Props for the link, but the full text seems to be pay walled?

And the important bit seems to be

>nicotine concentration between 0.001 mM and 4.0mM.

And they found an effect starting at 1.0mW. But, this is what I hate about pretty much all scientific papers that clearly set out with a purpose in mind (good or bad) is the abstract doesn't mention what the hell 1.0mW. Is that even a feasible amount? Is that one puff? Is that 100% nicotine being directly vaped? What on earth is it? None of this is mentioned, for free anyways.

The full study mentions that other studies found nasal snuff produced the highest plasma nicotine concentration at 0.8 uM, with speculation that a large (emphasis mine) pinch would produce mM concentrations in the nasal cavity, right on target for observed DNA damage, yet incidents of nasal cancer among western nasal snuff users are practically unheard of. Similarly, rates of oral cancer among Swedish Snus users are so low that several studies now have failed to find any association with oral cancer.

This says nothing about rates of other non-site specific cancers of course (pancreatic being a big one), or the other health risks that are still associated with smokeless tobacco (stroke, cardiovascular disease, impotency), but it's somewhat telling that even anti-nicotine advocacy groups rarely mention the risk of cancer for smokeless tobacco products in their publications.