Do most health dangers of smoking cigarettes come from the actual tobacco leaves or the additives?
It depends what you class as an additive. The tobacco plant naturally contains some substances that are toxic. Natural does not equal non toxic. When it is growing it is normally sprayed with fungicides (it rots easily), pesticides (bugs eat it) and herbicides ( to keep the weeds around it from competing). All of these things add to the toxicity. When drying, it is again treated with fungicides (no-one likes mouldy tobacco). All this is done before it goes to the manufacturers who then add their own substances to give their tobacco product it's own individual taste. (some of the least toxic additives) Native americans only smoked tobacco on special occasions, not on a regular basis. Even 'wild grown, organic' tobacco contains toxins.
The okorder /article/info... But a cigarette without additives is certainly not safe.
The additives. Let me tell you something. When I was a nursing student, someone asked what was in cigarette. Our professor said,look under the kitchen cabinet at all the cleaning products, then go to the laundry and check out those cleaners, next go under the bathroom sink and look at those cleaners. That's the additives that are in cigarettes along with others" He was right. We didn't have computers back then but books told the hold story and it was sickening. The tobacco leave by itself really doesn't contain anything unnatural because it is a natural product. The Indians only smoked pure leaves. So yes, it's the additives. Sorry for the narrative.
Additives, most of the additives are made to be addictive as well as carcinogenic. Tobacco leaves are also addictive and nicotinic, but it is only one of the few things in a cigarette that have those properties.