Modern tests have shown clove cigarettes to be just as unhealthy or dangerous as regular cigarettes. Rats exposed to kretek smoke systematically over a 14 day period showed the exact same signs as those exposed to Marlboro smoke. Cloves only will cause vomiting because they may slow the gag reflex by numbing the throat. On the cancer part, you need to remember one thing.

Anything involving smoke entering your body can or will give you cancer if repeated. It isn't tobacco that will cause cancer, it is the fact that you are inhaling smoke of any kind. The same goes for cloves, or even marijuana. If you are that concerned about cancer, look into vaporizers. A vaporizer creates a steam of a plant's essential oils that can be inhaled safely. All in all, do not believe everything the government tells you and peek around at other people's info. :)