4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (abbreviated<unk>  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.
NNK
HM 
EVAR
ALARA
CHHIP
ISREC
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ISFET