Acrylamide in Food
- In 2002, Swedish studies showed that relatively high levels of acrylamide are formed during frying or baking of starch-containing foods such as potatoes and cereal products. Acrylamide is a potentially cancer causing chemical. This finding is the first research report of the presence of such elevated levels of acrylamide in food after high temperature cooking.
- The international scientific community, the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) took the findings seriously. A WHO/FAO Infonet (www.acrylamide-food.org/) was subsequently set up to facilitate the international exchange of relevant data and ongoing investigations as well as ways to reduce acrylamide in foods.
What is Acrylamide?
- Acrylamide is an odourless, white, crystalline organic solid. It readily undergoes polymerization to form polyacrylamide, which is a highly cross-linked gel polymer with many uses in industry. The polymer of acrylamide is sometimes used as a coagulant aid in the treatment of drinking water and wastewater.
- Acrylamide is a chemical used in a variety of industrial applications. It is also used in paper, textile and plastic industries, synthesis of dyes, as a grouting agent in the construction of dam foundations, tunnels and sewers, as thickener in soap and cosmetics, etc.
- Acrylamide is an inadvertent contaminant produced by cooking food, generally above 120oC and found in foods produced in food establishments and in the home.
- Information shows that acrylamide is formed when certain foods, particularly plant-based foods that are rich in carbohydrates and low in proteins, are cooked at high temperatures such as in frying, roasting or baking.
- Major food items contaminated by acrylamide include potato chips, crisps, coffee, pastries, cookies, bread, rolls and toasts. Foods prepared by boiling do not produce acrylamide.
- Acrylamide is also present in tobacco smoke.
- Acrylamide is biodegradable and will not accumulate in the environment. The most important environmental contamination caused by acrylamide releases was primarily from plastic industries.
Public Health Significance of Acrylamide
- In 1994, the International Agency on Research of Cancer (IARC) evaluated acrylamide as "probably carcinogenic to humans" (Group 2A) after taking into consideration its genotoxic properties and evidence of carcinogenicity in experimental animals. However, IARC also stated that the evidence available was not adequate to establish the carcinogenicity of acrylamide to humans.
- Prior to the announcement of the Swedish studies, the major public health concerns of acrylamide were from occupational and accidental exposures through inhalation and skin contact, and contamination of the chemical in drinking water. Polyacrylamide is added to drinking water as a coagulant aid to assist in removing unwanted substances from the water. The non-toxic form of the cross-linked polymer is used in treatment of water, but the health concern is the very small amount of the remaining non-polymerized acrylamide.
- The WHO Guidelines for Drinking-water Quality (1993) has established a guideline value of 0.5μg/litre for acrylamide in drinking water.
- In Hong Kong, the Water Supplies Department (WSD) adopts the WHO's recommended guideline value of 0.5μg/litre for acrylamide in drinking water. Laboratory tests done by WSD show that the level of acrylamide in our local drinking water is consistently well below the WHO guideline level. The amount of acrylamide exposure from drinking water is very small.
- Studies showed that acrylamide was genotoxic to tested animals and caused reproductive and developmental problems, and cancer in experimental animals.
- In February 2005, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) met to evaluate health risks of acrylamide and reviewed all data since 2002. JECFA concluded that adverse effects including nervous system damage, reproductive and developmental problems were unlikely at average intakes but nerve structural changes could not be excluded at very high intakes.
- JECFA concluded that the most important toxic effect of acrylamide was cancer causing.
- JECFA used the Margin of Exposure (MOE) approach to evaluate risks of acrylamide to humans. MOE is a quotient of the lower limit of the dose (derived statistically from animal experiments or human studies) that causes an undesirable health response divided by the estimated intake of this substance in the general human population. The lower the MOE the greater is the public health concern.
- According to the JECFA's calculations, MOE values of acrylamide for the assessment of carcinogenicity are 300 and 75 for average and high consumers respectively.
- JECFA considered the MOE values of acrylamide are low and indicate human health concern. On this basis, WHO and FAO also concluded that the presence of relatively high levels of acrylamide in food was of human health concern.
- Apart from the above-mentioned conclusions, JECFA noted that several additional studies on carcinogenicity and neurotoxicity of acrylamide were currently underway. JECFA would re-evaluate the chemical when results of these studies became available in two to three years' time.
- In 2003, the Food and Environmental Hygiene Department (FEHD) of the Hong Kong Special Administrative Region Government conducted two studies on "Acrylamide in Food" and "Acrylamide in Fried Fritters".
- Results of the first study showed that in general, levels of acrylamide in commonly consumed foods such as rice, noodles, bakery and batter-based products were low, while higher levels were present in snack foods such as chips, crisps and biscuits.
- As for the second study, results showed that fried fritters cooked at lower temperatures and longer time had lower levels of acrylamide when compared with those fried at higher temperatures and shorter time cooked to the same organoleptic quality.
- FEHD would keep in view and closely monitor the development on this issue.
Advice to the Public
- To minimise the risk of acrylamide in food, FAO and WHO advised that food should not be cooked excessively, i.e. for too long or at too high temperature. However, all food particularly meat and meat products should be cooked thoroughly to destroy foodborne pathogens.
- On the basis of information available on acrylamide, FAO and WHO reconfirm that the general advice on healthy eating remains valid and encourage consumers to eat balanced and varied diet, to eat more fruits and vegetables, and to moderate the consumption of fried and fatty foods so as to reduce the intake of foods high in acrylamide.
Advice to the Trade
- Food industries should research and develop new cooking methods to reduce acrylamide in foods particularly potato chips and crisps, coffee, pastries, cookies, breads, rolls and toasts.
- Food industries should be cautious so as to ensure that the new food preparation methodologies would not affect the nutritional quality and increase or introduce microbiological and chemical hazards in foods.
- According to the results of the above-mentioned local studies that cooking foods at a lower temperature for a longer time can reduce the formation of acrylamide in the food. The food trade should as far as practicable not to fry, roast or bake foods, especially those rich in carbohydrates and low in proteins, at too high temperatures and for too long.
Risk Assessment Section