Nicotine is sort of a mixed bag, but it isn't really the bad part of tobacco products. Cigarettes are generally bad for you because of all of the other things in them besides nicotine. The bad part of nicotine is that it is so highly addictive, but it's health benefits for things like ulcerative colitis and other afflictions are becoming better studied.
> But as laboratory scientists know, getting mice or other animals hooked on nicotine all by its lonesome is dauntingly difficult. As a 2007 paper in the journal Neuropharmacology put it, “Tobacco use has one of the highest rates of addiction of any abused drug. Paradoxically, in animal models, nicotine appears to be a weak reinforcer.”
It's not entirely true. Even though the vast majority of tobacco-related cancer deaths may be caused by polonium, cancer deaths are still only around a third (iirc) of total tobacco deaths.
