Not trying to be a smartass but I thought i'de share the odd reason why this is wrong, its actually the opposite. Weed is illegal in America because in order to legally posses weed, you need a tax stamp. In order to get a tax stamp you need to have your weed properly inspected by the government. Problem is, its always illegal because in the process of getting a tax stamp, your weed doesnt have a tax stamp yet, making it illegal to posses. Its and odd law, but theres a reason for it and the governemnt did the same thing to enforce the banning of fully automatic weapons. (in the 30s i think?)
Ohurcool, of course smoking weed can give you lung cancer, smoking anything for too long can give you lung cancer. There are many other ways to ingest weed however, like eating it.
Burning all that weed will have the same effect that smashing barrels of alchohol in the 20s had on prohibition.