weed DOES NOT cause lung cancer

yes, you are inhaling carcinogens by smoking, but your lungs can handle it and expel all that nasty excess stuff you get by smoking it. if you live in a city, your lungs are doing this on a daily basis.

nicotine (amongst other ADDED chems) is the primary cancer causing agent in tobacco

studies (as old as 1974) have shown mj to slow and inhibit growth of tumors, quite the opposite of causing cancer

if you live in a major city, you inhale the cig smokers equivalent of a pack and half a day in carcinogens, you don't get cancer like a cig smoker because you arent inhaling nicotine. nicotine, opon entering the lungs, takes a white blood cell and stops all cell respiration, temporarily. putting the cell in a 'suspended animation' state. over time, cells can go into this state permanently, becoming cancerous or 'rogue cells'. they then go out into the bloodstream from the lungs, this is why cig smokers end up with cancer in some very odd places other than the lungs.

mj, not containing nicotine, does not have this effect, in fact, the effects of mj are basically the exact opposite of tobacco in almost every capacity. for example, mj is shown to stimulate the cardiovascular and dialate blood vessels, where tobacco constricts blood vessels.