Tobacco-specific nitrosamines (TSNAs) comprise one of the most important groups of

carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive subs ...

s in

tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...

products, particularly

cigarette A cigarette is a narrow cylinder containing a combustible material, typically tobacco, that is rolled into thin paper for smoking. The cigarette is ignited at one end, causing it to smolder; the resulting smoke is orally inhaled via the opp ...

s (traditional and

electronic Electronic may refer to: *Electronics, the science of how to control electric energy in semiconductor * ''Electronics'' (magazine), a defunct American trade journal *Electronic storage, the storage of data using an electronic device *Electronic co ...

) and fermented dipping snuff.

Background

These nitrosamine carcinogens are formed from

nicotine Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...

and related compounds by a

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 ...

reaction that occurs during the curing and processing of tobacco. Essentially the plant's natural

alkaloids Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar st ...

combine with

nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zer ...

forming the nitrosamines. They are called tobacco-specific nitrosamines because they are found only in tobacco products, and possibly in some other nicotine-containing products. The tobacco-specific nitrosamines are present in

smoke and to a lesser degree in "smokeless" tobacco products such as

dipping tobacco Dipping tobacco is a type of finely ground or shredded, moistened smokeless tobacco product. It is commonly and idiomatically known as "dip". Dipping tobacco is used by placing a pinch, or "dip", of tobacco between the lip and the gum ( sublab ...

and

chewing tobacco Chewing tobacco is a type of smokeless tobacco product that is placed between the cheek and lower gum to draw out its flavor. Some users chew it, others do not. It consists of coarsely chopped aged tobacco that is flavored and often sweetened; ...

; additional information has shown that trace amounts of NNN and NNK have been detected in e-cigarettes. They are present in trace amounts in

snus Snus ( , ) is a tobacco product, originating from a variant of dry snuff in early 18th-century Sweden. It is placed between the upper lip and gum for extended periods, as a form of sublabial administration. Snus is not fermented. Although used ...

. They are important carcinogens in cigarette smoke, along with combustion products and other carcinogens. Among the tobacco-specific nitrosamines, nicotine-derived nitrosamine ketone (NNK) and ''N''-nitrosonornicotine (NNN) are the most carcinogenic. Others include ''N′''-nitrosoanatabine (NAT) and ''N''-nitrosoanabasine (NAB). NNK and its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) are potent systemic lung carcinogens in rats. Tumors of the nasal cavity, liver, and pancreas are also observed in NNK- or NNAL-treated rats. NNN is an effective esophageal carcinogen in the rat, and induces

respiratory tract tumor The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies grea ...

s in mice, hamsters, and mink. A mixture of NNK and NNN caused

oral tumor The word oral may refer to: Relating to the mouth * Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid **Oral administration of medicines ** Oral examination (also known as an oral exam or or ...

s when swabbed in the rat oral cavity. Thus, considerable evidence supports the role of tobacco-specific nitrosamines as important causative factors for cancers of the

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

pancreas The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e. it has both an end ...

esophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...

, and

oral cavity In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on t ...

in people who use tobacco products. Metabolism and chemical binding to DNA (

adduct An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all co ...

formation) are critical in

cancer induction Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic, and epigenetic levels and abno ...

by NNK and NNN. Human metabolism of NNK and NNN varies widely from individual to individual, and current research is attempting to identify those individuals who are particularly sensitive to the carcinogenic effects of these compounds. Such individuals would be at higher risk for cancer when they use tobacco products or are exposed to secondhand smoke. Identification of high-risk individuals could lead to improved methods of prevention of tobacco-related cancer, and improved risk valuation for insurers.

References

''This article is based in part on public domain text taken from an article on the website of the National Cancer Institute, a U.S. Federal Government agency''

External links

* {{cite web , title = Carcinogens Form from Third-Hand Smoke , publisher = ScienceDaily , date = February 9, 2010 , url = https://www.sciencedaily.com/releases/2010/02/100208154651.htm Carcinogens Nitrosamines

Background

See also

References

External links