Benzene is in tobacco smoke. Benzene causes cancer.
"Smoking and Tobacco Control." U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, National Cancer Institute. Bethesda, MD. Risks Associated with Smoking Cigarettes with Low Machine-Measured Yields of Tar and Nicotine. 19 Nov. 2001: 176.http://1.usa.gov/KGCnCy
Hoffman, Diertrich, Ilse Hoffman, and Karen El-Bayoumy. "The Less Harmful Cigarette: A Controversial Issue. A Tribute to Ernst L. Wynder." Chemical Research in Toxicology. The American Chemical Society. 14 (7). 28 June 2001: 5. Web.http://pubs.acs.org/doi/abs/10.1021/tx000260u