Significations et usages de acrylamide

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Acrylamide
IUPAC name prop-2-enamide
Identifiers
CAS number	79-06-1 Y
PubChem	6579
ChemSpider	6331 Y
UNII	20R035KLCI Y
KEGG	C01659 Y
ChEBI	CHEBI:28619 Y
ChEMBL	CHEMBL348107 Y
Jmol-3D images	Image 1 Image 2
SMILES O=C(C=C)N C=CC(=O)N
InChI InChI=1S/C3H5NO/c1-2-3(4)5/h2H,1H2,(H2,4,5) Y Key: HRPVXLWXLXDGHG-UHFFFAOYSA-N Y InChI=1/C3H5NO/c1-2-3(4)5/h2H,1H2,(H2,4,5) Key: HRPVXLWXLXDGHG-UHFFFAOYAS
Properties
Molecular formula	C3H5NO
Molar mass	71.08 g mol−1
Density	1.13 g/cm3
Melting point	84.5 °C, 358 K, 184 °F
Boiling point	– (polymerization)
Solubility in water	2.04 kg/L (25 °C)
Hazards
MSDS	ICSC 0091
GHS pictograms	[1]
GHS hazard statements	H301, H312, H315, H317, H319, H332, H340, H350, H361, H372[1]
GHS precautionary statements	P201, P280, P301+310, P305+351+338, P308+313[1]
EU Index	616-003-00-0
EU classification	Toxic (T) Carc. Cat. 2 Muta. Cat. 2 Repr. Cat. 3
R-phrases	R45, R46, R20/21, R25, R36/38, R43, R48/23/24/25, R62
S-phrases	S53, S45
NFPA 704	2 3 2
Flash point	138 °C
Autoignition temperature	424 °C
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Acrylamide (or acrylic amide) is a chemical compound with the chemical formula C₃H₅NO. Its IUPAC name is prop-2-enamide. It is a white odourless crystalline solid, soluble in water, ethanol, ether, and chloroform. Acrylamide is incompatible^[vague] 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.

Acrylamide is prepared on an industrial scale by the hydrolysis of acrylonitrile by nitrile hydratase.

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 is a known lethal neurotoxin (median lethal dose in rabbit = 150mg/kg) and animal carcinogen. Its discovery in some cooked starchy foods in 2002 prompted concerns about the carcinogenicity of those foods.

  Uses

  Molecular biology laboratories

Polyacrylamide was first used in a laboratory setting in the early 1950s. In 1959, the groups of Davis and Ornstein^[2] and of Raymond and Weintraub^[3] independently published on the use of polyacrylamide gel electrophoresis to separate charged molecules.^[4] The technique is widely accepted today, and remains a common protocol in molecular biology labs.

Acrylamide has many other uses in molecular biology laboratories, 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 for this use.^[5]

  Other uses

The majority of acrylamide is used to manufacture various polymers.^[6] These are used as binding, thickening or flocculating agents in grout, cement, sewage/wastewater treatment, pesticide formulations, cosmetics, sugar manufacturing, soil erosion prevention, ore processing, food packaging and plastic products.^[6] Polyacrylamide is also used in some potting soil.^[6]

  Toxicity and carcinogenicity

There is evidence to suggest 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.^[7][8] Ingested acrylamide is metabolised to a chemically reactive epoxide, glycidamide.^[9]

  Occurrence in food and associated health risks

  Discovery of acrylamide in foods

Acrylamide has been found to occur in many cooked starchy foods and is of concern as a possible carcinogen.^[10] Acrylamide was accidentally discovered in foods in April 2002 by scientists in Sweden when they found 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-dependent).^[10] It was not found in food that had been boiled^[10][11] or in foods that were not heated.^[10]

Acrylamide levels appear to rise as food is heated for longer periods of time. Though researchers are still unsure of the precise mechanisms by which acrylamide forms in foods, many^[who?] believe it is a byproduct of the Maillard reaction. In fried or baked goods, acrylamide may be produced by the reaction between asparagine and reducing sugars (fructose, glucose, etc.) or reactive carbonyls at temperatures above 120 °C (248 °F).^[12][13]

Later studies have found acrylamide in black olives,^[14] prunes,^[15] dried pears^[15] and coffee.^[16] Estimates for the proportion of acrylamide in adults’ diet coming from the consumption of coffee range from twenty to forty percent; prune juice has a high concentration of acrylamide, though adults consume it in far smaller quantities.^[17]

The FDA has analyzed a variety of U.S. food products for levels of acrylamide since 2002.^[18]

A 72-hour study of urine from six young healthy volunteers who had consumed a meal containing 0.94 mg of acrylamide concluded that “most of the acrylamide ingested with food is absorbed in humans.”^[19]

  Acrylamide toxicity from food exposure

Although acrylamide has known toxic effects on the nervous system and on fertility, a June 2002 report by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) concluded that the intake level required to observe neuropathy (0.5 mg/kg body weight/day) was 500 times higher than the average dietary intake of acrylamide (1 μg/kg body weight/day). For effects on fertility, the level is 2,000 times higher than the average intake.^[20] From this they concluded that acrylamide levels in food were safe in terms of neuropathy, but raises concerns over human carcinogenicity based on known carcinogenicity in laboratory animals.^[20]

  Human cancer risk of acrylamide exposure from food

Acrylamide causes cancer in rats when administered orally in high-dose experiments, increasing tumors in the nervous system, oral cavity, peritoneum, thyroid gland, mammary gland, uterus, and clitoris.^[21] There is a margin of 900-fold between the dose that gave cancer to 10% of rats and human exposure to acrylamide in the diet.^[22]

To determine the human cancer risk from acrylamide, several studies have been conducted using food frequency data to estimate acrylamide intake and its effect on cancer risk. A Swedish study using 1,525 patients failed to find a link between acrylamide in food and liver, kidney and bowel cancers.^[23] A larger Swedish study on 45,306 men also found no link between dietary intake of acrylamide and risk for colorectal cancer.^[24] A large Italian study covering 1991–2000 in Italy and Switzerland analyzed the risk of cancer of the oral cavity and pharynx, esophagus, larynx, large bowel, breast, and ovaries from consumption of fried/baked potatoes, and found no association.^[25] A 2005 study of 43,404 Swedish women in the Women’s Lifestyle and Health Cohort found that the women’s greatest sources of acrylamide were from coffee (54% of intake), fried potatoes (12% of intake), and crisp bread (9% of intake), but found no association between breast cancer risk and higher intake of any specific foods.^[16] A 2009 Swedish follow-up study study on 61,433 women also found no association between long-term dietary acrylamide intake and breast cancer.^[26] Another 2009 study on 90,628 premenopausal women in the United States also found no relationship between dietary acrylamide intake and breast cancer risk.^[27] A Dutch study on 62,573 women aged 55–69 years did find a link between acrylamide intake and increased risks of postmenopausal endometrial and ovarian cancer after adjusting for smoking, but not with breast cancer.^[28]

Although only one of these studies found an association between dietary acrylamide and cancer, it has been pointed out that food frequency questionnaires do not give a very precise measure of actual acrylamide exposure.^[29] A 2008 study using blood acrylamide levels after adjusting for smoking did find a 2.7-fold increase in risk for estrogen receptor-positive breast cancer for every 10-fold increase of acrylamide.^[30]

  Opinions of health organisations

The World Health Organization (WHO) has set up a clearinghouse for information about acrylamide that includes a database of researchers/data providers; references for research published elsewhere; information updates about the current status of research efforts; and updates on information relevant to the health risk of acrylamide in food.^[31]

One question the site’s FAQ addresses is whether there can be an acceptable level of acrylamide in food. The WHO states that “Acrylamide belongs to the group of chemicals thought to have no reliably identifiable ‘threshold’ of effects, meaning that very low concentrations will also result in very low risks, but not in zero risk: Some risk is always present when the chemical is ingested. However, for these carcinogens, risk is thought to increase with increasing exposure. Very low risks (even of cancer), such as those that are less than one in one million, are considered to be acceptable to some consumers. To others this is unacceptable. The important pre-requisite for any decision is, however, a clear picture of the nature and level of the risk, as well as the potential for lowering this level. This clear picture does not exist for acrylamide at present.” ^[32]

In February 2009, Health Canada announced that they were assessing whether acrylamide, which occurs naturally during the cooking of French fries, potato chips, and other processed foods, is a hazard to human health and whether any regulatory action needs to be taken. They are currently collecting information on the properties and prevalence of acrylamide in order to make their assessment.^[33] In December 2009, after a positive reception from the food industry, Health Canada invited comment from the public on this proposal.^[34] The European Chemical Agency added acrylamide to the list of substances of very high concern in March 2010.^[35]

  Heat-generated food toxicants (HEATOX) study

The Heat-generated Food Toxicants (HEATOX) Project was a European Commission-funded multidisciplinary research project running from late 2003 to early 2007. Its objectives were to “estimate health risks that may be associated with hazardous compounds in heat-treated food [, and] find cooking/processing methods that minimise the amounts of these compounds, thereby providing safe, nutritious, and high-quality food-stuffs.”^[36][37] It found that "the evidence of acrylamide posing a cancer risk for humans has been strengthened,"^[29] and that "compared with many regulated food carcinogens, the exposure to acrylamide poses a higher estimated risk to European consumers."^[36] HEATOX sought also to provide consumers with advice on how to lower their intake of acrylamide, specifically pointing out that home-cooked food tends to contribute far less to overall acrylamide levels than food that was industrially prepared, and that avoiding overcooking is one of the best ways to minimize exposure at home.^[36]

  Public awareness

On April 24, 2002, the Swedish National Food Administration 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 probable 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.^[38] The lawsuit was settled on 2008-08-01, with the food producers agreeing to cut acrylamide levels in half.^[39]

In 2007, more than 100 articles were written about acrylamide, according to Nexis and Factiva, including pieces in the LA Times,^[40] the Boston Globe,^[41] the Guardian,^[42] and the Wall Street Journal, among others. Of these articles, nearly half appeared in November and December, when people were frying potatoes for latkes, and roasting pigs and turkeys.

On August 1, 2008, four food manufacturers – H.J. Heinz Co., Frito-Lay, Kettle Foods Inc., and Lance Inc. – agreed to reduce levels of acrylamide in their products (such as potato chips and French fries) over a three-year period and pay a combined $3 million in fines as a settlement with the California attorney general's office. California had sued these four companies in 2005, alleging they violated a state requirement that companies post warning labels on products with carcinogens.^[43]

  Occurrence in other products

  Herbicides

Acrylamide may be a natural decay product of the polyacrylamide used as a thickening agent in some commercial herbicides. Lab tests have shown that heat and light can decompose polyacrylamide into acrylamide.^[44]

  Cigarettes

Cigarette smoking is a major acrylamide source.^[45] It has been shown in one study to cause a 3-fold greater increase in blood acrylamide levels than any dietary factor.^[30]

  See also

• Acrydite: research on this compound casts light on acrylamide
• Acrolein
• Deep-frying
• Deep fryer
• Vacuum fryer
• Substance of very high concern

  References

  External links

• Acrylamide Infonet
• Acrylamide Facts
• California Wants to Serve a Warning With Fries
• Center for Food Safety and Nutrition (cfsan.fda.gov) FAQ
• Court case about a suspected acrylamide poisoning
• Environmental Protection Agency Acrylamide and Food
• EPA releases a Toxicological Review of Acrylamide (External Review Draft) for public comment – 01/2008
• Girls who eat chips more likely to get breast cancer
• 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
• IARC Monograph "Acrylamide."
• International Chemical Safety Card 0091
• Institut national de recherche et de sécurité (1992). "Acrylamide." Fiche toxicologique n° 119. Paris:INRS. (French)
• National Pollutant Inventory – Acrylamide
• NIOSH Pocket Guide to Chemical Hazards 0012
• World Health Organization