My father died of cancer in the mouth, almost 100% sure from smoking. Anyone who thinks smoking is the thing to do should take a look at a picture of someone with cancer in the mouth. You bet it will be a real eye opener.
My grandfather had a pretty large tobacco planting in his farm, for a cash crop. He warned all of us not to smoke, not because of the tobacco but because of all the stuff they sprayed on the leaves to keep the bugs off them. He used to say that there was enough poison on one of those leaves to kill a horse.