Fact
There's hydrogen cyanide in rat poison. The same stuff is in cigarette smoke.
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. 56, 176, 251.
Source 2:
"Toxicological Profile for Cyanide." Agency for Toxic Substances and Disease. 8.