my teens I was a social pot-head and even did my final research paper on its legalization. As to its chemicals, there are over 400. THC being the phycoactive ingredient that produces the "high". Its been said that chemicals get added by dealers to enhance the addictability of it. As for organically grown "pot" its all natural, but does contain the tar equal to about 7 cigarettes. For industrial use(hemp), it has amazing capalities, but has been regulated because in some theories it could hurt areas of our economy such as the cotton industries or "dupont" plastics industries as well as paper, rope, nylon, canvas and similarly related material industries. Medically I've heard it has value, but the pharmacutical indusrty has the money to keep that research in check. The gov't has for the past few years had a research cannibus farm somewhere in Kentucky if I remember right.