Fact
Radioactive Polonium-210 is found in cigarette smoke. Polonium-210 contributes to cancer.
Source 1:
"Smoking and Tobacco Control." U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, National Cancer Institute. Risks Associated with Smoking Cigarettes with Low Machine-Measured Yields of Tar and Nicotine. 19 Nov. 2001: 180.
http://cancercontrol.cancer.gov/brp/tcrb/monographs/13/m13_complete.pdf