I wonder if that's due to the other stuff typically added to chewing tobacco.
It'd be interesting if tobacco could be safer, but isn't, because the manufacturers don't want to incur the expense and anti-tobacco folks want to keep people from smoking at all, not make it safer (c.f. vaping, which is — I think — basically harmless and yet is banned as much as smoking is).
> The most harmful cancer-causing substances in smokeless tobacco are tobacco-specific nitrosamines.
> Cancers linked to the use of smokeless tobacco include:
* Mouth, tongue, cheek, and gum cancer
* Cancer in the esophagus
* Pancreatic cancer
You can also get other kinds of mouth and tooth problems, and of course nicotine is still a definite health risk.
If there were a way to make tobacco healthy, I think the manufacturers would have spared no expense to do so, because the death of a customer prevents them from spending more money on what is sold.
It's based on roasting/burning it, the same reason why meat is cancer-causing. That's also why Swedish snus probably isn't cancer causing, because instead of being roasted, the tobacco is steam pasteurized.
I can't imagine that cigarettes would work with steamed leaves.
edit: And you'd have to vape the steamed leaf cigarettes, of course.