Acrylamide
Acrylamide is a vinyl monomer mainly used to make polyacrylamide materials. However,
it may be found in certain foods that are processed at high temperatures above 120°C.
These include potato chips, french fries, bread, and coffee.
Heating starchy foods cause their browning and provide a particular smell. This transformation is a result of the Maillard reaction between reducing sugars and amino acids. Although browning and flavor are favored; baking, frying, or roasting cause a formation of acrylamide. The precursors for acrylamide are organic compound asparagine and suitable carbonyl compounds, mainly reducing sugars. Given how popular fried, roasted, and baked plant foods are, dietary exposure to acrylamide is of concern for public health officials.
The International Agency for Research on Cancer (IARC) classifies acrylamide as a “probable human carcinogen.” It is recognized as a carcinogenic, teratogenic, or mutagenic compound that's neurotoxic to the central nervous system. Acrylamide is easily absorbed by gastrointestinal and respiratory tracts. Concurrently, skin absorption is slower, and a large amount of the dose remains on the skin. Acrylamide and glycidamide exhibit preferential bioconcentration in plasma, erythrocytes, and testes. Studies of highly exposed workers suggest that the mode of action for acrylamide also includes a combination of DNA damage, interference with mitosis, meiosis, and oxidative stress.
When consumed acrylamide is quickly metabolized via cytochrome P450 oxidation to the epoxide glycidamide or conjugated with glutathione by glutathione S-transferases. If glycidamide is hydrolyzed by the microsomal epoxide hydrolase to glyceramide, it is then converted to 2,3-dihydroxypropanoic acid. Glutathione conjugates and glycidamide are next converted to mercapturic acid conjugates.
Human studies showed that around 60% of absorbed acrylamide is excreted with the urine mostly in a form of glutathione conjugates and to a less extent as unchanged form. Hemoglobin adducts of acrylamide and glycidamide reflect the exposure to acrylamide over the last four months and may be considered a biomarker of long-term exposure to acrylamide. On the opposite hand, the mercapturic acid metabolites of acrylamide and glycidamide may be considered biomarkers of recent acrylamide exposure (from hours up to a few days). Since any level of exposure to a genotoxic substance could potentially damage DNA and result in cancer, EFSA’s scientists conclude that they can not set a tolerable daily intake (TDI) of acrylamide in food. In the United States, it's been estimated that foods containing acrylamide contribute 38% of daily calories, 36% of fiber, 33%of carbohydrates, and greater than 25% for several micronutrients.
There are numerous studies to lower the quantity of acrylamide in foods. Some were successfully implemented on an industrial scale, however, many stayed as a laboratory experiment. Nevertheless, available epidemiological and toxicological observations suggest that exposure to acrylamide in a normal diet isn't likely to increase the risk of cancer in humans.