Acrylamide

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.^[1] It is not found in food which has been boiled.^[2]

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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 120^oC.^[3][4] 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 ^[5]

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.^[6][7] Ingested acrylamide is metabolised to a chemically reactive epoxide, glycidamide.^[8]

Cancer

Acrylamide reliably produces various types of cancer in experimental mice and rats.^[9][10][11] 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.^[12]

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.^[13]

See also

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

References

• IARC Monograph "Acrylamide."
• National Pollutant Inventory - Acrylamide
• World Health Organization
• Environmental Protection Agency

'Acrylamide and Food'

• 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
• www.foodrisk.org/acrylamide
• Court case about a suspected acrylamide poisoning
• Center for Food Safety and Nutrition (cfsan.fda.gov) FAQ