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PHILIP MORRIS U. S. A.
C90-03093
INTER-OFFICE CORRESPONDENCE
Richmond, Virginia
To: Richard Carchman
Date: May 24, 1990
From: Martha Smith
Marcta Smith
Subject: NNK or 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone
NNK or 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone is a tobacco- specific
nitrosamine which is formed during the curing and smoking of tobacco. Formation during
curing occurs through nitrosation. Occurrence in smoke results from pyrosynthesis or by direct
transfer from tobacco. NNK is found in both mainstream smoke and in sidestream smoke.
NNK is carcinogenic in laboratory animals. Hoffmann et al , 1981, (Reference 1) states NNK is
a strong carcinogen which induces lung adenomas in mice, carcinomas in the nasal cavity, liver
and lung of rats, tracheal tumors and carcinomas of the nasal cavity and lung of hamsters.
Hoffmann et al, 1986, (Reference 2) depict NNK as one of the most powerful carcinogens in
tobacco smoke. They say NNK induces benign and malignant tumors in laboratory animals in
both the upper respiratory tract and in the lung. According to Hoffman et al, 1985, (Reference
3) 1 mg of NNK will induce lung tumors in hamsters.
Burley tobacco contains higher levels of NNK and other tobacco-specific nitrosamines
than do other types of tobaccos. Air-curing under hot, humid conditions increases the amounts
found (Reference 4). Andersen et al, 1985, (Reference 5) measured levels of NNK. They used
Ky 14 burley grown under different shade conditions and air-cured. They also used air-cured
and homogenized-leaf-cured burley tobaccos from conventionally grown tobaccos with
different alkaloid genotypes. They found NNK contents ranged from 0.2/g/g - 0.5 g/g in air-
cured Ky 14 tobacco lamina from leaves grown under 0 - 65% shade (100, 65, 35% of natural
light). The highest NNK concentrations were from 45% shade-grown lamina from the lower
leaf positions on stalks according to this study. Andersen et al concluded that NNK contents
increased in lamina from successively lower leaf positions of non-shade-grown and 45% shade-
grown plants. They believe this is due to the leaves of the lower stalk positions being more
mature than the leaves from the upper stalk positions. Andersen et al concluded that levels of
NNK increased during each stage of homogenized-leaf-curing in the tested tobacco genotypes.
Their study indicated that NNK accumulated to a larger extent than NNN'in the homogenized-
leaf-cured high-alkaloid burley tobacco. NNK was significantly lower in the low-alkaloid line
than in the high-alkaloid line for both the air-cured and the homogenized-leaf-cured tobaccos at
each period of measurement throughout storage according to this study. Mackown et al, 1984,
(Reference 6) postulate that fertilization with nitrogen plays a role in the amounts of tobacco-
specific nitrosamines found in tobacco. Burley tobacco generally receives more nitrogen
fertilizer than does flue-cured tobacco. NNK levels were measured in several burley genotypes
in 1981 when there was no nitrogen fertilization. The levels ranged from 0.05 - 0.23 ppm. In
1982, with nitrogen fertilizer applied, the levels ranged from 0.08 - 0.71 ppm. Their findings
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Source: https://www.industrydocuments.ucsf.edu/docs/phxj0037

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