Chemistry:Nitrosamine
Nitrosamines (or more formally N-nitrosamines) are organic compounds produced by industrial processes.[1]
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The chemical structure is R
2N–N=O, where R is usually an alkyl group.[2] Nitrosamines have a nitroso group (NO+
) that are "probable human carcinogens",[3] bonded to a deprotonated amine. Most nitrosamines are carcinogenic in animals.[4] A 2006 systematic review supports a "positive association between nitrite and nitrosamine intake and gastric cancer, between meat and processed meat intake and gastric cancer and oesophageal cancer, and between preserved fish, vegetable and smoked food intake and gastric cancer, but is not conclusive".[5]
Chemistry

The organic chemistry of nitrosamines is well developed with regard to their syntheses, their structures, and their reactions.[7][8] They usually are produced by the reaction of nitrous acid (HNO
2) and secondary amines, although other nitrosyl sources (e.g. N2O4, NOCl, RONO) have the same effect:[9]
- HONO + R
2NH → R
2N-NO + H
2O
The nitrous acid usually arises from protonation of a nitrite. This synthesis method is relevant to the generation of nitrosamines under some biological conditions.[10] The nitrosation is also reversible, particularly in acidic solutions of nucleophiles.[11] Aryl nitrosamines rearrange to give a para-nitroso aryl amine in the Fischer-Hepp rearrangement.[12]
With regards to structure, the C
2N
2O core of nitrosamines is planar, as established by X-ray crystallography. The N-N and N-O distances are 132 and 126 pm, respectively in dimethylnitrosamine,[13] one of the simplest members of a large class of N-nitrosamines.
Nitrosamines are not directly carcinogenic. Metabolic activation is required to convert them to the alkylating agents that modify bases in DNA, inducing mutations. The specific alkylating agents vary with the nitrosamine, but all are proposed to feature alkyldiazonium centers.[14][6]
History and occurrence
In 1956, two British scientists, John Barnes and Peter Magee, reported that a simple member of the large class of N-nitrosamines, dimethylnitrosamine, produced liver tumours in rats. Subsequent studies showed that approximately 90% of the 300 nitrosamines tested were carcinogenic in a wide variety of animals.[15]
Tobacco exposure
A common way ordinary consumers are exposed to nitrosamines is through tobacco use and cigarette smoke.[14] Tobacco-specific nitrosamines also can be found in American dip snuff, chewing tobacco, and to a much lesser degree, snus (127.9 ppm for American dip snuff compared to 2.8 ppm in Swedish snuff or snus).[16]
Dietary exposure
Nitrosamine formation during digestion
Medication impurities
There have been recalls for various medications due to the presence of nitrosamine impurities. There have been recalls for angiotensin II receptor blockers, ranitidine, valsartan, duloxetine, and others.
The US Food and Drug Administration published guidance about the control of nitrosamine impurities in medicines.[17][18] Health Canada published guidance about nitrosamine impurities in medications[19] and a list of established acceptable intake limits of nitrosamine impurities in medications.[20]
Examples
| Substance name | CAS number | Synonyms | Molecular formula | Physical appearance | Carcinogenity category |
|---|---|---|---|---|---|
| N-Nitrosonornicotine | 16543-55-8 | NNN | C9H11N3O | Light yellow low-melting solid | |
| 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone[21] | 64091-91-4 | NNK, 4′-(nitrosomethylamino)-1-(3-pyridyl)-1-butanone | C10H15N3O2 | Light yellow oil | |
| N-Nitrosodimethylamine | 62-75-9 | Dimethylnitrosamine, N,N-dimethylnitrosamine, NDMA, DMN | C2H6N2O | Yellow liquid | EPA-B2; IARC-2A; OSHA carcinogen; TLV-A3 |
| N-Nitrosodiethylamine | 55-18-5 | Diethylnitrosamide, diethylnitrosamine, N,N-diethylnitrosamine, N-ethyl-N-nitrosoethanamine, diethylnitrosamine, DANA, DENA, DEN, NDEA | C4H10N2O | Yellow liquid | EPA-B2; IARC-2A |
| 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol | 76014-81-8 | NNAL | |||
| N-Nitrosoanabasine | 37620-20-5 | NAB | C10H13N3O | Yellow Oil | IARC-3 |
| N-Nitrosoanatabine | 71267-22-6 | NAT | C10H11N3O | Clear yellow-to-orange oil | IARC-3 |
See also
- Hydrazines derived from these nitrosamines, e.g. UDMH, are also carcinogenic.
- Possible health hazards of pickled vegetables
- Tobacco-specific nitrosamines
Additional reading
- Altkofer, Werner; Braune, Stefan; Ellendt, Kathi; Kettl-Grömminger, Margit; Steiner, Gabriele (2005). "Migration of nitrosamines from rubber products - are balloons and condoms harmful to the human health?". Molecular Nutrition & Food Research 49 (3): 235–238. doi:10.1002/mnfr.200400050. PMID 15672455.
- Proctor, Robert N. (2012). Golden Holocaust: Origins of the Cigarette Catastrophe and the Case for Abolition. Berkeley: University of California Press. ISBN 9780520950436. OCLC 784884555.
References
- ↑ California Water Boards, State Water Resources Control Board, "Nitrosamines", 09 December 2024
- ↑ Beard, Jessica C.; Swager, Timothy M. (21 January 2021). "An Organic Chemist's Guide to N-Nitrosamines: Their Structure, Reactivity, and Role as Contaminants". The Journal of Organic Chemistry 86 (3): 2037–2057. doi:10.1021/acs.joc.0c02774. PMID 33474939.
- ↑ World Health Organization, Medical product alert, Note on Nitrosamine impurities, "Update on Nitrosamine impurities", 20 November 2019
- ↑ Yang, Chung S.; Yoo, Jeong-Sook H.; Ishizaki, Hiroyuki; Hong, Junyan (1990). "Cytochrome P450IIe1: Roles in Nitrosamine Metabolism and Mechanisms of Regulation". Drug Metabolism Reviews 22 (2–3): 147–159. doi:10.3109/03602539009041082. PMID 2272285.
- ↑ Jakszyn, Paula; Gonzalez, Carlos (2006). "Nitrosamine and related food intake and gastric and oesophageal cancer risk: A systematic review of the epidemiological evidence". World Journal of Gastroenterology 12 (27): 4296–4303. doi:10.3748/wjg.v12.i27.4296. PMID 16865769.
- ↑ 6.0 6.1 Tricker, A.R.; Preussmann, R. (1991). "Carcinogenic N-Nitrosamines in the Diet: Occurrence, Formation, Mechanisms and Carcinogenic Potential". Mutation Research/Genetic Toxicology 259 (3–4): 277–289. doi:10.1016/0165-1218(91)90123-4. PMID 2017213.
- ↑ Anselme, Jean-Pierre (1979). "The Organic Chemistry of N-Nitrosamines: A Brief Review". N-Nitrosamines. ACS Symposium Series. 101. pp. 1–12. doi:10.1021/bk-1979-0101.ch001. ISBN 0-8412-0503-5.
- ↑ Vogel, A. I. (1962). Practical Organic Chemistry (3rd ed.). Impression. p. 1074.
- ↑ Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, pp. 846-847, ISBN 978-0-471-72091-1, https://books.google.com/books?id=JDR-nZpojeEC&printsec=frontcover
- ↑ Williams 1988, p. 142.
- ↑ Williams, D. L. H. (1988). Nitrosation. Cambridge, UK: Cambridge University. pp. 128–139. ISBN 0-521-26796-X. https://archive.org/details/nitrosation0000will.
- ↑ Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, p. 739, ISBN 978-0-471-72091-1, https://books.google.com/books?id=JDR-nZpojeEC&printsec=frontcover
- ↑ Krebs, Bernt; Mandt, Jürgen (1975). "Kristallstruktur des N-Nitrosodimethylamins". Chemische Berichte 108 (4): 1130–1137. doi:10.1002/cber.19751080419.
- ↑ 14.0 14.1 Hecht, Stephen S. (1998). "Biochemistry, Biology, and Carcinogenicity of Tobacco-Specific N-Nitrosamines". Chemical Research in Toxicology 11 (6): 559–603. doi:10.1021/tx980005y. PMID 9625726.
- ↑ Advances in Agronomy. Academic Press. 2013-01-08. p. 159. ISBN 978-0-12-407798-0. https://books.google.com/books?id=lMrEEB3rhV8C&pg=PA159.
- ↑ Gregory N. Connolly; Howard Saxner (August 21, 2001). Informational Update Research on Tobacco Specific Nitrosamines (TSNAs) in Oral Snuff and a Request to Tobacco Manufacturers to Voluntarily Set Tolerance Limits For TSNAs in Oral Snuff.
- ↑ "Control of Nitrosamine Impurities in Human Drugs". 24 February 2021. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/control-nitrosamine-impurities-human-drugs.
- ↑ "Control of Nitrosamine Impurities in Human Drugs - Guidance for Industry". https://www.fda.gov/media/141720/download.
- ↑ "Nitrosamine impurities in medications: Guidance". 4 April 2022. https://www.canada.ca/en/health-canada/services/drugs-health-products/compliance-enforcement/information-health-product/drugs/nitrosamine-impurities/medications-guidance.html.
- ↑ "Nitrosamine impurities in medications: Established acceptable intake limits". 15 March 2024. https://www.canada.ca/en/health-canada/services/drugs-health-products/compliance-enforcement/information-health-product/drugs/nitrosamine-impurities/established-acceptable-intake-limits.html.
- ↑ Hecht, Steven S.; Borukhova, Anna; Carmella, Steven G. "Tobacco specific nitrosamines" Chapter 7; of "Nicotine safety and toxicity" Society for Research on Nicotine and Tobacco; 1998 - 203 pages
External links
- Oregon State University, Linus Pauling Institute article on Nitrosamines and cancer, including info on history of meat laws
- Risk factors in Pancreatic Cancer
