Levels of Polychlorinated Biphenyls in Human Adipose Tissue

May 6, 2010 - A large number of samples (n = 303) were selected for a number of PCB congeners (n = 62) which were analyzed by highly sensitive gas ...
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Environ. Sci. Technol. 2010, 44, 4334–4340

Levels of Polychlorinated Biphenyls in Human Adipose Tissue Samples from Southeast China N A W A N G , †,‡ D E Y A N G K O N G , †,‡ D A O J I C A I , †,‡ L I L I S H I , * ,†,‡ YANZHONG CAO,§ GUOFANG PANG,§ AND RONGBIN YU| Nanjing Institute of Environmental Science, Ministry of Environmental Protection of China, Nanjing 210042, China, Key Laboratory of Pesticide Environmental Assessment and Pollution Control, Ministry of Environmental Protection of China, Nanjing 210042, China, Technological Center of Qin Huangdao Entry-Exit Inspection and Quarantine Bureau, Qinhuangdao 066002, China, and Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing 210029, China

Received December 22, 2009. Revised manuscript received April 22, 2010. Accepted April 22, 2010.

This paper presents a comprehensive study of polychlorinated biphenyl (PCB) levels and homologue profiles in human adipose tissues among residents of Southeast China. A large number of samples (n ) 303) were selected for a number of PCB congeners (n ) 62) which were analyzed by highly sensitive gas chromatography-tandem mass spectrometry (GC-MS/MS). The total mean PCB concentrations were 27.2 µg/kg fat (n ) 159) in Anhui Province and 17.2 µg/kg fat (n ) 144) in Jiangsu Province. A significant correlation was observed between age and PCB levels but not found between gender and PCB levels. The relationship between the environmental contaminant levels and the PCB concentration in adipose tissue was also investigated. It was found that the higher PCB concentrations in human adipose tissue were associated with the higher environmental PCB levels in the corresponding regions. The PCB homologue profiles of the human adipose tissue in China are different from those in the world, similarly to the different PCB homologue pattern between Chinese and global soils. The concept of the urban fractionation effect in the environment may be applicable to explain the PCB homologue profiles and PCB levels in the human adipose tissues collected from different provinces in China. The data presented in this study can provide useful information on human exposures to PCBs in the general population of Southeast China.

Introduction Polychlorinated biphenyl (PCB) has been used widely in heat exchangers and dielectric fluids, as stabilizers in paints, polymers, and adhesives, and as lubricants in various * Corresponding author phone: 86-25-8528-7074; fax: 86-25-85287074; e-mail: [email protected]. † Nanjing Institute of Environmental Science. ‡ Key Laboratory of Pesticide Environmental Assessment and Pollution Control. § Technological Center of Qin Huangdao Entry-Exit Inspection and Quarantine Bureau. | Nanjing Medical University. 4334

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industrial processes (1). As a consequence, PCB-containing products are present extensively in our daily life. PCBs comprise 209 congeners with different numbers and positions of the chlorine atoms on the biphenyl, which determines their stability and hydrophobic/lipophilic properties. Once introduced into the environment, the stable PCBs degrade very slowly and undergo transport among the various components of the ecosystem (2).With their high lipid solubility, PCBs bind readily to the lipid components in animal tissues and accumulate in organisms throughout the food chain (3). One of the important routes for human exposure is food consumption with products of animal origin. Additional exposure can occur from soils, drinking water, and indoor air and through various sources in workplaces (4, 5). PCBs are known to cause chronic reproductive effects, gastric disorders, and skin lesions in laboratory animals (6). In addition, the U.S. Environmental Protection Agency (1996) classified PCBs as probable human carcinogens (6). Because of the bioaccumulation and toxicity, PCBs were listed as 1 of the 12 persistent organic pollutants (POPs) established at the Stockholm convention in 2001 (7). Human samples such as breast milk, serum, and adipose tissues have been used as biomarkers to assess the extent of human exposure to PCBs. Most recent reports have been focused on breast milk and serum samples (8-13) due to their convenient and inexpensive availability. Because of the high lipid solubility it is important to monitor the levels of PCBs in the adipose tissues for exposure assessments. However, past PCB studies in human adipose have mostly been conducted in industrially developed countries/regions such as Europe and Japan. In recent years, some Chinese researchers have focused on PCB concentrations in environmental matrices, such as soil, air, water, and aquatic species (14-17), but investigations on human samples are rare. The aim of this study was to monitor PCB concentrations in human adipose tissue samples from individuals of Southeast China. The potential influence of age, sex, and habitat environment on the tissue PCB levels was also investigated. This is the first comprehensive study of PCB levels and homologue profiles in human adipose tissues in the southeast region of China.

Experimental Section Sample Collection and Storage. Collection of human adipose tissue samples were conducted by the Ethics Committee of Nanjing Medical University in China between April 2008 and June 2009. Three hundred and three human adipose tissue samples from patient abdominal operations were collected from the Second People’s Hospital of Hexian, Anhui Province, and Dachang Hospital of Nanjing, Jiangsu Province. All collected samples were placed into a glass vial in ice, labeled, and frozen to -70 °C until analysis. Donors of the adipose tissue samples had all lived in the area for at least 10 years at the time of sampling. Hexian is located in an agricultural region representing a rural environment in Anhui Province, whereas the sampling site of Dachang is in a chemical industrial area, thus representing an urban environment in Jiangsu Province (the map is given in Figure 1). The mean age of the studied subjects in Anhui Province was 46.13 years old, ranging from 15 to 91 years (with 16.23% 15-25 years old, 33.77% 26-45 years old, and 50.00% 46-91years old). The mean age of the studied subjects in Jiangsu Province was 36.49 years, ranging from 14 to 88 years old (with 25.00% 15-25 years old, 25.78% 26-45 years 10.1021/es9038775

 2010 American Chemical Society

Published on Web 05/06/2010

FIGURE 1. Map of the sampling sites. old, and 49.22% 46-91years old). After signing the informed consent, the subjects were interviewed in person by a trained researcher using a structured questionnaire for basic information as required by the study. Sample Preparation and Purification. A total of 5 ( 0.01 g of adipose tissue sample was extracted two times with 35 mL of acetonitrile (plus 15 g of anhydrous sodium sulfate). The concentrated supernatant, mixed with the internal standard solution,wasdilutedto10mLwithaceticether-hexamethylene (1:1). After membrane filtration (0.45 µm), the sample solution was cleaned by gel-permeation chromatography (GPC) to remove the lipid of the adipose sample. The elute was concentrated to about 1 mL in a 45 °C water bath with nitrogen before GC-MS/MS determination. Instrumental Analysis. A total of 62 PCB congeners were analyzed by GC-MS/MS using an Agilent 7890 gas chromatograph coupled with Waters Quattro micro triple quadrupole MS/MS, operating in EI mode. The final sample extract (1 µL) was injected in the splitless mode onto a DB-1701 capillary column (30 m × 0.25 mm × 0.25 µm; Agilent, USA) with helium as the carrier gas at a constant flow rate of 1.2 mL/min. The injector temperature was 290 °C, and the interface temperature was 250 °C. The oven was programmed to warm up from 40 (1 min) to 130 °C at a rate of 30 °C/min, then to 250 °C at a rate of 5 °C/min, and then to 300 °C (5 min) at a rate of 10 °C/min. The ionization energy was 70 eV. The mode of acquiring signal was Multiple Reaction Monitor (MRM) with which two parent-product ion transitions were monitored for quantification and qualitation (see Table 1). PCB Congener Options for Monitoring. Most studies on PCB exposure have focused on a few selected congeners rather than on the total profile of the congener (3, 18). In fact, for practical and economic reasons, several attempts have been made to minimize the number of PCB congeners to be monitored for assessment of general or occupational exposure (19, 20). Especially in China, the species of PCB

manufactured and utilized were limited, which indicates that it is not necessary to study all PCB congeners. According to the reports (20), there has been a general agreement in Europe that quantification of seven PCB congeners (i.e., marker PCBs 28, 52, 101, 118, 138, 153, and 180) offers a good picture of PCB exposure and two PCB congeners (i.e., marker PCBs 77 and 126) are suggested as toxic equivalency factors. A total of 62 PCB congeners including the seven marker PCBs and the two toxic equivalency factors were analyzed in this study. Quality Control and Assurance. The analytical method was subject to a whole validation process and showed no interference in the retention time (tR) region of the test substances. The levels of quantification (LOQ) of all PCBs in the lipid matrix were between 0.6 and 1.8 ng/g with recoveries at between 70.66% and 96.48%. The laboratory reagent, blank pig fat samples, and spiked pig fat samples were treated and analyzed using the same method as the actual samples (1 reagent blank, 1 matrix blank, and 1 control sample for every 10 samples). The relative standard deviation (RSD) of all 30 controls was between 5.82% and 9.69%, which showed that sample processing was stable. The chemistry laboratory at the Technological Center of Qin Huangdao Entry-Exit Inspection and Quarantine Bureau, in which the analytical work was conducted, is an accredited testing laboratory in China.

Results and Discussion PCBs Levels in Human Adipose Tissue. Table 2 shows the frequencies of detection and maximum and mean concentrations of 62 PCB congeners in human adipose samples collected from 2 regions of Southeast China. The results below the LOQ were assumed to be zero in our calculation. Only 20 PCB congeners were frequently detected in samples, which included all 7 marker PCBs (i.e., PCBs 28, 52, 101, 118, 138, 153, and 180). The total PCB concentration ranged between 0 and 387 µg/kg fat with a mean value of 27.2 µg/kg fat VOL. 44, NO. 11, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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TABLE 1. MRM Transitions of PCBs in the GC-MS/MS Method no.

name

retention time

quantification/qualitation ions

1 4 8 19 12 27 16 25 28 21 20 36 52 43 65 104 72 103 41 67 40 74 102 95 92 101 99 84 109 83 86 125 87 110 135 124 123 118 134 114 153 168 127 137 163 138 178 187 162 202 204 197 192 180 193 190 169 195 206 209

2-chlorobiphenyl 2,2′-dichlorobiphenyl 2,4′-dichlorobiphenyl 2,2′,6-trichlorobiphenyl 3,4-dichlorobiphenyl 2,3′,6-trichlorobiphenyl 2,2′,3-trichlorobiphenyl 2,3′,4-trichlorobiphenyl 2,4,4′-trichlorobiphenyl 2,3,4-trichlorobiphenyl 2,3,3′-trichlorobiphenyl 3,3′,5-trichlorobiphenyl 2,2′,5,5′-tetrachlorobiphenyl 2,2′,3,5-tetrachlorobiphenyl 2,3,5,6-tetrachlorobiphenyl 2,2′,4,6,6′-pentachlorobiphenyl 2,3′,5,5′-tetrachlorobiphenyl 2,2′,4,5′,6-pentachlorobiphenyl 2,2′,3,4-tetrachlorobiphenyl 2,3′,4,5-tetrachlorobiphenyl 2,2′,3,3′-tetrachlorobiphenyl 2,4,4′,5-tetrachlorobiphenyl 2,2′,4,5,6′-pentachlorobiphenyl 2,2′,3,5′,6-pentachlorobiphenyl 2,2′,3,5,5′-pentachlorobiphenyl 2,2′,4,5,5′-pentachlorobiphenyl 2,2′,4,4′,5-pentachlorobiphenyl 2,2′,3,3′,6-pentachlorobiphenyl 2,3,3′,4,6-pentachlorobiphenyl 2,2′,3,3′,5-pentachlorobiphenyl 2,2′,3,4,5-pentachlorobiphenyl 2′,3,4,5,6′-pentachlorobiphenyl 2,2′,3,4,5′-pentachlorobiphenyl 2,3,3′,4′,6-pentachlorobiphenyl 2,2′,3,3′,5,6′-hexachlorobiphenyl 2′,3,4,5,5′-pentachlorobiphenyl 2′,3,4,4′,5-pentachlorobiphenyl 2,3′,4,4′,5-pentachlorobiphenyl 2,2′,3,3′,5,6-hexachlorobiphenyl 2,3,4,4′,5-pentachlorobiphenyl 2,2′,4,4′,5,5′-hexachlorobiphenyl 2,3′,4,4′,5′,6-hexachlorobiphenyl 3,3′,4,5,5′-pentachlorobiphenyl 2,2′,3,4,4′,5-hexachlorobiphenyl 2,3,3′,4′,5,6-hexachlorobiphenyl 2,2′,3,4,4′,5′-hexachlorobiphenyl 2,2′,3,3′,5,5′,6-heptachlorobiphenyl 2,2′,3,4′,5,5′,6-heptachlorobiphenyl 2,3,3′,4′,5,5′-hexachlorobiphenyl 2,2′,3,3′,5,5′,6,6′-octachlorobiphenyl 2,2′,3,4,4′,5,6,6′-octachlorobiphenyl 2,2′,3,3′,4,4′,6,6′-octachlorobiphenyl 2,3,3′,4,5,5′,6-heptachlorobiphenyl 2,2′,3,4,4′,5,5′-heptachlorobiphenyl 2,3,3′,4′,5,5′,6-heptachlorobiphenyl 2,3,3′,4,4′,5,6-heptachlorobiphenyl 3,3′,4,4′,5,5′-hexachlorobiphenyl 2,2′,3,3′,4,4′,5,6-octachlorobiphenyl 2,2′,3,3′,4,4′,5,5′,6-nonachlorobiphenyl 2,2′,3,3′,4,4′,5,5′,6,6′-decachlorobiphenyl

11.04 13.39 14.91 15.77 16.55 16.94 17.40 17.93 18.22 18.60 18.81 19.24 19.56 19.57 19.67 19.84 20.52 20.73 20.93 21.22 21.43 21.57 21.72 21.97 22.46 22.66 22.77 22.92 23.24 23.42 23.53 23.66 23.87 24.29 24.58 24.83 24.97 25.13 25.31 25.45 25.67 25.69 26.27 26.43 26.86 26.87 26.93 27.25 27.70 28.07 28.30 28.58 28.96 29.23 29.31 30.19 30.48 31.18 32.44 32.78

188/152; 188/153 152/151; 152/150 224/152; 224/151 256/221; 256/186 222/152; 222/151 186/151; 186/150 256/186; 256/221 256/186; 256/151 256/151; 256/150 256/186; 186/151 186/151; 186/150 186/151; 186/150 220/150; 220/185 294/222; 294/150 292/222; 292/220 254/184; 254/219 292/220; 292/150 326/256; 326/184 292/220; 292/150 292/220; 292/185 292/220; 292/150 290/220; 290/150 254/184; 254/219 254/184; 254/219 184/149; 328/256 328/256; 328/293 326/184; 326/256 254/184; 254/219 326/184; 326/256 184/149; 184/123 326/291; 326/256 254/184; 254/219 328/256; 328/258 324/254; 324/184 325/290; 325/288 326/256; 326/254 328/256; 328/258 326/256; 326/254 325/290; 325/288 254/184; 254/219 290/218; 290/220 358/218; 358/288 326/256; 326/254 362/290; 362/292 360/290; 360/288 360/290; 360/288 396/326; 396/324 396/361; 396/359 358/288; 358/218 432/360; 432/362 432/360; 432/362 428/358; 428/356 396/324; 396/326 396/324; 396/326 324/254; 324/252 394/324; 394/322 358/288; 362/290 428/358; 428/356 466/394; 466/396 500/429; 500/428

(n ) 159) in Anhui Province and between 0 and 239 µg/kg fat with a mean value of 17.2 µg/kg fat (n ) 144) in Jiangsu Province. The concentrations of PCBs in human adipose tissues from different countries are shown in Figure 2, indicating that the concentrations of PCBs in human adipose tissues in these two Chinese southeastern sites are much lower than those in European countries (2, 6, 21, 23, 24) but comparable to those in Japan (22) and Chile (23). The reason could be attributed to the longer history and larger amount of industrial PCB production in the European countries 4336

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including Spain, Belgium, Turkey, Italy, and Sweden. The PCB levels of Southeast China were close to the data reported for Chile in 2000 as both are developing countries with a shorter history of and smaller PCB production and usage. It is worthwhile to note that the 11 PCB congeners studied in Japan (22) did not contain the 7 marker PCBs, and the total concentration of these 11 PCB congeners in Japan was about at the same level as in China for all 20 congeners, including all 7 marker PCBs. Moreover, differences in dietary structure between the European countries and China may have also

TABLE 2. Results of 62 PCB Congeners in Human Adipose Sample from 2 Regions of Southeast China location

Hexian, Anhui

Dachang, Jiangsu

age range (no. of sample)

15-91(159)

14-88(144)

PCB 001 PCB 004 PCB 008 PCB 012 PCB 016 PCB 019 PCB 020 PCB 021 PCB 025 PCB 027 PCB 028 PCB 036 PCB 040 PCB 041 PCB 043 PCB 052 PCB 065 PCB 067 PCB 072 PCB 074 PCB 077 PCB 083 PCB 084 PCB 086 PCB 087 PCB 092 PCB 095 PCB 099 PCB 101 PCB 102 PCB 103 PCB 104 PCB 109 PCB 110 PCB 114 PCB 118 PCB 123 PCB 124 PCB 125 PCB 126 PCB 127 PCB 134 PCB 135 PCB 137 PCB 138 PCB 153 PCB 162 PCB 163 PCB 168 PCB 169 PCB 178 PCB 180 PCB 187 PCB 190 PCB 192 PCB 193 PCB 195 PCB 197 PCB 202 PCB 204 PCB 206 PCB 209 SUM

frequency (%)

max value (ng/g)

mean value (ng/g)

frequency (%)

max value (ng/g)

mean value (ng/g)

0.00 77.99 0.00 0.00 0.00 0.00 0.00 37.74 0.00 4.40 35.85 0.00 0.00 0.00 0.00 0.63 0.00 0.00 0.00 61.01 0.00 0.00 19.50 0.00 0.00 0.00 0.00 0.00 47.17 0.00 0.00 0.00 0.00 0.00 0.00 87.42 0.00 0.00 0.00 0.00 44.65 0.00 0.00 0.00 93.71 68.55 0.00 98.74 69.81 0.00 0.00 64.78 4.40 34.59 32.08 14.47 0.00 0.00 0.63 0.00 0.00 0.00

0.00 29.43 0.00 0.00 0.00 0.00 0.00 11.90 0.00 2.26 12.77 0.00 0.00 0.00 0.00 2.15 0.00 0.00 0.00 53.51 0.00 0.00 6.20 0.00 0.00 0.00 0.00 0.00 12.91 0.00 0.00 0.00 0.00 0.00 0.00 43.53 0.00 0.00 0.00 0.00 8.35 0.00 0.00 0.00 50.52 31.29 0.00 43.80 42.33 0.00 0.00 9.18 1.62 5.42 12.61 6.33 0.00 0.00 1.21 0.00 0.00 0.00

0.00 4.31 0.00 0.00 0.00 0.00 0.00 0.51 0.00 0.07 0.76 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 1.30 0.00 0.00 0.26 0.00 0.00 0.00 0.00 0.00 0.94 0.00 0.00 0.00 0.00 0.00 0.00 2.56 0.00 0.00 0.00 0.00 0.48 0.00 0.00 0.00 3.26 3.28 0.00 3.16 3.31 0.00 0.00 1.17 0.06 0.32 1.06 0.35 0.00 0.00 0.01 0.00 0.00 0.00 27.17

0.00 38.89 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 31.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 36.81 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6.94 9.03 0.69 0.00 0.00 0.00 0.00 0.00 64.58 0.00 0.00 0.00 0.00 15.97 0.00 0.00 0.00 83.33 43.75 0.00 87.50 40.97 0.00 0.00 25.69 0.00 18.06 21.53 0.00 0.00 0.00 0.00 0.00 0.00 0.00

0.00 53.44 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 8.65 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4.82 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6.21 6.66 3.48 0.00 0.00 0.00 0.00 0.00 16.44 0.00 0.00 0.00 0.00 7.33 0.00 0.00 0.00 23.11 29.50 0.00 21.99 29.01 0.00 0.00 10.84 0.00 1.76 15.77 0.00 0.00 0.00 0.00 0.00 0.00 0.00

0.00 2.99 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.80 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.42 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.15 0.17 0.02 0.00 0.00 0.00 0.00 0.00 1.70 0.00 0.00 0.00 0.00 0.17 0.00 0.00 0.00 2.51 2.49 0.00 2.55 2.21 0.00 0.00 0.42 0.00 0.11 0.49 0.00 0.00 0.00 0.00 0.00 0.00 0.00 17.22

lead to the different PCB concentrations in the adipose tissues. European populations tend to have a larger consumption of meat and/or fish.

Age- and Gender-Dependent Accumulation of PCBs. In order to study the relation of the PCB body burden with age, mean values in the different age categories were calculated. VOL. 44, NO. 11, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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FIGURE 2. Comparative concentration of PCBs in human adipose tissues from different countries (Data sources: Spain, (21); Belgium, (2); Turkey, (6); Japan, (22); Italy and Chile, (23); Sweden, (24); China, this study).

FIGURE 3. Mean total PCB concentrations in different age groups in Anhui and Jiangsu Provinces. Three age groups have been chosen for the study: those less than 26 years old, the age group of 26-45 years old, and those older than 45 years old. Since PCBs were manufactured in China from 1965 to 1974 when they were banned, the age group of less than 26 years old represents the population who have lower exposure to PCBs, the age group of 26-45 years old represents the population who have medium exposure to PCBs, and the age group of more than 45 years old represents the population who have highest exposure to PCBs. Figure 3 shows the mean total PCB concentrations in three age groups for the two different regions studied. It is obvious from the figure that higher PCB levels were found in the older generation, indicating the trend of PCB accumulation in human bodies as exposure time increases. This result is in agreement with reports from other countries (2). The subjects in the age category from 25 to 60 years old were selected as the targets to study the correlation between PCB levels in the adipose samples and the gender of the donors. As seen in Figure 4, the total mean PCB concentrations of males tend to be higher than those of females. However, followed by the t test (R ) 0.05), the conclusion was that these differences were not statistically significant (t ) 1.99, p ) 0.13 for Anhui Province; t ) 2.07, p ) 0.29 for Jiangsu Province). This is also consistent with the findings of Kunisue et al. (25, 26). This may be attributed to that there was no significant difference in the metabolism function of PCBs and/or diets between the males and females.

Comparison of PCBs Levels in Human Adipose Tissues and in Soil PCBs Concentrations. Soil is usually the receptor and also the source of environmental pollutants. The levels for PCBs in surface soil across China have been previously reported (14, 17). The average soil concentration of a total of 51 PCBs among the 52 sites was 515 pg/g dw (dry weight), ranging 4338

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FIGURE 4. Mean total PCB concentrations in different gender groups in Anhui and Jiangsu Provinces. from 138 to 1840 pg/g dw. Compared to a global survey of background soils in 1998 (27), the Chinese soil level is approximately one-tenth of that found in the global background soils (5410 pg/g dw), mostly in soil of developed countries. The lower PCB levels in Chinese soils may be owing to the much lower production of PCBs in the country compared to global production (1 × 104 t to 1.3 × 106 t) and also to the much later production period (between 1965 and 1974) than the industrial countries. The pattern of much lower PCB concentrations in Chinese soil in comparison to soil in developed countries is also observed in human adipose tissues between these two regions. It is true that both soil and human adipose tissue can be treated as indicators for the contamination levels of the PCBs in the region. The report established by Ren and co-workers (17) also showed a declining PCB soil concentration gradient from east to west in China, which may be attributed to the fact that Southeast China is more developed than the western regions of the country. Among the southeastern regions, the contamination level of PCB in Zhejiang Province was relatively higher (17, 28, 29), which was an electronic waste (e-waste) recycling site in Southeast China. Meanwhile, the research conducted by Zhang et al. indicated that the pollution level of PCBs was comparatively lower in Jiangsu Province (16). Shen et al. (28) studied the PCBs level in human adipose tissue from Zhejiang Province of China. It was reported that the mean total 18 PCB concentration (n ) 24) was 136.8 ng/g, which is much higher than the values of 27.2 and 17.2 found in the present study. Therefore, it could be concluded that pollution levels of PCBs in Anhui and Jiangsu Provinces of our study were relatively lower than in Zhejiang Province. PCB Homologue Profiles. It is interesting to compare PCB homologue profiles in background/rural soils from China with those from other regions in the world. Ren and coworkers (17) found that heavier homologue groups were found predominantly in the global surface soils (most samples came from industrialized countries in which PCBs production had ceased long time ago), while the PCB profile was found to consist of major lighter homologues in the Chinese background/rural soils. The PCB homologue profiles in the Chinese background/rural soils were dominated by tri-PCB (∼44%) followed by di-PCB (∼28%). The PCB homologue profiles in global background soils were dominated by hexaPCB (∼46%) followed by penta-PCB (∼27%), which is closer to the PCB homologue profile in Chinese urban soil than that in Chinese background/rural soil (17). The PCB homologue profiles in the human tissue samples were also compared between China and European countries in the present study. In order to compare the data of various reports rigorously, seven marker PCBs were selected to generally represent the congener profiles. The seven marker

Acknowledgments We thank Nanjing Medical University, Second People’s Hospital of Hexian in Anhui Province, and Dachang Hospital of Nanjing in Jiangsu Province for sample collection. Thanks also go to the Technological Center of Qin Huangdao EntryExit Inspection and Quarantine Bureau for sample preparation. Financial support from the 2008 Commonweal and Environmental protection project of the Ministry of Environmental Protection of the People’s Republic of China (MEP), “Bioconcentration of Toxic Hazardous Substances in body adipose tissue and risk analysis on human health”, is appreciated. We acknowledge Daoji Cai and Guofang Pang, both academicians of the China Engineering Academy, for their strong support to this project.

Supporting Information Available How PCBs are like grasshoppers. This material is available free of charge via the Internet at http://pubs.acs.org.

Literature Cited

FIGURE 5. Comparison of PCB composition in the human adipose samples in different sites. (B). Composition normalized to the percent composition for CB-118, where all values for all sites are unity. (Data sources: Belgium, (2); Turkey, (6); Sweden, (24); Anhui and Jiangsu, this study; Zhejiang, (28)). PCBs comprise trichlorinated to heptachlorinated biphenyls, including both lighter and heavier homologues. Figure 5A gives the PCB composition in human adipose samples in different sites, where Figure 5B shows the composition normalized to the percent composition for CB118, where all values for all sites are unity. It is clear that the major PCB homologues in the human adipose tissue were penta-PCB to hepta-PCB for all countries. However, the percentage of hexa-PCB (PCB-153) and hepta-PCB (PCB180) was higher in the European countries than in China, while the proportion of tri-PCB (PCB-28) and penta-PCB (PCB-118) were much higher in China, consistent with the PCB homologue profiles in soil mentioned above. Highly chlorinated congeners may be good indicators of general exposure (20). The result is also consistent with the suggestion that a significant proportion of the total PCB body burden comes from dietary intake (30). It is known that Western populations are accustomed to a diet that is rich in fish, meat, and seafood, which are sources of PCBs (31), and the heavier PCBs have a stronger tendency to bind to lipid components in adipose tissues and accumulate in organisms. Comparing the results within China, it is interesting to find that while the compositions of PCB congeners were similar between Anhui and Jiangsu, that for Zhejiang Province was quite different, consisting of much higher amounts of heavy PCB congeners hexa-PCB (138 and 153) and heptaPCB (180). This may be explained by the “urban fractionation effect” (29). The heavier homologues have a larger tendency to stay near the sources, while the lighter ones travel further away from their source regions. Zhejiang Province is a more developed region for production of electronic appliances containing significant PCBs. Thus, the PCB in Zhejiang Province has an “urban” pattern, higher concentration levels in all PCB concentrations, and also higher compositions in heavier congeners/homologues.

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