Acrylamide (or amide) is an organic compound with the chemical formula CH2=CHC(O)NH2. It is a white odorless solid, soluble in water and several organic solvents. From the chemistry perspective, acrylamide is a vinyl-substituted primary amide (CONH2). It is produced industrially mainly as a precursor to , which find many uses as water-soluble and flocculation.[
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Acrylamide forms in burnt areas of food, particularly starchy foods like , when cooked with high heat, above .[
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Production
Acrylamide can be prepared by the hydration of acrylonitrile, which is catalyzed enzymatically:
- CH2=CHCN + H2O → CH2=CHC(O)NH2
This reaction also is catalyzed by sulfuric acid as well as various metal salts. Treatment of acrylonitrile with sulfuric acid gives acrylamide sulfate, . This salt can be converted to acrylamide with a base or to methyl acrylate with methanol.
Uses
The majority of acrylamide is used to manufacture various polymers, especially polyacrylamide. This water-soluble polymer, which has very low toxicity, is widely used as thickener and flocculating agent. These functions are valuable in the purification of drinking water, corrosion inhibition, mineral extraction, and paper making. Polyacrylamide gels are routinely used in medicine and biochemistry for purification and assays.[
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Toxicity and carcinogenicity
Acrylamide can arise in some cooked foods via a series of steps by the reaction of the amino acid asparagine and glucose. This condensation, one of the Maillard reactions, followed by dehydrogenation produces N-(D-glucos-1-yl)-L-asparagine, which upon pyrolysis generates some acrylamide.
The discovery in 2002 that some cooked foods contain acrylamide attracted significant attention to its possible biological effects.[
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Europe
According to the EFSA, the main toxicity risks of acrylamide are "Neurotoxicity, adverse effects on male reproduction, developmental toxicity and ".[
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United States
Acrylamide is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.
Acrylamide is considered a potential occupational carcinogen by U.S. government agencies and classified as a Group 2A carcinogen by the IARC.
Opinions of health organizations
Baking, grilling or broiling food causes significant concentrations of acrylamide. This discovery in 2002 led to international health concerns. Subsequent research has however found that it is not likely that the acrylamides in burnt or well-cooked food cause cancer in humans; Cancer Research UK categorizes the idea that burnt food causes cancer as a "myth".
The American Cancer Society says that laboratory studies have shown that acrylamide is likely to be a carcinogen, but that evidence from epidemiological studies suggests that dietary acrylamide is unlikely to raise the risk of people developing most common types of cancer.
Hazards
Radiolabeled acrylamide is also a skin irritant and may be a tumor initiator in the skin, potentially increasing risk for skin cancer. Symptoms of acrylamide exposure include dermatitis in the exposed area, and peripheral neuropathy.[
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Laboratory research has found that some may have the potential to be developed into drugs which could alleviate the toxicity of acrylamide.
Mechanism of action
Acrylamide is metabolized to the genotoxic derivative glycidamide. On the other hand, acrylamide and glycidamide can be detoxified via conjugation with glutathione.
Occurrence in food
Acrylamide was discovered in foods, mainly in foods, such as (UK: potato crisps), French fries (UK: chips), and bread that had been heated higher than . Production of acrylamide in the heating process was shown to be temperature-dependent. It was not found in food that had been boiled,
Acrylamide has been found in roasted barley tea, called mugicha in Japanese. The barley is roasted so it is dark brown prior to being steeped in hot water. The roasting process produced 200–600 micrograms/kg of acrylamide in mugicha.[
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Acrylamide levels appear to rise as food is heated for longer periods of time. Although researchers are still unsure of the precise mechanisms by which acrylamide forms in foods,
Later studies have found acrylamide in black olives,[ "Acrylamide detected in prune juice and olives" Food Safety & Quality Control Newsletter 26 March 2004, William Reed Business Media SAS, citing "Survey Data on Acrylamide in Food: Total Diet Study Results" United States Food and Drug Administration February 2004; later updated in June 2005, July 2006, and October 2006] dried plums,[ Top Eight Foods by Acrylamide Per Portion . p. 17. jifsan.umd.edu (2004). Retrieved on 2012-06-11.] and .
The US FDA has analyzed a variety of U.S. food products for levels of acrylamide since 2002.
Occurrence in cigarettes
tobacco smoking is a major acrylamide source.
See also
Further reading
External links
