Levels and concentration ratios of polychlorinated biphenyls and polybrominated diphenyl ethers in serum and breast milk in Japanese mothers.

Blood and/or breast milk have been used to assess human exposure to various environmental contaminants. Few studies have been available to compare the concentrations in one matrix with those in another. The goals of this study were to determine the current levels of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in Japanese women, with analysis of the effects of lifestyle and dietary habits on these levels, and to develop a quantitative structure-activity relationship (QSAR) with which to predict the ratio of serum concentration to breast milk concentration. We measured PBDEs and PCBs in 89 paired samples of serum and breast milk collected in four regions of Japan in 2005. The geometric means of the total concentrations of PBDE (13 congeners) in milk and serum were 1.56 and 2.89 ng/g lipid, respectively, whereas those of total PCBs (15 congeners) were 63.9 and 37.5 ng/g lipid, respectively. The major determinant of total PBDE concentration in serum and milk was the geographic area within Japan, whereas nursing duration was the major determinant of PCB concentration. BDE-209 was the most predominant PBDE congener in serum but not in milk. The excretion of BDE 209 in milk was lower than that of BDE 47 and BDE 153. QSAR analysis revealed that two parameters, calculated octanol/water partition and number of hydrogen-bond acceptors, were significant descriptors. During the first weeks of lactation, the predicted partitioning of PBDE and PCB congeners from serum to milk agreed with the observed values. However, the prediction became weaker after 10 weeks of nursing. Key words: breast milk, partition coefficient, polybrominated diphenyl ethers, polychlorinated biphenyls, quantitative structure-activity relationship, serum. Environ Health Perspect 114:1179-1185 (2006). doi:10.1289/ehp.9032 available via http://dx.doi.org/ [Online 18 April 2006]

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Polybrominated diphenyl ethers (PBDEs) have been found in human breast milk (Darnerud et al. 1998; Noren and Meironyte 1998, 2000). This route is a potential excretion pathway for the mother and a route of exposure to these compounds for the neonate. Thus, the monitoring of breast milk provides data for not only adult exposure but also neonatal exposure.

Recently, an examination of Swedish human milk samples from 1972 to 1997 revealed exponential increases in the concentrations of PBDEs (Darnerud et al. 1998; Noren and Meironyte 1998, 2000). Deca-BDE is used primarily in electrical and electronic applications (e.g., television housing, wire and cable insulation) and to a lesser extent in upholstery textiles. Penta-BDE was formerly used in flexible polyurethane foam for cushions. Octa-BDE was used in acrylonitrile-butadiene-styrene resins intended for business equipment housings. PBDEs are now found as residues in sediment (Song et al. 2004); in marine mammals, fish, and bird eggs (Covaci et al. 2005; Kajiwara et al. 2004; Watanabe et al. 2004); and in the breast milk, serum, whole blood, and adipose tissue of humans (Eslami et al. 2005; Koizumi et al. 2005; Lind et al. 2003; She et al. 2002; Takasuga et al. 2004). In contrast to PBDEs, banning the production and use of polychlorinated biphenyls (PCBs) in the 1970s has decreased PCB serum levels and dietary exposure to PCBs since the 1980s (Koizumi et al. 2005).

The aims of the present study were 2-fold. The first was to determine the current levels of PBDEs and PCBs in Japanese women of reproductive age and to analyze the effects of lifestyle and dietary habits on these levels. The second was to develop a quantitative structure-activity relationship (QSAR) model, which enables us to predict the relationship between serum and breast milk. The second aim addresses the importance of translatability between the serum and milk data.

Materials and Methods

Target populations. The present study was approved by the Ethics Committee of the Kyoto University Institutional Review Board, and appropriate written informed consent was obtained from all the participants before sample collection.

After obtaining formal informed consent, we collected blood and breast milk samples from mothers who had delivered and were lactating in maternity hospitals in four regions: Sendai city (population, 1 million) in Miyagi Prefecture, Takarazuka city (population, 250,000) in Hyogo Prefecture, Takayama city (population, 200,000) in Gifu Prefecture, and Shizunai-cho (population, 23,000) in Hokkaido Prefecture.

Collection of serum samples and breast milk samples. Milk samples were self-collected manually into breast pumps with glass containers at the individual hospitals and transferred to 50-mL polypropylene conical tubes (milk tube) that had been thoroughly rinsed with methanol and acetone before use; samples were kept frozen at -20[degrees]C. The target volume was > 20 mL from each mother per sample. Blood samples (10 mL) were collected into two 5-mL vacuum blood collection polypropylene tubes (Venoject II; TERUMO Inc., Tokyo, Japan) (blood tube) from cubital vein by physicians or nurses. The blood and milk samples were shipped within 48 hr to Kyoto University. The serum samples were separated by centrifugation at 3,000g for 15 min, transferred to new blood tubes, and stored at -20[degrees]C in the Department of Health and Environmental Sciences, Kyoto University Graduate School of Medicine, until analysis.

When the milk samples were collected, we asked the mothers to fill out questionnaires that contained necessary items for milk surveillance (LaKind et al. 2004) and sources of exposure to PBDEs (Ohta et al. 2002; Sakai et al. 2001; Schecter et al. 2005; Wilford et al. 2003), including the duration of lactation, parity, residential history within the previous 5 years, lifestyle and habits, and indoor environment (Supplemental Table 1; available online at http://www.ehponline.org/docs/2006/9032/suppl.pdf).

We prepared eight field blanks per site, each consisting of an empty milk tube and an empty blood tube. In addition, we prepared eight milk tube/blood tube pairs filled with 5 mL of distilled water at the sampling site as field operational blanks. All the blank samples were sent to Kyoto University and run through complete extraction, cleanup, and analysis procedures.

Serum extraction. The internal standard from mono- to deca-[.sup.13.C.sub.12]-PBDE and mono- to deca-[.sup.13.C.sub.12]-PCB was spiked in the serum (3 g) and extracted by liquid-liquid extraction following the method of Takasuga et al. (2004, 2006). Briefly, in the serum spiked with internal standard, 3 mL ammonium sulfate, 1 mL ethanol, and 2 mL hexane were mixed and extracted twice. The final extract was washed with hexane-washed water, dehydrated with sodium sulfate, and concentrated to 5 mL for further cleanup.

Milk extraction. The internal standard from mono- through deca-[.sup.13.C.sub.12]-PBDE and mono- to deca-[.sup.13.C.sub.12]-PCB was spiked in the milk (3 g) and extracted by liquid-liquid extraction. Briefly, in the milk spiked with internal standard, 1 mL saturated potassium oxalate, 2 mL ethanol, 2 mL diethyl ether, and 1 mL hexane were mixed and extracted twice. The final extract was washed with 1 mL of 5% sodium chloride and then dehydrated with sodium sulfate and concentrated to 5 mL for further cleanup.

Cleanup of serum and milk. The 5-mL extract from serum or milk was subjected to multilayer Florisil silica gel column cleanup (Takasuga et al. 2004, 2006). The multilayer cleaned samples were further concentrated to the injection volume by nitrogen purge.

Identification and quantification of PBDEs and PCBs. We used high-resolution gas chromatography (HRGC; HP6890, Agilent)/high-resolution mass spectrometry (HRMS; Autospec Ultima; Micromass, Cary, NC, USA) for analysis of PBDEs and PCBs. Details on the HRGC/HRMS program are reported elsewhere (Takasuga et al. 2004, 2006). Briefly, for PBDE analysis we used either a BP-1 [15 m x 0.25 mm i.d. (0.1 [micro]m); SGE Analytical Science Pty. Ltd., Austin, TX, USA] column or a ENV-5MS [15 m x 0.25 mm i.d. (0.1 [micro]m)] column. The column was used with a temperature program of 120[degrees]C (1 min), increased 20[degrees]C/min to 160[degrees]C (0 min), 10[degrees]C/min to 260[degrees]C (0 min), and 20[degrees]C/min to 300[degrees]C (8 min). For analysis of PCBs, we used an HT-8 PCB column (60 m x 0.25 mm i.d.; SGE Analytical), which was used with an initial temperature of 150[degrees]C (0 min), increased 20[degrees]C/min to 200[degrees]C (0 min), 5[degrees]C/min to 260[degrees]C (0 min), and 10[degrees]C/min to 300[degrees]C (11.5 min). We used an on-column injection program with a 2-[micro]L sample injection volume and with a resolution of M/[DELTA]M > 10,000 (10% valley). We determined the individual and total concentrations of 13 PBDE congeners [[SIGMA]PBD[E.sub.13]; International Union of Pure and Applied Chemistry (IUPAC) congeners 15, 28, 47, 99, 100, 153, 154, 183, 196, 197, 206, 207, and 209] and 15 PCB congeners ([SIGMA]PC[B.sub.15]; IUPAC congeners 74, 99, 118, 138, 146, 153, 156, 163/164, 170, 180, 182/187, 194, 199, 206, and 209).

The limit of detection (LOD) for each PCB congener was 1 pg/g in both serum and breast milk. The LOD of each PBDE congener in serum and milk was between 0.2 and 2 pg/g for di-BDE to hepta-BDE and between 0.3 and 2 pg/g for octa-BDE to deca-BDE. The serum and milk concentrations of PCBs and PBDEs were expressed as nanograms per gram lipid. The lipid content in the serum samples was estimated from the total cholesterol and triglyceride concentrations (Phillips et al. 1989). The lipid content of the milk samples was determined from 2 mL crude extracts by gravimetric method.

Quality assurance and quality control. PBDE and PCB (native as well as [.sup.13.C.sub.12]-labeled) standard solutions that contained the major congeners of mono-BDE or mono-CB to deca-BDE or deca-CB (> 95% pure) were purchased from Wellington Laboratories (Guelph, Ontario, Canada). The average recovery of individual PBDE congeners was 54-84% in serum (n = 100) and 54-103% in milk (n = 100), and the average recovery of PCB congeners was 61-79% in serum (n = 100) and 68-115% in milk (n = 100). The coefficient of variation for each determination was within 15% for both PBDEs and PCBs.

For all field blanks and field operational blanks, all PBDE and PCB congeners were < LOD. Operational blank tubes filled with 5 mL distilled water in an analytical laboratory (Shimadzu Techno-Research Inc., Kyoto, Japan) were also prepared for each eight-sample batch. These operational blanks were < LOD for all PBDE and PCB congeners in both the serum and milk batches. Thus, we did not correct the results for background levels.

Structure-activity relationship. For the QSAR analysis, we chose congeners that were detected in > 50% of both the serum and milk samples. Theoretical molecular descriptors for the compounds, which included constitutional descriptors, atom-centered fragments, and molecular properties, such as hydrophilicity, molar refractivity, polar surface area, and octanol/water partition coefficient ([K.sub.ow]), were calculated using Dragon software (version 5.0; Milano Chemo Metrics and QSAR Research Group, Milan, Italy) and ADMET Predictor 1.2.3 (Simulations Plus, Lancaster, CA, USA). The [K.sub.ow] calculated by Hansch's method (CLogP) and the molar refractivity calculated by Hansch's method (CMR) were calculated using Web applications provided by Daylight Chemical Information Systems (Aliso Viejo, CA, USA). Descriptors that had a bivariate correlation > 0.70 were removed.

We performed a stepwise multiple linear regression analysis using the SAS statistical package (version 8.2; SAS Institute Inc., Cary, NC, USA). All independent variables in the regressions had a significance of at least 95%, based on Student's t-score.

Statistical analysis. Statistical analyses were conducted after logarithmic transformation of the concentrations of the PBDEs and PCBs. We tested differences between means by analysis of variance (ANOVA) or Student's t-test when appropriate. A stepwise multiple regression analysis was used to explore determinants for the serum and milk levels of contaminants using a forward-backward stepwise regression model (F-statistic to enter and stay in the model with a p-value of < 0.25). We evaluated the determinants for PBDEs and PCBs in serum and breast milk using a conservative approach based on multiple comparisons of the questionnaire items. Thus, a p-value of < 0.01 was considered significant in the multiple regression analysis for the questionnaire items. For the other analyses, a p-value of < 0.05 was considered significant. All statistical analyses were carried out with SAS software.

Results

Demographic features of the participants. On the whole, there were 20 participants from Hokkaido, 40 from Miyagi, 20 from Gifu, and 9 from Hyogo. The ages of the participants ranged from 20 to 43 years (mean [+ or -] SD, 30.1 [+ or -] 4.6 years). The results of the questionnaires are summarized in Table 1.

Determination of PBDEs and PCBs in serum and milk. The concentrations of some congeners in the human samples were < LOD. We treated these samples as 0 pg/g lipid when we calculated the total amount.

The distributions of [SIGMA]PBD[E.sub.13] in serum and milk followed log-normal distributions (Kolmogorov-Smirnov-Lilliefors test, p > 0.05). The geometric mean (GM) values for the total amounts of [SIGMA]PBD[E.sub.13] in the milk and serum samples were 1.56 and 2.89 ng/g lipid, respectively (Table 2). The PBDE congener levels and detection rates for milk and serum are available online (Supplemental Tables 2 and 3, respectively; http://www.ehponline.org/docs/2006/9032/suppl.pdf). BDE-209 was the predominant congener in serum and accounted for 38% of the total PBDEs but was a minor congener in milk and accounted for 8% of the [SIGMA]PBD[E.sub.13] (Figure 1A). In milk, BDE-47 and BDE-153 were the major congeners and accounted for 28 and 23% of the total PBDEs, respectively.

The distributions of the [SIGMA]PC[B.sub.15] in serum and milk also followed log-normal distributions (Kolmogorov-Smirnov-Lilliefors test, p > 0.05). The GM values for [SIGMA]PC[B.sub.15] in the milk and serum samples were 63.9 and 37.5 ng/g lipid, respectively (Table 2). The PCB congener levels and detection rates for milk and serum are available online (Supplemental Tables 4 and 5, respectively; http://www.ehponline.org/docs/2006/9032/suppl.pdf). CB-153, CB-138, and CB-180 were the major congeners in both milk and serum (30, 17, and 13% of the total for milk and 28, 16, and 15% of the total for serum, respectively) (Figure 1B).

It should be noted that approximately the same concentrations of the lighter PBDEs (e.g., BDE-47) are present in serum and milk, but BDE-209 is found at 10 times lower concentrations in milk than in serum (Supplemental Tables 2 and 3; available online at http://www.ehponline.org/docs/2006/9032/suppl.pdf). Likewise, almost double the serum concentration of CB-153 is found in milk, whereas more than double the milk concentration of CB-209 is found in serum (Supplemental Tables 4 and 5; available online at http://www.ehponline.org/docs/2006/9032/suppl.pdf).

Determinants for PCBs and PhBDEs in serum and milk. We found significant correlations between [SIGMA]PC[B.sub.15] and [SIGMA]PBD[E.sub.13] levels in both milk and serum ([r.sup.2] = 0.194, p < 0.0001 for milk; [r.sup.2] = 0.1808, p < 0.0001 for serum). There were also significant geographic differences in [SIGMA]PBD[E.sub.13] concentrations in milk and serum (ANOVA, p = 0.00095 and p = 0.00030, respectively; Table 2). The GM for [SIGMA]PBD[E.sub.13] in the milk samples was higher for Hokkaido than for the other areas [Tukey's honest significant difference (HSD) test, p < 0.05], whereas the GM for [SIGMA]PBD[E.sub.13] in serum samples was higher in Miyagi than in Gifu (Tukey's HSD test, p < 0.05). The PCB levels also exhibited geographic differences (ANOVA, p = 0.0029 for milk and p < 0.0001 for serum; Table 2). The GMs for [SIGMA]PBD[E.sub.13] in both milk and serum samples were higher in Miyagi and Hyogo than in Gifu (Tukey's HSD test, p < 0.05).

Multiple regression analysis revealed that the geographic factor was the primary determinant for the PBDE levels in both milk and serum (data not shown). In contrast, nursing duration was the significant determinant for PCB levels in both serum and milk (data not shown). To investigate the possible association between hospitals and nursing durations, we tested whether nursing duration was a determinant for PBDE or PCB levels within a single hospital. The nursing duration was correlated with the [SIGMA]PBD[E.sub.13] in serum in Miyagi (n = 38, Kendall's [tau] = -0.266, p = 0.0187) and the [SIGMA]PC[B.sub.15] in both serum and milk in Miyagi (n = 38, Kendall's [tau] = -0.426, p = 0.0002, and Kendall's [tau] = -0.312, p = 0.0059, respectively; data not shown).

QSAR analysis. BDE-154, BDE-183, BDE-196, and BDE-206 were eliminated from the analysis because of their low detection rates in serum and/or milk (< 50%). In the first step, we calculated the mean ratios of milk concentrations (nanograms per gram lipid) to serum concentrations (nanograms per gram lipid) for individual congeners from milk and serum as surrogates for their partition coefficients (Supplemental Table 6; available online at http://www.ehponline.org/docs/2006/9032/suppl.pdf). Using these mean ratios, we then applied a multiple linear regression analysis using various descriptors for individual PCB and PBDE congeners. The descriptors that have been used for QSAR analysis include hydrophobicity [log [K.sub.ow], CLogP, (octanol/water partition coefficient calculated by Hansch's method), and MLogP (octanol/water partition coefficient calculated by Moriguchi's method)], size [MW (molecular weight) and MgVol (molar volume calculated by McGowan's method)], polarizability [CMR, (molar refractivity calculated by Hansch's method), AMR (calculated by Ghose and Crippen's method), and PolarizG (polarizability calculated by Glen's method)], and constitutional descriptors [TPSA (topologic polar surface area), HBA (number of hydrogen-bond acceptors), nCL (number of chlorines), and nBR (number of bromines)] (Table 3) (Abraham and McGowan 1987; Ghose and Crippen 1987; Glen 1994; Leo et al. 1971; Moriguchi et al. 1994).

Table 3 summarizes the correlation coefficients between pairs of the descriptors, together with regression coefficients for each descriptor. Regarding PCB and PBDE congeners, the descriptors for hydrophobicity (log [K.sub.ow], CLogP, and MLogP), molecular size (MW and MgVol), and polarizability (CMR, AMR, and PolarizG) were collinear, and each correlated well with the milk/serum partition coefficient (log P). We explored the combination of the descriptors that exhibited the highest multiple regression coefficient (r) and obtained the following equation:

log P = 1.664 - 0.1871 ClogP - 0.2092 HBA (r = 0.955, F = 108.8, p < 0.001). [1]

Because partition coefficients have been reported to be dependent on the nursing period (LaKind et al. 2004), we tested the relationship between the predicted and observed mean partition coefficients for three nursing durations (Figure 2). For nursing durations [less than or equal to] 10 weeks, the partition coefficients predicted by the QSAR analysis agreed with the observed values. However, the coefficient of x was smaller for nursing durations > 10 weeks, suggesting that the prediction became weaker for longer nursing periods.

Discussion

In this article we have reported the current levels of [SIGMA]PBD[E.sub.13], including deca-BDE (BDE-209), in serum and milk from Japanese mothers. We found that BDE-209 was the most abundant congener in serum but a minor congener in milk. Its abundance in serum suggests that wide industrial use of BDE-209 may result in exposure (Watanabe and Sakai 2003). Thus, low partitioning of this congener from serum to milk might have resulted in the underestimation of human adult exposure to deca-BDE, if the exposure monitoring system used was dependent solely on milk surveillance.

Table 4 shows the recent data on PBDEs in breast milk and serum from 12 countries. The current total PBDE levels in Japan are significantly lower than those in most Western countries (Kalantzi et al. 2004; Lopez et al. 2004; Mazdai et al. 2003; Morland et al. 2005; Pereg et al. 2003; Ryan and Patry 2000; Ryan and van Oostdam 2004; Schecter et al. 2003; She et al. 2004; Sjodin et al. 2004) and appear to be approximately equal to those of Sweden (Guvenius et al. 2003; Kalantzi et al. 2004; Lind et al. 2003; Sjodin et al. 1999), Spain (Schuhmacher et al. 2004), Italy (Ingelido et al. 2004), Germany (Vieth et al. 2004), and Finland (Strandman et al. 2000). Even for BDE-209, exposure was relatively lower in Japan than in the United States and Mexico. Even taking into account the variations in the measured PBDE congeners, the above argument holds true.

We investigated factors that may influence the PBDE or PCB levels in serum and milk. We found that the geographic factor was the major determinant of PBDE levels in Japan. In contrast, current nursing duration was most significant for PCBs. Because the current nursing duration was confounded by the variation in the timing of milk collection in the different hospitals, one could argue that the apparent differences might be explained partly by the geographic factor. However, the current nursing duration remained significant for both PBDEs and PCBs even within sample series from a single hospital, indicating that their concentrations became lower as the nursing period became longer, as previously reported by others (Wilson et al. 1985).

Human milk or serum surveillance is typically performed to monitor temporal changes in the concentrations of environmental chemicals or to compare the concentrations of environmental chemicals among different populations. However, only a few trials to bridge the values for serum and milk have been carried out for environmental chemicals (Greizerstein et al. 1999). In contrast, there have been several models and methods for predicting drug transfer into human milk (Fleishaker 2003) using the QSAR approach. We applied the same approach for PCBs and PBDEs. The analysis revealed that CLogP and HBA are sufficient predictors of the transfer from serum to milk. For PBDEs, the oxygen atom bridging two halogenated aryl groups, which functions as a hydrogen-bond acceptor, appeared to reduce the transfer from serum to milk. On the other hand, the model only weakly predicted the partition coefficients in the later stages of nursing ([greater than or equal to] 11 weeks), as suggested by Wilson et al. (1985). With the limitation of the nursing period as a mode of prediction by Equation 1, the present model can be practically used for translating the concentrations in the two samples.

Conclusion

BDE-209 was the PBDE detected at the highest concentration in serum of Japanese lactating women, but its excretion in milk was lower than that of the lower brominated diphenyl ethers BDE-47 and BDE-153. Geographic location within Japan and the duration of nursing were discernible determinants for levels of PBDEs and PCBs in human serum and milk, respectively. The levels of PBDEs in Japan were much lower than those in the United States, Canada, and Mexico but similar to those in European countries. The application of QSAR for the structure-partition relationship revealed that the values for serum and milk are translatable to each other.

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Sjodin A, Hagmar L, Klasson-Wehler E, Kronholm-Diab K, Jakobsson E, Bergman A. 1999. Flame retardant exposure: polybrominated diphenyl ethers in blood from Swedish workers. Environ Health Perspect 107:643-648.

Sjodin A, Jones RS, Focant JF, Lapeza C, Wang RY, McGahee EE III, et al. 2004. Retrospective time-trend study of polybrominated diphenyl ether and polybrominated and polychlorinated biphenyl levels in human serum from the United States. Environ Health Perspect 112:654-658.

Song W, Ford JC, Li A, Mills WJ, Buckley DR, Rockne KJ. 2004. Polybrominated diphenyl ethers in the sediments of the Great Lakes. 1. Lake Superior. Environ Sci Technol 38:3286-3293.

Strandman T, Koistinen J, Vartiainen T. 2000. Polybrominated diphenyl ethers (PBDEs) in placenta and human milk. Organohalogen Compounds 47:61-64.

Takasuga T, Senthilkumar K, Matsumura T, Shiozaki K, Sakai S. 2006. Isotope dilution analysis of polychlorinated biphenyls (PCBs) in transformer oil and global commercial PCB formulations by high resolution gas chromatography-high resolution mass spectrometry. Chemosphere 62:469-484.

Takasuga T, Senthilkumar K, Takemori H, Ohi E, Tsuji H, Nagayama J. 2004. Impact of fermented brown rice with Aspergillus oryzae (FEBRA) intake and concentrations of polybrominated diphenylethers (PBDEs) in blood of humans from Japan. Chemosphere 57:795-811.

Thomsen C, Lundanes E, Becher G. 2002. Brominated flame retardants in archived serum samples from Norway: a study on temporal trends and the role of age. Environ Sci Technol 36:1414-1418.

Vieth B, Herrmann T, Mielke H, Ostermann B, Papke O, Rudiger T. 2004. PBDE levels in human milk: the situation in Germany and potential influencing factors--a controlled study. Organohalogen Compounds 66:2643-2648.

Watanabe I, Sakai S. 2003. Environmental release and behavior of brominated flame retardants. Environ Int 29:665-682.

Watanabe K, Senthilkumar K, Masunaga S, Takasuga T, Iseki N, Morita M. 2004. Brominated organic contaminants in the liver and egg of the common cormorants (Phalacrocorax carbo) from Japan. Environ Sci Technol 38:4071-4077.

Weiss J, Meijer L, Sauer P, Linderholm L, Athanassiadis I, Bergman A. 2004. PBDE and HBCDD levels in blood from Dutch mothers and infants--analysis of a Dutch Groningen Infant Cohort. Organohalogen Compounds 66:2677-2682.

Wilford BH, Thomas GO, Alcock RE, Jones KC, Anderson DR. 2003. Polyurethane foam as a source of PBDEs to the environment. Organohalogen Compounds 61:219-222.

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Kayoko Inoue, (1*) Kouji Harada, (1*) Katsunobu Takenaka, (2) Shigeki Uehara, (3) Makoto Kono, (4) Takashi Shimizu, (5) Takumi Takasuga, (6) Kurunthachalam Senthilkumar, (6) Fumiyoshi Yamashita, (7) and Akio Koizumi (1)

(1) Department of Health and Environmental Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan; (2) Department of Neurosurgery, Takayama Red Cross Hospital, Takayama, Japan; (3) Department of Obstetrics and Gynecology, Tohoku Kosai Hospital, Sendai, Japan; (4) Kono Obstetrics and Gynecology Clinic, Shizunai, Japan; (5) Shimizu Woman's Clinic, Takarazuka, Japan; (6) Shimadzu Techno-Research Inc., Kyoto, Japan; (7) Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan

Address correspondence to A. Koizumi, Department of Health and Environmental Sciences, Kyoto University Graduate School of Medicine, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan. Telephone: [phone]. Fax: [phone]. E-mail: [e-mail]

*These authors contributed equally to this study.

Supplemental Material is available online at http://www.ehponline.org/docs/2006/9032/suppl.pdf

This study was supported primarily by a Grant-in-Aid for Health Sciences Research from the Ministry of Health, Labor, and Welfare of Japan (H15-Chemistry-004), but also received funding from and by the Nippon Life Insurance Foundation (Environment-04-08).

The authors declare they have no competing financial interests.

Received 21 January 2006; accepted 18 April 2006.

Table 1. Characteristics of the participants.

                          Total               Hokkaido

No. of participants       89                  20
Age (years)
  20-29                   45                  13
  30-39                   40                   6
  40-49                    4                   1
  Mean [+ or -] SD        30.1 [+ or -] 4.6   27.7 [+ or -] 4.8
Parity (mean               1.45 [+ or -] 0.6   1.55 [+ or -] 0.8
  [+ or -] SD)
Nursing week at milk      13.6 [+ or -] 22.1   1.55 [+ or -] 1.6
  collection (mean
  [+ or -] SD)
Occupation [no. (%)]
  Housewife               50 (56.2)           13 (65.0)
  Office worker           16 (18.0)            1 (5.0)
  Technical professional  22 (24.7)            5 (25.0)
  Farmer                   1 (1.1)             1 (5.0)
Use electronic equipment [no. (%)]
  Personal computer
    Frequent use          43 (48.3)            4 (20.0)
    Rare use              46 (51.7)           16 (80.0)
  Mobile phone
    Frequent use          58 (65.2)           13 (65.0)
    Rare use              31 (34.8)            7 (35.0)
  Television
    Frequent use          69 (77.5)           17 (85.0)
    Rare use              20 (22.5)            3 (15.0)
Household furnishings [no. (%)]
  Carpet
    Frequent use          65 (73.0)           18 (90.0)
    Rare use              24 (27.0)            2 (10.0)
  Cushions
    Frequent use          52 (58.4)           10 (50.0)
    Rare use              37 (41.6)           10 (50.0)
  Sofa
    Frequent use          66 (74.2)           18 (90.0)
    Rare use              23 (25.8)            2 (10.0)
  Curtains
    Frequent use          81 (91.0)           18 (90.0)
    Rare use               8 (9.0)             2 (10.0)
  Blinds
    Frequent use          42 (47.2)           10 (50.0)
    Rare use              47 (52.8)           10 (50.0)
Fish consumption (> once/week) [no. (%)]
  Yellowtail and young
    yellowtail
    Yes                   14 (15.7)            0 (0.0)
    No                    75 (84.3)           20 (100.0)
  Mackerel
    Yes                   34 (38.2)            5 (25.0)
    No                    55 (61.8)           15 (75.0)
  Salmon
    Yes                   56 (62.9)           13 (65.0)
    No                    33 (37.1)            7 (35.0)
Smoking status [no. (%)]
  Nonsmoker               56 (62.9)           10 (50.0)
  Ex-smoker               25 (28.1)            8 (40.0)
  Current smoker           4 (4.5)             2 (10.0)
  Passive smoker           4 (4.5)             0 (0.0)
Alcohol consumption [no. (%)]
  Nondrinker              35 (39.3)           12 (60.0)
  Ex-drinker              48 (53.9)            7 (35.0)
  Current drinker          6 (6.7)             1 (5.0)

                          Miyagi              Gifu

No. of participants       40                  20
Age (years)
  20-29                   19                  10
  30-39                   20                   9
  40-49                    1                   1
  Mean [+ or -] SD        30.7 [+ or -] 4.1   30.0 [+ or -] 4.3
Parity (mean               1.33 [+ or -] 0.5   1.55 [+ or -] 0.7
  [+ or -] SD)
Nursing week at milk      12.0 [+ or -] 18.6  33.4 [+ or -] 30.3
  collection (mean
  [+ or -] SD)
Occupation [no. (%)]
  Housewife               21 (52.5)            9 (45.0)
  Office worker           11 (27.5)            4 (20.0)
  Technical professional   8 (20.0)            7 (35.0)
  Farmer                   0                   0
Use electronic equipment [no. (%)]
  Personal computer
    Frequent use          27 (67.5)            8 (40.0)
    Rare use              13 (32.5)           12 (60.0)
  Mobile phone
    Frequent use          26 (65.0)           15 (75.0)
    Rare use              14 (35.0)            5 (25.0)
  Television
    Frequent use          29 (72.5)           17 (85.0)
    Rare use              11 (27.5)            3 (15.0)
Household furnishings [no (%)]
  Carpet
    Frequent use          28 (70.0)           12 (60.0)
    Rare use              12 (30.0)            8 (40.0)
  Cushions
    Frequent use          24 (60.0)           10 (50.0)
    Rare use              16 (40.0)           10 (50.0)
  Sofa
    Frequent use          30 (75.0)           11 (55.0)
    Rare use              10 (25.0)            9 (45.0)
  Curtains
    Frequent use          37 (92.5)           17 (85.0)
    Rare use               3 (7.5)             3 (15.0)
  Blinds
    Frequent use          19 (47.5)            9 (45.0)
    Rare use              21 (52.5)           11 (55.0)
Fish consumption (> once/week) [no. (%)]
  Yellowtail and young
    yellowtail
    Yes                    4 (10.0)            8 (40.0)
    No                    36 (90.0)           12 (60.0)
  Mackerel
    Yes                   12 (30.0)           10 (50.0)
    No                    28 (70.0)           10 (50.0)
  Salmon
    Yes                   30 (75.0)            9 (45.0)
    No                    10 (25.0)           11 (55.0)
Smoking status [no. (%)]
  Nonsmoker               27 (67.5)           11 (55.0)
  Ex-smoker               10 (25.0)            7 (35.0)
  Current smoker           1 (2.5)             1 (5.0)
  Passive smoker           2 (5.0)             1 (5.0)
Alcohol consumption [no. (%)]
  Nondrinker              12 (30.0)            7 (35.0)
  Ex-drinker              26 (65.0)           10 (50.0)
  Current drinker          2 (5.0)             3 (15.0)

                          Hyogo               p-Value

No. of participants        9
Age (years)
  20-29                    3                    0.66
  30-39                    5
  40-49                    1
  Mean [+ or -] SD        33.3 [+ or -] 4.5     0.01
Parity (mean               1.56 [+ or -] 0.5    0.43
  [+ or -] SD)
Nursing week at milk       3.11 [+ or -] 0.9  < 0.0001*
  collection (mean
  [+ or -] SD)
Occupation [no. (%)]
  Housewife                7 (77.8)             0.21
  Office worker            0
  Technical professional   2 (22.2)
  Farmer                   0
Use electronic equipment [no. (%)]
  Personal computer
    Frequent use           4 (44.4)             0.004*
    Rare use               5 (55.6)
  Mobile phone
    Frequent use           4 (44.4)             0.47
    Rare use               5 (55.6)
  Television
    Frequent use           6 (66.7)             0.36
    Rare use               3 (33.3)
Household furnishings [no (%)]
  Carpet
    Frequent use           7 (77.8)             0.14
    Rare use               2 (22.2)
  Cushions
    Frequent use           8 (88.9)             0.15
    Rare use               1 (11.1)
  Sofa
    Frequent use           7 (77.8)             0.08
    Rare use               2 (22.2)
  Curtains
    Frequent use           9 (100.0)            0.46
    Rare use               0 (0.0)
  Blinds
    Frequent use           4 (44.4)             0.99
    Rare use               5 (55.6)
Fish consumption (> once/week) [no. (%)]
  Yellowtail and young
    yellowtail
    Yes                    2 (22.2)             0.003*
    No                     7 (77.8)
  Mackerel
    Yes                    7 (77.8)             0.03
    No                     2 (22.2)
  Salmon
    Yes                    4 (44.4)             0.30
    No                     5 (58.6)
Smoking status [no. (%)]
  Nonsmoker                8 (88.9)             0.17
  Ex-smoker                0 (0.0)
  Current smoker           0 (0.0)
  Passive smoker           1 (11.1)
Alcohol consumption [no. (%)]
  Nondrinker               4 (44.4)             0.21
  Ex-drinker               5 (55.6)
  Current drinker          0 (0.0)

*p < 0.01; p-values were calculated for continuous values by ANOVA and
for categorical values for the chi-square test or Fisher's exact test.

Table 2. Concentrations (ng/g lipid) of PBDEs or PCBs in human milk or
serum samples.

                No. of
Measure/area    participants  GM (GSD) (a)       Mean [+ or -] SD

PBDE in milk
  Hokkaido      20             2.23 (1.47) (A)     2.39 [+ or -] 0.94
  Miyagi        40             1.42 (1.56) (B)     1.55 [+ or -] 0.65
  Gifu          20             1.45 (1.51) (B)     1.58 [+ or -] 0.71
  Hyogo          9             1.30 (1.65) (B)     1.45 [+ or -] 0.70
    Total       89             1.56 (1.59)         1.74 [+ or -] 0.81
PBDE in serum
  Hokkaido      20             2.75 (1.47) (AB)    2.93 [+ or -] 1.04
  Miyagi        40             3.64 (1.66) (B)     4.21 [+ or -] 3.14
  Gifu          20             2.06 (1.55) (A)     2.24 [+ or -] 0.92
  Hyogo          9             2.52 (1.76) (AB)    2.84 [+ or -] 1.32
    Total       89             2.89 (1.68)         3.34 [+ or -] 2.37
PCB in milk
  Hokkaido      20            58.91 (1.53) (AB)   64.50 [+ or -] 29.91
  Miyagi        40            70.75 (1.56) (B)    78.48 [+ or -] 40.66
  Gifu          20            47.24 (1.76) (A)    54.95 [+ or -] 30.17
  Hyogo          9            94.64 (1.75) (B)   109.44 [+ or -] 58.41
    Total       89            63.86 (1.69)        73.18 [+ or -] 40.90
PCB in serum
  Hokkaido      20            35.92 (1.61) (AB)   40.65 [+ or -] 24.49
  Miyagi        40            45.80 (1.72) (B)    53.00 [+ or -] 31.24
  Gifu          20            22.26 (1.88) (A)    27.25 [+ or -] 18.86
  Hyogo          9            54.32 (1.85) (B)    65.22 [+ or -] 40.67
    Total       89            37.52 (1.89)        45.67 [+ or -] 30.58

Measure/area    Range        Q25    Median  Q75

PBDE in milk
  Hokkaido       1.02-4.55    1.72   2.22     2.97
  Miyagi         0.49-3.11    1.06   1.46     1.98
  Gifu           0.82-3.30    1.01   1.40     2.00
  Hyogo          0.66-2.38    0.83   1.31     2.31
    Total        0.49-4.55    1.13   1.54     2.24
PBDE in serum
  Hokkaido       1.04-5.43    2.24   2.96     3.50
  Miyagi         1.33-21.19   2.68   3.56     4.93
  Gifu           0.74-4.50    1.45   2.34     2.71
  Hyogo          0.76-5.38    1.78   3.13     3.41
    Total        0.74-21.19   2.16   2.99     3.76
PCB in milk
  Hokkaido      20-160       50.0   60.0     71.0
  Miyagi        29-250       54.5   72.5     89.3
  Gifu          18-130       33.3   51.5     72.0
  Hyogo         39-190       65.0   93.0    170.0
    Total       18-250       47.0   65.0     88.0
PCB in serum
  Hokkaido      14-130       29.8   35.0     49.0
  Miyagi        15-170       32.8   51.0     62.3
  Gifu           7.9-82      14.0   22.0     35.5
  Hyogo         23-130       34.0   50.0     89.0
    Total        7.9-170     26.0   38.0     57.0

Abbreviations: GSD, geometric SD; Q25, first quartile; Q75, third
quartile.
(a) Different letters (A, B, or AB) indicate that the corresponding
values are statistically different by Tukey's HSD test after ANOVA
(p < 0.05).

Table 3. Correlation coefficients between pairs of molecular descriptors
or log P for PCBs and PBDEs.

                log [K.sub.ow]  CLogP   MLogP   MW      MgVol   CMR

log [K.sub.ow]   1
CLogP            0.978           1
MLogP            0.899           0.948   1
MW               0.876           0.835   0.634   1
MgVol            0.900           0.866   0.677   0.998   1
CMR              0.967           0.958   0.832   0.956   0.972   1
AMR              0.968           0.960   0.836   0.954   0.970   1.000
PolarizG         0.964           0.954   0.823   0.961   0.975   1.000
TPSA             0.270           0.189  -0.125   0.667   0.631   0.437
HBA              0.270           0.189  -0.125   0.667   0.631   0.437
nCL             -0.102           0.008   0.305  -0.540  -0.490  -0.270
nBR              0.648           0.570   0.301   0.928   0.903   0.778
log P           -0.891          -0.894  -0.731  -0.921  -0.933  -0.940

                AMR     PolarizG  TPSA    HBA     nCL     nBR

log [K.sub.ow]
CLogP
MLogP
MW
MgVol
CMR
AMR              1
PolarizG         1.000   1
TPSA             0.430   0.450     1
HBA              0.430   0.450     1.000   1
nCL             -0.263  -0.286    -0.936  -0.936   1
nBR              0.773   0.788     0.871   0.871  -0.816   1
log P           -0.939  -0.941    -0.499  -0.499   0.326  -0.777

Table 4. PBDE levels in human milk and blood samples from different
countries.

                                        [SIGMA]PBDE
                No. of       Year of    (ng/g lipid)
Country/type    samples      sampling   Mean   Median  BDE-209 mean

Japan
  Milk          105          2004        2.54   1.28
  Milk           89          2005        1.74   1.54   0.12
  Serum          40          1995        1.8    1.3
  Serum          89          2005        3.34   2.99   1.20
  Milk           12          1999        1.72
  Milk            1(27) (a)  2000        1.39          0.04
  Blood         156          1999-2001  13      6.9    9.20
  Milk            4          2003        1.04
  Blood           4          2003        0.3
United States
  Milk           47          2002       73.9   34      0.92
  Milk           16          2004       77.5   48.5    0.38
  Serum          93          2001-2003  24.6
  Serum           7          2000-2002         61
  Serum          12          2001              37
Canada
  Milk           10          1992        5.65   3.03
  Milk           98          2001-2002  22
  Plasma         10          1994-1999  23.3   20.3
Mexico
  Milk            7          2003        4.4           0.30
  Plasma          5          2003       29.1           9.50
United Kingdom
  Milk           54          2001-2003   8.9    6.3
Sweden
  Milk           93          1996-1999   4.01   3.15
  Serum          20          1997               3.3
  Milk           15          2000-2001          2.14
  Plasma         15          2000-2001          2.07
Norway
  Serum           1(29) (a)  1999        3.34
Finland
  Milk           11          1994-1998   2.25   1.62
Germany
  Milk           93          2001-2003   2.23   1.78   0.17
Netherlands
  Serum          78          2001-2002  10.7    9.3
Spain
  Milk           15          2002        2.41   1.7
Italy
  Milk            4(40) (a)  2000-2001   2.75

                PBDE congeners included in
Country/type    [SIGMA]PBDE                    Reference

Japan
  Milk          28, 47, 99, 100, 153, 154      Eslami et al. 2005
  Milk          15, 28, 47, 99, 100, 153,      Present study
                  154, 183, 196, 197, 206,
                  207, 209
  Serum         47, 99, 100, 153               Koizumi et al. 2005
  Serum         15, 28, 47, 99, 100, 153,      Present study
                  154, 183, 196, 197, 206,
                  207, 209
  Milk          28, 47, 99, 153, 154           Ohta et al. 2002
  Milk          28, 37, 47, 66, 75, 77, 85,    Akutsu et al. 2003
                  99, 100, 138, 153, 154,
                  183
  Blood         3, 7, 15, 17, 28, 47, 49,      Takasuga et al. 2004
                  66, 71, 77, 85, 99, 100,
                  119, 126, 138, 139, 153,
                  154, 183, 209
  Milk          17, 25, 28, 30, 32, 33, 35,    Hirai et al. 2004
                  37, 47, 49, 66, 71, 75,
                  77, 85, 99, 100, 116, 119,
                  126, 138, 153, 154, 155,
                  166
  Blood         17, 25, 28, 30, 32, 33, 35,    Hirai et al. 2004
                  37, 47, 49, 66, 71, 75, 77,
                  85, 99, 100, 116, 119, 126,
                  138, 153, 154, 155, 166
United States
  Milk          28, 47, 99, 100, 153, 154      Schecter et al. 2003
  Milk          28, 32, 33, 47, 66,71, 85,     She et al. 2004
                  99, 100, 153, 154, 183,
                  209
  Serum         47, 85, 99, 100, 153, 154,     Morland et al. 2005
                  183
  Serum         17, 28, 47, 66, 85, 99,        Sjodin et al. 2004
                  100, 153, 154, 183, 203,
                  209
  Serum         47, 99, 100, 153, 154, 183     Mazdai et al. 2003
Canada
  Milk          28, 47, 99, 100, 153           Ryan and Patry 2000
  Milk          28, 47, 99, 100, 153           Pereg et al. 2003
  Plasma        28, 47, 85, 99, 100, 153,      Ryan and van Oostdam 2004
                  154, 183
Mexico
  Milk          47, 99, 100, 153, 154, 209     Lopez et al. 2004
  Plasma        47, 99, 100, 153, 154, 209     Lopez et al. 2004
United Kingdom
  Milk          17, 28, 32, 35, 37, 47, 49,    Kalantzi et al. 2004
                  71, 75, 85, 99, 100, 119,
                  153, 154
Sweden
  Milk          47, 99, 100, 153, 154          Lind et al. 2003
  Serum         47, 153, 154, 183, 209         Sjodin et al. 1999
  Milk          17, 28, 47, 66, 85, 99,        Guvenius et al. 2003
                  100, 153, 154, 183
  Plasma        17, 28, 47, 66, 85, 99,        Guvenius et al. 2003
                  100, 153, 154, 183
Norway
  Serum         28, 47, 99, 100, 153, 154      Thomsen et al. 2002
Finland
  Milk          28, 47, 99, 153                Strandman et al. 2000
Germany
  Milk          28, 47, 99, 153, 154, 183,     Vieth et al. 2004
                  209
Netherlands
  Serum         47, 99, 100, 153, 154          Weiss et al. 2004
Spain
  Milk          15 congeners                   Schuhmacher et al. 2004
Italy
  Milk          28, 47, 66, 85, 99, 100, 138,  Ingelido et al. 2004
                  153, 154, 183

(a) The numbers of pooled samples are shown in parentheses.