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Food Additives & Contaminants: Part A Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfac20
Dietary exposure of Hong Kong adults to acrylamide: results of the first Hong Kong Total Diet Study a
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Waiky W.K. Wong , Stephen W.C. Chung , Chi-ho Lam , Y.Y. Ho & Ying Xiao
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Risk Assessment Section, Food and Environmental Hygiene Department, Centre for Food Safety, Hong Kong, China b
Food Research Laboratory, Food and Environmental Hygiene Department, Centre for Food Safety, Hong Kong, China Accepted author version posted online: 25 Feb 2014.Published online: 10 Apr 2014.
Click for updates To cite this article: Waiky W.K. Wong, Stephen W.C. Chung, Chi-ho Lam, Y.Y. Ho & Ying Xiao (2014) Dietary exposure of Hong Kong adults to acrylamide: results of the first Hong Kong Total Diet Study, Food Additives & Contaminants: Part A, 31:5, 799-805, DOI: 10.1080/19440049.2014.898189 To link to this article: http://dx.doi.org/10.1080/19440049.2014.898189
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Food Additives & Contaminants: Part A, 2014 Vol. 31, No. 5, 799–805, http://dx.doi.org/10.1080/19440049.2014.898189
Dietary exposure of Hong Kong adults to acrylamide: results of the first Hong Kong Total Diet Study Waiky W.K. Wonga, Stephen W.C. Chungb, Chi-ho Lamb, Y.Y. Hoa and Ying Xiaoa* a
Risk Assessment Section, Food and Environmental Hygiene Department, Centre for Food Safety, Hong Kong, China; bFood Research Laboratory, Food and Environmental Hygiene Department, Centre for Food Safety, Hong Kong, China
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(Received 8 January 2014; accepted 21 February 2014) Acrylamide is a processing contaminant in food formed during cooking at high temperature, such as frying and baking. To assess the associated health risk of the Hong Kong population, the dietary exposure of Hong Kong adults to acrylamide was estimated in the first Hong Kong Total Diet Study (TDS), where food samples were collected and prepared “as consumed”. A total of 532 composite food samples were analysed for acrylamide using LC-MS/MS. Dietary exposures were estimated by combining the analytical results with the food consumption data of the Hong Kong adults. The mean and 95th percentile exposures to acrylamide of the Hong Kong population were 0.213 and 0.538 μg kg−1 body weight (bw) day−1, respectively, and their margins of exposure (MOEs) were all below 10 000. The main dietary source of acrylamide was “Vegetables and their products” (52.4% of the total exposure), particularly stir-fried vegetables (44.9%), followed by “Cereals and their products” (14.7%) and “Mixed dishes” (9.43%). The study findings suggest that the relatively low figures for MOE for a genotoxic carcinogen may indicate human health concern of the Hong Kong population. Efforts should continue to be made in the interest of reducing acrylamide levels in food locally. Keywords: acrylamide; fried vegetables; margin of exposure (MOE); total diet study
Introduction Acrylamide is an industrial chemical that has been used since the mid-1950s in the production of polyacrylamide, which has multiple applications in chemical and manufacturing industries, e.g. as a flocculant for clarifying drinking water (FAO/WHO 2011). It was first reported by Swedish researchers in 2002 as being formed in a variety of baked and fried foods cooked at high temperature (Mottram et al. 2002; Tareke et al. 2002; WHO 2002). Since then, similar findings have been reported by numerous countries that acrylamide is formed primarily in carbohydrate-rich foods prepared or cooked at high temperature (FAO/WHO 2011). Acrylamide is formed where foods are cooked or processed in high temperature (usually > 120°C), mainly via Maillard reactions. Upon heating, the free amino acid asparagine in food, the most important precursor, reacts with reducing sugars or other carbonyl compounds to form acrylamide (WHO 2006; FAO/WHO 2011). Other formation mechanisms have also been identified, e.g. formation through pyrolysis of the wheat protein gluten or via enzymatic decarboxylation of asparagine in raw potatoes, but these routes may be of minor importance (FAO/WHO 2011). In contrast, only trace amounts of acrylamide will be formed by boiling (WHO 2006). Potato crisps, French fries, biscuits, crisp bread and crackers were reported to contain acrylamide in significant levels (up to the “mg kg−1” *Corresponding author. Email: [email protected] © 2014 Taylor & Francis
level) in many countries (FAO/WHO 2011). Vegetables other than potatoes cooked in high temperature such as baking, grilling, roasting and pan-frying were also reported to contain acrylamide (up to the “μg kg−1” level) in some overseas surveys and researches (Takatsuki et al. 2004; Şenyuva & Gökmen 2005; FAO/WHO 2011). Acrylamide is a genotoxic carcinogen and may also cause toxic effects on the nervous system, and adverse reproductive and developmental effects in experimental animals. However, epidemiological studies do not provide any consistent evidence to show a positive correlation between the level of dietary exposure to acrylamide and the incidence of cancer in humans (FAO/WHO 2011). JECFA evaluated the safety of acrylamide for the first time in 2005 and re-evaluated it in 2010. It considered it appropriate to use the benchmark dose lower confidence limit for a 10% extra risk of tumours (BMDL10) in animals for assessing the risk of acrylamide exposure. The end-points in mice and rats with the lower BMDL10, i.e. Harderian gland tumours in male mice (0.18 mg kg−1 body weight (bw) day−1) and mammary tumours in female rats (0.31 mg kg−1 bw day−1), were used for determining the margin of exposure (MOE) (WHO 2006; FAO/WHO 2011). MOE is defined as the ratio of BMDL10 from the animal study to the estimated dietary exposure to acrylamide of the population, and it can provide an indication of the health concern level without actually quantifying the
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risk. For genotoxic carcinogens, an MOE exceeding 10 000, based on a BMDL10 from the animal study, would be of low concern from a public health point of view (CAC 2012). The Centre for Food Safety (CFS), the food safety control authority of Hong Kong Special Administrative Region Government, started to conduct its first Hong Kong Total Diet Study (TDS) in 2010, aiming to provide the dietary exposure estimates to various contaminants and nutrients of the Hong Kong people and various age–gender subgroups. TDS has been recognised internationally as one of the most cost-effective ways to estimate the dietary exposures to food chemicals or nutrients (WHO 2005). It focuses on substances in the whole diet where foods are prepared prior to analysis, and thus a more realistic dietary exposure assessment of substances actually ingested by the population can be conducted. The first Hong Kong TDS determined the contents of acrylamide in food as consumed and estimated the dietary exposures of the Hong Kong population to assess the associated health risk of the population.
occurrence in food (i.e. acrylamide is formed in food mainly through high temperature processing). A total of 532 composite samples were used for testing. Chemical analysis of acrylamide Laboratory analysis of acrylamide was conducted by the Food Research Laboratory (FRL) of the CFS. The analytical method was described by Wenzl et al. (2009). In brief, 2 g of sample portion were extracted with water and defatted by n-hexane. The sample extract was then cleaned up by two SPEs. The analytical quantification of acrylamide was performed by LC-MS/MS (Agilent 1100 LC; Santa Clara, CA, USA)–API4000 (Framingham, MA, USA). d3-Acrylamide was used as an internal reference for the analysis. LOD and LOQ were 1 and 3 μg kg−1 in food and 0.03 and 0.1 μg kg−1 in water, respectively. Analytical quality assurance
The latest food consumption data of Hong Kong population were taken from the Hong Kong population-based Food Consumption Survey (FCS) conducted by the CFS in 2005–07 (FEHD 2010a). In the FCS, 5008 Hong Kong adults aged 20–84 years were invited through quota sampling by gender and age groups and completed two nonconsecutive 24-h dietary intake questionnaires.
The test method was validated by single-laboratory validation against certified reference materials, ERM BD272 (Crispbread), ERM BD273 (Toast bread), ERM BD274 (Rusk) and KRISS 108-10-003 (Potato chip). Average recoveries ranged between 92% and 98% with RSD < 5%. LOQ was established as the lowest quantifiable concentration tested, for which recovery and precision were 104% and 4.7% RSD (n = 10), respectively. The proficiency test, FAPAS round 3030, was participated and the results were found to be satisfactory. The accuracy and precision of the methods were monitored by spiked recovery experiments of duplicate real sample spikes. Results of spiked recoveries were felt within the range of 102% (RSD = 5.9%).
Food sampling and preparation
Dietary exposure estimates
A total of 150 commonly consumed food items were selected for the study, based on the food consumption pattern of the Hong Kong population obtained from the FCS (FEHD 2010a). Three samples of each TDS food item were collected and prepared on each of the four occasions from March 2010 to February 2011. The samples were purchased from a range of retail outlets in different parts of Hong Kong, based on the buying habits of the majority of the Hong Kong population. They were then prepared as food normally consumed, in a manner consistent with local cultural habits, and were homogenised individually. The three prepared samples of the same food item were combined into a composite sample. A total of 1800 samples were collected and combined into 600 composite samples for chemical analysis. The prepared samples were kept at – 18°C prior to laboratory analysis (FEHD 2011). Among the 150 TDS food items, 133 of them (excluding 17 fruit items which were mainly fresh fruits) were selected for testing acrylamide with reference to the
The FCS results revealed that over 1400 food items were being consumed by the Hong Kong population (FEHD 2010a). In order to cover the whole diet of the Hong Kong population, a food mapping process was carried out by mapping the TDS food items with food items captured by FCS. The mean levels of the TDS food items were assigned to the mapped FCS food items with an application of conversion factors taking reference to the differences of water content (FEHD 2011). To cite an example, celery in TDS food was mapped to celery and other stalk and stem vegetables in the FCS. As a result, over 99% of the average diet of the Hong Kong people was covered in the dietary exposure estimation after food mapping. The dietary exposure of individual respondent was then estimated by multiplying the consumption amounts of the mapped FCS food items consumed by the respondent and their assigned levels individually and then summing up all together and finally dividing by the respondent’s body weight. A weighting based on the
Materials and methods Food consumption data
Food Additives & Contaminants: Part A population distribution by age and gender in the 2006 Population By-census was applied to adjust for bias arising from the age–gender quotas (FEHD 2010a, 2011). The mean and 95th percentile exposure levels among the FCS respondents after weighting by age–gender were used to represent the dietary exposures of the average and the high consumer of the Hong Kong population, respectively. Dietary exposure estimation was performed with the aid of an in-house-developed web-based computer system, Exposure Assessment System (named EASY), that takes food mapping and weighting of data into consideration.
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Results and discussion A total of 532 composite samples on four occasions were analysed for acrylamide. Acrylamide was detected in nearly half of the composite samples (47%). The nondetected results were treated according to the recommendation of WHO on the evaluation of low-level contamination of food in the treatment for those non-detected results (WHO 1995). All non-detected results were assigned with levels at half the LOD for expressing the acrylamide contents and estimating the dietary exposures. Table 1 shows the concentrations of acrylamide in different food groups. The group “Snack foods” was found to contain the highest acrylamide level (mean = 680 μg kg−1), followed by the groups “Vegetables and their products”
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(mean = 53 μg kg−1) and “Legumes, nuts and seeds and their products” (mean = 40 μg kg−1). On the other hand, in the majority (95%) of samples of the group “Fish and seafood and their products”, and all samples of the groups “Eggs and their products” and “Beverages, alcoholic”, acrylamide was not detected. Among the TDS food items, a relatively high level of acrylamide was detected in potato chips (mean = 680 μg kg−1, range = 430–1100 μg kg−1) and fried potato (mean = 390 μg kg−1, range = 290– 490 μg kg−1). The levels detected were similar to those reported in other places (mean = 399–1202 μg kg−1 for potato chips and 159–963 μg kg−1 for fried potato) (FAO/ WHO 2011) and previous local study (mean = 788 μg kg−1 for potato chips and 382 μg kg−1 for fried potato) (FEHD 2010b). Apart from fried potato products, some stir-fried vegetables (zucchini, garlic, onion, sweet pepper and water spinach) were found to contain relatively high level of acrylamide (ranging from 140 to 360 μg kg−1) and their levels also varied among vegetables of the same kinds. In contrast, only low levels of acrylamide (< 10 μg kg−1) were found in some kinds of stir-fried vegetables such as Chinese spinach, watercress, spinach and Chinese lettuce. Table 2 showed the acrylamide contents among the 22 stir-fried vegetable items. On the other hand, acrylamide was not detected in eight non-fried vegetable items (i.e. fresh, boiled or steamed).
Table 1. Acrylamide contents (μg kg−1) in food groups of the first Hong Kong Total Diet Study. Food group Snack foods Vegetables and their products Legumes, nuts and seeds and their products Cereals and their products Sugars and confectionery Mixed dishes Beverages, non-alcoholic Meat, poultry and game and their products Condiments, sauces and herbs Dairy and its products Fish and seafood and their products Fats and oils Eggs and their products Beverages, alcoholic Total
Consumption (g/person day−1)a
Number of composite samples
Percentage of composite samples < LOD
1 177 18
4 140 24
0 31 50
680 53 40
[430–1100] [n.d.–490] [n.d.–250]
491 5 222 1625 113
76 8 48 40 48
30 50 42 63 63
26 19 5 2 2
[n.d.–220] [n.d.–53] [n.d.–43] [n.d.–27] [n.d.–14]
11
20
60
2
[n.d.–14]
38 71
20 76
75 95
1 1
[n.d.–8] [n.d.–3]
8 15 33
8 12 8 532
88 100 100 53
1 0.5 0.5
[n.d.–2] [n.d.] [n.d.]
Mean [range] (μg kg−1)b
Notes: aThe consumption amount in each food group was the weighted average consumption of the Hong Kong population extracted from the Hong Kong Population-based Food Consumption Survey (FSC), which was generated by combining the food items in that group after food mapping. Over 99% of food intake is covered. The consumption in food group “Fruits”, which was excluded from the dietary exposure assessment, was 147 g/person day−1. The weight of liquid food was assumed to be 1 g per 1 ml when calculating the consumption amount in each food group. The average body weight of the Hong Kong population is 61 kg. b As only 53% of results are below the LOD, half the LOD is used for all results less than the LOD when calculating the mean concentration. n.d., Not detected, i.e. results less than the LOD.
W.W.K. Wong et al. (FSANZ 2011; MAF 2011), it may not truly reflect the situation of domestic cooking and may introduce bias in the test results. Nevertheless, the results suggested that frying vegetables would induce the formation of acrylamide. Its formation may be affected by many factors such as the presence of asparagines and reducing sugars in the vegetables, and the frying temperature and time (Takatsuki et al. 2004; FAO/WHO 2011).
Table 2. Acrylamide contents in the 22 stir-fried vegetables of the first Hong Kong Total Diet Study.a Mean [range] (μg kg−1)c
Zucchini Garlic Onion Sweet pepper Water spinach Eggplant Chinese kale Sponge gourd Celery Leaf mustard Cabbage, Chinese flowering Cabbage, Chinese Tomato Broccoli Mung bean sprout Cabbage, Petiole Chinese Cabbage, European variety Bitter melon Chinese spinach Watercress Spinach Lettuce, Chinese
360 200 150 140 140 77 61 60 54 52 46 29 24 20 19 15 12 6 5 5 4 1
[160–480] [120–300] [62–240] [94–180] [50–310] [36–110] [22–140] [43–88] [24–110] [4–160] [34–70] [18–46] [3–39] [4–38] [1–35] [3–37] [7–19] [2–12] [1–10] [1–14] [n.d.–15] [n.d.–1]
Dietary exposure estimation The mean and 95th percentile exposures of the Hong Kong population to acrylamide were 0.213 and 0.538 μg kg−1 bw day−1, respectively. Further analysis of dietary exposures of the individual age–gender population subgroups was performed, and the results are shown in Figure 1. Overall, the dietary exposures of females were higher than those of males within most age groups, and the highest dietary exposure among all age–gender population subgroups was found in females aged 20–29 years (mean = 0.253 μg kg−1 bw day−1; 95th percentile = 0.710 μg kg−1 bw day−1). According to the FCS, females consumed vegetables and their products in an amount higher than males, but females have lighter body weights (mean consumption amount of vegetables and their products = 184 g/person day−1 (female) and 170 g/person day−1 (male); average body weight = 56 kg (female) and 67 kg (male)). Both factors may contribute to higher dietary exposures among female than male. The MOEs of acrylamide at mean and 95th percentile exposures of the Hong Kong population were determined from the two BMDL10 values for Harderian gland tumours in male mice (0.18 mg kg−1 bw day−1) and mammary tumours in female rats (0.31 mg kg−1 bw day−1). The MOEs at mean exposure were 847 and 1459, and at 95th percentile exposure were 334 and 576. All these MOEs, determined from the
Notes: aApart from the 22 stir-fried vegetables, eight non-fried vegetables, including carrot/radish, potato, cucumber, European lettuce, hairy gourd, pumpkin, wax gourd and spring onion, were not detected with acrylamide in all samples. b Each vegetable was composed of four composite samples and each composite sample comprised three individual samples. c Half the LOD is used for all results less than the LOD in calculating the mean concentration. Levels below 10 μg kg−1 were rounded to one significant figure and levels equal to or above 10 μg kg−1 were rounded to two significant figures. n.d., Not detected, i.e. results less than the LOD.
In this study, the vegetables were stir-fried without added cooking oil. Although it was consistent with the general food preparation procedures in the TDS conducted by overseas countries such as Australia and New Zealand 0.8
Mean
95th percentile
0.7 0.6 0.5 0.4 0.3 0.2 0.1 Fem ale 70– 84 Ma le 70– 84 Fem ale 20– 84 Ma le 20– 84 Fem ale
Ma le
69 60–
60–
69
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50– 59
ale
50– 59
ale
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49
Fem
ale
9M
Fem
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Fem
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29 20–
20– 29
30– 3
ale
0.0 le
Dietary Exposure (µg kg–1 bw day–1)
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Stir-fried vegetablesb
Fem
802
Age–gender Groups
Figure 1. Mean and 95th percentile dietary exposures to acrylamide of the individual age–gender groups of the Hong Kong population of the first Hong Kong Total Diet Study.
Food Additives & Contaminants: Part A Table 3. Mean dietary exposure (μg kg−1 bw day−1) of the Hong Kong population to acrylamide in food groups of the first Hong Kong Total Diet Study and their contribution of the total exposure.
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Food group
Dietary exposure (μg kg−1 bw day−1)a
Vegetables and their products Cereals and their products Mixed dishes Legumes, nuts and seeds and their products Beverages, non-alcoholic Snack foods Meat, poultry and game and their products Condiments, sauces and herbs Other six food groupsb Totalc
Percentage contribution of total exposure
0.111
52.4
0.0313 0.0200 0.0157
14.7 9.43 7.41
0.0148 0.00995 0.00417
6.94 4.68 1.96
0.00290
1.36
0.00226 0.213
1.06 100
Notes: aAs only 53% of results are below the LOD, half the LOD is used for all results less than the LOD in calculating the exposure estimates. b Other six food groups include “Beverages, alcoholic”, “Dairy products”, “Eggs and their products”, “Fats and oils”, “Fish and seafood and their products”, and “Sugars and confectionery”. c Figures may not add up to total due to rounding.
increase in cancer risk of animals, were below 10 000, which may indicate human health concern because of the relatively low figures for a genotoxic carcinogen. Table 3 shows the mean dietary exposures of the Hong Kong population to acrylamide in food groups and their contribution of the total exposure. The main dietary source of acrylamide was the group “Vegetables and their products” (52.4% of the total exposure), followed by the groups “Cereals and their products” (14.7%) and “Mixed dishes” (9.43%). Similar findings were also reported for mainland China that vegetables are the major food contributor (48.4%) to dietary acrylamide exposure (Zhou et al. 2013). In
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contrast, the major food contributors to acrylamide dietary exposure in other countries were reported to be French fries (10–60%), potato chips (10–22%), bread and rolls/toast (13– 34%), and pastry and sweet biscuits (or cookies) (10–15%) in most countries (FAO/WHO 2011). In the food group “Vegetables and their products”, stirfried vegetables amounted to 44.9% of the total exposure. Chinese flowering cabbage was the major contributor (16.2% of the total exposure), followed by water spinach (5.83%), zucchini (3.95%) and onion (3.38%). The high contribution to acrylamide exposure from vegetables and their products in this study is likely because most leafy vegetables were prepared by stir-frying which may incur the formation of acrylamide and also they are consumed in a large amount among the local population. Potato chips, fried potato, breakfast cereals and biscuits were also significant sources of exposure (3.35%, 7.17%, 2.34% and 5.35% of the total exposure respectively) due to the high acrylamide level found in these food items (mean = 680, 390, 160 and 150 μg kg−1 respectively). Some food items such as dried fruits may contain acrylamide that are not covered in the current study. It may lead to a slight underestimation of the dietary exposure to acrylamide. For instance, the additional exposure from dried fruits is estimated to be less than 0.3% of total exposure (mean level in dried fruits = 47 μg kg−1 (FAO/ WHO 2011) and its average consumption amount = 0.62 g/person day−1 (FEHD 2010a)). Moreover, potato chips was the only item in “Snack foods” and therefore the dietary exposure from the snack foods other than potato chips was estimated by mapping of the potato chips to other snack foods. It may introduce uncertainty to the dietary exposure estimates. Nevertheless, the snack foods were consumed in a low amount (1 g/person day−1) and therefore the dietary exposure assessment would not be affected significantly. The dietary exposures of the Hong Kong population to acrylamide were also compared with those reported for other places that are summarised in Table 4. The dietary exposure
Table 4. Comparison of dietary exposures of acrylamide. Dietary exposure of adult (μg kg−1 bw day−1) Places Hong Konga China (Zhou et al. 2013) UK (FSA 2005) Canada (HC 2012) Europe (EFSA 2011) USA (USFDA 2006b) France (Sirot et al. 2012) Ireland (FSAI 2011) New Zealand (MAF 2012) Notes: aData from the current study.
Mean 0.213 0.286 0.3 0.3–0.4 0.31–1.1 0.4 (age 2+) 0.43 0.59 0.84 (male 25+) 0.66 (female 25+)
95th or 97.5th percentile 0.537 (95th percentile) 0.490 (95th percentile) 0.6 (97.5th percentile) 0.58–2.3 (95th percentile) 1.02 (95th percentile) 1.75 (97.5th percentile) 1.39 (male 25+) (95th percentile) 1.15 (female 25+) (95th percentile)
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estimated in this study is around the lower end of the range of the exposure estimates obtained from other places. However, caution should be exercised in making any direct comparison of the data due to the difference in time the reported studies were carried out, the methods of collection of consumption data, the methods of contaminant analysis and the methods of treating results below detection limits. Subsequent to the reports on the formation of acrylamide in food, international bodies and many national authorities have made efforts to explore ways to reduce the acrylamide in foods. National authorities, such as the USFDA, Health Canada and EFSA, are also implementing monitoring programme on the acrylamide levels in food (USFDA 2006a; EFSA 2012; HC 2012). In 2009, the Codex Alimentarius Commission (CAC) adopted a Code of Practice for Reduction of Acrylamide in Foods, aiming to provide national and local authorities, manufacturers and other relevant bodies with guidance to prevent and reduce formation of acrylamide in potato products and cereal products (CAC 2009). JECFA mentioned in its 2010 evaluation that the mitigation after 2003 was reported mainly for food types with comparably high acrylamide levels or single products with acrylamide levels in the high end within their food types and thus the exposure for some individuals or population subgroups might significantly be reduced. However, it would have little effect on the dietary exposure for the general population in most countries. JECFA recommended the pursuit of further efforts on developing and implementing mitigation methods for acrylamide in foods as a subject of major importance for dietary exposure (FAO/WHO 2011).
Conclusion In summary, the estimated mean dietary exposure of the Hong Kong population to acrylamide was 0.213 μg kg−1 bw day−1 and its 95th percentile was 0.538 μg kg−1 bw day−1 (their MOEs were all below 10 000). It may indicate human health concern because of the relatively low figures for a genotoxic carcinogen. Frying vegetables can induce the formation of acrylamide and fried vegetables were found to be the major contributor of the exposure due to the relatively high acrylamide level in most stir-fried vegetables and the high consumption amount. Besides, fried potato, potato chips, biscuits and breakfast cereals were also significant sources of exposure due to the high acrylamide level found in these food items. Efforts should continue to be made in the interest of reducing acrylamide levels in food locally.
References [CAC] Codex Alimentarius Commission. 2009. Code of practice for the reduction of acrylamide in food (CAC/RCP 67–2009) [Internet]. [cited 2013 Nov 4]. Available from: http://www.
codexalimentarius.org/input/download/standards/11258/CXP_ 067e.pdf [CAC] Codex Alimentarius Commission. 2012. Guidance for risk management options in light of different risk assessment outcomes. Appendix XIII in the report of the sixth session of the Codex Committee on Contaminants in foods, Maastricht, the Netherlands; 2012 Mar 26–30 [Internet]. [cited 2013 Nov 4]. Available from: http://www.codexalimentarius.net/down load/report/776/REP12_CFe.pdf [EFSA] European Food Safety Authority. 2011. Results on acrylamide levels in food from monitoring years 2007–2009 and exposure assessment. EFSA J. 9:2133 [Internet]. [cited 2013 Nov 19]. Available from: http://www.efsa.europa.eu/en/efsajournal/doc/2133.pdf [EFSA] European Food Safety Authority. 2012. Update on acrylamide levels in food from monitoring years 2007–2010. EFSA J. 10:2938 [Internet]. [cited 2013 Nov 19]. Available from: http://www.efsa.europa.eu/en/efsajournal/doc/2938.pdf FAO/WHO. 2011. WHO food additives series: 63/FAO JECFA monographs 8–safety evaluation of certain contaminants in food, prepared by the seventy-second meeting of the Joint FAO/WHO Expert Committee on Food Additives (JECFA) [Internet]. [cited 2013 Nov 19]. Available from: http://whqlib doc.who.int/publications/2011/9789241660631_eng.pdf [FEHD] Food and Environmental Hygiene Department. 2010a. Hong Kong population-based food consumption survey 2005–2007 final report [Internet]. Hong Kong: FEHD. [cited 2013 Nov 19]. Available from: http://www.cfs.gov.hk/english/ programme/programme_firm/files/FCS_final_report.pdf [FEHD] Food and Environmental Hygiene Department. 2010b. Dietary exposure to acrylamide of Hong Kong adult population [Internet]. Hong Kong: FEHD. [cited 2013 Nov 19]. Available from: http://www.cfs.gov.hk/english/programme/ programme_rafs/files/programme_rafs_fc_01_25.pdf [FEHD Food and Environmental Hygiene Department. 2011. The first Hong Kong total diet study: methodology [Internet]. Hong Kong: FEHD. [cited 2013 Nov 19]. Available from: http://www.cfs.gov.hk/english/programme/ programme_firm/files/1st_HKTDS_Report_e.pdf. [FSAI] Food Safety Authority of Ireland. 2011. Report on a total diet study carried out by the Food Safety Authority of Ireland in the period 2001–2005 [Internet]. Ireland: FSAI. [cited 2013 Nov 19]. Available from: http://www.fsai.ie/reportonatotaldietstudycarriedoutbythefood safetyauthorityofirelandintheperiod2001-2005.html [FSA] Food Standard Agency of the UK. 2005. Food survey information sheet no. 71/05: analysis of total diet study samples for acrylamide [Internet]. [cited 2013 Nov 19]. Available from: http://www.food.gov.uk/multimedia/pdfs/fsis712005.pdf [FSANZ] Food Standards Australia New Zealand. 2011. Appendices of the 23rd Australian total diet study [Internet]. Australia: FSANZ. [cited 2013 Nov 19]. Available from: http://www.foodstandards.gov.au/publications/documents/Appendices.doc [HC] Health Canada. 2012. Health Canada’s revised exposure assessment of acrylamide in food. [Internet]. [cited 2013 Nov 19]. Available from: http://www.hc-sc.gc.ca/fn-an/securit/ chem-chim/food-aliment/acrylamide/rev-eval-exposure-exposi tion-eng.php [MAF] Ministry of Agriculture and Forestry. 2011. 2009 New Zealand total diet study [Internet]. New Zealand: MAF. [cited 2013 Nov 19]. Available from: http://www.foodsaf ety.govt.nz/elibrary/industry/total-diet-study.pdf [MAF] Ministry of Agriculture and Forestry. 2012. Acrylamide in New Zealand food and updated exposure assessment [Internet].
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Food Additives & Contaminants: Part A MAF Technical Paper No: 2011/19. New Zealand: MAF. [cited 2013 Nov 19]. Available from: http://www.foodsafety.govt.nz/ elibrary/industry/acrylamide-in-nz-food-updated-exposure-ass essment.pdf Mottram DS, Wedzicha BL, Dodson AT. 2002. Food chemistry: acrylamide is formed in the Maillard reaction. Nature. 419:448–449. Şenyuva Hz, Gökmen V. 2005. Survey of acrylamide in Turkish foods by an in-house validated LC-MS method. Food Addit Contam. 22:204–209. Sirot V, Hommet F, Tard A, Leblanc Jean- C. 2012. Dietary acrylamide exposure of the French population: results of the second French total diet study. Food Chem Toxicol. 50:889–894. Takatsuki S, Nemoto S, Sasaki K, Maitani T. 2004. Production of acrylamide in agricultural products by cooking. [in Japanese] Food Hyg Safety Sci. 45:44–48. Tareke E, Rydberg P, Karlsson P, Eriksson S, Törnqvist M. 2002. Analysis of acrylamide, a carcinogen formed in heated foodstuffs. J Agric Food Chem. 50:4998–5006. [USFDA] U.S. Food and Drugs Administration. 2006a. Survey data on acrylamide in food: individual food products [Internet]. [cited 2013 Nov 19]. Available from: http://www.fda.gov/ Food/FoodborneIllnessContaminants/ChemicalCont aminants/ ucm053549.htm [USFDA] U.S. Food and Drugs Administration. 2006b. The 2006 exposure assessment for acrylamide [Internet]. [cited 2013 Nov 19]. Available from: http://www.fda.gov/downloads/Food/ FoodSafety/FoodContaminantsAdulteration/ChemicalContam inants/Acrylamide/UCM197239.pdf Wenzl T, Szilagyi S, Rosén J, Karasek L. 2009. Validation by collaborative trial of an isotope dilution liquid chromato-
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Food Additives & Contaminants: Part A Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfac20
Dietary exposure of Hong Kong adults to acrylamide: results of the first Hong Kong Total Diet Study a
b
b
a
Waiky W.K. Wong , Stephen W.C. Chung , Chi-ho Lam , Y.Y. Ho & Ying Xiao
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a
Risk Assessment Section, Food and Environmental Hygiene Department, Centre for Food Safety, Hong Kong, China b
Food Research Laboratory, Food and Environmental Hygiene Department, Centre for Food Safety, Hong Kong, China Accepted author version posted online: 25 Feb 2014.Published online: 10 Apr 2014.
Click for updates To cite this article: Waiky W.K. Wong, Stephen W.C. Chung, Chi-ho Lam, Y.Y. Ho & Ying Xiao (2014) Dietary exposure of Hong Kong adults to acrylamide: results of the first Hong Kong Total Diet Study, Food Additives & Contaminants: Part A, 31:5, 799-805, DOI: 10.1080/19440049.2014.898189 To link to this article: http://dx.doi.org/10.1080/19440049.2014.898189
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Food Additives & Contaminants: Part A, 2014 Vol. 31, No. 5, 799–805, http://dx.doi.org/10.1080/19440049.2014.898189
Dietary exposure of Hong Kong adults to acrylamide: results of the first Hong Kong Total Diet Study Waiky W.K. Wonga, Stephen W.C. Chungb, Chi-ho Lamb, Y.Y. Hoa and Ying Xiaoa* a
Risk Assessment Section, Food and Environmental Hygiene Department, Centre for Food Safety, Hong Kong, China; bFood Research Laboratory, Food and Environmental Hygiene Department, Centre for Food Safety, Hong Kong, China
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(Received 8 January 2014; accepted 21 February 2014) Acrylamide is a processing contaminant in food formed during cooking at high temperature, such as frying and baking. To assess the associated health risk of the Hong Kong population, the dietary exposure of Hong Kong adults to acrylamide was estimated in the first Hong Kong Total Diet Study (TDS), where food samples were collected and prepared “as consumed”. A total of 532 composite food samples were analysed for acrylamide using LC-MS/MS. Dietary exposures were estimated by combining the analytical results with the food consumption data of the Hong Kong adults. The mean and 95th percentile exposures to acrylamide of the Hong Kong population were 0.213 and 0.538 μg kg−1 body weight (bw) day−1, respectively, and their margins of exposure (MOEs) were all below 10 000. The main dietary source of acrylamide was “Vegetables and their products” (52.4% of the total exposure), particularly stir-fried vegetables (44.9%), followed by “Cereals and their products” (14.7%) and “Mixed dishes” (9.43%). The study findings suggest that the relatively low figures for MOE for a genotoxic carcinogen may indicate human health concern of the Hong Kong population. Efforts should continue to be made in the interest of reducing acrylamide levels in food locally. Keywords: acrylamide; fried vegetables; margin of exposure (MOE); total diet study
Introduction Acrylamide is an industrial chemical that has been used since the mid-1950s in the production of polyacrylamide, which has multiple applications in chemical and manufacturing industries, e.g. as a flocculant for clarifying drinking water (FAO/WHO 2011). It was first reported by Swedish researchers in 2002 as being formed in a variety of baked and fried foods cooked at high temperature (Mottram et al. 2002; Tareke et al. 2002; WHO 2002). Since then, similar findings have been reported by numerous countries that acrylamide is formed primarily in carbohydrate-rich foods prepared or cooked at high temperature (FAO/WHO 2011). Acrylamide is formed where foods are cooked or processed in high temperature (usually > 120°C), mainly via Maillard reactions. Upon heating, the free amino acid asparagine in food, the most important precursor, reacts with reducing sugars or other carbonyl compounds to form acrylamide (WHO 2006; FAO/WHO 2011). Other formation mechanisms have also been identified, e.g. formation through pyrolysis of the wheat protein gluten or via enzymatic decarboxylation of asparagine in raw potatoes, but these routes may be of minor importance (FAO/WHO 2011). In contrast, only trace amounts of acrylamide will be formed by boiling (WHO 2006). Potato crisps, French fries, biscuits, crisp bread and crackers were reported to contain acrylamide in significant levels (up to the “mg kg−1” *Corresponding author. Email: [email protected] © 2014 Taylor & Francis
level) in many countries (FAO/WHO 2011). Vegetables other than potatoes cooked in high temperature such as baking, grilling, roasting and pan-frying were also reported to contain acrylamide (up to the “μg kg−1” level) in some overseas surveys and researches (Takatsuki et al. 2004; Şenyuva & Gökmen 2005; FAO/WHO 2011). Acrylamide is a genotoxic carcinogen and may also cause toxic effects on the nervous system, and adverse reproductive and developmental effects in experimental animals. However, epidemiological studies do not provide any consistent evidence to show a positive correlation between the level of dietary exposure to acrylamide and the incidence of cancer in humans (FAO/WHO 2011). JECFA evaluated the safety of acrylamide for the first time in 2005 and re-evaluated it in 2010. It considered it appropriate to use the benchmark dose lower confidence limit for a 10% extra risk of tumours (BMDL10) in animals for assessing the risk of acrylamide exposure. The end-points in mice and rats with the lower BMDL10, i.e. Harderian gland tumours in male mice (0.18 mg kg−1 body weight (bw) day−1) and mammary tumours in female rats (0.31 mg kg−1 bw day−1), were used for determining the margin of exposure (MOE) (WHO 2006; FAO/WHO 2011). MOE is defined as the ratio of BMDL10 from the animal study to the estimated dietary exposure to acrylamide of the population, and it can provide an indication of the health concern level without actually quantifying the
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risk. For genotoxic carcinogens, an MOE exceeding 10 000, based on a BMDL10 from the animal study, would be of low concern from a public health point of view (CAC 2012). The Centre for Food Safety (CFS), the food safety control authority of Hong Kong Special Administrative Region Government, started to conduct its first Hong Kong Total Diet Study (TDS) in 2010, aiming to provide the dietary exposure estimates to various contaminants and nutrients of the Hong Kong people and various age–gender subgroups. TDS has been recognised internationally as one of the most cost-effective ways to estimate the dietary exposures to food chemicals or nutrients (WHO 2005). It focuses on substances in the whole diet where foods are prepared prior to analysis, and thus a more realistic dietary exposure assessment of substances actually ingested by the population can be conducted. The first Hong Kong TDS determined the contents of acrylamide in food as consumed and estimated the dietary exposures of the Hong Kong population to assess the associated health risk of the population.
occurrence in food (i.e. acrylamide is formed in food mainly through high temperature processing). A total of 532 composite samples were used for testing. Chemical analysis of acrylamide Laboratory analysis of acrylamide was conducted by the Food Research Laboratory (FRL) of the CFS. The analytical method was described by Wenzl et al. (2009). In brief, 2 g of sample portion were extracted with water and defatted by n-hexane. The sample extract was then cleaned up by two SPEs. The analytical quantification of acrylamide was performed by LC-MS/MS (Agilent 1100 LC; Santa Clara, CA, USA)–API4000 (Framingham, MA, USA). d3-Acrylamide was used as an internal reference for the analysis. LOD and LOQ were 1 and 3 μg kg−1 in food and 0.03 and 0.1 μg kg−1 in water, respectively. Analytical quality assurance
The latest food consumption data of Hong Kong population were taken from the Hong Kong population-based Food Consumption Survey (FCS) conducted by the CFS in 2005–07 (FEHD 2010a). In the FCS, 5008 Hong Kong adults aged 20–84 years were invited through quota sampling by gender and age groups and completed two nonconsecutive 24-h dietary intake questionnaires.
The test method was validated by single-laboratory validation against certified reference materials, ERM BD272 (Crispbread), ERM BD273 (Toast bread), ERM BD274 (Rusk) and KRISS 108-10-003 (Potato chip). Average recoveries ranged between 92% and 98% with RSD < 5%. LOQ was established as the lowest quantifiable concentration tested, for which recovery and precision were 104% and 4.7% RSD (n = 10), respectively. The proficiency test, FAPAS round 3030, was participated and the results were found to be satisfactory. The accuracy and precision of the methods were monitored by spiked recovery experiments of duplicate real sample spikes. Results of spiked recoveries were felt within the range of 102% (RSD = 5.9%).
Food sampling and preparation
Dietary exposure estimates
A total of 150 commonly consumed food items were selected for the study, based on the food consumption pattern of the Hong Kong population obtained from the FCS (FEHD 2010a). Three samples of each TDS food item were collected and prepared on each of the four occasions from March 2010 to February 2011. The samples were purchased from a range of retail outlets in different parts of Hong Kong, based on the buying habits of the majority of the Hong Kong population. They were then prepared as food normally consumed, in a manner consistent with local cultural habits, and were homogenised individually. The three prepared samples of the same food item were combined into a composite sample. A total of 1800 samples were collected and combined into 600 composite samples for chemical analysis. The prepared samples were kept at – 18°C prior to laboratory analysis (FEHD 2011). Among the 150 TDS food items, 133 of them (excluding 17 fruit items which were mainly fresh fruits) were selected for testing acrylamide with reference to the
The FCS results revealed that over 1400 food items were being consumed by the Hong Kong population (FEHD 2010a). In order to cover the whole diet of the Hong Kong population, a food mapping process was carried out by mapping the TDS food items with food items captured by FCS. The mean levels of the TDS food items were assigned to the mapped FCS food items with an application of conversion factors taking reference to the differences of water content (FEHD 2011). To cite an example, celery in TDS food was mapped to celery and other stalk and stem vegetables in the FCS. As a result, over 99% of the average diet of the Hong Kong people was covered in the dietary exposure estimation after food mapping. The dietary exposure of individual respondent was then estimated by multiplying the consumption amounts of the mapped FCS food items consumed by the respondent and their assigned levels individually and then summing up all together and finally dividing by the respondent’s body weight. A weighting based on the
Materials and methods Food consumption data
Food Additives & Contaminants: Part A population distribution by age and gender in the 2006 Population By-census was applied to adjust for bias arising from the age–gender quotas (FEHD 2010a, 2011). The mean and 95th percentile exposure levels among the FCS respondents after weighting by age–gender were used to represent the dietary exposures of the average and the high consumer of the Hong Kong population, respectively. Dietary exposure estimation was performed with the aid of an in-house-developed web-based computer system, Exposure Assessment System (named EASY), that takes food mapping and weighting of data into consideration.
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Results and discussion A total of 532 composite samples on four occasions were analysed for acrylamide. Acrylamide was detected in nearly half of the composite samples (47%). The nondetected results were treated according to the recommendation of WHO on the evaluation of low-level contamination of food in the treatment for those non-detected results (WHO 1995). All non-detected results were assigned with levels at half the LOD for expressing the acrylamide contents and estimating the dietary exposures. Table 1 shows the concentrations of acrylamide in different food groups. The group “Snack foods” was found to contain the highest acrylamide level (mean = 680 μg kg−1), followed by the groups “Vegetables and their products”
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(mean = 53 μg kg−1) and “Legumes, nuts and seeds and their products” (mean = 40 μg kg−1). On the other hand, in the majority (95%) of samples of the group “Fish and seafood and their products”, and all samples of the groups “Eggs and their products” and “Beverages, alcoholic”, acrylamide was not detected. Among the TDS food items, a relatively high level of acrylamide was detected in potato chips (mean = 680 μg kg−1, range = 430–1100 μg kg−1) and fried potato (mean = 390 μg kg−1, range = 290– 490 μg kg−1). The levels detected were similar to those reported in other places (mean = 399–1202 μg kg−1 for potato chips and 159–963 μg kg−1 for fried potato) (FAO/ WHO 2011) and previous local study (mean = 788 μg kg−1 for potato chips and 382 μg kg−1 for fried potato) (FEHD 2010b). Apart from fried potato products, some stir-fried vegetables (zucchini, garlic, onion, sweet pepper and water spinach) were found to contain relatively high level of acrylamide (ranging from 140 to 360 μg kg−1) and their levels also varied among vegetables of the same kinds. In contrast, only low levels of acrylamide (< 10 μg kg−1) were found in some kinds of stir-fried vegetables such as Chinese spinach, watercress, spinach and Chinese lettuce. Table 2 showed the acrylamide contents among the 22 stir-fried vegetable items. On the other hand, acrylamide was not detected in eight non-fried vegetable items (i.e. fresh, boiled or steamed).
Table 1. Acrylamide contents (μg kg−1) in food groups of the first Hong Kong Total Diet Study. Food group Snack foods Vegetables and their products Legumes, nuts and seeds and their products Cereals and their products Sugars and confectionery Mixed dishes Beverages, non-alcoholic Meat, poultry and game and their products Condiments, sauces and herbs Dairy and its products Fish and seafood and their products Fats and oils Eggs and their products Beverages, alcoholic Total
Consumption (g/person day−1)a
Number of composite samples
Percentage of composite samples < LOD
1 177 18
4 140 24
0 31 50
680 53 40
[430–1100] [n.d.–490] [n.d.–250]
491 5 222 1625 113
76 8 48 40 48
30 50 42 63 63
26 19 5 2 2
[n.d.–220] [n.d.–53] [n.d.–43] [n.d.–27] [n.d.–14]
11
20
60
2
[n.d.–14]
38 71
20 76
75 95
1 1
[n.d.–8] [n.d.–3]
8 15 33
8 12 8 532
88 100 100 53
1 0.5 0.5
[n.d.–2] [n.d.] [n.d.]
Mean [range] (μg kg−1)b
Notes: aThe consumption amount in each food group was the weighted average consumption of the Hong Kong population extracted from the Hong Kong Population-based Food Consumption Survey (FSC), which was generated by combining the food items in that group after food mapping. Over 99% of food intake is covered. The consumption in food group “Fruits”, which was excluded from the dietary exposure assessment, was 147 g/person day−1. The weight of liquid food was assumed to be 1 g per 1 ml when calculating the consumption amount in each food group. The average body weight of the Hong Kong population is 61 kg. b As only 53% of results are below the LOD, half the LOD is used for all results less than the LOD when calculating the mean concentration. n.d., Not detected, i.e. results less than the LOD.
W.W.K. Wong et al. (FSANZ 2011; MAF 2011), it may not truly reflect the situation of domestic cooking and may introduce bias in the test results. Nevertheless, the results suggested that frying vegetables would induce the formation of acrylamide. Its formation may be affected by many factors such as the presence of asparagines and reducing sugars in the vegetables, and the frying temperature and time (Takatsuki et al. 2004; FAO/WHO 2011).
Table 2. Acrylamide contents in the 22 stir-fried vegetables of the first Hong Kong Total Diet Study.a Mean [range] (μg kg−1)c
Zucchini Garlic Onion Sweet pepper Water spinach Eggplant Chinese kale Sponge gourd Celery Leaf mustard Cabbage, Chinese flowering Cabbage, Chinese Tomato Broccoli Mung bean sprout Cabbage, Petiole Chinese Cabbage, European variety Bitter melon Chinese spinach Watercress Spinach Lettuce, Chinese
360 200 150 140 140 77 61 60 54 52 46 29 24 20 19 15 12 6 5 5 4 1
[160–480] [120–300] [62–240] [94–180] [50–310] [36–110] [22–140] [43–88] [24–110] [4–160] [34–70] [18–46] [3–39] [4–38] [1–35] [3–37] [7–19] [2–12] [1–10] [1–14] [n.d.–15] [n.d.–1]
Dietary exposure estimation The mean and 95th percentile exposures of the Hong Kong population to acrylamide were 0.213 and 0.538 μg kg−1 bw day−1, respectively. Further analysis of dietary exposures of the individual age–gender population subgroups was performed, and the results are shown in Figure 1. Overall, the dietary exposures of females were higher than those of males within most age groups, and the highest dietary exposure among all age–gender population subgroups was found in females aged 20–29 years (mean = 0.253 μg kg−1 bw day−1; 95th percentile = 0.710 μg kg−1 bw day−1). According to the FCS, females consumed vegetables and their products in an amount higher than males, but females have lighter body weights (mean consumption amount of vegetables and their products = 184 g/person day−1 (female) and 170 g/person day−1 (male); average body weight = 56 kg (female) and 67 kg (male)). Both factors may contribute to higher dietary exposures among female than male. The MOEs of acrylamide at mean and 95th percentile exposures of the Hong Kong population were determined from the two BMDL10 values for Harderian gland tumours in male mice (0.18 mg kg−1 bw day−1) and mammary tumours in female rats (0.31 mg kg−1 bw day−1). The MOEs at mean exposure were 847 and 1459, and at 95th percentile exposure were 334 and 576. All these MOEs, determined from the
Notes: aApart from the 22 stir-fried vegetables, eight non-fried vegetables, including carrot/radish, potato, cucumber, European lettuce, hairy gourd, pumpkin, wax gourd and spring onion, were not detected with acrylamide in all samples. b Each vegetable was composed of four composite samples and each composite sample comprised three individual samples. c Half the LOD is used for all results less than the LOD in calculating the mean concentration. Levels below 10 μg kg−1 were rounded to one significant figure and levels equal to or above 10 μg kg−1 were rounded to two significant figures. n.d., Not detected, i.e. results less than the LOD.
In this study, the vegetables were stir-fried without added cooking oil. Although it was consistent with the general food preparation procedures in the TDS conducted by overseas countries such as Australia and New Zealand 0.8
Mean
95th percentile
0.7 0.6 0.5 0.4 0.3 0.2 0.1 Fem ale 70– 84 Ma le 70– 84 Fem ale 20– 84 Ma le 20– 84 Fem ale
Ma le
69 60–
60–
69
ale
le Ma
50– 59
ale
50– 59
ale
40–
49
Fem
ale
9M
Fem
40– 4
ale
39 30–
9M
Fem
Ma
29 20–
20– 29
30– 3
ale
0.0 le
Dietary Exposure (µg kg–1 bw day–1)
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Stir-fried vegetablesb
Fem
802
Age–gender Groups
Figure 1. Mean and 95th percentile dietary exposures to acrylamide of the individual age–gender groups of the Hong Kong population of the first Hong Kong Total Diet Study.
Food Additives & Contaminants: Part A Table 3. Mean dietary exposure (μg kg−1 bw day−1) of the Hong Kong population to acrylamide in food groups of the first Hong Kong Total Diet Study and their contribution of the total exposure.
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Food group
Dietary exposure (μg kg−1 bw day−1)a
Vegetables and their products Cereals and their products Mixed dishes Legumes, nuts and seeds and their products Beverages, non-alcoholic Snack foods Meat, poultry and game and their products Condiments, sauces and herbs Other six food groupsb Totalc
Percentage contribution of total exposure
0.111
52.4
0.0313 0.0200 0.0157
14.7 9.43 7.41
0.0148 0.00995 0.00417
6.94 4.68 1.96
0.00290
1.36
0.00226 0.213
1.06 100
Notes: aAs only 53% of results are below the LOD, half the LOD is used for all results less than the LOD in calculating the exposure estimates. b Other six food groups include “Beverages, alcoholic”, “Dairy products”, “Eggs and their products”, “Fats and oils”, “Fish and seafood and their products”, and “Sugars and confectionery”. c Figures may not add up to total due to rounding.
increase in cancer risk of animals, were below 10 000, which may indicate human health concern because of the relatively low figures for a genotoxic carcinogen. Table 3 shows the mean dietary exposures of the Hong Kong population to acrylamide in food groups and their contribution of the total exposure. The main dietary source of acrylamide was the group “Vegetables and their products” (52.4% of the total exposure), followed by the groups “Cereals and their products” (14.7%) and “Mixed dishes” (9.43%). Similar findings were also reported for mainland China that vegetables are the major food contributor (48.4%) to dietary acrylamide exposure (Zhou et al. 2013). In
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contrast, the major food contributors to acrylamide dietary exposure in other countries were reported to be French fries (10–60%), potato chips (10–22%), bread and rolls/toast (13– 34%), and pastry and sweet biscuits (or cookies) (10–15%) in most countries (FAO/WHO 2011). In the food group “Vegetables and their products”, stirfried vegetables amounted to 44.9% of the total exposure. Chinese flowering cabbage was the major contributor (16.2% of the total exposure), followed by water spinach (5.83%), zucchini (3.95%) and onion (3.38%). The high contribution to acrylamide exposure from vegetables and their products in this study is likely because most leafy vegetables were prepared by stir-frying which may incur the formation of acrylamide and also they are consumed in a large amount among the local population. Potato chips, fried potato, breakfast cereals and biscuits were also significant sources of exposure (3.35%, 7.17%, 2.34% and 5.35% of the total exposure respectively) due to the high acrylamide level found in these food items (mean = 680, 390, 160 and 150 μg kg−1 respectively). Some food items such as dried fruits may contain acrylamide that are not covered in the current study. It may lead to a slight underestimation of the dietary exposure to acrylamide. For instance, the additional exposure from dried fruits is estimated to be less than 0.3% of total exposure (mean level in dried fruits = 47 μg kg−1 (FAO/ WHO 2011) and its average consumption amount = 0.62 g/person day−1 (FEHD 2010a)). Moreover, potato chips was the only item in “Snack foods” and therefore the dietary exposure from the snack foods other than potato chips was estimated by mapping of the potato chips to other snack foods. It may introduce uncertainty to the dietary exposure estimates. Nevertheless, the snack foods were consumed in a low amount (1 g/person day−1) and therefore the dietary exposure assessment would not be affected significantly. The dietary exposures of the Hong Kong population to acrylamide were also compared with those reported for other places that are summarised in Table 4. The dietary exposure
Table 4. Comparison of dietary exposures of acrylamide. Dietary exposure of adult (μg kg−1 bw day−1) Places Hong Konga China (Zhou et al. 2013) UK (FSA 2005) Canada (HC 2012) Europe (EFSA 2011) USA (USFDA 2006b) France (Sirot et al. 2012) Ireland (FSAI 2011) New Zealand (MAF 2012) Notes: aData from the current study.
Mean 0.213 0.286 0.3 0.3–0.4 0.31–1.1 0.4 (age 2+) 0.43 0.59 0.84 (male 25+) 0.66 (female 25+)
95th or 97.5th percentile 0.537 (95th percentile) 0.490 (95th percentile) 0.6 (97.5th percentile) 0.58–2.3 (95th percentile) 1.02 (95th percentile) 1.75 (97.5th percentile) 1.39 (male 25+) (95th percentile) 1.15 (female 25+) (95th percentile)
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estimated in this study is around the lower end of the range of the exposure estimates obtained from other places. However, caution should be exercised in making any direct comparison of the data due to the difference in time the reported studies were carried out, the methods of collection of consumption data, the methods of contaminant analysis and the methods of treating results below detection limits. Subsequent to the reports on the formation of acrylamide in food, international bodies and many national authorities have made efforts to explore ways to reduce the acrylamide in foods. National authorities, such as the USFDA, Health Canada and EFSA, are also implementing monitoring programme on the acrylamide levels in food (USFDA 2006a; EFSA 2012; HC 2012). In 2009, the Codex Alimentarius Commission (CAC) adopted a Code of Practice for Reduction of Acrylamide in Foods, aiming to provide national and local authorities, manufacturers and other relevant bodies with guidance to prevent and reduce formation of acrylamide in potato products and cereal products (CAC 2009). JECFA mentioned in its 2010 evaluation that the mitigation after 2003 was reported mainly for food types with comparably high acrylamide levels or single products with acrylamide levels in the high end within their food types and thus the exposure for some individuals or population subgroups might significantly be reduced. However, it would have little effect on the dietary exposure for the general population in most countries. JECFA recommended the pursuit of further efforts on developing and implementing mitigation methods for acrylamide in foods as a subject of major importance for dietary exposure (FAO/WHO 2011).
Conclusion In summary, the estimated mean dietary exposure of the Hong Kong population to acrylamide was 0.213 μg kg−1 bw day−1 and its 95th percentile was 0.538 μg kg−1 bw day−1 (their MOEs were all below 10 000). It may indicate human health concern because of the relatively low figures for a genotoxic carcinogen. Frying vegetables can induce the formation of acrylamide and fried vegetables were found to be the major contributor of the exposure due to the relatively high acrylamide level in most stir-fried vegetables and the high consumption amount. Besides, fried potato, potato chips, biscuits and breakfast cereals were also significant sources of exposure due to the high acrylamide level found in these food items. Efforts should continue to be made in the interest of reducing acrylamide levels in food locally.
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