Acrylamide (AA — molecular formula C3H5ON) is a colorless, odorless, crystalline solid that is highly soluble in water and polar solvents such as acetone and ethanol. It is an important manufacturing chemical used in the production of polymers and copolymers. Since 1970, it has been allocated to the production of mortars and soil stabilizers.
AA is a newly formed impurity (NFC) in carbohydrate-rich foods when processed at high temperatures (>120°C), such as when boiling, frying, toasting, or baking. It occurs when the amino acid asparagine reacts with sugars — especially glucose and fructose — as a result of the Maillard reaction. Potato chips, roasted cereals, coffee and baked goods are the main sources of this impurity.
Following oral administration, AA is rapidly absorbed and distributed throughout the body, including muscles, skin, blood, liver, and nerve tissue. It is rapidly metabolized by cytochrome P450 2E1 (CYP2E1) to form epoxide derivatives, such as glycidamide, which is more reactive with DNA and proteins than the parent compound. AA and its metabolite (glycidamide) bind to glutathione (GSH) and are excreted in human urine with a terminal half-life of 2.4-7 hours.
In 2001, the Scientific Committee on Toxicity, Ecotoxicity and the Environment identified inherent toxicities of acrylamide, including neurotoxicity, genotoxicity (DNA damage) in both the body and germ cells, carcinogenicity and reproductive toxicity. The average dietary exposure estimated by the World Health Organization (WHO) is 0.001 mg/kg/day. Many studies have implied that AA may be known as a potent neurotoxicant, and its neurotoxic effects have been demonstrated in both human and animal occupational exposures.
AA has been classified as “probably carcinogenic to humans” by the International Agency for Research on Cancer (IARC). That said, evidence of a carcinogenic effect of AA in humans is inadequate from epidemiological studies or occupational exposures. It is structurally similar to carcinogenic compounds such as vinyl carbamate and acrylonitrile, both of which are potentially carcinogenic molecules too. AA’s carcinogenicity has been described in several studies, and results indicate that it may increase the risk of certain types of cancer. For example, exposure was indeed found to be associated with kidney and breast cancer in postmenopausal women, but not positively associated with bladder and prostate cancer risk. There is no evidence of reproductive or immunotoxicity of AA in humans.
Due to the extensive use of AA in industry and the high content of AA in dietary foods, exposure to the compound is unavoidable and its toxic effects and mechanisms need to be known. Interestingly, the use of antioxidant compounds such as vitamin E and carnitine can greatly reduce its toxicity.