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Acrylamide cannot be created by boiling, and very few uncooked foods contain any detectable amounts.
Acrylamide cannot be created by boiling, and very few uncooked foods contain any detectable amounts.


[[Maillard reaction|Browning]] during [[baking]], [[frying]] or [[deep-frying]] will produce acrylamide, and over-cooking foods may 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 [http://www.cfsan.fda.gov/~dms/acrydata.html here].
[[Maillard reaction|Browning]] during [[baking]], [[frying]] or [[deep-frying]] will produce acrylamide, and over-cooking foods may 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 [http://www.fda.gov/Food/FoodSafety/FoodContaminantsAdulteration/ChemicalContaminants/Acrylamide/ucm053549.htm here].


==Reduction of acrylamide formation==
==Reduction of acrylamide formation==

Revision as of 11:34, 12 July 2009

Acrylamide
Names
IUPAC name
prop-2-enamide
Identifiers
3D model (JSmol)
ECHA InfoCard 100.001.067 Edit this at Wikidata
  • C=CC(=O)N
Properties
C3H5NO
Molar mass 71.079 g·mol−1
Density 1.13 g/cm³
Melting point 84.5 °C
Boiling point -
204 g/100 ml (25 °C)
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
3
2
2
Flash point 138 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Acrylamide (or acrylic amide) is a chemical compound with 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.

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 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).[1] It was not found in food that had been boiled[1][2] nor in foods that were not heated.[1]

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. [3]

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[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]

Prepared foods

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 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).[6][7]

A study by the U.S. Food and Drug Administration (FDA) proposed a mechanism that involves asparagine, which, when heated in the presence of glucose, forms acrylamide.

Based on current stage of knowledge, acrylamide is a natural byproduct that forms when certain carbohydrate-rich foods are fried, baked, or roasted at high temperatures above 120 °C. 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. [8] There is a margin of 900-fold between human exposure to acrylamide in the diet and the dose that gave cancer to 10% of rats. [9]

Raw, dried, and pickled foods

Acrylamide in olives, prunes, and dried pears[10] develops through another process. Genetics professor Joe Cummins suggests a link between acrylamide and herbicides such as glyphosate (Roundup), citing studies which show that heat and light can decompose polyacrylamide, the thickening agent used in commercial herbicides, into acrylamide.[11]

Tobacco

Cigarette smoking is also a major acrylamide source.[12]

Beverages

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.[13]

Cooking methods that affect acrylamide production

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 foods may 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

The Confederation of the Food and Drink Industries in the EU (CIAA) has published a number of brochures to help people reduce the amount of acrylamide formed in their food. They offer a general acrylamide “toolbox” as well as publications specific to reducing the acrylamide in biscuits, crackers & crispbreads, bread products, breakfast cereals, potato crisps (chips), and French fries.

Storage

In the case of potatoes, for instance, the storage temperature should not drop below 8 °C (46 °F). When the temperature is as low as 4 °C (39 °F) the fructose content rises sharply, so that the acrylamide formation during baking or deep-frying will be higher.

Raw material

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

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. [14]

Published articles on the potential health risks to humans

Inhaled, absorbed or ingested acrylamide

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.[15][16] Ingested acrylamide is metabolised to a chemically reactive epoxide, glycidamide.[17]

British Journal of Cancer

In 2003, the British Journal of Cancer published an article titled “Dietary acrylamide and cancer of the large bowel, kidney, and bladder: Absence of an association in a population-based study in Sweden.”

The article was based on a study led by L A Mucci that reanalysed a population-based Swedish case-control study encompassing cases with cancer of the large bowel, bladder and kidney, and 538 healthy controls. Researchers assessed the impact of dietary acrylamide “by linking extensive food frequency data with acrylamide levels in certain food items recorded by the Swedish National Food Administration. Unconditional logistic regression was used to estimate odds ratios, adjusting for potential confounders.” Dr. Mucci’s group “found consistently a lack of an excess risk, or any convincing trend, of cancer of the bowel, bladder, or kidney in high consumers of 14 different food items with a high (range 300-1200 µg kg-1) or moderate (range 30-299 µg kg-1) acrylamide content.”

Dr. Mucci’s group was surprised by one finding, writing “Unexpectedly, an inverse trend was found for large bowel cancer (P for trend 0.01) with a 40% reduced risk in the highest compared to lowest quartile.” Sounding a note of cautious optimism, the article concludes “We found reassuring evidence that dietary exposure to acrylamide in amounts typically ingested by Swedish adults in certain foods has no measurable impact on risk of three major types of cancer. It should be noted, however, that relation of risk to the acrylamide content of all foods could not be studied.” [18]

Cancer, epidemiology, biomarkers, and prevention

A number of studies pertaining to acrylamide have appeared in various issues of Cancer, Epidemiology, Biomarkers & Prevention. Two of the more germane are Prospective Study of Dietary Acrylamide Intake and the Risk of Endometrial, Ovarian, and Breast Cancer” and “Toxicokinetics of Acrylamide in Humans after Ingestion of a Defined Dose in a Test Meal to Improve Risk Assessment for Acrylamide Carcinogenicity.”

The first study was led by Dr. Janneke G. Hogervorst and included 62,573 women, aged 55–69 years. The acrylamide intake of subcohort members and cases was assessed with a food frequency questionnaire and was based on chemical analysis of all relevant Dutch foods. Subgroup analyses were done for never-smokers to eliminate the influence of smoking, an important source of acrylamide.

After 11.3 years of follow-up, the researchers observed 327, 300, and 1,835 cases of endometrial, ovarian, and breast cancer, respectively. Hogervorst’s group concluded that his subjects faced “increased risks of postmenopausal endometrial and ovarian cancer with increasing dietary acrylamide intake, particularly among never-smokers. Risk of breast cancer was not associated with acrylamide intake.” [19]

The second study was led by Dr. Uwe Fuhr and sought to evaluate the how much of the acrylamide humans eat is absorbed into the body. The study consisted of six young healthy volunteers consuming a meal containing 0.94 mg of acrylamide and then providing urine was for up to 72 hours thereafter. Fuhr’s group concluded that “most of the acrylamide ingested with food is absorbed in humans.” [20]

Heat-generated food toxicants (HEATOX)

The Heat-generated Food Toxicants (HEATOX) Project was a “multidisciplinary research project involving 24 partners in 14 countries.” It ran 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 which minimise the amounts of these compounds, thereby providing safe, nutritious and high-quality food-stuffs.”[21] Its final report is located here. Unlike more academic studies, HEATOX sought also to provide consumers with advice on how to lower their intake of acrylamide. The group recommends that national authorities highlight the following[21]:

Potatoes low in sugar

  • Low sugar potato varieties
  • Maintenance of suitable storage temperature during the supply chain
  • Low sugar levels in prefabricated potato products for domestic frying.

Best frying temperature

  • Frying temperature in the range 145 to 170 °C (300 to 350 °F) for deep frying potatoes.
  • Clear and accurate cooking instruction on the package of pre-fried products.
  • Clear and accurate instruction for fryers for domestic use.

Golden, not brown!

  • French fries and roast potatoes cooked to a golden-yellow rather than golden-brown colour.
  • Bread toasted to the lightest colour acceptable.

International Journal of Cancer

In March, 2003, the International Journal of Cancer published an article with the forthright title “Fried potatoes and human cancer.” The article reported on a study conducted between 1991 – 2000 in Italy and Switzerland that analyzed the risk of cancer of the oral cavity and pharynx, esophagus, larynx, large bowel, breast and ovaries. It was led by Claudio Pelucchi whose team found “reassuring evidence for the lack of an important association between consumption of fried/baked potatoes and cancer risk.”[22]

More recently, in January, 2008, one of the HEATOX members published “Acrylamide exposure and incidence of breast cancer among postmenopausal women in the Danish Diet, Cancer and Health Study.” The article addresses a study led by Dr. PT Olesen of the National Food Institute, Technical University of Denmark. The abstract to the study states “So far, epidemiological studies have not shown any association between human cancer risk and dietary exposure to acrylamide. The purpose of this study was to conduct a nested case control study within a prospective cohort study on the association between breast cancer and exposure to acrylamide using biomarkers.” The study found that “[a]fter adjustment for smoking behavior. . . a positive association was seen between acrylamide-hemoglobin levels and estrogen receptor positive breast cancer. . . . A weak association between glycidamide hemoglobin levels and incidence of estrogen receptor positive breast cancer was also found, this association, however, entirely disappeared when acrylamide and glycidamide hemoglobin levels were mutually adjusted.” [23]

Journal of the American Medical Association

The March 15, 2005 issue of the Journal of the American Medical Association (JAMA) contained an article titled “Acrylamide Intake and Breast Cancer Risk in Swedish Women,” written by Lorelei A. Mucci, ScD, MPH. The study cohort consisted of 43,404 Swedish women in the Women’s Lifestyle and Health Cohort. The women’s greatest single source of acrylamide was from coffee (54% of intake), fried potatoes (12% of intake), and crisp bread (9% of intake).

The study concluded “Compared with the lowest quintile of acrylamide intake, there was no significantly increased risk of breast cancer in the higher quintiles and no evidence of a linear dose response. For quintile 5 compared with quintile 1, the relative risk was 1.19 (95% confidence interval, 0.91-1.55). Furthermore, there was no association between breast cancer risk and higher intake of any specific foods including coffee, fried potatoes, and crisp bread.” [24]

World Health Organization

The World Health Organization WHO has set up a clearinghouse for information about acrylamide that includes 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.

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.” [25]

American Journal of Epidemiology

The February 1, 2009, issue of the American Journal of Epidemiology included a study conducted at the Karolinska Institute in Stockholm concerning the relationship between dietary intake of acrylamide and breast cancer. Researchers found no statistically significant association between long-term dietary acrylamide intake and breast cancer. The study examined 61,433 Swedish women who were cancer free and completed a food frequency questionnaire in 1987–1990 and again in 1997.[26]

On February 18, 2009, the same journal Advance Access published[27] a study by researchers at the Harvard School of Public Health and Brigham and Women’s Hospital in Boston, MA , on the relationship between dietary acrylamide intake and premenopausal breast cancer. Similar to the Swedish study, the research revealed no association between dietary acrylamide intake and breast cancer risk. The study examined 90,628 premenopausal women.

European Journal of Cancer

The March 2009 issue of the European Journal of Cancer published a study examining the relationship between dietary intake of acrylamide and colorectal cancer. Conducted by Swedish researchers at the Karolinska Institute, this study of 45,306 men found no evidence of a link between dietary intake of acrylamide and risk for colorectal cancer.[28]

Safe levels of acrylamide

In June 2002, the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) issued a report about the health implications of acrylamide in food. After study, the Consultation concluded that the no observed adverse effect level (NOAEL) for acrylamide neuropathy is 0.5 mg/kg body weight/day and the NOAEL for fertility changes is four times higher than for peripheral neuropathy. The study continued, “On the basis of current knowledge, controlling for peripheral neuropathy is expected to control for effects on fertility. The estimated average chronic human dietary intake is in the order of 1 μg/kg body weight/day. This provides a margin between exposure and the NOAEL of 500.” [29]

Hence, a woman weighing 132 pounds (60 kg) could safely consume 30 mg of acrylamide daily; a man weighing 180 pounds (82 kg), about 41 mg; a child weighing 40 pounds (18 kg), 9 mg. [30]

Referring to the chart below for the amount of acrylamide in foods, in a single day, the child can eat 13 kg (28 lb) of French fried potatoes, the woman can drink 86 kg (~86 L, or 23 US gal) of prune juice, and the man can eat 29 kg (63 lb) of oven baked potatoes, and each of them will have ingested less than 50 percent of the NOAEL of acrylamide.

Food AA concentration
(μg/kg) 		Portion size
(g) 		AA per portion
(µg)
French fries (OB) 698 70 48.8
Prune juice 174 140 24.4
French fries (RF) 334 70 23.3
Postum 93 240 22.3
Potato chips 546 30 16.4
Canned black olives 550 15 8.2
Breakfast cereal 131 55 7.3
Brewed coffee 8.5 240 3.2

(adapted from Table: Top Eight Foods by Acrylamide Per Portion, page 17)

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.[31] The lawsuit was settled on 2008-08-01 with the food producers agreeing to cut acrylamide levels in half.[32]

In 2007, more than 100 articles were written about acrylamide, according to Nexis and Factiva, including pieces in the LA Times[33], the Boston Globe [34], the Guardian[35], 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.[36]

See also

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. {{cite journal}}: Explicit use of et al. in: |author= (help)
  2. ^ Food Standards Agency, Acrylamide: your questions answered [1] Retrieved on 2008-01-01
  3. ^ [ http://www.hc-sc.gc.ca/fn-an/securit/chem-chim/food-aliment/acrylamide/index-eng.php Health Canada: Acrylamide]
  4. ^ Reynolds S, Weintraub L. (1959). "Acrylamide Gel as a Supporting Medium for Zone Electrophoresis". Science. 130 (3377): 711. PMID 14436634.
  5. ^ Linear Polyacrylamide as a commercially sold DNA carrier.[2]
  6. ^ Mottram DS, Wedzicha BL. and Dodson AT. (2002). "Acrylamide is formed in the Maillard reaction". Nature. 419 (6906): 448–449. PMID 12368844.
  7. ^ Chemistry World, Acrylamide cancer link confirmed [3] Retrieved on 2008-01-01
  8. ^ Animal Test Results on Acrylamide in the Carcinogenic Potency Database
  9. ^ Comparing Possible Cancer Hazards from Human Exposures to Rodent Carcinogens
  10. ^ Acrylamide in dried Fruits
  11. ^ Cummins, Joe (2002-08-01). "Acrylamide In Cooked Foods: The Glyphosate Connection". Institute of Science in Society. Retrieved 2008-08-20.
  12. ^ [ http://cebp.aacrjournals.org/cgi/content/abstract/16/11/2471 Assessment of the Relation between Biomarkers for Smoking and Biomarkers for Acrylamide Exposure in Humans]
  13. ^ page 17 Top Eight Foods by Acrylamide Per Portion
  14. ^ Kornbrust, B. A. (September 17–20, 2006). "Enzymatic reduction of acrylamide formation using asparaginase from Aspergillus oryzae". World Grains Summit: Foods and Beverages. San Francisco, California USA. {{cite conference}}: Unknown parameter |booktitle= ignored (|book-title= suggested) (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: date format (link)
  15. ^ Kuperman AS. (1958). "Effects of acrylamide on the central nervous system of the cat". J. Pharmacol. Exp. Ther. 123 (3): 182–192. PMID 13564393.
  16. ^ Alberts, Lewis, Johnson, Raff, Roberts, and Walter ,Molecular Biology of the Cell, 4th Edition, Routledge, March, 2002, ISBN 0-8153-3218-1
  17. ^ 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
  18. ^ “Dietary acrylamide and cancer of the large bowel, kidney, and bladder: Absence of an association in a population-based study in Sweden.”
  19. ^ “A Prospective Study of Dietary Acrylamide Intake and the Risk of Endometrial, Ovarian, and Breast Cancer”
  20. ^ “Toxicokinetics of Acrylamide in Humans after Ingestion of a Defined Dose in a Test Meal to Improve Risk Assessment for Acrylamide Carcinogenicity”
  21. ^ a b http://www.slv.se/upload/heatox/documents/D62_final_project_leaflet_.pdf
  22. ^ “Fried potatoes and human cancer”
  23. ^ “Acrylamide exposure and incidence of breast cancer among postmenopausal women in the Danish Diet, Cancer and Health Study.”
  24. ^ “Acrylamide Intake and Breast Cancer Risk in Swedish Women,”
  25. ^ WHO | Frequently asked questions - acrylamide in food
  26. ^ Long-term Dietary Acrylamide Intake and Breast Cancer Risk in a Prospective Cohort of Swedish Women
  27. ^ Dietary Acrylamide Intake and Risk of Premenopausal Breast Cancer
  28. ^ Dietary acrylamide intake and risk of colorectal cancer in a prospective cohort of men
  29. ^ FAO/WHO Consultation on the Health Implications of Acrylamide in Food; Geneva, 25-27 June 2002, Summary Report
  30. ^ for these and all other unit conversions, see this)
  31. ^ Office of the attorney general, State of California, Department of justice [5] Retrieved on 2008-01-01
  32. ^ Lawsuit over potato chip ingredients settled [6] Retrieved on 2008-08-02
  33. ^ KFC to tell diners of chemical in potatoes - Los Angeles Times
  34. ^ Does a chemical formed in cooking french fries really cause cancer? - The Boston Globe
  35. ^ The question: Is cooked food dangerous? | Science | The Guardian
  36. ^ "Settlement will reduce carcinogens in potato chips". Associated Press. Retrieved 2008-08-02.
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