Chemosphere 46 (2002) 1423–1427 www.elsevier.com/locate/chemosphere
Determining dioxin-like compounds in selected Korean food Dongmi Choi *, Soojung Hu, Jiyoon Jeong, Kyungpoong Won, Insang Song Department of Food Evaluation, Korea Food and Drug Administration, #5 Nokbun-Dong, Eunpyung-Ku, Seoul 122-704, South Korea
Abstract To measure the levels of dioxin-like compounds, pork, mackerel, cheese and milk were analyzed. The food samples were obtained at three different markets in Seoul. All the samples were animal origin and their lipid contents ranged from 4% to 34%. After extraction, extracts were cleaned up by sulfuric acid impregnated silica gel, purified on a series of silica gel, alumina, carbon column chromatography and then analyzed by high resolution gas chromatography/high resolution mass spectrometry. The levels of polychlorinated dibenzo-p-dioxins/furans for pork, mackerel, cheese and milk were 0.0008, 0.8663, 0.002 and 0.0236 pgTEQ/g wet weight, respectively. In addition, the levels of non-ortho coplanar polychlorinated biphenyls for pork, mackerel, cheese and milk were 0.0041, 1.5781, 0.0259 and 0.0353 pgTEQ/g wet weight, respectively. Among food samples analyzed, pork showed the lowest level of dioxin-like compounds. Ó 2002 Published by Elsevier Science Ltd. Keywords: Polychlorinated dibenzo-p-dioxins; Polychlorinated dibenzo-p-furans; Polychlorinated biphenyls; Food; Korea
1. Introduction Because of toxicity, wide spread presence and persistance in the environment, 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), and co-planar polychlorinated biphenyls (PCBs) are regarded as dioxin-like compounds (Den Berg et al., 1998). From the Viet Nam war in 1970s to the Belgium crisis happened in 1999, a great concern has been raised about contaminating food by dioxin-like compounds in the world. Since the food consumption is the main route of human exposure to the toxicants, almost all dioxin-like compounds found in human are believed to come from food (Scheter, 1994; Roeder et al., 1998). Especially meat, milk and fish are accumulating dioxin-like compounds in tissue lipid. During the last two decades, many industrialized countries were continuously and routinely
*
Corresponding author. Tel.: +82-2-380-1674; fax: +82-2382-4892. E-mail address:
[email protected] (D. Choi).
monitoring levels of PCDD/Fs and PCBs in food. However, there are relatively little data available on dioxin levels in Korean-intaking food. Schecter et al. (1997) has shown that levels of PCDD/Fs and PCBs from US food were 0.32 for pork, 1.43 for fresh fish, 0.40 for cheese and 0.12 pgTEQ/g wet weight for milk. Ministry of Health and Welfare, Japan (1999) reported that dioxins were determined as 0.0165 in pork, 0.069 (clam)–8.005 (perch) in fish, 0.067 in cheese, and 0.08743 pgTEQ/g wet weight in milk from Japanese food. Moreover, levels of PCDD/Fs and PCBs were 0.74 for fresh fish and 0.045 pgTEQ/g wet weight for milk in British food (Startin et al., 1990). Beside these, there are many valuable monitoring results for other countries (Birmingham et al., 1989; Furst et al., 1990; Theelen et al., 1993). The present study reports the levels of PCDDs, PCDFs (17 congeners) and non-ortho PCBs (#77, #126, and #169) in Korean food. The food samples (pork, mackerel, cheese, and milk) mostly of animal origin were obtained from the markets at three different sites in Seoul and analyzed for dioxin-like compounds using an US EPA Method 1613 with a modification to include non-ortho PCBs (Hayward, 1997; USEPA, 1997; Shin et al., 1999).
0045-6535/02/$ - see front matter Ó 2002 Published by Elsevier Science Ltd. PII: S 0 0 4 5 - 6 5 3 5 ( 0 1 ) 0 0 2 7 9 - X
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2. Experimental 2.1. Sampling Food samples were randomly obtained from markets at the northern, southern and western part of Seoul. Samples were prepared by grinding the edible portion using a meat mincer three times and kept frozen until analyzed.
increased at 3 °C/min to 270 °C (held for 3 min). Helium at a flow rate 0.8 ml/min was used as a carrier gas. Injector and transfer line temperature were 260 °C each. The samples were splitlessly injected (1 ll). HRMS analysis was performed with a Finnigan MAT95XL in MID mode operating positive EI ionization at a resolving power of >10 000 at m=z 314 of PFTBA. The ion source temperature was 250 °C.
2.2. Materials
3. Results and discussion
All chemicals used were pesticide grade and were purchased from Baker (USA). The standard solution (EDF-7999, EDF-4143 and EDF-4145) were purchased from Cambridge Isotope Laboratories (USA). The sulfuric acid impregnated silica gel was prepared as follows; the pre-washed silica gel (100 g, 60–200 mesh) with methanol and dichloromethane was activated in the oven at 130 °C at least for two days and then mixed with conc. sulfuric acid (37.5 ml).
Table 1 presents the food samples and food consumption obtained from a report on 1998 National Health and Nutrition Survey–Dietary Intake Survey performed by Ministry of Health and Welfare, Korea in 1999. Total food consumption is 1290 g/day for average Korean and the rate of animal food consumption (247.5 g) is 19.2%. Table 2 provides the results for the simultaneous determination of PCDDs, PCDFs and nonortho PCBs in pork, mackerel, cheese, and milk samples. The contaminating levels were calculated as the TEQ values by multiplying with the corresponding WHOTEFs for each congener (WHO-ECHS, IPCS, 1998). For generating results, non-detects were assigned to zero. As might be expected, contamination levels appear to differ among species. Pork contains the lowest levels of PCDD/Fs (0.001 pgTEQ/g ww) as well as the lowest levels of non-ortho PCBs (0.004 pgTEQ/g ww). While mackerel has the highest levels of those compounds (PCDD/Fs; 0.866 pgTEQ/g ww, non-ortho PCBs; 1.578 pgTEQ/g ww). In case of cheese samples, the levels of dioxin-like compounds range from 0.0001 to 0.0327 and in milk samples they are ranged from 0.032 to 0.111 pgTEQ/g ww. On the whole, the overall TEQ level of PCDD/Fs is as much as lower than that of non-ortho PCBs in food samples studied. In other words, PCB contribution is greater than that of PCDD/Fs, although the industrial use of PCBs has been severely restricted in Korea from year 1984. It can be seen in Fig. 1, the congener pattern is quite different in food samples studied. Among 20 toxic congeners in selected Korean food, PCB #77 is the highest contributing congener as shown at the left side of Fig. 1 and regarding WHOTEQ values, PCB #126 is the highest contributing congener as shown at the right side of Fig. 1. However, in case of PCDD/Fs only, the congener pattern is strongly dependent on the food samples that vary in species, fat content and living circumstances. In conclusion, contamination levels in Korean food reported here is slightly lower than the previously reported dioxin food data from the industrialized countries and give no indication of particular health risk associating with consumption of food samples. Further studies need to be done to fully characterize the levels of dioxin-like compounds in Korean food, but this study could be
2.3. Methods The samples (pork, mackerel and cheese) were ground and homogenized three times. About 20 g of each sample were taken, transferred to a pre-extracted cellulose thimble and mixed with 80 g of sodium sulfate, anhydrous. The samples were then fortified with the 13 Clabeled standards and extracted with Soxhlet extractor using a mixture of hexane/methylene chloride (1:3) for 18 h. After extraction, the solvent was removed and the lipid content was determined gravimetrically. The extract was cleaned up using sulfuric acid impregnated silica gel and purified on a series of silica gel, alumina and carbon column prior to analysis by HRGC/HRMS. In case of milk, about 150 g was taken, homogenized and worked up as identical as above. For each run, samples were prepared including a method blank and a QC sample. HRGC separation was accomplished using HP6890 with a DB-5MS column (30 m, 0.25 mmid, 0:1 lm film thickness). The oven temperature program was 140 °C (held for 1 min), increased at 15 °C/min to 220 °C and
Table 1 Food samples and consumption Food category
Samples
Consumption (g/day)
Lipid (%)
Meat Fish Dairy
Pork, belly Mackerel Cheese, slice Milk, whole
27.7 6.1 0.8 71.0
33.8 12.2 23.4 4.0
Report on 1998 National Health and Nutrition Survey (Dietary Intake Survey), Ministry of Health and Welfare, Korea, 1999.
Table 2 Results of determining dioxin-like compounds in selected Korean food (unit: pg/g ww) Compound
WHO-TEF
Pork
Mackerel
Cheese
Milk
2a
3a
1
2
3
1
2
3
1
2
3
NDc ND ND ND ND ND 0.88
ND ND ND ND ND ND 1.75
ND ND ND ND ND 0.23 0.10
ND 0.22 ND ND ND ND ND
ND ND 0.03 ND ND ND 0.41
ND ND ND ND 0.02 ND ND
ND ND ND ND ND ND 0.55
ND ND ND ND ND ND ND
ND ND ND ND ND ND ND
ND ND ND ND ND 0.09 ND
ND ND ND ND ND ND ND
ND ND ND ND ND ND ND
0.88
1.75
0.33
0.22
0.44
0.02
0.55
0.00
0.00
0.09
0.00
0.00
ND ND ND ND ND ND ND ND ND ND
ND ND ND ND ND ND ND ND ND ND
ND ND ND ND ND ND ND ND ND ND
1.50 0.29 0.82 0.20 ND ND ND 0.06 ND ND
2.00 0.36 1.81 0.08 0.12 ND ND 0.05 ND ND
1.18 0.24 1.00 ND ND ND ND ND ND ND
ND ND ND 0.03 0.02 ND ND ND ND ND
ND ND ND ND ND ND ND ND ND ND
ND ND ND ND ND ND ND ND ND ND
ND ND 0.10 ND ND 0.04 ND 0.06 ND ND
ND ND ND 0.03 ND ND ND 0.05 ND ND
ND ND ND 0.06 0.04 ND ND 0.03 ND ND
0.00
0.00
0.00
2.87
4.42
2.42
0.05
0.00
0.00
0.20
0.08
0.13
1.56 0.11 ND
3.49 ND ND
2.85 ND ND
34.02 13.32 3.41
34.48 19.47 4.97
25.64 13.31 3.12
1.11 0.28 ND
2.38 0.49 ND
1.41 ND ND
0.44 0.53 0.15
0.35 0.30 0.07
0.23 0.21 0.07
Total co-PCB
1.67
3.49
2.85
50.75
58.92
42.07
1.39
2.87
1.41
1.12
0.72
0.51
% Lipid
33.07
31.02
37.18
14.68
12.55
9.33
18.80
25.15
26.32
3.61
4.51
3.89
PCDD TEQ PCDF TEQ PCDD/PCDF TEQ PCB TEQ PCDD/PCDF/PCB TEQ
0.0001 0.0000 0.0001 0.0115 0.0116
0.0002 0.0000 0.0002 0.0004 0.0006
0.0023 0.0000 0.0023 0.0003 0.0026
0.2245 0.5942 0.8187 1.3698 2.1885
0.0029 1.1459 1.1488 1.9997 3.1485
0.0020 0.6294 0.6314 1.3649 1.9963
0.0001 0.0046 0.0047 0.0280 0.0327
0.0000 0.0000 0.0000 0.0496 0.0496
0.0000 0.0000 0.0000 0.0001 0.0001
0.0009 0.0559 0.0568 0.0545 0.1113
0.0000 0.0033 0.0033 0.0302 0.0335
0.0000 0.0107 0.0107 0.0213 0.0320
2378-TCDD (D4)b 12378-PeCDD (D5) 123478-HxCDD (D6) 123678-HxCDD (D6) 123789-HxCDD (D6) 1234678-HpCDD (D7) OCDD (D8)
1.0 1.0 0.1 0.1 0.1 0.01 0.0001
Total PCDD 2378-TCDF (F4)b 12378-PeCDF (F5) 23478-PeCDF (F5) 123478-HxCDF (F6) 123678-HxCDF (F6) 234678-HxCDF (F6) 123789-HxCDF (F6) 1234678-HpCDF (F7) 1234789-HpCDF (F7) OCDF (F8)
0.1 0.05 0.5 0.1 0.1 0.1 0.1 0.01 0.01 0.0001
Total PCDF 0
0
33 44 -TCB (77) 330 440 5-PeCB (126) 330 440 550 -HxCB (169)
0.0001 0.1 0.01
D. Choi et al. / Chemosphere 46 (2002) 1423–1427
1a
a
The number indicates three different sampling sites in Seoul. The letter D and F refer to dioxin and furan, and the number indicates the level of chlorination. c ND is assigned to zero value. b
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Fig. 1. Congener profiles in pg/g ww (left) and in pgWHO-TEQ/g ww (right).
useful as a reference to evaluate dietary based exposure assessment.
Acknowledgements This study was supported by a grant of the Korean Health 21 R&D Project, Ministry of Health and Welfare, Republic of Korea (HMP-98-P-0041).
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