"Smokeless tobacco is, without a question of a doubt, far less harmful than cigarette smoking," said Ken Warner, dean of the University of Michigan School of Public Health.
But public health advocates disagree about how much safer smokeless tobacco is. One study by London's Royal College of Physicians found it to be more than 10 times safer than cigarettes.
Both products contain large amounts of nicotine. But nicotine alone is about as unhealthy as caffeine. It is the cigarette's smoke, which delivers the nicotine to the lungs, that is most lethal.
"I think there's a great opportunity here to understand the difference between the drug and how it's delivered, and if we can move to cleaner forms of delivery for nicotine, far, far fewer people are going to die," said David Sweanor, legal counsel for the Non-Smokers' Rights Association.
The safest way to deliver nicotine, health experts say, is through a patch, inhaler or gum. But those products provide such small amounts of nicotine that only about 10 percent of smokers who use them succeed in quitting.
Smokeless tobacco -- with high amounts of nicotine -- may be a more realistic alternative.
Sweden has developed a safer, less toxic kind of smokeless tobacco called "snus," and sales are booming.
"In two or three years, we're going to sell as much in cigarettes as snus," said a Swedish store owner.
With far fewer dangerous chemicals than American products, many Swedes have made the switch from cigarettes to snus. Cancer rates, including oral cancer, are on the decline.
"There's a tremendous amount of debate about it," said Sweanor. "There are some Americans who have published studies saying that this would clearly be a part of the solution to the smoking epidemic."
Surgeon General Admiral Richard Carmona says he cannot endorse any smokeless tobacco until there are a lot more studies about its relative safety.
"What I do know is that smokeless tobacco has carcinogens and can cause oral cancers and can cause nicotine addiction and can cause significant problems," Carmona said. "So I couldn't possibly recommend that because I'd really be asking you to substitute one form of carcinogen for another form of carcinogen."
Many fear that if smokeless tobacco is endorsed as an alternative to smoking, companies could use that to draw in new customers.
Since tobacco is unregulated, it would be up to tobacco companies decide what the products contain.
"The level of trust with the tobacco industry is virtually nil, and if this is the industry we're going to rely upon to come up with safer products, we are going to be very, very cautious, very cautious," said Maureen Connelly of the Harvard School of Public Health.
That caution is necessary. But in the meantime, every year, nearly half a million American smokers who can't quit die -- nearly all of them from the smoke.
ABC News' Bob Woodruff filed this report for "World News Tonight."