Have you brought up the polonium argument yet? I'm lazy, so I'm just copying and pasting this from another post of mine.

Quote Originally Posted by graph
Cancer is a very dangerous thing, and there have been arguments back and forth about what is worse. Keep in mind, while tar has shown to be one of many contributing factors in lung cancer, what has shown to be more prevalent in causing any type of cancer is radioactivity. Tobacco industries use polonium-210, which is a radioactive substance, to grow tobacco plants. While the FDA says that polonium-210 was shown to have no negative side affects while ingesting plants grown using the radioactive substance, it is still inconclusive if smoking such plant can cause lung cancer. Also, keep in mind cannabis users don't smoke leaves, but the bud, which contains 33% less tar, and cannabis does not narrow the air passages in the lungs like tobacco.
Now, smoking anything is harmful to you, but there are other ways to use cannabis. For example, you could eat or vaporize.
graph Reviewed by graph on . PROVE MY DUMBASS FRIEND WRONG PLEASE GOD ok. every fucking day i have the same debate with the same kid. he is trying to tell me that smoking weed can, and will give you lung cancer and you will die if enough is smoked. his argument is that smoking anything (smoke inhalation) will give you cancer and youll die. and i say...hmm...that explains why there has never been a single documented case of lung cancer or death as a result of cannabis alone.... if im wrong, please someone tell me, but lets hear what you guys think. Rating: 5