Thats mostly conjecture, give me some real anti-cannabis claims and i'll gladly debunk them.

Some things I can correct on that page are that not much THC is stored in your fat cells, rather THC metabolites. The 'contains 400 chemicals..' claim is true but means nothing. Coffee contains over 800 chemicals...oh no!
It is possible to become 'addicted' to virtually anything. Marijuana smokers are at somewhat greater a risk of developing lung problems such as bronchitis.
Cannabis smoke does not contain polonium 210. No medical literature exists stating cannabis as a sole cause of cancer.