Editing Pyridine (section)

==Occurrence==
Pyridine is not abundant in nature, except for the leaves and roots of belladonna (''[[Atropa belladonna]]'')<ref>{{cite book|editor-last=Burdock |editor-first=G. A. |title=Fenaroli's Handbook of Flavor Ingredients |volume=2 |edition=3rd |publisher=CRC Press |location=Boca Raton |date=1995 |isbn=0-8493-2710-5}}</ref> and in marshmallow (''[[Althaea officinalis]]'').<ref>{{cite book|last1=Täufel |first1=A. |last2=Ternes |first2=W. |last3=Tunger |first3=L. |last4=Zobel |first4=M. |title=Lebensmittel-Lexikon |edition=4th |page=450 |publisher=Behr |date=2005 |isbn=3-89947-165-2}}</ref> Pyridine derivatives, however, are often part of biomolecules such as [[alkaloid]]s.

In daily life, trace amounts of pyridine are components of the [[volatile organic compound]]s that are produced in roasting and [[canning]] processes, e.g. in fried chicken,<ref>{{cite journal|last1=Tang|first1=Jian|last2=Jin|first2=Qi Zhang|last3=Shen|first3=Guo Hui|last4=Ho|first4=Chi Tang|last5=Chang|first5=Stephen S.|title=Isolation and identification of volatile compounds from fried chicken|journal=Journal of Agricultural and Food Chemistry|volume=31|pages=1287|year=1983|doi=10.1021/jf00120a035|issue=6}}</ref> [[sukiyaki]],<ref>{{cite journal|last1=Shibamoto|first1=Takayuki|last2=Kamiya|first2=Yoko|last3=Mihara|first3=Satoru|title=Isolation and identification of volatile compounds in cooked meat: sukiyaki|journal=Journal of Agricultural and Food Chemistry|volume=29|pages=57–63|year=1981|doi=10.1021/jf00103a015}}</ref> roasted coffee,<ref>{{cite journal|last1=Aeschbacher|first1=HU|last2=Wolleb|first2=U |last3=Löliger|first3=J|last4=Spadone|first4=JC|last5=Liardon|first5=R|title=Contribution of coffee aroma constituents to the mutagenicity of coffee|journal=[[Food and Chemical Toxicology]] |volume=27|issue=4|pages=227–232|year=1989|pmid=2659457|doi=10.1016/0278-6915(89)90160-9|doi-access=free}}</ref> potato chips,<ref>{{cite journal |last1=Buttery |first1=Ron G. |last2=Seifert |first2=Richard M. |last3=Guadagni |first3=Dante G. |last4=Ling |first4=Louisa C. |year=1971 |title=Characterization of Volatile Pyrazine and Pyridine Components of Potato Chips |journal=Journal of Agricultural and Food Chemistry |volume=19 |issue=5 | pages= 969–971|location= Washington, DC|publisher=ACS |doi= 10.1021/jf60177a020 }}</ref> and fried [[bacon]].<ref>{{cite journal|last1=Ho|first1=Chi Tang|last2=Lee|first2=Ken N.|last3=Jin|first3=Qi Zhang|title=Isolation and identification of volatile flavor compounds in fried bacon|journal=Journal of Agricultural and Food Chemistry|volume=31|pages=336|year=1983|doi=10.1021/jf00116a038|issue=2}}</ref> Traces of pyridine can be found in [[Beaufort (cheese)|Beaufort cheese]],<ref>{{cite journal|last1=Dumont|first1=Jean Pierre|last2=Adda|first2=Jacques|title=Occurrence of sesquiterpene in mountain cheese volatiles|journal=Journal of Agricultural and Food Chemistry|volume=26|pages=364|year=1978|doi=10.1021/jf60216a037|issue=2}}</ref> [[Vaginal lubrication|vaginal secretion]]s,<ref>{{cite book |last1= Labows | first1= John N. Jr. |editor1-first=Howard R. |editor1-last= Moskowitz |last2= Warren|first2= Craig B.|title= Odor Quality and Chemical Structure |year=1981 |publisher=American Chemical Society |location=Washington, DC|isbn= 9780841206076 |doi= 10.1021/bk-1981-0148.fw001 |pages=195–210 |chapter= Odorants as Chemical Messengers}}</ref> [[black tea]],<ref>{{cite journal|last1=Vitzthum|first1=Otto G.|last2=Werkhoff|first2=Peter|last3=Hubert|first3=Peter|title=New volatile constituents of black tea flavor|journal=Journal of Agricultural and Food Chemistry|volume=23|pages=999|year=1975|doi=10.1021/jf60201a032|issue=5}}</ref> saliva of those suffering from [[gingivitis]],<ref>{{cite journal |last1=Kostelc |first1=J. G. |last2=Preti |first2=G. |last3=Nelson |first3=P. R. |last4=Brauner |first4=L. |last5=Baehni |first5=P. |year=1984 |title= Oral Odors in Early Experimental Gingivitis |journal= Journal of Periodontal Research |volume=19 |pages=303–312|doi= 10.1111/j.1600-0765.1984.tb00821.x |issue= 3 |pmid= 6235346}}</ref> and [[Monofloral honey|sunflower honey]].<ref>{{cite book|last1=Täufel |first1=A. |last2=Ternes |first2=W. |last3=Tunger |first3=L. |last4=Zobel |first4=M. |title=Lebensmittel-Lexikon |edition=4th |page=226 |publisher=Behr |date=2005 |isbn=3-89947-165-2}}</ref>

<gallery class="centered skin-invert-image">
File:4-Bromopyridine.svg|4-bromopyridine
File:2,2'-Bipyridine.svg|2,2'-[[bipyridine]]
File:Dipicolinic acid.svg|pyridine-2,6-dicarboxylic acid ([[dipicolinic acid]])
File:PyridiniumVerbindungen.svg|General form of the [[pyridinium]] cation
</gallery>

Trace amounts of up to 16&nbsp;μg/m<sup>3</sup> have been detected in tobacco smoke.<ref name=osha/> Minor amounts of pyridine are released into environment from some industrial processes such as steel manufacture,<ref>{{cite journal|last1=Junk|first1=G. A.|last2=Ford|first2=C. S.|title=A review of organic emissions from selected combustion processes|journal=Chemosphere|volume=9|pages=187|year=1980|doi=10.1016/0045-6535(80)90079-X|issue=4|bibcode=1980Chmsp...9..187J|osti=5295035 }}</ref> processing of [[oil shale]], [[coal gasification]], [[coking]] plants and [[Incineration|incinerators]].<ref name=osha/> The atmosphere at oil shale processing plants can contain pyridine concentrations of up to 13&nbsp;μg/m<sup>3</sup>,<ref>{{cite journal|last1=Hawthorne|first1=Steven B.|last2=Sievers|first2=Robert E.|title=Emissions of organic air pollutants from shale oil wastewaters|journal=Environmental Science & Technology|volume=18|pages=483–90|year=1984|doi=10.1021/es00124a016|issue=6|pmid=22247953|bibcode = 1984EnST...18..483H }}</ref> and 53&nbsp;μg/m<sup>3</sup> levels were measured in the [[groundwater]] in the vicinity of a coal gasification plant.<ref>{{cite journal|last1=Stuermer|first1=Daniel H.|last2=Ng|first2=Douglas J.|last3=Morris|first3=Clarence J.|title=Organic contaminants in groundwater near to underground coal gasification site in northeastern Wyoming|journal=Environmental Science & Technology|volume=16|pages=582–7|year=1982|doi=10.1021/es00103a009|issue=9|pmid=22284199|bibcode = 1982EnST...16..582S }}</ref> According to a study by the US [[National Institute for Occupational Safety and Health]], about 43,000 Americans work in contact with pyridine.<ref>{{cite book|title=National Occupational Exposure Survey 1981–83 |location=Cincinnati, OH |publisher=Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occuptional Safety and Health}}</ref>

===In foods===
Pyridine has historically been added to foods to give them a bitter flavour, although this practise is now banned in the U.S.<ref>{{Federal Register|83|50490}}</ref><ref>{{Cite news|url=https://www.fda.gov/Food/NewsEvents/ConstituentUpdates/ucm622475.htm|title=FDA Removes 7 Synthetic Flavoring Substances from Food Additives List|date=5 October 2018|access-date=8 October 2018|archive-date=7 October 2018|archive-url=https://web.archive.org/web/20181007053921/https://www.fda.gov/Food/NewsEvents/ConstituentUpdates/ucm622475.htm|url-status=live}}</ref> It may still be added to [[ethanol]] to make it unsuitable for drinking.<ref name=roempp/>