Re: Nicotine addiction?
I don't have links to studies handy, but I have a ton of anecdotal evidence that suggests that "nicotine only being addictive in tobacco smoke" is hokum.
I grew up in a culture of smokeless tobacco use. I started young as did one of my brothers and several friends. I know in passing upwards of 1000 people who use smokeless tobacco. Of those of us who have successfully quit, the nicotine was the hardest part to kick in the first 3 months approximately and then it was the sensation of a "chew" or "dip" for the rest of a calendar year or so. Those numbers vary fairly widely dependent on the individual. Most of those who failed did so within the 3 month period (as I did twice before being successful).
I had periodic nicotine urges, separate from the sensation urge of a dip, up to 5 years after quitting. Others have reported similar but that information is much less reliable and consistent. I wouldn't submit that as evidence of any kind, only my personal experience.
Several comments have suggested that the nicotine liquids available have been instrumental in helping the commenters quit real smoking (and good for them!) which suggests that nicotine in non-smoke form is a substitute for smoked nicotine.
I'm not suggesting that the 1988 study is not flawed, because it appears to be and it was a product of some pretty virulent pushback against Big Tobacco's "studies". I am suggesting that there is probably a middle ground where nicotine is addictive but on a scale of alcohol rather than heroin.
I'm still waiting for a decent long term study of the effects of nicotine separate from smoke tobacco. We probably won't have that for another 20 years and by that time it will be too late for the current generation *if* there are long term negative side effects of nicotine itself.