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4-甲基咪唑：修订间差异

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'''4-甲基咪唑'''（{{lang|en|'''4-Methylimidazole'''}}，經常簡寫作{{lang|en|'''4-MEI'''}}）是一個[[有機化合物|有機]][[雜環]] [[化合物]]，[[化學式]]為：{{chem|CH|3}}–{{chem|C|3|H|3|N|2}} 或 {{chem|C|4|H|6|N|2}}。它是透過把[[咪唑]]在第4位置的氫變成[[甲基]][[官能团]]而成。4-甲基咪唑是一種帶微黃色的固體，[[密度]]有1.02 [[公克|g]]/[[立分厘米|cm<sup>3</sup>]]，[[溶點]] 46-48 [[攝氏度|°C]], [[沸點]] 263 °C，[[闪点]] 157 °C。
'''4-甲基咪唑'''（{{lang|en|'''4-Methylimidazole'''}}，經常簡寫作{{lang|en|'''4-MEI'''}}）是一個[[有機化合物|有機]][[雜環]] [[化合物]]，[[化學式]]為：{{chem|CH|3}}–{{chem|C|3|H|3|N|2}} 或 {{chem|C|4|H|6|N|2}}。它是透過把[[咪唑]]在第4位置的氫變成[[甲基]][[官能团]]而成。4-甲基咪唑是一種帶微黃色的固體，[[密度]]有1.02 [[公克|g]]/[[立分厘米|cm<sup>3</sup>]]，[[溶點]] 46-48 [[攝氏度|°C]], [[沸點]] 263 °C，[[闪点]] 157 °C。

4-Methylimidazole may be formed in the [[browning]] of certain foods through the [[Maillard reaction]] between [[carbohydrate]]s and [[amino]]-containing compounds. In particular, it is found in [[roasting|roasted]] foods and in types of [[caramel coloring]] produced with [[ammonia]]-based processes.<ref name=jac/> It may arise also by [[fermentation]].


== 健康考量 ==
== 健康考量 ==
美國非營利健康機構[[公共利益科學中心]]（CSPI）於2012年2月16日發佈新聞稿，向美國政府建議禁止在飲品中使用4-甲基咪唑跟[[2-甲基咪唑]]作[[焦糖|焦糖色]]的著色劑，原因是這兩種化合物已被[[食物及藥品管理局]]確認為[[致癌物]]<ref name=abc_usa>{{cite news |url=http://abcnews.go.com/Health/cspi-caramel-coloring-cola-cancer-soft-drink-industry/story?id=12932008#.T1erd3n4LZg |title=CSPI: Caramel Coloring in Coke, Pepsi Can Cause Cancer; Industry Disputes Claim |trans_title=公共利益科學中心：可口可樂跟百事使用的焦糖色著色劑可致癌；業界對有關指控意見紛紜 |author=Ben Forer |accessdate=2012-03-07 |date=2012-02-16 |language=en }}</ref><ref name=epochtimes>{{cite news |url=http://www.epochtimes.com/b5/12/3/7/n3532852.htm%E5%90%8D%E7%89%8C%E9%A3%B2%E6%96%99%E5%90%AB%E9%AB%98%E5%8A%91%E9%87%8F%E8%87%B4%E7%99%8C%E7%89%A9%EF%BC%9F%E7%BE%8E%E7%9B%A3%E7%AE%A1%E6%A9%9F%E6%A7%8B%E8%B5%B7%E7%B4%9B%E7%88%AD |title=名牌飲料含高劑量致癌物？美監管機構起紛爭 |date=2012-03-07 |editor=[[王嫣然]]編譯報導 |accessdate=2012-03-07 |language=zh-hant |publisher=[[大紀元時報]]}}</ref>。這兩種著色劑普遍用於[[可樂]]飲品中。
Recently there has been concern about the presence of 4-MEI in industrial caramel extract (which is the most used food and beverage coloring), typically at a concentration between 50 and 700 [[parts per million|ppm]].<ref name=who75> World Health Organization (1975) [http://www.inchem.org/documents/jecfa/jecmono/v06je13.htm Toxicological evaluation of some food colours, enzymes, flavour enhancers, thickening agents, and certain food additives]. Accessed on 2011-01-11.</ref>. Dark [[beer]]s and common brands of [[cola|cola drinks]] may contain more than 100 [[microgram|μg]] of this compound per 12-[[ounce]] serving.<ref name=jac>Michael F. Jacobson (2011) [http://cspinet.org/new/pdf/caramel_coloring_petition.pdf ''Petition to Bar the Use of Caramel Colorings Produced With Ammonia and Containing the Carcinogens 2-Methylimidazole and 4-Methylimidazole'']. Accessed on 2011-01-11.</ref>

At very high doses (360 [[milligram|mg]]/[[kilogram|kg]] of body weight), 4-methylimidazole is a [[convulsant]] for [[rabbit]]s, [[mouse|mice]] and [[chicken|chicks]], and was the likely cause of acute intoxication observed in [[cattle]] fed with [[ammonia|ammoniated]] [[sugar]]-containing [[cattle feed]] supplements in the 1960s.<ref name=who75/> On the other hand, several studies found no ill effect in [[rat]]s and [[dog]]s for the concentrations found in caramel coloring.<ref name=who75/> A study even found that 4-MEI had an anti-carcinogenic effect on rats.<ref name=chan>P. C. Chan, G. D. Hills, G. E. Kissling (2008) ''Toxicity and carcinogenicity studies of 4-methylimidazole in F344/N
rats and B6C3F1 mice.'' Arch Toxicol. volume 82 issue 1, pages 45-53.</ref><ref name=jac/> Based on these studies, caramel coloring of all types has been considered safe until recently. In the [[European Union]] the legal limit for 4-MEI in caramel coloring is 250 mg/kg.<ref name=efsa>European Food Safety Authority (2004) [http://www.efsa.europa.eu/en/efsajournal/doc/2004.pdf ''Scientific opinion on the re-evaluation of caramel colours (E 150 a,b,c,d) as food additives'']. EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS). Acessed on 2011-01-11.</ref>

Yet, a 2007 study by the [[National Toxicology Program]] (NTP) found that 4-MEI was [[carcinogen|carcinogenic]] in [[mouse|mice]] and in female [[rat]]s.<ref name=ntp07>National Toxicology Program (2007) [http://ntp.niehs.nih.gov/index.cfm?objectid=9B956B07-F1F6-975E-79BBCDCCD57001C8 ''Toxicology and Carcinogenesis Studies of 4-Methylimidazole (CAS No. 822-36-6) in F344/N Rats and B6C3F1 Mice (Feed Studies)'']. NTP report TR-535. Acessed on 2011-01-11.</ref> Similar effects were observed for the [[isomer]] [[2-Methylimidazole|2-methylimidazole]], also found in caramel coloring. It also has been claimed that the reduction in tumor rates seen by Chan and others were due to lower body weight rather than a true anti-carcinogenic effect.<ref name=jac/>

In light of these new findings, on January 2011 the state of [[California]] added 4-MEI to its [[California Proposition 65|list of probable carcinogens]] and stipulated 16 μg per day as the "[[No Significant Risk Level]]" (NRSL) intake. This is considerably less than the mean intake of 4-MEI by many americans, such as regular cola drinkers.<ref name=jac/> The food industry has strongly opposed that decision, as it implies the need for additional warning labels on many products; and disputes the validity of the NTP study.<ref name=jac/>


==參看==
==參看==
* [[1-甲基咪唑]]
* [[1-甲基咪唑]]
* [[公益科學中心]]
* [[公共利益科學中心]]


== 參考資料 ==
== 參考資料 ==

2012年3月7日 (三) 18:46的版本

4-甲基咪唑
IUPAC名
5-Methyl-1H-imidazole
识别
CAS号 822-36-6  checkY
PubChem 13195
ChemSpider 12640
SMILES
 
  • n1cc(nc1)C
InChI
 
  • 1/C4H6N2/c1-4-2-5-3-6-4/h2-3H,1H3,(H,5,6)
InChIKey XLSZMDLNRCVEIJ-UHFFFAOYAA
性质
化学式 C4H6N2
摩尔质量 82.1 g·mol−1
密度 1.02 g/cm3
熔点 46-48 °C（319-321 K）
沸点 263 °C（536 K）
危险性
闪点 157 °C（315 °F）
若非注明，所有数据均出自标准状态（25 ℃，100 kPa）下。

4-甲基咪唑（4-Methylimidazole，經常簡寫作4-MEI）是一個有機雜環 化合物，化學式為：CH
3–C
3H
3N
2 或 C
4H
6N
2。它是透過把咪唑在第4位置的氫變成甲基官能团而成。4-甲基咪唑是一種帶微黃色的固體，密度有1.02 g/cm3，溶點 46-48 °C, 沸點 263 °C，闪点 157 °C。

健康考量

美國非營利健康機構公共利益科學中心（CSPI）於2012年2月16日發佈新聞稿，向美國政府建議禁止在飲品中使用4-甲基咪唑跟2-甲基咪唑作焦糖色的著色劑，原因是這兩種化合物已被食物及藥品管理局確認為致癌物[1][2]。這兩種著色劑普遍用於可樂飲品中。

參看

參考資料

  1. ^ Ben Forer. CSPI: Caramel Coloring in Coke, Pepsi Can Cause Cancer; Industry Disputes Claim [公共利益科學中心：可口可樂跟百事使用的焦糖色著色劑可致癌；業界對有關指控意見紛紜]. 2012-02-16 [2012-03-07] （英语）. 
  2. ^ 王嫣然編譯報導 (编). 名牌飲料含高劑量致癌物？美監管機構起紛爭. 大紀元時報. 2012-03-07 [2012-03-07] （中文（繁體））. 
检索自“https://zh.wikipedia.org/w/index.php?title=4-甲基咪唑&oldid=19490832”