Report No. 11

Chemical Hazard Evaluation

Acrylamide in Food

December 2003
Food and Environmental Hygiene Department
The Government of the Hong Kong Special Administrative Region

Correspondence:

Risk Assessment Section

Food and Environmental Hygiene Department

43/F, Queensway Government Offices,

66 Queensway, Hong Kong.

Email: enquiries@fehd.gov.hk

Table of Contents

Risk Assessment Studies -

Acrylamide in Food

An investigation of acrylamide in Asian Food available in Hong Kong

INTRODUCTION

Background 

  In April 2002, the Swedish National Food Administration (NFA) and researchers from Stockholm University released a study finding that acrylamide was detected in a variety of common foods cooked at high temperature such as chips (French fries), potato crisps, breakfast cereals and cookies etc.  Subsequent studies from Norway, Switzerland, United Kingdom and United States had also found elevated levels of acrylamide in such foods.  The discovery of acrylamide in food is a public health concern because acrylamide is a potential carcinogen and genotoxicant. 

2.   In view of the findings, an expert consultation convened jointly by the Food and Agriculture Organisation of the United Nation (FAO) and the World Health Organisation (WHO) in June 2002.  The Consultation recognized that the issue is a major concern and acknowledged the potential link between acrylamide and carbohydrate-rich foods cooked at high temperature.  The Consultation considered that the existing data is insufficient to allow a quantitative estimate of cancer risks from dietary acrylamide.  Besides, data in food consumed in regions other than Europe and North America is lacking and called for more research in this area.

3.   In view of the public health risk of this issue, the Food and Environment Hygiene Department (FEHD) thus considered that there is a need to conduct a study to determine the acrylamide levels in foods of our local diets especially Asian food (e.g. fried rice, fried noodles, fried dim sum (點心) and yau-hei (i.e. deep-fried dough) (油器) etc.). 

Use of acrylamide  4. Acrylamide is an odourless, white, crystalline organic solid with melting point of 84-86°C. [1]   It readily undergoes polymerization to form polyacrylamide, which is a highly cross-linked gel polymer with many uses in industry.  Polyacrylamides are used as a coagulant aid in the treatment of drinking water and waste water.  It is also used in paper, textile and plastic industries, and synthesis of dyes, as a grouting agent in the construction of dam foundation, tunnels and sewers. 

Source of exposure

5.   Prior to NFA’s announcement, the major health concerns associated with acrylamide were the exposure through drinking water and in occupational exposure, while acrylamide from diet is not known as an exposure.  Polyacrylamide is used as a coagulant aid in drinking water treatment and trace amounts of non-polymerized acrylamides may present in drinking water. [2]   The WHO Guideline for Drinking Water Quality has established a guideline value of 0.5 mg/litre for acrylamide in drinking water.  Residual acrylamide from packaging material contributes a negligible exposure. [3]  

6.   Ingested acrylamide is readily absorbed from the gastrointestinal tract and mainly excreted via urine, with small amounts eliminated via faeces and exhalation.

7.   Acute toxicity caused by acrylamide is rarely encountered in humans.  Neurotoxicity is the only recognized adverse effect of oral acrylamide exposure for humans, affecting sensory and/or motor functions.  The WHO Consultation in June 2002 supported the "No Observed Adverse Effect Level" (NOAEL) for acrylamide neurotoxicity of 0.5 mg per kg body weight per day previously established.  The LD₅₀ values ranged from 107 - 203 mg/kg body weight was shown in rats. [4]  

8.   Acrylamide is genotoxic in vivo, therefore acrylamide has the potential to induce heritable damage at gene and chromosome level. 

9.     Acrylamide is carcinogenic in experimental animals producing increased incidences of a number of benign and malignant tumours in various organs, including thyroid, adrenal, brain, lung, skin, etc.  For humans, the relative potencies of cancer causation due to acrylamide in food are not known. [5]  

10.   In 1994, International Agency for Research on Cancer (IARC) evaluated acrylamide and considered that there was sufficient evidence of carcinogencity in experimental animals but inadequate evidence of carcinogenicity in humans and classified it as Group 2A (probably carcinogenic to humans).  This classification was endorsed by the WHO Consultation in 2002. 

Formation of acrylamide in food

11.     At present, research findings revealed that raw food and foodstuffs that are prepared by boiling do not contain appreciable levels of acrylamide. [6] Acrylamide is formed when food, particularly those rich in carbohydrate are cooked at above 120°C. [5] Current evidence suggests that acrylamide may be formed in food in chemical reaction which requires the presence of the amino acid, asparagines and reducing sugars under certain conditions.

12.     The mechanism involved in acrylamide formation during the food processing is still uncertain.  Researches are underway in many parts of the world to find out the exact mechanism of formation of acrylamide in food. 

OBJECTIVE 

13. This study aims to determine the levels of acrylamide in food available in local market.

METHODS 

Sampling

14.   For the purpose of this study, a wide range of carbohydrate-rich food was taken for acrylamide analysis.  These food were subjected to high-temperature cooking, principally >120°C such as grilling, roasting, baking, barbecuing, frying and deep-frying.  Asian style foods such as Chinese, Japanese, Indian, Indonesian, Malaysian, Thai, Vietnamese style, as well as some Western foods were included.  They might be in a form of ready-to-eat, mixed dishes and pre-packaged.  Food samples were collected from various restaurants, supermarkets, bakeries and other retail outlets. 

15.     The popularity and availability of the food / products formed the major selection criteria.  Mixed dishes were mainly in a form of "composite sample".  Samples collected randomly from three to four sources were mixed and homogenized, otherwise, food samples were analysed individually.  The food groups are shown in Annex I.

Laboratory analysis

16.   Laboratory analyses were conducted by the Food Research Laboratory (FRL) of the FEHD.

17.   The edible portion of the food sample was homogenized and an appropriate test portion (1-4 g) was taken. The acrylamide in the test portion was extracted by water and then, cleaned up by solid phase extraction, and subsequently determined by Liquid Chromatograph-Tandem Mass Spectrometry (LC-MS/MS) technique. Acrylamide-1,2,3-C¹³ was used as an internal reference (surrogate) for the analysis.  The test method was validated by single-laboratory validation.  The limit of detection and the limit of quantification were 3µg/kg and 10µg/kg respectively.   

RESULTS AND DISCUSSION

18. Some 450 food samples were collected and sent to the FRL for acrylamide analysis.  A total of 156 analyses had been conducted.  The results are listed in Annex II.

19. On the whole, high-temperature treated carbohydrate-rich foods contained acrylamide. The levels of acrylamide in the more commonly consumed Asian style food items in the food groups rice and rice product dishes, noodles, bakery products and batter-based products were low and generally less than 60 mg/kg, except for deep-fried sizzling rice (guo-ba) and Japanese fried noodle (teppan-yaki soba) with levels up to 67 mg/kg and 84 mg/kg respectively. Similar levels were found in most of the food items in the Asian delicacies food group, which included Chinese dim sum and other deep-fried products. Higher levels were detected in deep-fried taro meat dumpling at 190 mg/kg and Chinese fried fritters with range 95 to 170 mg/kg.  On the other hand, staple food of steamed rice, soup noodles and congee were not found to contain appreciable amount of acrylamide.

20. Higher acrylamide levels up to above 1000 mg/kg were found in the two food groups biscuit related products and crisps. The ranges of acrylamide content in some of the subgroups were quite wide, probably due to the variation in food processing conditions. The highest levels were found in potato crisps with range 1500 to 1700 mg/kg. Apart from banana crisp (770 mg/kg) and taro crisp (320 mg/kg), the acrylamide levels in other fruit/vegetable-based crisps were quite low, ranging from less than 3 to 86 mg/kg. The acrylamide levels in rye flour-based crisps (440 mg/kg) were considerably lower than those in the potato ones, followed by corn-based (65 to 230 mg/kg) and wheat flour-based crisps (61 to 200 mg/kg), and then rice flour-based crisps (17 to 42 mg/kg). The products in these two food groups are crispy with low moisture content. Moreover, the crisps are in thin slice forms with large specific surface area. As the amount of acrylamide was measured per unit weight of food and the acrylamide would be formed mainly on the food surface during heating, these two factors of low moisture content and large specific surface area would contribute to the generally higher acrylamide level.

21. In general, the acrylamide level in processed meat and seafood products was very low, less than 3 mg/kg. The exception was grilled fish slice in Indonesian style with acrylamide at a level of 93 mg/kg. This might require further investigation as to the ingredients and processing conditions of the food product.

22. The results for potato crisps, corn crisps, potato chips and batter-based products were within the ranges reported by some European countries and the USA in the FAO/WHO consultation meeting in June 2002. [5]  For the case of Asian foods, the results for spring roll, rice cracker and battered fried vegetables (tempura) were comparable to those reported elsewhere. [7]

Estimation of dietary exposure

23. Dietary exposure to acrylamide in the local population was estimated by combining the results of the present study and data from the Hong Kong Adult Dietary Survey 1995 [8] and the Food Consumption Survey in Secondary School Student 2000 [9] .  The result revealed that dietary exposure to acrylamide of an average citizen in Hong Kong is about 0.3 µg/kg body weight /day while that for an average secondary school student is about 0.4 µg/kg body weight /day.  Both of them fell within the lower end of the range of dietary intake of acrylamide in the western diet (i.e. 0.3 to 0.8 µg/kg body weight /day) as estimated by the WHO at the expert consultation meeting in June 2002

CONCLUSIONS AND RECOMMENDATIONS

24. Acrylamide was found present in heated carbohydrate-rich foods such as those prepared by grilling, roasting, baking, frying and deep-frying. The levels varied according to the food material and processing conditions. The study on Asian indigenous foods available in Hong Kong showed that the levels of acrylamide in the commonly consumed foods such as rice, noodles, bakery and batter-based products were in general low, while higher levels were present in snack foods such as biscuits, chips and crisps.  Local staple foods of steamed rice, soup noodles and congee were not found to contain appreciable amount of acrylamide.  Dietary exposure to acrylamide in the local population is on the low side when compared with dietary intake of acrylamide in the western diet.

25. At present, the data on acrylamide are not sufficient to warrant changes in basic dietary advice on healthy eating, i.e., have a balanced and varied diet, eat more fruits and vegetables, and should moderate consumption of fried and fatty foods.

26. To minimize the risk of acrylamide in food, 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.

REFERENCES

[1] The Commission of European Union. The International Chemical Safety Cards: Acrylamide - ICSC: 0091. 2000 Apr. [cited 2002 Nov 20]. Available from : URL: http://www.inchem.org/documents/icsc/icsc/eics0091.htm

[2] WHO.  Guidelines for drinking-water quality. 2nd ed. Geneva:WHO; 1993.

[3] WHO.  Acrylamide. Health and Safety Guide No. 45 Geneva: WHO; 1991. [cited 2002 Nov 20]. Available from: URL: http://www.inchem.org/documents/hsg/hsg/hsg045.htm

[4] European Commission. Risk Assessment of Acrylamide. 2000 Oct. [cited 2002 Nov 20]. Available from: URL:http://ecb.jrc.it/Documents/Existing-Chemicals/RISK_ASSESSMENT/DRAFT/R011_0010env_hh.pdf

[5] WHO. Health Implications of Acrylamide in Food: Report of a joint FAO/WHO consultation, WHO Headquarters, Geneva, Switerland, 25-27 June 2002.  Geneva: WHO; 2002.

[6] European Commission. Opinion of the Scientific Committee on Food on new findings regarding the presence of acrylamide in food.  Belgium: European Commission; 2002 [cited 2002 Nov 20]. Available from: URL: http://europa.eu.int/comm/food/fs/sc/scf/out131_en.pdf

[7] Ono H, Chuda Y, Ohnishi-kameyama M, Yada H, Ishizaka M, Kobayashi H, et al.  Analysis of acrylamide by LC-MS/MS and GC-MS in processed Japanese foods.  Food Additives and Contaminants 2003; 20:215 - 20.

[8] Leung S, Ho S, Woo J, Lam TH, Janus ED.  Hong Kong Adult Dietary Sruvey 1995.  Hong Kong: Chinese University of Hong Kong and University of Hong Kong; 1995.

[9] FEHD.  Food Consumption Survey 2000.  Hong Kong: FEHD; 2001.

Annex I : Food Groups for acrylamide analysis

Annex II : Levels of acrylamide in various food groups

* 1/2 LOD and 1/2(LOD+ LOQ) were assigned to non-detects and results below quantification respectively for the calculation of median and mean levels

^† Composite sample,

^‡ Single sample .