People often think that it's the smoke in cigarettes that causes cancer, but that is not necessarily the case. Chewing tobacco is also associated with cancer, so the issue is not just smoke. What is the cause? During the curing process, when tobacco is dried, there is oxidation in the air. This oxidation helps contribute to the pleasant aroma of tobacco through the breakdown of pigment compounds called carotenoids, but it also causes some of the nicotine, the major pharmacologically active component in tobacco, to be transformed into a cancer-causing chemical called N-nitrosonornicotine (abbreviated NNN). There could be two potential solutions to deal with this. One is to use strains of tobacco that are very low in nicotine to begin with. Japanese scientists have recently even used genetic engineering to develop tobacco free of nicotine. Then either nicotine itself, or a little bit of a very high nicotine fresh uncured tobacco could be mixed in. Alternatively, tobacco extract could be treated and filtered to remove nicotine (similar process to removing caffeine from coffee) and then artificially "cured" to develop aroma, then this concentrated extract could be added back in to fresh tobacco. The tobacco could be stored in air-tight packaging without exposure to oxygen and humidity, to avoid breakdown of the nicotine. This type of smoking tobacco wouldn't be completely risk-free, because of the smoke, but it might have a much lower risk. Perhaps used as a vapor, it might even be completely risk-free altogether.