N-Nitrosonornicotine
Encyclopedia
N-Nitrosonornicotine is a nitrosamine
found in tobacco
that has been classified by the IARC
as a Group 1 carcinogen.
Although no adequate studies of the relationship between exposure to NNN and human cancer
have been reported, there is sufficient evidence that NNN causes cancer in experimental animals.
NNN is found in a variety of tobacco products including chewing tobacco
, snuff
, cigarette
s, and cigar
s. It is present in smoke from cigars and cigarettes, in the saliva
of people who chew betel quid
with tobacco, and in the saliva of oral-snuff users. NNN is produced by the nitrosation
of nicotine during the curing, ageing, processing, and smoking of tobacco. Roughly half of the NNN originates in the unburnt tobacco, with the remainder being formed during burning.
Some of the NNN present in the saliva
of tobacco users is produced endogenous
ly from nitrite
in saliva and tobacco alkaloid
s including nicotine
.
Nitrosamine
Nitrosamines are chemical compounds of the chemical structure R1N-N=O, some of which are carcinogenic.-Usages:Nitrosamines are used in manufacture of some cosmetics, pesticides, and in most rubber products. -Occurrences:...
found in tobacco
Tobacco
Tobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...
that has been classified by the IARC
International Agency for Research on Cancer
The International Agency for Research on Cancer is an intergovernmental agency forming part of the World Health Organisation of the United Nations....
as a Group 1 carcinogen.
Although no adequate studies of the relationship between exposure to NNN and human cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
have been reported, there is sufficient evidence that NNN causes cancer in experimental animals.
NNN is found in a variety of tobacco products including chewing tobacco
Chewing tobacco
Chewing tobacco Chewing tobacco Chewing tobacco (also known colloquially as hoobastank, backy, tobac, doogooos,Hogleg, chewpoos, chits, chewsky, chawsky, dip, flab, chowers, guy, or a wad, as well as referred to as dipsky, snuff, a pinch, a yopper, a Packing a bomb, a tobbackey or packing a...
, snuff
Snuff
Snuff is a product made from ground or pulverised tobacco leaves. It is an example of smokeless tobacco. It originated in the Americas and was in common use in Europe by the 17th century...
, cigarette
Cigarette
A cigarette is a small roll of finely cut tobacco leaves wrapped in a cylinder of thin paper for smoking. The cigarette is ignited at one end and allowed to smoulder; its smoke is inhaled from the other end, which is held in or to the mouth and in some cases a cigarette holder may be used as well...
s, and cigar
Cigar
A cigar is a tightly-rolled bundle of dried and fermented tobacco that is ignited so that its smoke may be drawn into the mouth. Cigar tobacco is grown in significant quantities in Brazil, Cameroon, Cuba, the Dominican Republic, Honduras, Indonesia, Mexico, Nicaragua, Philippines, and the Eastern...
s. It is present in smoke from cigars and cigarettes, in the saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...
of people who chew betel quid
Betel
The Betel is the leaf of a vine belonging to the Piperaceae family, which includes pepper and Kava. It is valued both as a mild stimulant and for its medicinal properties...
with tobacco, and in the saliva of oral-snuff users. NNN is produced by the nitrosation
Nitrosation
Nitrosation is a process of converting organic compounds into nitroso derivatives, i.e. compounds containing the R-NO functionality.-C-Nitroso compounds:C-Nitroso compounds, such as nitrosobenzene, are typically prepared by oxidation of hydroxylamines:...
of nicotine during the curing, ageing, processing, and smoking of tobacco. Roughly half of the NNN originates in the unburnt tobacco, with the remainder being formed during burning.
Some of the NNN present in the saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...
of tobacco users is produced endogenous
Endogenous
Endogenous substances are those that originate from within an organism, tissue, or cell. Endogenous retroviruses are caused by ancient infections of germ cells in humans, mammals and other vertebrates...
ly from nitrite
Nitrite
The nitrite ion has the chemical formula NO2−. The anion is symmetric with equal N-O bond lengths and a O-N-O bond angle of ca. 120°. On protonation the unstable weak acid nitrous acid is produced. Nitrite can be oxidised or reduced, with product somewhat dependent on the oxidizing/reducing agent...
in saliva and tobacco alkaloid
Alkaloid
Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...
s including nicotine
Nicotine
Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...
.