When I was in high school, I was heavily into the anti-tobacco movement. It was a founding time for me, and though I don't regret those days (tobacco companies did and do things that are utterly reprehensible), my thinking has definitely evolved considerably since then. I think that what started as a legitimate campaign against sleazebag advertising and murderous delaying tactics of tobacco companies has gradually taken a sheen of moral disapproval of all tobacco use, smoking or no, and I believe free adults should be allowed to poison themselves in whatever way(s) they see fit. (It's an extreme view, I suppose, but lets set that aside for now.)
However, smoking still remains about the only form of drug use where one can passively kill innocent bystanders. Thus—though I think it has gone a bit far in some places—I understand and basically support regulations restricting smoking in public places. But that argument does not apply to non-smoking forms of tobacco like dip (chewing tobacco), snus, and snuff. (For the curious, snus is similar to dip, but a finer grain that normally comes in pouches that doesn't require spitting. It is also steam rather than fire-cured. Snuff refers to insufflated tobacco, even finer than snus.)
So when I was offered a pinch of snuff by some friendly Afrikaners at the end of our Namibia trip, I was game, if just as a joke. It was a rather painful experience, but certainly less so than smoking one's first cigarette. The very existence of the stuff made me curious. Who buys snuff, and where does it come from, how popular is it? A few hours later, I emerged from one of the more productive sessions of googling I've experienced. To wit—
Snus is mostly made and consumed in Sweden (and Norway to a lesser extent), but it is illegal in the rest of the European Union, purportedly for health reasons. This bizarre result—as smoking is legal throughout Europe—has the whiff of cigarette company rent-seeking about it. Regardless, Sweden has the lowest smoking and lung cancer rate in Europe and from the studies I've managed to track down (some of them probably funded by the snus industry, but still...good list here), it seems unequivocally less dangerous than cigarettes and probably quite a bit less dangerous than American-style dip. Common sense leads me to trust this conclusion, as smoke itself is filled with free radical products from partial combustion. I believe in harm reduction, and if Swedes can use snus rather than tobacco, that is a good thing relative to just smoking.
Snuff is less popular even than snus, though it is legal throughout Europe. It's such a tiny portion of the tobacco market that I reckon it hasn't caught anyone's attention yet, and there are not many studies about its risk. About the only one I could find concluded that though there was probably some risk of nasal and throat cancer, it was definitely less dangerous than smoking. I was also surprised at the price—several weeks supply for a regular user runs between $2 and $5.
Dip is probably more dangerous than either snuff or snus, though less dangerous than smoking. It is definitely associated with mouth and throat cancer, and probably associated with cardiovascular problems. Plus, it's gross.
This leads me to the PACT (Prevent All Cigarette Trafficking, pdf summary here) Act, which was apparently signed with no fanfare whatsoever this March. First, it requires all applicable taxes must be paid on internet-purchased tobacco, a stipulation aimed directly at the Seneca Indian Reservation, who were selling cheap cigarettes by the cubic meter in New York (as it has the highest cigarette taxes in the nation). Second, it forbids tobacco from being shipped via the USPS, which not only will seal the fate of the Senecas, but destroy the market for Swedish snus. American cigarette manufacturers have stepped in with their own version (Camel and Marlboro snus) but the product is quite different from the Swedish product (primarily in that they have very low nicotine), and one NIH paper I found speculated that they should not be called true snus, and are really designed to keep people smoking while creating a new expensive habit, similar to nicotine gum or patches. Philip Morris and the National Association of Convenience Stores supported the PACT Act, and once again I detect the distinctive odor of rent-seeking.
For more, see this interesting article on snuff in Wired.