The case of the disappearing nitrosamines: a potentially global phenomenon.

The cigarette usually carries in its smoke significant doses of carcinogenic tobacco specific nitrosamines (TSNAs), which have been implicated as causes of oral, lung, oesophageal, and pancreatic cancer. However, there is substantial variation in nitrosamine content of the smoke of modern cigarettes. This variation is both unacceptable and unnecessary, as TSNAs can be readily removed during the manufacturing process. Removing a known carcinogen needs no justification, even though proof of benefit may not be forthcoming for decades.