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Structure of the nitrosamino group

Nitrosamines are chemical compounds of the chemical structure R1N(-R2)-N=O, some of which are carcinogenic.

Contents

Usages

  • Most rubber products
  • Pesticides
  • Certain cosmetics

Occurrences

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Food

Nitrosamines are produced from nitrites and secondary amines, which often occur in the form of proteins. Their formation can occur only under certain conditions, including strongly acidic conditions such as that of the human stomach. High temperatures, as in frying, can also enhance the formation of nitrosamines. These cooking styles may be responsible for thousands of cases of colon cancer per year across the world. The presence of nitrosamines may be identified by the Liebermann's reaction. [1]

Under acidic conditions the nitrite forms nitrous acid (HNO2), which is protonated and splits into the nitrosonium cation N≡O+ and water: H2NO2+ = H2O + NO+. The nitrosonium cation then reacts with an amine to produce nitrosamine.

Nitrosamines are found in many foodstuffs, especially beer, fish, and fish byproducts, and also in meat and cheese products preserved with nitrite pickling salt. The U.S. government established limits on the amount of nitrites used in meat products in order to decrease cancer risk in the population. There are also rules about adding ascorbic acid or related compounds to meat, because they inhibit nitrosamine formation.

Consumer products

Nitrosamines can be found in tobacco smoke, American dip snuff and to a much lesser degree, snus. (127.9 PPM for American dip snuff compared to 2.8 PPM in Swedish snuff or snus.)[2]

It is also found in latex products. A test of party balloons and condoms indicated that many of them release small amounts of nitrosamines.[1] However, nitrosamines from condoms are not expected to be of toxicological significance.[3]

Cancer

In 1956, two British scientists, John Barnes and Peter Magee, reported that dimethylnitrosamine produced liver tumours in rats. Research was undertaken and around 90% of nitrosamine compounds were deemed to be carcinogenic.[4]

In the 1970s, there was an increased frequency of liver cancer found in Norwegian farm animals. The farm animals had been fed on herring meal, which was preserved using sodium nitrite. The sodium nitrite had reacted with dimethylamine in the fish and produced dimethylnitrosamine.[4]

Nitrosamines can cause cancers in a wide variety of animal species, a feature that suggests that they may also be carcinogenic in humans. "At present, available epidemiological evidence from case-control studies on nitrite and nitrosamine intake supports a positive association with gastric cancer risk. The evidence in relation with oesophageal cancer is insufficient."[5]

Examples of nitrosamines

Substance Name CAS # Synonyms Molecular Formula Physical Appearance Carcinogenicity Category
N-Nitrosonornicotine 16543-55-8 NNN C9H11N3O Oily yellow liquid
4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone[6] 64091-91-4 NNK, 4'-(nitrosomethylamino)-1-(3-pyridyl)-1-butanone C10H13N3O2
N-Nitrosodimethylamine 62-75-9 Dimethylnitrosamine, N,N-Dimethylnitrosamine, NDMA, DMN C2H6N2O Yellow liquid EPA-B2; IARC-2A; OSHA Carcinogen; TLV-A3
N-Nitrosodiethylamine[7] [8] [9] 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 IARC-3
N-Nitrosoanatabine 71267-22-6 IARC-3

See also

  • Nitroamine (without the 's'), compounds of the formula R2N-NO2.
  • Nitroso, compounds of the formula R-NO

References

  1. ^ Mulliken, Samuel Parsons "A method for the identification of pure organic compounds" John Wiley & Sons; 1916; 327 pages
  2. ^ Gregory N. Connolly, and 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. http://smallbusiness.findlaw.com/finances-taxes/news/hdocs/docs/tobacco/masnuffsstudy.pdf.  
  3. ^ Proksch E. Toxicological evaluation of nitrosamines in condoms. Int J Hyg Environ Health. 2001 Nov;204(2-3):103-10. PubMed
  4. ^ a b ""Nitrosamines and Cancer"". http://lpi.oregonstate.edu/f-w00/nitrosamine.html. Retrieved 2009-09-06.  
  5. ^ Jakszyn P, Gonzalez CA. Nitrosamine and related food intake and gastric and oesophageal cancer risk: a systematic review of the epidemiological evidence. World J Gastroenterol. 2006 Jul 21;12(27):4296-303. PubMed
  6. ^ 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
  7. ^ NIH Substance Profile
  8. ^ Spectrum; Chemical Fact Sheet
  9. ^ Safety data for N-nitrosodiethylamine

External links


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