Article snapshot taken from Wikipedia with creative commons attribution-sharealike license.
Give it a read and then ask your questions in the chat.
We can research this topic together.
Nicotine-derived nitrosamine ketone (NNK), or 4-(methylnitrosamino)- 1-(3-pyridyl)-1-butanone, is a nitrosamine present in tobacco that is a potent procarcinogen. It is activated by CYP2A6. It is a biomarker of exposure to cigarette smoke. It is produced upon the curing of tobacco.