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Food Additives & Contaminants: Part B: Surveillance Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfab20

Lead, cadmium and mercury levels in the 2010 Korean diet Jae Hoon Kim c

a b

a

a

c

c

, Ji Yeon Lee , Joo Ee Seo , Ji Yoon Jeong , Ki Kyung Jung , Hae Jung

Yoon & Kyung Su Park

a

a

Advanced Analysis Center, Korea Institute of Science and Technology , Seoul , Republic of Korea b

Department of Chemistry, Research Institute for Basic Sciences , Research Center for New nano Bio Fusion Technology, Kyung Hee University , Seoul , Republic of Korea c

National Institute of Food and Drug Safety Evaluation , Seoul , Republic of Korea Accepted author version posted online: 18 Jun 2012.Published online: 30 Jul 2012.

To cite this article: Jae Hoon Kim , Ji Yeon Lee , Joo Ee Seo , Ji Yoon Jeong , Ki Kyung Jung , Hae Jung Yoon & Kyung Su Park (2012) Lead, cadmium and mercury levels in the 2010 Korean diet, Food Additives & Contaminants: Part B: Surveillance, 5:4, 260-264, DOI: 10.1080/19393210.2012.703699 To link to this article: http://dx.doi.org/10.1080/19393210.2012.703699

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Food Additives and Contaminants: Part B Vol. 5, No. 4, December 2012, 260–264

Lead, cadmium and mercury levels in the 2010 Korean diet Jae Hoon Kimab, Ji Yeon Leea, Joo Ee Seoa, Ji Yoon Jeongc, Ki Kyung Jungc, Hae Jung Yoonc and Kyung Su Parka* a

Advanced Analysis Center, Korea Institute of Science and Technology, Seoul, Republic of Korea; bDepartment of Chemistry, Research Institute for Basic Sciences, Research Center for New nano Bio Fusion Technology, Kyung Hee University, Seoul, Republic of Korea; cNational Institute of Food and Drug Safety Evaluation, Seoul, Republic of Korea

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(Received 18 October 2011; final version received 13 June 2012) This study analysed the level of contamination of harmful heavy metals in 3820 food samples available in Korea in 2010. A total of 119 types of samples were collected, including corns, vegetables, fruits, fishes, mollusks, shellfish, crustaceans, seaweed, bean products, meats and eggs from seven major cities. These samples were analysed using ICP-MS after pre-treatment with a microwave-digestion system. Results of lead, cadmium and mercury analyses were compared with the standard specifications of Korea Food Standards Codex. As a result, high levels of Pb, Cd and Hg were detected in ‘‘cockle,’’ ‘‘dried-squid’’ and ‘‘shark-meat.’’ Acceptable intake for consumers was checked using provisional tolerable weekly intake values. Such results will be utilised as data on the exposure of human body through foods. In addition, satisfactory results were obtained through purchase and analysis of National Institute of Science and Technology–certified reference materials to obtain reliability on analysis results. Keywords: lead; cadmium; mercury; diet

Introduction With industrial development, risk of heavy metal contamination of foodstuffs as well as environmental pollution has increased. Heavy metals can penetrate and accumulate in the body. The amount of absorption varies, depending on food type and health status of the individual consumer. In this regard, continuous research should be conducted to check the source of exposure. Heavy metal is one of the most dangerous pollutants in foodstuffs. It is reported that heavy metals in the environment such as soil and air contaminate agricultural products due to use of agricultural pesticides in the process of pest control for increased yield of agricultural products as well as in the preservation process of agricultural products (Tanaka et al. 1992). In particular, increased exhaust from extended use of cars contaminates the air and is sometimes deposited along the path of environmental circulation. Because polluted soils from mines – abandoned or in operation – may be used to cultivate grains or vegetables, these may contaminate various agricultural or marine products. For this reason, foodstuffs should be regularly analysed for heavy metals. For risk assessment, analytical data are required. In light of this, quantitative analysis by an inductively coupled plasma–mass spectrometer (ICP-MS) was *Corresponding author. Email: [email protected] ISSN 1939–3210 print/ISSN 1939–3229 online ß 2012 Taylor & Francis http://dx.doi.org/10.1080/19393210.2012.703699 http://www.tandfonline.com

performed on lead and cadmium in foodstuffs after pretreatment using a microwave digestion system. For mercury analysis, cold vapour atomic absorption spectrometry (CVAAS) is often utilised as sample pre-treatment, but it has the shortcomings of long analysis time and possible loss of mercury that may occur as a result of this process. On the other hand, a gold amalgam method that burns the sample and collects and analyses the gold amalgam does not require separate pre-treatment and is utilised widely for mercury analysis because it can improve the shortcomings of existing test methods. In this respect, mercury analysis was performed using the gold amalgam method.

Material and methods Reagents and samples Water passing a Milli-Q system (Millipore, Bedford, MA, USA) was used as a solvent for manufacturing test solutions and glass cleaning. Nitric acid (67% v/v) and hydrogen peroxide (31% v/v) were obtained from Dongwoo fine chemicals (Ik-san, Korea, Electronic grade). Standard stock solutions containing 10 mg/kg of each element (Pb, Cd) were purchased from PerkinElmer (New York, USA). A mercury standard solution

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Food Additives and Contaminants: Part B containing 1000 mg/kg was purchased from KantoChemical (Tokyo, Japan). These were used to prepare calibration standards. Tuning solution 10 mg/kg (Ba) and 1 mg/kg (Be, Ce, Co, Fe, In, Mg, Pb, Th, U) were from Perkin-Elmer. Certified reference materials NIST 8433 (Corn Barn) and NIST 1566B (Oyster Tissue) were obtained from the National Institute of Standards and Technology (NIST, Gaithersburg, MD, USA). Ultrapure grade carrier (argon [Ar], 99.9995% pure) was supplied by Shin-Yang (Korea). A total of 119 types of foodstuffs such as grains, vegetables, fruits, fishes, mollusks, shellfish, shell, seaweeds, bean products, meats and eggs were selected. At least three brands of food samples were purchased at three large-scale marts and markets of seven cities throughout the country (Seoul, Daejeon, Daegu, Busan, Incheon, Gwangju and Gangreung).

Sample digestion procedures for Pb and Cd Up to now in the Korean Food Standards Codex (KFDA 2010), ICP, AAS and ICP-MS methods have been used with an Ethos1 Microwave system (Milestone, Milan, Italy). The sample digestion procedure was performed according to the manual (Table 1). One randomly selected vessel was filled with reagents only and taken through the entire procedure as a blank. After cooling to room temperature, sample solutions were quantitatively transferred into 25-mL flasks. The digested samples were then filled up with ultrapure water to the final volume before analysis by inductively coupled plasma–mass spectrometry (ICP-MS).

ICP-MS procedure For this study, an Elan 6100 DRC Plus ICP-MS from Perkin-Elmer was used. The operating conditions of this device are as shown in Table 2.

Optimisation The isotopes 111Cd, 112Cd, 114Cd, 204Pb, 206Pb, 207Pb and 208Pb were selected as analytical mass in the ICPMS standard mode for these two elements and monitored with regard to sensibility of element and/ or possible isobaric and polyatomic interferences. Torch position, ion lenses and gas yield were optimised daily with the tuning solution (1 mg/kg) as a short-term stability test of the instrument, to maximise ion signals and to minimise interference effects from polyatomic and doubly charged ions. In all experiments, a relative standard deviation (RSD) of 3% was achieved. To obtain precise and accurate results, signals of elements were monitored in real-time display (RTD), which showed the constant sensitivity over time for the

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Table 1. Operating conditions: microwave digestion system. Digestion program Step Step Step Step

1 2 3 4

5 min. 80 C, 1000 W 5 min. 50 C, 1000 W 15 min. 190 C, 1000 W 20 min. 190 C, 1000 W

Table 2. Operating conditions: ICP-MS. Parameter RF generator RF powder Coolant gas flow rate Auxiliary gas flow rate Nebuliser gas flow rate Sample uptake flow Nebuliser Spray chamber Torch Interface cones Quadrupole chamber Dwell time Pb/Mass Cd/Mass

Condition Free-running type, 40 MHz 1400 W 17.0 L/min 2.00 L/min 1.05 L/min 1.00 mL/min Concentric type Cychronic type Demountable Platinum 1  106 torr 600 ms 206, 208 112, 114

selected masses and the ratios of masses, calculated for each sample with three readings.

Calibration Multi-element standard solutions were used for external calibration. Cd and Pb standards with internal standard were prepared at levels ranging from 0 (blank) to 100 mg/kg and subject to standard linear regression drawn from eight points, resulting in R2 ¼ 0.99 values for both curves.

Gold amalgamation procedure For this study, a gold amalgamation method was used that measures the atomic absorption spectrum from a single mercury light source in the selective collection of combustion products created with pyrolysis through the amalgam formation of mercury steam and gold coil as listed in the Korean Food Standards Codex. This method has the advantage of reduction of analysis time and easy change of operating conditions such as drying and carbonisation as well as simple spectrum of atomic absorption spectroscopy (KFDA 2010). A DMA-80 (direct mercury analyzer) of Milestone (Milestone Korea, Seoul) was used as an analysis device to analyse total mercury in foodstuffs (Table 3).

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Table 3. Instrumental parameters for DMA. Descriptions

Table 5. Results materials.

of

two

analysed

certified

reference

Conditions

Wavelength Interface filter Detector Catalyst Drying Decomposition Purge Amalgam Record

253.65 nm 254 nm Silicon UV photodetector Platinum 300 C, 60 sec 850 C, 180 sec 60 sec 12 sec 30 sec

Pb Cd Hg

NIST 8433 corn barn (mg/kg)

NIST 1566B oyster tissue (mg/kg)

0.145 (0.140  0.034) 0.012 (0.012  0.005) –

0.316 (0.308  0.009) 2.58 (2.48  0.08) 0.036 (0.037  0.0013)

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Table 6. Average metal content in analysed food samples. Food Table 4. Limit of detection (LOD) and limit of quantification (LOQ) of analysed elements.

Elements Pb Cd Hg

LOD (mg/kg)

LOQ (mg/kg)

Instrument

0.20 0.20 0.19

0.40 0.40 0.38

ICP-MS ICP-MS Gold amalgam method

Calibration As reported in previous studies, fish, shellfish and mollusks were found to have high exposure to mercury compared to other food groups (Kim et al. 2005, 2007; Jeong et al. 2007). Accordingly, the calibration curve was separated into a range of low concentration, to be applied to samples with relatively low mercury content, and a range of high concentration, to be applied to samples with relatively high mercury content. For low concentrations, a calibration curve was constructed with 8 points from 0 (blank) to 100 mg/kg. For high concentrations, it was drawn with 5 points from 200 to 5000 mg/kg (R2 ¼ 0.99).

Limits of Detection (LOD) and Quantification (LOQ) Because there was no application standard of detection limits for heavy metal in element test methods based on the recently revised and announced Korean Food Standards Codex, British standards (EN15510:2007:E) were applied, where LOD is defined as 3  SD and LOQ as 6  SD. The calculated values are given in Table 4.

Quality control To evaluate the reliability of the analytical results, 2 NIST CRMs were analysed and the results were obtained within the range of certification (Table 5).

Category Cereals Root and crops Culinary vegetables Fruits Fishes Mollusks Shellfish and crustacean Seaweeds Pulse crops Meats Eggs Bovine milks Sugars Seeds and nuts Fats and oils Beverage varieties Liquor Seasoning

Pb

Cd

Hg

mg/kg 10.5 26.0 22.1 24.7 39.8 72.7 134 116 11.3 10.4 6.42 20.0 41.6 5.60 17.7 18.9 11.1 17.7

mg/kg 14.0 9.30 23.3 2.10 10.4 677 280 639 15.0 0.70 0.40 1.80 1.58 26.9 0.60 0.77 0.60 33.5

mg/kg 10.9 3.20 5.30 10.8 234 51.0 28.5 16.0 4.00 5.50 7.20 3.00 20.2 57.4 7.20 3.26 2.60 4.56

Results and discussion Table 6 summarises the analytical results of 18 groups of food samples. The complete set, with samples of various brands from various regions, can be found in the database. Among them were groups showing high average Pb content. Figure 1 shows that detected contents in shellfish, crustaceans and cockle were found to have a highest concentration of 356 mg/kg, which is still below the Korean food standards specification (Table 7). Figure 2 shows the contents in seaweeds, mollusks and dried squid, with a highest content of 1140 mg/kg but still below the Korean food standards specification. Figure 3 shows the mercury concentration of fish, with an average content of 234 mg/kg, and the highest level in shark meat was found to be 2110 mg/kg. Considering that the latter value exceeded the Korean food standards specification, so it was confirmed by a duplicate analysis. Daily intake of total mercury was calculated to examine the risk of shark meat exceeding the food standards specification. Provisional tolerable weekly intake (PTWI) of mercury was specified as 5.00 mg/kg bw/week by the FAO/WHO Joint Expert Committee

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Food Additives and Contaminants: Part B

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Figure 1. Mean Pb levels in shellfish and crustaceans (mg/kg).

Table 7. Standard levels listed in the Korean Food Standards Codex (KFDA 2007). Element

Food type

Standard level (mg/kg)

Lead

Fish and shellfish, coarse fish, coffee, powdered tea, cocoa products, salt Rice, corn, soybean, adzuki beans, sweet potato, potato Spring onion, radish, infant food Cabbage, spinach, beverages, ginseng beverage, red ginseng beverage, kimchi Sugar (white sugar), grape sugar, fructose Sugar (black sugar), taffies, dextrin, sugar syrups Leached tea

2.0 0.2 0.1 0.3 0.5 1.0 5.0

Cadmium

Shellfish, seaweeds Rice, cabbage, spinach, kimchi (brown rice excluded) Corn, soybean, adzuki beans, sweet potato, potato, radish, beverage Spring onion Salt

2.0 0.2 0.1 0.05 0.5

Mercury

Fish, shellfish (deep sea fish, tuna and marlin excluded) Salt Shark meat

0.5 0.1 1.0

Figure 2. Mean Cd levels in seaweeds and mollusks (mg/kg).

on Food Additives (JECFA) (FAO/WHO 2006). Thus, the permissible amount of total mercury intake of an adult who weighs 60 kg is 300 mg/week. Based on 2.11 mg/kg as the maximum of total mercury contents

of shark meat, this corresponds to an intake of shark meat of 20.3 g/day (142 g/week). The third national nutrition survey of 2005 reported that average daily intake of shark meat per person was 0.20 g

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Figure 3. Mean Hg levels in fish (mg/kg).

(KHIDI 2005–2007). Thus, the total mercury intake is 0.29 mg/kg bw/day (2.07 mg/kg bw/week), 0.98% of PTWI. Accordingly, for Koreans the potential risks from consuming shark meat were low and found to be within safety levels unless more than 20.3 g/day (142 g/week) of shark meat is consumed continuously.

Conclusions This study examined the exposure of consumers to heavy metals in foodstuffs that are frequently consumed in large quantities reflecting the Korean diet. For lead and cadmium analysis, ICP-MS was used after pre-treatment using microwave digestion. Mercury was analysed using DMA, which required no pre-treatment. Before sample analysis, calibration and optimisation were performed. In general, the analytical results did not raise concern for consumers, but some values exceeded the Korean food standards specification. Therefore, the present data could be a firm basis for further studies.

Acknowledgements This study was conducted with fund support for research and development projects of KFDA for 2010 (10162 Harm Assessment 994 and 11162 Harm Assessment 701).

References European standard EN 15510:2007:E. Animal feeding stuffs – Determination of calcium, sodium, phosphorus, magnesium, potassium, iron, zinc, copper, manganese, cobalt, molybdenum, arsenic, lead and cadmium by ICPAES. FAO/WHO. 2006. Codex general standard for contaminants and toxins in foods. FAO/WHO Rome, Italy. Codex STAN 193-1995. p. 35. Jeong I-H, Xu X-M, Jun J-Y. 2007. Heavy metal contents of fish collected from the Korean coast of the East Sea (Donghae). Korean J Fish Soc. 40(6):362–366. KFDA. 2007. Korean Food Standards Codex. Korean Food and Drug Administration, Cheongwon, Korea. 2007–124. KFDA. 2010. Korean Food Standards Codex. Korean Food and Drug Administration, Cheongwon, Korea. pp. 10–7–1. KHIDI. 2005–2007. In-depth analysis on the 3rd Korea health and nutrition examination survey – nutrition survey. Korea Health Industry Development Institute, Seoul, Korea. Kim J-C, Kim H-Y, Kim S-Y, Lee J-H. 2007. Monitoring of heavy metals in fishes in Korea. Korean J Food Sci Technol. 39(4):353–359. Kim J-H, Mok J-S, Park H-Y. 2005. Trace metal contents in seaweeds from Korean coastal area. Korean J Food Sci Nutr. 34(7):1041–1051. Tanaka K, Aoki Y, Tamase K, Umoto F, Ohbayashi H, Sasaki M. 1992. Improved methods for determination of total mercury and its application to vegetables and fruit in markets. Japan J Food Hyg Soc. 33:359–364.

Lead, cadmium and mercury levels in the 2010 Korean diet.

This study analysed the level of contamination of harmful heavy metals in 3820 food samples available in Korea in 2010. A total of 119 types of sample...
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