Acrylamide

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The chemical compound acrylamide (acrylic amide) has the chemical formula C3H5NO. Its IUPAC name is 2-propenamide. It is a white odourless crystalline solid, soluble in water, ethanol, ether and chloroform. Acrylamide is incompatible with acids, bases, oxidizing agents, iron and iron salts. It decomposes non-thermally to form ammonia and thermal decomposition produces carbon monoxide, carbon dioxide and oxides of nitrogen.

Most acrylamide is used to synthesize polyacrylamides which find many uses as water-soluble thickeners. These include use in wastewater treatment, gel electrophoresis (SDS-PAGE), papermaking, ore processing, and the manufacture of permanent press fabrics. Some acrylamide is used in the manufacture of dyes and the manufacture of other monomers.

Acrylamide was accidentally discovered in foods in April 2002 by scientists in Sweden when they found large amounts of the chemical in starchy foods, such as potato chips, French fries and bread that had been heated (production of acrylamide in the heating process was shown to be temperature-dependant).[1] It was not found in food which had been boiled[1][2] in foods that were not heated.[1]

 

Laboratory Use

Polyacrylamide was first used in a laboratory setting in the early 1950s. In 1959 two independent groups published papers; Davis and Ornstein, and Raymond and Weintraub) on the use of polyacrylamide gel electrophoresis to separate charged molecules[3]. Unfortunately, the Davis publication is no longer available online, although references to it can be found in numerous successive papers. The technique is widely accepted today, and is still an extremely common protocol in molecular biology labs.

Acrylamide also has many other uses in the modern molecular biology laboratory, including the use of linear polyacrylamide (LPA) as a carrier which aids in the precipitation of small amounts of DNA. Many laboratory supply companies sell LPA as a commercial product for just this use. [4]

 

Occurrence in daily life

Acrylamide in fried or baked goods is produced by the reaction between asparagine and reducing sugars (fructose, glucose, etc.) or reactive carbonyls at temperatures above 120oC.[5][6] Acrylamide in olives and prune juice comes through another process. It has been suggested that environmental pathways, such as the breakdown of the herbicide glyphosate (Roundup), are sources too. Smoking is also a major acrylamide producer. Estimates for the proportion in the diet coming from the consumption of coffee range from twenty to forty percent. Acrylamide cannot be created by boiling, and very few uncooked foods contain any detectable amounts. Browning during baking, frying or deep-frying will produce acrylamide and over-cooking of foods will produce large amounts of acrylamide. Acrylamides can also be created during microwaving.

The FDA has analyzed a variety of U.S. food products for levels of acrylamide since 2002, these results can be found here.

 

Reduction of acrylamide formation

 

Storage

In the case of potatoes for instance the storage temperature should not drop below 8°C. When the temperature is as low as 4°C the fructose content rises sharply, so that the acrylamide formation during baking or deep-frying will be higher.

 

Raw Material

New varieties of potatoes are being bred that produce less or no acrylamide.

 

Production methods

In many cases it is advisable to lower the maximum temperature during baking. Also new production methods such as vacuum frying may lower the acrylamide formation. When silicone is used as a foam inhibitor in deep-frying fats in the food industry the acrylamide content is doubled.

 

Recipe formulation

Asparaginase, a naturally-occurring enzyme, can be added to bread or potato mixtures to reduce formation of acrylamide during cooking. [7]

 

Potential health risk

There is evidence that exposure to large doses can cause damage to the male reproductive glands. Direct exposure to pure acrylamide by inhalation, skin absorption, or eye contact irritates the exposed mucous membranes, e.g. the nose, and can also cause sweating, urinary incontinence, nausea, myalgia, speech disorders, numbness, paresthesia, and weakened legs and hands. In addition, the acrylamide monomer is a potent neurotoxin, causing the disassembly or rearrangement of intermediate filaments.[8][9] Ingested acrylamide is metabolised to a chemically reactive epoxide, glycidamide.[10]

 

Cancer

Acrylamide reliably produces various types of cancer in experimental mice and rats.[11][12][13] However, studies in human populations have failed to produce consistent results, and it remains unclear whether this is due to a reduced risk in a natural setting or the methodological difficulties inherent in such studies. For example, it might be difficult to isolate the effects of acrylamide because it is so ubiquitous in Western diets. A Dutch study on 62000 women over an 11 year period has recently concluded that those who ingest more acrylamide in their regular diet are twice as likely to develop endometrial or ovarian cancer.[14]

 

Public awareness

On April 24, 2002, the Swedish National Food Administration (Livsmedelsverket) announced that acrylamide can be found in baked and fried starchy foods, such as potato chips, breads and cookies. Concern was raised mainly because of the carcinogenic effects of acrylamide. This was followed by a strong but short-lived interest from the press. On 2005-08-26, California attorney general Bill Lockyer filed a lawsuit against top makers of french fries and potato chips to warn consumers of the potential risk from consuming acrylamide.[15]

 

See also

  • Acrydite- research on this compound casts light on Acrylamide
  • Deep-frying
  • Deep fryer
  • Vacuum fryer

 

References

  1. ^ a b c Tareke E, Rydberg P. et al. (2002). "Analysis of acrylamide, a carcinogen formed in heated foodstuffs". J. Agric. Food. Chem. 50 (17): 4998-5006. PMID 12166997. 
  2. ^ Food Standards Agency, Acrylamide: your questions answered [1] Retrieved on 2008-01-01
  3. ^ Reynolds S, Weintraub L. (1959). "Acrylamide Gel as a Supporting Medium for Zone Electrophoresis". Science 130 (3377): 711. PMID 14436634. 
  4. ^ Linear Polyacrylamide as a commercially sold DNA carrier.[2]
  5. ^ Mottram DS, Wedzicha BL. and Dodson AT. (2002). "Acrylamide is formed in the Maillard reaction". Nature 419 (6906): 448-449. PMID 12368844. 
  6. ^ Chemistry World, Acrylamide cancer link confirmed [3] Retrieved on 2008-01-01
  7. ^ KORNBRUST, B. A.; Stringer, M. A., Hendriksen, H. V. (September 17-20, 2006). "Enzymatic reduction of acrylamide formation using asparaginase from Aspergillus oryzae". World Grains Summit: Foods and Beverages. 
  8. ^ Kuperman AS. (1958). "Effects of acrylamide on the central nervous system of the cat". J. Pharmacol. Exp. Ther. 123 (3): 182-192. PMID 13564393. 
  9. ^ Alberts, Lewis, Johnson, Raff, Roberts, and Walter ,Molecular Biology of the Cell, 4th Edition, Routledge, March, 2002, ISBN 0-8153-3218-1
  10. ^ Joint FAO/WHO expert committee on food additives, Sixty-fourth meeting, Rome, 8-17 February 2005, Summary and conclusions. [4] Retrieved on 2008-01-01
  11. ^ Rice, Jerry M (2005). "The carcinogenicity of acrylamide". Mutation Research/Genetic Toxicology and Environmental Mutagenesis 580 (1-2): 3-20. PMID 15668103. 
  12. ^ Bull RJ, Robinson M, et al. (1984). "Carcinogenic effects of acrylamide in Sencar and A/J mice". Cancer. Res. 44 (1): 107-111. PMID 6360343. 
  13. ^ Johnson KA, Gorzinski SJ, et al. (1986). "Chronic toxicity and oncogenicity study on acrylamide incorporated in the drinking water of Fischer 344 rats". Toxicol. Appl. Pharmacol. 85 (2): 154-168. PMID 3764902. 
  14. ^ Hogervorst JG, Schouten LJ, et al. (2007). "A prospective study of dietary acrylamide intake and the risk of endometrial, ovarian, and breast cancer". Cancer. Epidemiol. Biomarkers. Prev. 16 (11): 2304-2313. PMID 18006919. 
  15. ^ Office of the attorney general, State of California, Department of justice [5] Retrieved on 2008-01-01

 

External links

  • International Chemical Safety Card 0091
  • NIOSH Pocket Guide to Chemical Hazards 0012
  • Institut national de recherche et de sécurité (1992). "Acrylamide."PDF Fiche toxicologique n° 119. Paris:INRS. (French)
  • IARC Monograph "Acrylamide."
  • National Pollutant Inventory - Acrylamide
  • World Health Organization
  • Environmental Protection Agency'Acrylamide and Food'
  • EPA releases a Toxicological Review of Acrylamide (External Review Draft) for public comment - 01/2008
  • Harvard School of Public Health press release; baked and fried food does not increase risk of certain cancers in humans
  • Harvard School of Public Health press release; no breast cancer risks from acrylamide via food
  • Acrylamide Infonet
  • Girls who eat chips more likely to get breast cancer
  • California Wants to Serve a Warning With Fries
  • Prospective study of dietary acrylamide and risk of colorectal cancer among women
  • Report about acrylamide in food and cancer risks
  • Information about Acrylamide from www.foodrisk.org
  • Court case about a suspected acrylamide poisoning
  • Center for Food Safety and Nutrition (cfsan.fda.gov) FAQ
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