If you haven't yet swapped the Skoal for sunflower seeds, here's one more reason to do so: While smokeless tobacco has been linked to cancer, scientists haven't been able to pinpoint one specific chemical as cancer-causing, until now.

After 24 rats were exposed to the chemical (S)NNN, present in smokeless tobacco products, for more than two years (a dose comparable to half a tin a day for 30 years), all were dead within 17 months. All of them developed oral tumors. "These rats weren't blasted with the chemical either," says Silvia Balbo, Ph.D., a researcher at the Masonic Cancer Center of the University of Minnesota. "They were exposed to an amount similar to chronic use in a human."

Here's the problem: While trend reports suggest cigarette sales are on the decline, smokeless tobacco sales are on the rise. (Of course, not all guys have kicked the habit, chronic obstructive pulmonary disease is the fourth biggest mankiller in the country. Will you be able to put down the butts for good? Take our smoking quiz to find out.)

But while dip might carry a lower cancer risk than cigarettes, the severity of the chemical effect depends on your body's capacity to metabolize and detoxify the carcinogens, Balbo says.

Worried about your habit? Check in with your dentist. He'll be able to ID signs of danger. Then reconsider your spending: According to the National Institute of Dental and Craniofacial research, a can of dip runs about $3.00, which means a can-a-day habit costs you nearly $1,100 annually. And besides the fact that it's a turn-off (black spit and bad, bad breath), there's also the implications down there: A recent study found that nicotine can restrict blood flow and weaken your erection.

And to reduce your risk of lighting up again, try exercising. Working out for 3 or 4 days per week might produce positive psychological effects that can help you stop smoking. For ultra-effective, superfast, and high-intensity workouts, check out The Men's Health 15-Minute Abs, Arms & Chest Workouts DVD. In just 15 minutes, the time it takes to shower and shave, check your e-mail, or visit your Facebook page, you can build big biceps, a steel gut, and a powerful chest.

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