Hmmm…

The major tobacco manufacturers discovered that polonium was part of tobacco and tobacco smoke more than 40 years ago and attempted, but failed, to remove this radioactive substance from their products. Internal tobacco industry documents reveal that the companies suppressed publication of their own internal research to avoid heightening the public’s awareness of radioactivity in cigarettes. Tobacco companies continue to minimize their knowledge about polonium-210 in cigarettes in smoking and health litigation. Cigarette packs should carry a radiation-exposure warning label.

ncbi.nlm.nih.gov

That’s from 2008 but this is the first time I heard about it. Glad I stopped smoking several years ago.