To be clear, we're discussing the effects of marijuana and [all] of it's chemical-constituents. Not THC in isolation.
And I've already posted peer-reviewed evidence for the presence of mutagens, carcinogens and polyaromatic hydrocarbons.
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find me one cancer patient that has cancer because of marijuana use. smoking anything is bad for you, doesn't matter what it is, there are better ways to ingest things than burning it. i'm not arguing with the study you posted, i'm saying that even though it contains those things, there's not one single case of marijuana causing cancer. so maybe the nicotine does play a larger part than you seem to want to admit.
something definitely does. if you have two things that contain many of the same chemicals, and one gives people cancer, and one doesn't, maybe you should look at the things that are different, instead of the things that are the same?