Food Additives and Contaminants: Part B Vol. 4, No. 3, September 2011, 195–204

Ethyl carbamate in fermented foods and beverages: dietary exposure of the Hong Kong population in 2007–2008 A.S.P. Tanga, S.W.C. Chungb, K. Kwongb, Y. Xiaoac, M.Y.Y. Chena, Y.Y. Hoa and S.W.Y. Maa* a Centre for Food Safety, Food and Environmental Hygiene Department, 43/F Queensway Government Offices, 66 Queensway, Hong Kong, China; bFood Research Laboratory, Food and Environmental Hygiene Department, 4/F Public Health Laboratory Centre, 382 Nam Cheong Street, Hong Kong, China; cSchool of Public Health, Peking University, 38 Xue Yuan Road, Beijing 100083, China

(Received 28 January 2011; final version received 12 July 2011) To evaluate the potential public health risk of ethyl carbamate (EC), EC exposure from fermented foods and beverages for Hong Kong population was estimated. In 276 samples analysed, EC was detected (limit of detection (LOD) at 0.4 mg kg1) in 202 samples (73%), with higher levels in fermented red bean curd (150–650 mg kg1) and yellow wine (140–390 mg kg1), while low or non-detected (ND) in preserved vegetables (ND–10 mg kg1) and fermented tea (ND–15 mg kg1). The estimated dietary exposure from all fermented foods and beverages was 8.27 ng kg1 bw day1, while exposure excluding alcoholic beverages was 5.42 ng kg1 bw day1, with calculated margins of exposure (MOEs) at 3.6  104 and 5.5  104 respectively. The risk of adverse health effects was low for the average population but higher (MOE of 103) for high consumers of alcoholic beverages especially habitual drinkers of alcoholic types with high EC contents. Keywords: beverages; processed foods; process contaminants; ethyl carbamate

Introduction Ethyl carbamate (EC), also known as urethane, is naturally formed in fermented foods during the fermentation process or during storage. Variable levels of EC have been found in different fermented foods such as bread, soy sauce and yogurt, and in alcoholic beverages such as spirits, grape wine and beer (Dennis et al. 1989; Diachenko et al. 1992; Food Standards Agency (FSA) 2000; Kim et al. 2000; Lachenmeier et al. 2005; Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) 2006a, 2006b; European Food Safety Authority (EFSA) 2007; Food Standards Australia and New Zealand (FSANZ) 2007; Park et al. 2007; Schlatter et al. 2010). In recent years, public health concerns regarding EC in foods were raised due to its genotoxic and carcinogenic potential. JECFA evaluated EC in its 64th Meeting in 2005 and concluded that EC was genotoxic and a multisite carcinogen in all animal species tested and a potential carcinogen in humans (JECFA 2006b). In 2007, the International Agency for Research on Cancer (IARC) reassessed EC and upgraded its classification from Group 2B (‘possibly carcinogenic to humans’) to Group 2A (‘probably carcinogenic to humans’) (IARC 2007). *Corresponding author. Email: [email protected] ISSN 1939–3210 print/ISSN 1939–3229 online ß 2011 Taylor & Francis http://dx.doi.org/10.1080/19393210.2011.605524 http://www.tandfonline.com

In the JECFA evaluation, a carcinogenicity study of EC in mice was identified as the pivotal toxicological study for risk assessment. The increased incidence of lung tumour (alveolar and bronchiolar adenoma or carcinoma) was considered the critical toxicological endpoint of concern. The associated dose–response data were analysed and the benchmark dose lower confidence limit 10% (BMDL10) for EC was determined. The EC margin of exposure (MOE), defined as the ratio of BMDL10 to the estimated dietary intake of EC in humans, was then calculated and used by the Committee as an index for the assessment of the potential health risk posed by EC to humans (JECFA 2006b). When the estimated intake of EC in foods excluding alcoholic beverages (15 ng kg1 bw day1) was compared with the lower end (0.3 mg kg1 bw day1) of the range of BMDL10 values (0.3–0.5 mg kg1 bw day1) for alveolar/bronchiolar neoplasms in mice, a MOE of 2.0  104 was estimated. With the inclusion of alcoholic beverages in the estimated intake of EC (80 ng kg1 bw day1), the resulting MOE was only 3.8  103. The Committee concluded that exposure to EC in foods other than alcoholic beverages would be of low concern, but the estimated health risk posed by total dietary exposure to EC (in all foods and beverages) would be a cause of

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potential concern and therefore mitigation measures to reduce concentrations of EC in some alcoholic beverages should be continued (JECFA 2006b). Previous studies investigating the level of EC in fermented foods and beverages and risk assessments mainly focused on the food items of the Western diet. Little is known about the amount of EC in fermented foods and alcoholic beverages of the Eastern diet which are commonly consumed in many parts of the world, including Hong Kong. The aim of this study was to examine the level of EC in local fermented foods and beverages, and to assess the associated health risk posed to the Hong Kong population through dietary exposure to EC. Since the types and origins of fermented foods and beverages commonly consumed in Hong Kong are diverse, risk assessment was conducted based on EC levels measured in this study as well as data reported overseas.

Materials and methods Sampling Fermented food and beverage products, both prepackaged and non-prepackaged, readily available in Hong Kong were sampled. A total of 276 food and beverage samples were purchased from various local sources, including wet markets, supermarkets and bakery shops, in different districts of Hong Kong during 2007–2008. The samples covered nine major categories: (1) fermented cereals and grains products (bread/rolls/ buns and crackers); (2) legumes (fermented soy products); (3) preserved/dried vegetables; (4) meat products (fermented pork products); (5) fermented dairy products; (6) fermented fish products; (7) condiments and sauces; (8) non-alcoholic beverages; and (9) alcoholic beverages.

Analytical procedure Determination of EC was conducted on an individual sample basis. A total of 276 food and beverage samples were analysed. For perishable food items, samples were kept at 20 C until analysis. All food samples were similarly prepared and analysed. Alcoholic beverages (excluding beer) and soy sauce were extracted by ChemElut method and analysed by GC-MS according to the AOAC official method (AOAC International 2005), using deuterated EC (d5-EC) as the internal standard. For those alcoholic beverage or soy sauce samples tested to contain less than 10 mg kg1 EC and all other fermented food samples, extraction was done by the Extrelut method and analysed by LC-MS/MS according to the method developed by Park et al. (2007) and confirmed by GC-HRMS (Chung et al. 2010). In brief, samples were spiked with d5-EC as internal standard

and mixed with 10 g of ExtrelutÕ powder before loading onto an alumina-Extrelut column. The alumina-Extrelut column was then washed with dichloromethane (DCM):n-pentane (20:80, v/v) mixture, followed by extracting the target analyte with DCM. After rotary evaporation, the concentrate was dissolved in methanol and underwent a florisil SPE cleanup to eliminate interferents from sample matrix. The EC fraction was eluted with 10 ml of 7% methanol in DCM. The eluate was then concentrated by nitrogen evaporator and analysed by respective instruments. For identity confirmation, the relative retention time as well as the response ratio of quantification and qualifier ions in the sample should be concordant to those in the calibration standards. The calibration curve, plotted by the peak area ratio of quantification ion of native EC to that of d5-EC against the EC content in the standard solutions, was used for quantitation. For each batch of 20 samples or fewer, the following QC criteria must be fulfilled: (1) the EC content in the blank sample should be less than the LOD; (2) the relative per cent difference between the duplicate analyses should be less than 20%; and (3) the spike recovery should be within 80–120%. The limit of detection for both solid and liquid samples was 0.4 mg kg1.

Determination of ethyl carbamate concentration in brewed tea For tea samples, the tea leaf samples were first analysed for EC. For the tea leaf samples with detectable levels of EC, the concentration of EC in the brewed tea samples was further determined. Brewed tea was normally prepared and consumed at a concentration of 2 g of tea leaves in 200 ml water (Consumer Council 2000). In order to obtain measurable quantities of EC, a five times more concentrated liquid tea sample was prepared for chemical analysis, i.e., 200 ml of distilled water at 90 C were added to 10 g of tea leaves and the tea was brewed for 30 min. The tea liquid for EC determination was obtained after decanting the tea leaves.

Assessment of dietary exposure to ethyl carbamate The food consumption data used in this study were extracted from the Hong Kong Population-Based Food Consumption Survey 2005–2007 commissioned by the Food and Environmental Hygiene Department (FEHD) (2010). This survey investigated the food consumption of a population-based sample of 5008 Hong Kong adults aged 20–84 years, selected through an anonymous and scientific household address sampling procedure. Food consumption data were collected by both 24-h dietary recalls and a food

Food Additives and Contaminants: Part B frequency questionnaire. The survey results have been age- and gender-weighted and represent a population of 5 394 072 Hong Kong residents aged 20–84 years. To estimate dietary exposure to EC in the population, the mean EC concentration was used for each food item. Matching food items for which preliminary weighted consumption data were available from the Hong Kong Population-Based Food Consumption Survey 2005–2007 were used for exposure assessment. Daily dietary exposure to EC from each food item was obtained by combining the weighted population mean consumption data and the mean EC concentration of that food item. Total exposure for an individual was obtained by summing EC exposures from all food items investigated.

Risk assessment using the margin of exposure approach The EC margin of exposure (MOE) was calculated as the ratio of BMDL10 to the estimated dietary intake of EC in humans and used as an index for the assessment of the potential health risk posed by EC to humans. Taking reference from the JECFA evaluation of food contaminants at its 64th meeting in 2005, the estimated intake of certain contaminants with MOE values of 104 was considered to be of low concern for human health (JECFA 2006b).

Results A total of 276 food samples including 70 alcoholic beverage samples were analysed for individual EC levels. EC was detected in 202 of the 276 samples analysed (73%).

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(ND–1.1 mg kg1), fermented fish products (salted fish) (ND), and fermented tea (ND–15 mg kg1). For individual food items, highest EC levels were observed in fermented red bean curd (mean 386 mg kg1; range ¼ 150–650 mg kg1), followed by yellow wine (mean ¼ 265 mg kg1; range ¼ 140– 390 mg kg1). Food consumption data Table 1 shows the food consumption data for the nine groups of local fermented foods and beverages. The mean quantities of matched food items consumed per capita, weighted by age and gender, for the Hong Kong population were obtained from the average food consumption data of 5008 respondents. The various food groups relevant to this study were extracted, namely fermented cereals and grains products, legumes (fermented soy products), preserved/dried vegetables, meat products (fermented pork products), fermented dairy products, fermented fish products, condiments and sauces, non-alcoholic beverages, and alcoholic beverages. The calculated mean per capita consumption ranged from 0.40 g day1 for fermented fish products to 345 ml day1 for non-alcoholic beverages. Dietary exposure Table 2 shows the estimated dietary exposure to EC for the average population and the percentage contributions from different food groups to the total dietary exposure together with the means and concentration ranges of EC contamination in each food group. Based on the weighted population mean Table 1. Weighted mean per capita consumption (g day–1) for the nine groups of local fermented foods and beverages.

Concentrations of ethyl carbamate in local foods and beverages Concentrations of EC in local foods and beverages analysed ranged from non-detected (ND) to 650 mg kg1. The mean and median EC levels for all food samples investigated were 25.2 and 1.5 mg kg1, respectively. The large difference between the mean and median could be attributed to a sizeable number of non-detects (27%). The mean, median and concentration range of EC levels in individual food and beverage items are listed in Table A in the Appendix. Among the different food groups, legumes (fermented soy products) showed the highest mean EC concentration (mean ¼ 121 mg kg1; range ¼ ND– 650 mg kg1), followed by alcoholic beverages (mean 55.9 mg kg1; range ¼ ND–390 mg kg1). The levels of EC were low or non-detected in fermented cereals and grains products (ND–8.6 mg kg1), preserved vegetables (ND–10 mg kg1), fermented dairy products

Food group Fermented cereals and grains products (bread/rolls/buns and crackers) Legumes (fermented soy products) Preserved/dried vegetables Meat products (fermented pork products) Fermented dairy productsb Fermented fish products Condiments and saucesb Non-alcoholic beveragesb Alcoholic beveragesa

Mean per capita consumptiona,b 48.2 0.66 2.13 0.47 3.97 0.40 6.16 345 33.1

Notes: aMean per capita consumption for liquid item is expressed in ml day1. b Food group composed of solid and liquid items. The weight of liquid food was assumed to be 1 g ml1 when calculating the amount of food group consumption.

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Table 2. Ethyl carbamate concentrations (mg kg1) in various food groups and the estimated dietary exposure (ng kg1 bw day1) with percentage contributions for the average population.

Food/beverage group

Number of samples

EC concentration, mean; range

Dietary exposure

Percentage contribution

Fermented cereals and grains products Bread/rolls/buns – Chinese steamed bun – Bread and toasted bread Crackers

25 15 5 10 10

2.01 2.63 0.20 3.85 1.08

ND–8.6 ND–8.6 ND 1.0–8.6 ND–5.1

2.77

33.5

Legumes (fermented soy products) Fermented bean curd Fermented red bean curd Fermented black soy bean Stinky tofu

20 6 5 5 4

121 80.7 386 2.22 0.20

ND–650 11–130 150–650 ND–7.0 ND

0.98

11.8

Preserved/dried vegetables

45

3.03

ND–10

0.09

1.1

Meat products (fermented pork products)

5

12–29

0.14

1.7

Fermented dairy products Cheese Yogurt Dairy-based fermented beverages

11 5 3 3

0.39 0.44 0.50 0.20

ND–1.1 ND–1.1 ND–1.1 ND

0.02

0.3

Fermented fish products (salted fish)

5

0.20

ND

0.01

0.1

Condiments and sauces Soy sauce Oyster sauce Vinegar Condiment and savoury sauces

55 5 5 18 27

5.11 6.84 0.54 9.32 2.84

ND–44 1.8–17 ND–1.1 ND–37 ND–44

0.59

7.2

Non-alcoholic beverages Vinegar drink (fruit vinegar) Tea (tea leaves) – Fully fermented tea (black tea) – Semi-fermented tea (Chinese tea)

40 5 35 5 30

1.09 1.54 1.03 3.26 0.65

ND–15 0.4–3.0 ND–15 ND–15 ND–5.1

0.82

9.9

Alcoholic beverages Beer/ale Wine or spirit made from cereals and grains – Yellow wine – Sorghum-based spirit – Rice wine – Chinese rice wine – Sake Wine made from fruit – Grape wine – Red wine – White wine – Plum wine – Cider Compound alcoholic beverages Distilled spirits (Chinese distilled spirits)*

70 15 30 6 3 21 12 9

55.9 1.13 93.7 265 54.3 50.4 32.1 74.7

ND–390 ND–5.8 2.0–390 140–390 37–66 2.0–330 3.3–62 2.0–330

2.85

34.5

10 5 5 5 5 5 9

21.2 17.7 24.7 110 6.90 57.6 36.5

6.7–47 8.3–35 6.7–47 0.4–230 ND–31 17–150 20–66

Total

276

25.2

ND–650

8.27

100

18.0

Notes: ND ¼ non-detect. *Included distilled rice wine and distilled sorghum-based spirit listed above.

consumption data from the Hong Kong PopulationBased Food Consumption Survey, the total dietary exposure to EC from all foods and beverages was estimated to be 8.27 ng kg1 bw day1, while dietary exposure excluding alcoholic beverage was

estimated to be 5.42 ng kg1 bw day1. Among the nine food groups analysed, alcoholic beverages (34.5%) and fermented cereals and grains products (33.5%) were the major contributors to dietary exposure to EC, while fermented fish products

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Table 3. Estimated dietary exposure to ethyl carbamate (ng kg1 body weight day1) of high consumers of various local fermented food and beverage items.

Food/beverage item

95th percentile consumption (g)

Mean EC level (mg kg1)

Exposure

MOE

144 58.4 15.0 5.00 3.92 24.6 30.0 29.4 250 18.3 12.5 375 1350 1500 1650 0.03 0.59 0.43 250 76.0 270

2.63 1.08 80.7 386 2.22 3.03 18.0 0.44 0.50 6.84 9.32 1.54 0.18 0.08 1.13 265 54.3 32.1 21.2 110 36.5

6.18 1.03 19.7 31.5 0.14 1.22 8.81 0.21 2.04 2.04 1.90 9.42 3.96 1.96 30.4 0.13 0.52 0.23 86.5 136 161

4.9  104 2.9  105 1.5  104 9.5  103 2.1  106 2.5  105 3.4  104 1.4  106 1.5  105 1.5  105 1.6  105 3.2  104 7.6  104 1.5  105 9.9  103 2.3  106 5.7  105 1.3  106 3.5  103 2.2  103 1.9  103

Bread/rolls/buns Crackers Fermented bean curd Fermented red bean curd Fermented black soybean Preserved vegetables Chinese pork sausage Cheese Yogurt Soy saucea Vinegara Vinegar drinka Fully fermented teaa Semi-fermented teaa Beer/alea Yellow winea Sorghum-based spirita Chinese rice winea Grape winea Plum winea Distilled spiritsa

Note: aFor liquid items consumption is expressed in ml.

(0.1%) and dairy products (0.3%) contributed the least.

Margin of exposure (MOE) The MOE for dietary exposure to EC from fermented foods and beverages and the MOE for exposure excluding alcoholic beverages calculated were in the range of 3.6  104 and 5.5  104, respectively. Table 3 shows the MOE values for high consumers (95th percentile consumption pattern) of local fermented food items which showed high EC contamination levels and/or are major contributors to dietary EC exposure. For the majority of local fermented food items, the MOE values for the high consumers were in the order of 104 to 106, indicating low potential health concern even for this sub-population. Exceptions were the high consumers of alcoholic beverages such as distilled spirits, plum wine and grape wine.

Discussion Levels and patterns of ethyl carbamate in food commodities The majority of fermented food and beverage items analysed in this study showed low or non-detected levels of EC. For example, EC was below the detection limit in common local fermented foods such as Chinese steamed bun, stinky tofu, salted fish and fermented Chinese tea, shouwei tea.

A number of food items were found to have relatively high EC levels, namely fermented red bean curd, fermented bean curd, Chinese yellow wine (Shaoshing wine/huadiao), sake and plum wine. In particular, high levels of EC were found in the fermented red bean curd (mean ¼ 386 mg kg1; range ¼ 150– 650 mg kg1), and Chinese yellow wine (Shaoshing wine/huadiao) (mean ¼ 265 mg kg1; range ¼ 140– 390 mg kg1). The high levels measured in these food items in the present study are consistent with previous reports. High concentrations of EC have been reported in fermented bean curd (5.0–77.6 mg kg1) (Shi et al. 2009) and in Chinese yellow wine (ND–240.8 mg l1) (Wu and Chen 2004; Shi et al. 2009). Considering that these food items are usually consumed infrequently and in small amounts or are added only as seasoning in Chinese cooking, they would unlikely be a cause of significant health concern for the general population. Nevertheless, this study identifies the need for continuous efforts in the research and development in the processing of these foods and alcoholic beverages and calls for attention from the industry to devise methods to reduce EC to the lowest practicable level. In particular, there is a need to devise the optimal conditions in the processing and storage of these commodities. Previous reports have investigated such conditions where the reduction in the level of urea formed during the production process is the key (Wang et al. 2009; Xia et al. 2004). It is reported that since the high level of EC is related to the high content of arginine in Chinese yellow wine, the reduction of the initial arginine content is a

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possible way to curb EC formation in the final product (Xia et al. 2004; Gao and Bao 2006; Wang et al. 2009). It may be noted that a wide range of EC concentrations was measured among individual samples of each food item. The large variation could be the result of difference in precursors used, fermentation methods employed or storage conditions. It is therefore important for the industry to continue closely monitoring the manufacturing process, identify potentially problematic

conditions, and develop methods that would prevent or reduce the formation of EC and maintain EC contamination at the lowest level possible during processing and storage. The concentrations of EC in fermented foods measured in this study were compared with those previously reported by overseas countries (Table 4) (JECFA 2006b). Results of this study are in general agreement with previous reports from other countries,

Table 4. Comparison of ethyl carbamate concentrations in fermented foods measured in this study with those previously reported. Range of EC concentration (mg kg1) Food/beverage group

This study

Fermented cereals and grains products Bread/rolls/buns – Chinese steamed bun – Bread and toasted bread Crackers Legumes (fermented soy products) Fermented bean curd Fermented red bean curd Fermented black soy bean Stinky tofu Preserved/dried vegetables Fermented meat products (Chinese pork sausage) Fermented dairy products Cheese Yogurt Dairy-based fermented beverages Fermented fish products (salted fish) Condiments and sauces Soy sauce Oyster sauce Vinegar Condiment and savoury sauces Non-alcoholic beverages Vinegar drink (fruit vinegar) Tea (tea leaves) – Fully fermented tea (black tea) – Semi-fermented tea (Chinese tea) Alcoholic beverages Beer/ales Wine or spirit made from cereals and grains – Yellow wine – Sorghum-based white spirit – Rice wine – Chinese rice wine – Sake Wine made from fruit – Grape wine – Red wine – White wine – Plum wine – Cider Compound alcoholic beverages Distilled spirits (excluding fruit brandy)

ND–8.6 ND–8.6 ND 1.0–8.6 ND–5.1 ND–650 11–130 150–650 ND–7.0 ND ND–10 12–29 ND–1.1 ND–1.1 ND–1.1 ND ND ND–44 1.8–17 ND–1.1 ND–37 ND–44 ND–15 0.4–3.0 ND–15 ND–15 ND–5.1 ND–390 ND–5.8 2.0–390 140–390 37–66 2.0–330 3.3–62 2.0–330 0.4–230 6.7–47 8.3–35 6.7–47 0.4–230 ND–31 17–150 20–66

Notes: aSource of information: WHO (2006). b Range excluding the single highest value of 6131 mg kg1 is reported.

Previously reported by overseas countriesa ND–12

ND–16 (kimchi) ND–1.3 ND ND–1.3

ND–84 ND–84 0.3–26 ND–8 (soybean paste)

ND–262a ND–5

ND–202 ND–61

ND–3 ND–243b

Food Additives and Contaminants: Part B with the exception of distilled spirits for which the local samples show a narrower range at the low end of the overseas reported EC ranges. The smaller range of EC levels found in local samples is likely due to the smaller number of items and different kinds of distilled spirits (Chinese distilled spirits) analysed in this study.

Exposure assessment When the estimated dietary exposures of the average local population to EC from local fermented foods and alcoholic beverages were compared with the BMDL10 (i.e., for 10% extra risk of tumours) of 300 mg kg bw1 day1 for EC in experimental animals, large MOEs were observed. The MOEs for dietary exposure to EC from all fermented foods and beverages and from all fermented foods and beverages excluding alcoholic beverages were in the range of 3.6  104 and 5.5  104, respectively, indicating that EC exposure from consumption of local fermented foods and beverages would be of low potential health concern for the average local population. This is consistent with previous reports of high MOE for exposure to EC from wine in China (MOE for mean exposure: 1.88  105; MOE for high exposure: 2.3  104) (Zhou et al. 2008), but substantially higher than that reported by JECFA (2006b) (3.8  103), suggesting the lower EC exposure and higher MOE values observed in this study may reflect difference between Eastern and Western dietary habits. For high consumers of alcoholic beverages such as distilled spirits, plum wine and grape wine, however, it should be noted that the MOE values for estimated dietary EC exposure of this subpopulation were at the low end of the order of 103, suggesting a potential health concern for this subpopulation due to the high levels of EC contamination in these food items. Two other food items showed MOE values at the high end of the order of 103; they were the fermented red bean curd and the beer/ale. The former had the highest level of EC contamination but very low consumption value even for the high consumers, while the latter had the highest consumption value but very low level of EC contamination. In the Hong Kong Population-Based Food Consumption Survey 2005–2007, there was no reported consumption of fruit brandy. Fruit brandy has previously been reported to contain a much higher mean level of EC (EFSA 2007: 744–747 mg kg1). In this study, exposure from distilled spirits was estimated using the mean EC level of 36.5 mg kg1 for Chinese distilled spirits. Similar mean EC levels for distilled spirits excluding fruit brandy have been reported by overseas countries (JECFA 2006b: 37–64 mg kg1; EFSA 2007: 64–66 mg kg1) giving comparable estimated exposure and calculated MOE for the average population. If the distilled spirits consumed consisted solely of fruit

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brandies, the estimated exposure would be increased 20-fold, giving a calculated MOE of around 102, and a potential cause of greater health concerns. Achieving a reduction in the level of EC in alcoholic beverages, and thus its associated health risk, is now a priority in the international community (Codex Alimentarius Commission (CAC) 2009). This relies on the continued and concerted efforts in developing mitigating measures to reduce EC formation during the manufacturing process, storage and transport of alcoholic beverages by the trade, as well as by avoiding overindulgence at the individual level. In the exposure assessment, dietary exposure to EC was estimated for the average population in Hong Kong using the mean EC concentrations. Considering that a number of test samples had EC levels below the detection limit and the median EC values were in most cases lower than the mean EC values, the mean EC values were used for exposure estimate in this study as a conservative approach for the protection of public health. It may be mentioned that the mean contamination levels were also used for exposure assessment in the JECFA evaluation since it was assumed that the chronic nature of the hazard posed by EC would allow a consumer to be exposed to an average amount of EC in any given foodstuff over a lifetime (JECFA 2006a, 2006b). The estimated exposure due to the food group ‘fermented cereals and grains products’ (33.5%) is likely to be overestimated for the following reasons. First, not all bread/rolls/buns and crackers available on the market are fermented. While a large number of products are made from yeast fermentation, some products may use baking soda instead. Since no data were available for estimating the proportion of fermented products consumed, this study assumed that all the bread/rolls/buns and crackers consumed were fermented. Second, in the absence of detailed ingredients breakdown, the gross weight of the bread/rolls/ buns consumed including the non-fermented ingredients (e.g. sausage, raisins) were used to estimate the EC exposure. Therefore, the net quantity of fermented foodstuff consumed and hence the actual exposure to EC from the group ‘fermented cereals and grains products’ would likely be substantially lower and contribute a much smaller percentage to the total EC exposure. For distilled spirits, mean per capita consumption data were available only as a group. Individual consumption data for Western distilled spirits (e.g. brandy, whisky, rum, vodka, gin) and other alcoholic beverages such as sake, cider and fortified wine known to contain high levels of EC were not available. Given these factors of uncertainty, the actual exposure to alcoholic beverages would likely be higher, especially for individuals who consume the types of alcoholic beverages known to have high EC contents.

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Conclusion The results showed that variable amounts of EC were present at generally low levels in different fermented food and beverage items available in the Hong Kong market. Higher levels of EC were found in local Chinese fermented foods such as fermented red bean curd, fermented bean curd and Chinese yellow wine. The food group ‘alcoholic beverages’ was identified as the main dietary source of EC. When compared with a BMDL10 of 0.3 mg kg1 bw day1, the estimated total dietary exposure to EC for average local consumers of fermented foods and alcoholic beverages gives a large MOE of 3.6  104. While the potential health risk of EC exposure from the consumption of fermented foods and beverages posed to the average Hong Kong population via dietary intake is likely to be low, it cannot be ruled out for high consumers of alcoholic beverages, especially those who are habitual drinkers of the alcoholic types known to have high EC contents.

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Appendix A Table A. Mean, median and concentration range of ethyl carbamate in individual food and beverage items.

Food Group/Food Items

No. of samples

Mean concentration (mg kg1)

Median concentration (mg kg1)

Range (mg kg1)

FERMENTED FOODS Fermented cereals and grains products Bread/Rolls/Buns Chinese steamed bun* White bread* Toasted bread Crackers Crackers* Biscuit sticks

25

2.01

0.9

ND–8.6

15 5 5 5 10 5 5

2.63 0.2 5.04 2.66 1.08 1.86 0.3

1.7 0.2 5.1 2.5 0.4 0.9 0.2

ND–8.6 ND 1.5–8.6 1.0–5.4 ND–5.1 ND–5.1 ND–0.7

Legumes (fermented soy products) Fermented bean curd* Fermented red bean curd* Fermented black soy bean* Stinky tofu

20 6 5 5 4

121 80.7 386 2.22 0.2

45 83 320 1.4 0.2

ND–650 11–130 150–650 ND–7.0 ND

Preserved/dried vegetables Preserved leaf mustard* Preserved rakkyo* Preserved cabbage/‘‘Dong Choy’’* Preserved turnip* Preserved mustard greens* Preserved Sichuan mustard* Dried raddish* Preserved mustard/‘‘Mui Choy’’* Kimchi*

45 5 5 5 5 5 5 5 5 5

3.03 2.28 0.86 8.34 1.06 0.48 2.36 3.8 7.14 0.96

1.7 1.8 0.8 7.4 0.9 0.6 1.9 3.2 7.3 0.2

ND–10 ND–6.6 ND–1.7 7.0–10 0.8–1.7 ND–0.6 0.9–4.9 1.5–7.2 4.9–10 ND–3.8

Meat products (fermented pork products) Chinese pork sausage* Fermented dairy products Cheese* Yogurt* Dairy-based fermented beverage* Fermented fish products Salted fish* Condiments and sauces Soy sauce* Oyster sauce* Vinegar* Rice vinegar Sorghum vinegar Wine vinegar Condiments and savoury sauces Fish sauce* Worcestershire sauce*

5 5

18 18

18 18

12–29 12–29

11 5 3 3

0.39 0.44 0.5 0.2

0.2 0.2 0.2 0.2

ND–1.1 ND–1.1 ND–1.1 ND

5 5

0.2 0.2

0.2 0.2

ND ND

55 5 5 18 10 3 5 27 5 2

5.11 6.84 0.54 9.32 7.5 25 3.54 2.84 0.6 1.85

1.2 6.1 0.2 3.1 2.3 29 2.3 0.8 0.5 1.85

ND–44 1.8–17 ND–1.1 ND–37 ND–27 9.0–37 1.9–8.6 ND–44 ND–1.2 1.5–2.2 (continued )

204

A.S.P. Tang et al.

Table A. Continued. Mean concentration (mg kg1)

Median concentration (mg kg1)

Range (mg kg1)

5 5 5 5

1.18 10.4 1.1 1.28

0.2 2.8 0.8 0.8

ND–4.9 0.8–44 0.6–2.2 ND–3.1

Non-alcoholic beverages Vinegar drink (fruit vinegar)* Tea (tea leaves) Fully fermented tea* (black tea) Semi-fermented tea* (Chinese tea) Pu-er tea Oolong tea Jasmine tea Tieguanyin tea Shueixian tea Shouwei tea

40 5 35 5 30 5 5 5 5 5 5

1.09 1.54 1.03 3.26 0.65 0.7 0.76 1.38 0.64 0.24 0.2

0.2 1.3 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2

ND–15 0.4–3.0 ND–15 ND–15 ND–5.1 ND–2.7 ND–3.0 ND–5.1 ND–2.1 ND–0.4 ND

Alcoholic beverages Beer/ale* Draft (draught) beer Regular beer Dark (black) beer

70 15 5 5 5

55.9 1.13 0.54 0.7 2.16

20.7 0.7 0.6 0.7 1.4

ND–390 ND–5.8 0.4–0.7 ND–1.5 1.0–5.8

Wine/spirit made from cereals and grains Yellow wine* (Shaoshing wine/huadiao) Sorghum-based spirit* Rice wine* Chinese rice wine Sake

30

93.7

40

2.0–390

275

140–390

3 21 12 9

54.3 50.4 32.1 74.7

60 28 28.5 28

37–66 2.0–330 3.3–62 2.0–330

Wine made from fruit Grape wine Red wine* White wine* Plum wine* Cider

20 10 5 5 5 5

39.7 21.2 17.7 24.7 110 6.9

18.5 18.5 15 19 91 1.4

0.4–230 6.7–47 8.3–35 6.7–47 0.4–230 ND–31

Compound alcoholic beverage

5

57.6

32

17–150

Distilled spirit* # (distilled rice wine and distilled sorghum-based spirit)

9

36.5

37

20–66

276

25.2

Food Group/Food Items Shrimp paste* Broad bean paste* Miso* Soybean paste*

No. of samples

FERMENTED BEVERAGES

Total

6

265

1.5

ND–650

Notes: ND: non-detect. LOD for both solid and liquid samples ¼ 0.4 mg kg1. The value of 1/2 LOD was assigned to non-detects (results below limit of detection) for the calculation of mean levels. *Food items for which consumption data are available in the Population Based Food Consumption Survey used in exposure assessment. #Distilled spirits include distilled rice wine and distilled sorghum-based spirit listed above. Brewed tea (10 g of tea leaves in 200 ml water): 1. Black tea sample (EC at 15 mg kg1 before brewing): 0.9 mg kg1. 2. Pu-er tea sample (EC at 2.7 mg kg1 before brewing): ND. 3. Jasmine tea sample (EC at 5.1 mg kg1 before brewing): ND.

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Ethyl carbamate in fermented foods and beverages: dietary exposure of the Hong Kong population in 2007-2008.

To evaluate the potential public health risk of ethyl carbamate (EC), EC exposure from fermented foods and beverages for Hong Kong population was esti...
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