Nicotine replacement products aren't associated with cancer risk
There is evidence that Nicotine replacement products do increase the risk of cancer. Every source I've read says that the risk is less than smoking cigarettes, but vaping (for example) is still an increased risk over not using nicotine at all.
Current NHS advice puts vaping at 95% less risk than smoking, which is to say an increased risk (5% of the smoking risk), compared to not vaping.
Yeah, the research on nicotine replacement products isn't very mature. The links you gave are interesting, but more along the lines of "nicotine can do the same sort of things to mouth cells that happens when you have mouth cancer", not "we took a look at X number of people and looked at mouth cancer incident rates".
The NHS advice is interesting, thanks for contributing it. It's a good sign that I'm on the right track - I put it at "one to two orders of magnitude", or to use the same units, 1% to 10% of the cancer risk of cigarettes. The NHS is likely biased towards saying things cause cancer (because incentives - nobody causes a ruckus if something they thought causes cancer is safe, but everyone gets way riled up if something the NHS thinks is safe causes cancer). So my updated belief is now that vaping causes less than 1% of the cancer that smoking does, per user.
The NHS advice is interesting, thanks for contributing it. It's a good sign that I'm on the right track - I put it at "one to two orders of magnitude", or to use the same units, 1% to 10% of the cancer risk of cigarettes. The NHS is likely biased towards saying things cause cancer (because incentives - nobody causes a ruckus if something they thought causes cancer is safe, but everyone gets way riled up if something the NHS thinks is safe causes cancer). So my updated belief is now that vaping causes less than 1% of the cancer that smoking does, per user.