Tobacco-specific nitrosamines
Tobacco-specific nitrosamines (TSNAs) comprise one of the most important groups of carcinogens in tobacco products, particularly cigarettes (traditional and electronic) and fermented dipping snuff. == Background == These nitrosamine carcinogens are formed from nicotine and related compounds by a nitrosation reaction that occurs during the curing and processing of tobacco.
Source: Wikipedia — Tobacco-specific nitrosamines (CC BY-SA 4.0)