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| Names | |||
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| Preferred IUPAC name Prop-2-enamide[2] | |||
| Other names Acrylamide Acrylic amide[1] | |||
| Identifiers | |||
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3D model (JSmol) | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.001.067 | ||
| KEGG |
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| UNII | |||
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| Properties | |||
| C3H5NO | |||
| Molar mass | 71.079 g·mol−1 | ||
| Appearance | white crystalline solid, no odor[1] | ||
| Density | 1.322 g/cm3 | ||
| Melting point | 84.5 °C (184.1 °F; 357.6 K) | ||
| Boiling point | None (polymerization); decomposes at 175-300°C[1] | ||
| 390 g/L (25 °C)[3] | |||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards | potential occupational carcinogen[1] | ||
| GHS labelling: | |||
  [4] | |||
| H301,H312,H315,H317,H319,H332,H340,H350,H361,H372[4] | |||
| P201,P280,P301+P310,P305+P351+P338,P308+P313[4] | |||
| NFPA 704 (fire diamond) | |||
| Flash point | 138 °C (280 °F; 411 K) | ||
| 424 °C (795 °F; 697 K) | |||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) | 100-200 mg/kg (mammal, oral) 107 mg/kg (mouse, oral) 150 mg/kg (rabbit, oral) 150 mg/kg (guinea pig, oral) 124 mg/kg (rat, oral)[5] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 0.3 mg/m3 [skin][1] | ||
REL (Recommended) | Ca TWA 0.03 mg/m3 [skin][1] | ||
IDLH (Immediate danger) | 60 mg/m3[1] | ||
| Safety data sheet (SDS) | ICSC 0091 | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Acrylamide (oracrylicamide) is anorganic compound with thechemical formula CH2=CHC(O)NH2. It is a white odorless solid, soluble inwater and several organic solvents. From the chemistry perspective, acrylamide is a vinyl-substitutedprimary amide (CONH2). It is produced industrially mainly as a precursor topolyacrylamides, which find many uses as water-solublethickeners andflocculation agents.[6]
Acrylamide forms in burnt areas offood, particularlystarchy foods likepotatoes, when cooked with high heat, above 120 °C (248 °F).[7] Despitehealth scares following this discovery in 2002, and its classification as a probablecarcinogen, there is ongoing debate as to whether acrylamide consumed through diet is likely to cause cancer in humans;Cancer Research UK categorized the idea that eating burnt food causes cancer as a myth.[8][9]
Acrylamide can be prepared by the hydration ofacrylonitrile, which is catalyzed enzymatically:[6]
This reaction also is catalyzed bysulfuric acid as well as various metal salts. Treatment of acrylonitrile with sulfuric acid gives acrylamide sulfate,CH=CHC(O)NH2·H2SO4. This salt can be converted to acrylamide with a base or tomethyl acrylate with methanol.
The majority of acrylamide is used to manufacture various polymers, especiallypolyacrylamide. 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.[6]
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Acrylamide can arise in some cooked foods via a series of steps by the reaction of the amino acidasparagine and glucose. This condensation, one of theMaillard reactions, followed by dehydrogenation producesN-(D-glucos-1-yl)-L-asparagine, which uponpyrolysis generates some acrylamide.
The discovery in 2002 that some cooked foods contain acrylamide attracted significant attention to its possible biological effects.[11]IARC,NTP, and theEPA have classified it as a probable carcinogen, althoughepidemiological studies (as of 2019) suggest that dietary acrylamide consumption does not significantly increase people's risk of developingcancer.[8]
According to theEFSA, the main toxicity risks of acrylamide are "Neurotoxicity, adverse effects on male reproduction,developmental toxicity andcarcinogenicity".[9][12] However, according to their research, there is no concern on non-neoplastic effects. Furthermore, while the relation between consumption of acrylamide and cancer in rats and mice has been shown, it is still unclear whether acrylamide consumption has an effect on the risk of developing cancer in humans, and existingepidemiological studies in humans are very limited and do not show any relation between acrylamide and cancer in humans.[9][13] Food industry workers exposed to twice the average level of acrylamide do not exhibit higher cancer rates.[9]
Acrylamide is classified as anextremely 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.[14]
Acrylamide is considered a potential occupational carcinogen by U.S. government agencies and classified as aGroup 2A carcinogen by theIARC.[15] TheOccupational Safety and Health Administration and theNational Institute for Occupational Safety and Health have set dermal occupational exposure limits at 0.03 mg/m3 over an eight-hour workday.[5]
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".[9]
TheAmerican Cancer Society says thatlaboratory studies have shown that acrylamide is likely to be a carcinogen, but that as of 2019[update] evidence fromepidemiological studies suggests thatdietary acrylamide is unlikely to raise the risk of people developing most common types of cancer.[8]
Radiolabeled acrylamide is also askin irritant and may be atumor initiator in the skin, potentially increasing risk for skin cancer. Symptoms of acrylamide exposure includedermatitis in the exposed area, andperipheral neuropathy.[15]
Laboratory research has found that somephytochemicals may have the potential to be developed into drugs which could alleviate the toxicity of acrylamide.[16]
Acrylamide is metabolized to the genotoxic derivativeglycidamide. On the other hand, acrylamide and glycidamide can be detoxified via conjugation withglutathione.[17][18]
Acrylamide was discovered in foods, mainly instarchy foods, such aspotato chips (UK:potato crisps),French fries (UK:chips), and bread that had been heated higher than 120 °C (248 °F). Production of acrylamide in the heating process was shown to be temperature-dependent. It was not found in food that had been boiled,[19] or in foods that were not heated.[20]
Acrylamide has been found inroasted barley tea, calledmugicha in Japanese. Thebarley 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.[21] This is less than the >1000 micrograms/kg found in potato crisps and other fried whole potato snack foods cited in the same study and it is unclear how much of this enters the drink to be ingested.Rice cracker andsweet potato levels were lower than in potatoes. Potatoes cooked whole were found to have significantly lower acrylamide levels than the others, suggesting a link between food preparation method and acrylamide levels.[21]
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,[22] many believe it is a byproduct of theMaillard reaction. Infried orbaked goods, acrylamide may be produced by the reaction betweenasparagine andreducing sugars (fructose,glucose, etc.) or reactivecarbonyls at temperatures above 120 °C (248 °F).[23][24]
Later studies have found acrylamide inblack olives,[25]dried plums,[26][27] driedpears,[26]coffee,[28][29] andpeanuts.[27]
TheUS FDA has analyzed a variety of U.S. food products for levels of acrylamide since 2002.[30]
Cigarette smoking is a major acrylamide source.[31][32] It has been shown in one study to cause an increase in blood acrylamide levels three-fold greater than any dietary factor.[33]
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