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are not significantly different for the two years they measured. Usage of low-alkaloid burley
tobaccos are recommended by their study to reduce exposure to NNK. Hoffmann et al,
(Reference 1) measured levels of NNK which ranged from 0.13 - 35 ppm in tobacco products.
Andersen et al, (Reference 5), conclude usage of low-alkaloid burley tobaccos and control of
the postharvest processes can lower levels of NNK in tobacco products.
NNK is suspected to be a causative factor in oral cancers among smokeless tobacco
users. Hecht et al, 1988, (Reference 7) measured levels of NNK for smokeless tobacco
products as well as cigarette smoke. The amounts of NNK in smokeless tobacco ranged from
0.03 - 14 ppm. Hoffmann et al (Reference 1) measured levels of NNK in smokeless tobacco
products which ranged from 0.59 - 4.65 ppm. Chamberlain et al, 1988, (Reference 8)
measured levels of NNK between 0.3 - 7.37 ppm in smokeless tobacco products. Exposure of
humans to NNK and other nitrosamines is higher with smokeless tobacco products than from
cigar or cigarette smoke (Reference 9). Levels of NNK in the saliva of snuff-dipping women
ranged from 2.1 - 201 ng/g according to Hoffmann et al (Reference 1). Hecht et al (Reference
7) cite work done by Winn et al in 1981, (Reference 10), showing oral cancer rates among
snuff-dipping white non-smoking women to be 4.2 and among chronic users the risk increased
50-fold for cancers of the gum and buccal mucosa. Another study done by Winn et al, 1984,
(Reference 11) indicates a diet high in fruits and vegetables protects against the formation of
oral cancers among snuff dippers and cigarette smokers.
The largest nonoccupational exposure to preformed nitrosamines is derived from
tobacco products and tobacco smoke (Reference 9). It has been estimated that US residents
receive the highest degree of exposure to nitrosamines from cigarette smoking (Reference 2).
NNK is one of the most powerful carcinogens in cigarette smoke according to Hoffmann et al
(Reference 2). As previously discussed, NNK causes tumors and carcinomas in laboratory
animals. Hoffmann et al, 1980 (Reference 12) measured levels of NNK in mainstream smoke
which ranged from 0.11 - 4.2/g/cigarette in selected cigarettes and cigars. Hecht et al
(Reference 7) cites levels of NNK in mainstream smoke to range from 0.017 - 0.43ug/cigarette.
Hoffmann et al (Reference 3) states there is between 80 - 770 ng/cigarette of NNK in
mainstream smoke from nonfiltered cigarettes. They give a range of 30 - 150 ng/cigarette of
NNK in mainstream smoke of filtered cigarettes. For cigars, they give a range of 1,900 - 4,200
ng/cigar of NNK. They also state that a cigarette smoker inhales about 0.07 mol. of NNK/kg
per year on the average. Work by Adams et al, 1983, (Reference 12) indicate that 26 - 37% of
NNK found in mainstream smoke transfers directly from the tobacco. Their work also states
that 63 - 74% of the NNK found in mainstream smoke forms by pyrosynthesis during smoking.
Fischer et al, 1990, (Reference 13) conducted a study on German nonfiltered cigarettes. They
list values of NNK to range from 186 - 432 ng/cigarette. They indicate that the amount of
NNK in the mainstream smoke depends on the nitrate level of the tobacco. The tobacco type,
the filter type, and the butt length are factors which can influence the amounts of NNK found in
mainstream smoke. Fischer et al (Reference 13) believe that pyrosynthesis of NNK during
smoking is unlikely for tobaccos with lower nitrate levels. They indicate NNK formation
during smoking is possible for dark tobaccos or tobaccos with high nitrate levels. The results
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Source: https://www.industrydocuments.ucsf.edu/docs/phxj0037

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