IF it did, I would agree that logically that's where smoking would lead. I wanted the proof of that, is all. That weed has tar, yes, I have heard. It is produced from lighting and inhaling. But I heard that it was LESS destructive, with like 30 percent or so of the tar that tobacco has. I also have heard that there is no way you can get lung cancer from weed alone (or at least, in the history of lighting up, there is no documented instance.)
I'm not going to get too far into how many people personally are known to me, as I can't prove any of it, but I will say my Uncle is in his late 50s, been smoking since he was a teen and he LOOKS it from his yellowed fingers to his teeth, to his breath and from listening to him cough, his lungs. And here in sunny CA, most people smoke weed, and you could never tell. The smell doesn't last, the physical appearance doesn't change like that. It seems a lot less harmful. The immune system lowers from smoke as well, but yet again not quite lung cancer or harmful to the physical appearance.
Where would I research his research and how he acquired it exactly? I just have seriously heard the opposite my entire life (besides from the anti-weed commercials on TV), and most of my research has led to show me the opposite as well. Does the tobacco industry publish this online? I am not ratting on your friend, rather an industry that probably wouldn't like competition.
http://www.ukcia.org/research/cancer2.php