N'-nitrosonornicotine in tobacco.

N'-Nitrosonornicotine, a potential carcinogen, has been positively identified in unburned tobacco. The amount in commercial U.S. tobacco products is between 1.9 to 88.6 parts per million, one of the highest values of an environmental nitrosamine yet reported. The amount in food and drink rarely exceeds 0.1 part per million. This compound is the first example of a potential organic carcinogen isolated from tobacco.