Polybrominated diphenyl ethers (PBDEs) in U.S. mothers' milk.

No previous reports exist on polybrominated diphenyl ether (PBDE) congeners in human milk from individual U.S. mothers. This article on PBDEs is an extension of our previous studies on concentrations of dioxins, dibenzofurans, polychlorinated biphenyls, and other chlorinated organic compounds in human milk in a number of countries. PBDE commercial products are used as flame retardants in flexible polyurethane foam (penta-BDE), in acrylonitrile-butadienestyrene resins (octa-BDE), and in high-impact polystyrene resins (deca-BDE). Their use is permitted in the United States but is banned in some European countries because of presumed toxicity, demonstrated persistence, and bioaccumulation. Different commercial products can be found in various consumer products such as television sets, computers, computer monitors and printers, carpets, and upholstery. Analyses of human levels of these compounds suggest low but rising levels in European human milk, which may have peaked, at least in Sweden, in the late 1990s. Very few data exist on levels of PBDEs in humans in the United States, and none from milk from individual nursing mothers. To address this issue, we analyzed 47 individual milk samples from nursing mothers, 20-41 years of age, from a milk bank in Austin, Texas, and a community women's health clinic in Dallas, Texas. Up to 13 PBDE congeners were measured. The concentrations of the sum of PBDE congeners varied from 6.2 to 419 ng/g (or parts per billion) lipid, with a median of 34 ng/g and a mean of 73.9 ng/g lipid. The PBDE levels in breast milk from Texas were similar to levels found in U.S. blood and adipose tissue lipid from California and Indiana and are 10-100 times greater than human tissue levels in Europe. Their detection in breast milk raises concern for potential toxicity to nursing infants, given the persistence and bioaccumulative nature of some of the PBDE congeners. These results indicate a need for more detailed investigation of the levels of PBDE in people and food, as well as determining if animal fat in food is the major route of exposure of the general U.S. population. Other routes of intake may also be significant. Key words: brominated diphenyl ethers, brominated flame retardants, human milk, nursing mothers. Environ Health Perspect 111:1723-1729 (2003). doi:10.1289/ehp.6466 available via http://dx.doi.org/ [Online 5 August 2003]

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Synthetic halogenated compounds, including some of the persistent organic pollutants (POPs) such as chlorinated dioxins, dibenzofurans, and polychlorinated biphenyls (PCBs), have been identified as global environmental and human contaminants over the past 30 years. Some brominated flame retardants can also be persistent synthetic environmental contaminants. Within this group, brominated diphenyl ethers (BDEs) are One class of brominated flame retardants used in large amounts in the United States. Three commercial products are available: penta-BDE, octa-BDE, and deca-BDE. They are used as flame retardants in electrical appliances, including television sets, computers, computer printers, and fax machines, as well as in carpets and furniture upholstery [Bromine Science and Environmental Forum (BSEF) 2001]. These commercial mixtures differ in content of specific polybrominated diphenyl ether (PBDE) congeners, which in turn differ in their bioavailability, bioaccumulation, and toxicologic properties (de Wit 2002; Hardy 2002a, 2002b; McDonald 2002).

Regarding available commercial products, deca-BDE consists almost exclusively of deca-substituted BDE-209 (97%), with some 3% nona-BDE. In 2001, about 24,500 metric tons of penta-BDE was marketed in the United States. Smaller amounts of octa-BDE and penta-BDE mixtures are produced, 1,500 and 7,100 tons a year, respectively (BSEF 2001). Octa-BDE commercial mixtures include some hexa-BDE but mainly hepta-BDE and octa-BDE congeners, some nona-BDE and a very small amount of deca-BDE congeners. Almost all (98%) of the global penta-BDE is produced and used in the United States (BSEF 2001). The major use for penta-BDE has been in flame-retarding polyurethane foam, which is widely used in furniture upholstery. It consists of tetra-, penta-, and hexa-brominated congeners, especially BDE-47 (tetra), BDE-99 (penta), and BDE-153 (hexa), but also BDE-100 (penta) and BDE-154 (hexa) (Hale et al. 2002; de Wit 2002).

Lower brominated congeners, the tetra-BDEs and penta-BDEs, bioaccumulate to a greater degree than do the higher brominated BDEs such as deca-BDE. This may be caused by degradation of higher brominated congeners [International Program on Chemical Safety (IPCS) 1994]. Although the debromination of deca-BDE occurs under experimental conditions, it is not clear whether this decomposition occurs in the environment (Eriksson et al. 1998; Olsman et al. 2002). Results of a 2-year chronic rodent bioassay suggest that the deca-BDE mixture may be a possible human carcinogen, although this effect was observed in laboratory animals only at very high levels of exposure [National Toxicology Program (NTP) 1986]. Octa-BDE and penta-BDE are more bioactive, with possible endocrine, hepatic, reproductive, and neurodevelopmental toxicities (Branchi et al. 2002; Darnerud and Thuvander 1999; Darnerud et al. 2001; Eriksson et al. 1998, 1999, 2001; Fowles et al. 1994; Gillner and Jakobsson 1996; Hallgren and Darnerud 1998, 2002; Hallgren et al. 2001; Hardy 2002a, 2002b; Howie et al. 1990; McDonald 2002; Meerts et al. 1998, 2001, 2002; Morse et al. 1993; Pijnenburg et al. 1995).

Although levels of the dioxins, dibenzofurans, PCBs, and other organochlorines appear to be decreasing in humans living in industrialized countries over the past decades (Furst 2001; Furst and Papke 2002; Furst et al. 1994; Liem et al. 1995; Papke 1998; Schecter et al. 2000; Smith 1999), levels of BDEs seem to be rising in some European countries (Noren and Meironyte 1998, 2000). Recently, the lower brominated PBDEs have been found in humans, in a small number of U.S. studies of blood and adipose tissue (Mazdai et al. 2003; Petreas et al. 2003; She et al. 2000, 2002; Sjodin et al. 2001) and Canadian milk studies (Ryan and Patry 2000, 2001; Ryan et al. 2002). Six congeners (BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183) were measured in 12 fetal-maternal pairs in Indiana (Mazdai et al. 2003). Five congeners (BDE-47, BDE-99, BDE-100, BDE-153, and BDE-154) were measured in 23 adipose tissue samples collected from women living in the San Francisco Bay (California) area (She et al. 2000, 2002). She et al. (2002) measured the most prevalent congener, BDE-47, in 32 adipose and 50 serum samples. BDE-47 levels in these California women ranged from 5 to 510 ng/g (or parts per billion) lipid, with a median of 16.5 ng/g (Petreas et al. 2003). Levels of PBDEs (sum of seven congeners) in Canadian milk increased by about an order of magnitude between 1992 and 2002, from 3.0 ng/g (n = 72) to 22 ng/g (n = 92) (Ryan et al. 2002). Although human fat, blood, and milk levels detected in European countries are about 10 times lower than those found in Canada or the United States, in Sweden, for example, PBDE levels showed an exponential increase over the period from 1972 to 1997--from 0.07 ng/g to 4.02 ng/g in human milk (sum of nine BDE congeners), doubling about every 5 years (Meironyte Guvenius et al. 1999). A 9-fold increase in PBDE levels from 1977 to 1999 was observed in Norwegian stored blood samples (Thomsen et al. 2002). PBDE levels peaked in Sweden in 1997, after which a slight decrease was observed. This may have been the result of a "voluntary" ban on penta-BDE products in Sweden (Betts 2002) and some other European countries since the early 1990s. Levels in blood and milk in other European countries are similar to Swedish levels (Darnerud et al. 1998, 2002; Jakobsson et al. 2002; Schroeter-Kermani et al. 2000; Strandman et al. 2000; van Bavel et al. 2002). Comparison of the measured levels in most of these studies may be limited by the relatively small number of samples, different sampling procedures, and analysis conducted in laboratories using different methodologies. However, it is highly unlikely that the magnitude of the observed difference is only because of methodologic differences. The European Union (EU) will officially ban production, use, and import of penta-BDE and octa-BDE products in 2004 (European Parliament 2002). The decision about the ban of deca-BDE, which is still extensively used, is pending the outcome of the EU risk assessment.

BDE-47, BDE-99, BDE-100, and sometimes BDE-153 or BDE-154 dominate in environmental and human samples. BDE-47, BDE-99, BDE-153, and BDE-154 are major components of penta-BDE products. BDE-153 and BDE-154 are also found in octa-BDE. It is not clear how these relatively persistent toxic chemicals enter humans. With dioxins and dioxin-like chemicals, almost all enter the general population through the food chain, through meat, fish, or dairy products, as do many other fat-soluble chemicals. PBDEs may enter humans through food (Darnerud et al. 2001), by ingestion of dust (Knoth et al. 2002; Leonards et al. 2001), or by inhalation of some BDE congeners at home or on a job in the electronics and computer industries (Jakobsson et al. 2002; Johnson and Olson 2001; Sjodin et al. 1999, 2001, 2003). Dermal absorption in nonoccupational settings seems unlikely to substantially contribute to the elevated PBDE levels in the general population.

Although considerable data exist documenting the toxicity of dioxins, dibenzofurans, and PCBs [Agency for Toxic Substances and Disease Registry (ATSDR) 1994, 1998, 2000; International Agency for Research on Cancer (IARC) 1997; Institute of Medicine 1996, 1998, 2002; Schecter 1994; Schecter and Gasiewicz 2003; U.S. Environmental Protection Agency (EPA) 1984], fewer data exist on the toxicology of PBDEs. However, the information available does indicate the potential for neurodevelopmental and peripheral nervous system damage, endocrine disruption, and cancer (Darnerud et al. 2001; de Wit 2002; McDonald 2002). Ability of some PBDEs (BDE-47, BDE-99, BDE-153, and BDE-209) to disrupt thyroid hormone homeostasis and adversely affect behavioral development and cause learning deficits in rodents is of particular concern regarding potential exposure (Branchi et al. 2002; Eriksson et al. 2001, 2002; Lichtensteiger et al. 2003; Stoker et al. 2003; Viberg et al. 2002). Elevated levels of these compounds may thus represent a risk, especially to the developing fetus and nursing newborn. A recent study in Indiana showed that the individual fetal blood concentration did not substantially differ from the corresponding maternal concentration, ranging from 15 to 580 ng/g lipid in mothers and from 14 to 460 ng/g lipid in fetal serum (Mazdai et al. 2003). These U.S. levels were 106-fold and 69-fold higher for fetal and maternal serum, respectively, than levels found in maternal and fetal blood in a similar Swedish study (Meironyte Guvenius et al. 2003).

The detection of 200 ng/g lipid of PBDE congeners in a recent pooled milk sample (n = 20) from Austin, Texas, and Denver, Colorado (Papke et al. 2001), led us to investigate in more detail the concentration and distribution of up to 13 PBDE congeners in milk from 47 individual human milk donors in Texas.

Materials and Methods

Sample collection. Human milk was obtained from volunteer U.S. donors between August and December 2002 from the Austin Mothers' Milk Bank in Austin and from University of Texas Southwestern Medical Center community women's health clinics in Dallas, Texas. We will further refer to samples from Austin as "milk bank" samples, and to those from Dallas as "clinic" samples. A total of 24 milk bank samples from Austin and 23 clinic samples from Dallas were available for this study. Milk samples were collected by manual expression in most of the cases; only a few women used a breast pump. Information on age, height, weight, and weeks of nursing was available from most of the participants, who provided these data and milk samples after signing the Institutional Review Board-approved informed consent documents required by the participating institutions. Average age was 30.5 years for the milk bank cohort and was 26.6 years for the clinic cohort (Table 1). Although information on ethnic background and recent as well as past residence was available for the clinic cohort in the study, this information was not available for the milk bank cohort. Of 24 participants in the clinic sample, 13 were born in Mexico. Usually, about 30 mL milk was collected in chemically cleaned glass containers. It was frozen shortly after collection and shipped on dry ice to the German and Canadian laboratories for PBDE analysis. The PBDE congener analyses were conducted by two experienced analytical laboratories, ERGO Research in Hamburg, Germany, and Health Canada in Ottawa, Ontario. Both are certified by the World Health Organization (WHO) for congener-specific analysis of dioxins, dibenzofurans, and PCBs in human milk, blood, and food (International Comparisons on Dioxins 2001; WHO 1991).

ERGO Research chemical analyses. The German laboratory analyzed 13 PBDE congeners (BDE-17, BDE-28, BDE-47, BDE-66, BDE-77, BDE-85, BDE-99, BDE-100, BDE-138, BDE-153, BDE-154, BDE-183, and BDE-209) in 23 clinic milk samples from Dallas. All analyses were performed following the isotope dilution method. Twelve native standards ([sup.12]C-labeled BDE-17, BDE-28, BDE-47, BDE-66, BDE-77, BDE-85, BDE-99, BDE-100, BDE-138, BDE-153, BDE-154, and BDE-183) were obtained from Cambridge Isotope Laboratories (Andover, MA, USA). BDE-209 was obtained from Wellington Laboratories (Guelph, Canada). Out of seven internal [sup.13]C-labeled standards, six were puchased from Wellington (BDE-28, BDE-47, BDE-99, BDE-153, BDE-154, and BDE-183); BDE-209 was obtained from Cambridge Isotope Laboratories. Silica gel, alumina oxide, sodium sulfate, and potassium oxalate of the highest purity commercially available were used.

Before extraction, the mixture of seven internal BDE standards was added to the sample (500 pg for each congener except BDE-209, which was 50,000 pg/sample). We extracted 5 mL human milk three times with pentane, after adding 5 mL water, 1 mL potassium oxalate solution, 10 mL ethanol, and 5 mL ether. The extract was washed with water and dried over sodium sulfate. After solvent evaporation, gravimetric lipid determination was performed. The extract was cleaned up by acid treatment and passed through activated silica gel and an alumina oxide column. The final extract was reduced in volume by a stream of nitrogen. The final volume was 50 [micro]L containing [sup.13]C-labeled BDE-139 for recovery standard. Methods have been described elsewhere (Papke et al. 2001; Schroeter-Kermani et al. 2000).

The measurements were performed using high-resolution gas chromatography/high-resolution mass spectrometry at a resolution of 10,000 using a DB-5 column (30 m, 0.25 mm inner diameter, 0.1 [micro]m film) for gas chromatographic separation. The two most abundant masses were used for measurement ([M.sup.+] for tri- and tetra-BDE, and [M.sup.-2][Br.sup.+] for penta-to deca-BDE). The identification of PBDEs was based on retention time and correct isotope ratio. The quantification was performed using internal and external standards.

Reduction of solvents and control of blank data are important steps in quality control when analyzing PBDEs in ultratrace levels. Solvents and reagents were tested before the laboratory procedures. All glassware was rinsed with analytical-grade solvents before use. Silica gel and sodium sulfate were prewashed. Rotary evaporators were not used in order to reduce the risk of contamination. No plastic equipment was used. For quality control, a laboratory blank and a quality control pool of human milk was run with each batch of 10 samples. Quantification was only done if the sample level was at least twice the blank level.

Health Canada chemical analyses. The Canadian laboratory analyzed 10 PBDE congeners (BDE-28, BDE-47, BDE-66, BDE-85, BDE-99, BDE-100, BDE-138, BDE-153, BDE-154, and BDE-183) in 24 milk bank samples from Austin. Three PBDE congeners, BDE-17, BDE-77, and BDE-209, were not measured in this laboratory because levels below the limit of detection were expected for these congeners for the majority of milk samples. Six [sup.13]C-labeled BDEs were purchased as two mixtures from Wellington Laboratories. Most of the 18 [sup.12]C-labeled BDE congeners were obtained from Cambridge Isotope Laboratories.

A mixture of 500 pg each of six [sup.13]C-labeled PBDE congeners was added to 30 g human milk (~0.4-1.0 g milk fat). The samples were homogenized and extracted with acetone--hexane (a small aliquot was used for the lipid determination gravimetrically), defatted with concentrated sulfuric acid, adsorbed on acid silica, and separated on activated magnesium silicate. Chromatography on Florisil was adjusted so that the less polar PCBs were separated from the bulk of the PBDEs (Ryan and Parry 2001; Ryan et al. 2002).

A 30 M methyl silicone gas chromatographic column effected separation of the mono- to hepta-BDE homologs. Detection was performed with mass spectrometry in the electron impact mode at 10,000 resolution with monitoring of six groups of 5-10 ions per group of either [M.sup.+] or [M.sup.-2][Br.sup.+] (two ions per analyte). Quantification was carried out with isotope dilution using a five-point linear calibration curve containing 18 BDE congeners, six [sup.13]C-labeled BDE surrogates, and three recovery or performance standards (PCB-200, PCB-209, and decabromobiphenyl). The latter are used to check performance of the gas chromatograph and to calculate recovery of surrogates.

Each batch of 8-10 unknown samples contained a laboratory reagent blank and a quality control human milk repeat sample. The former was used to measure the contribution of BDEs in the laboratory to the total signal, which was then subtracted from the signal in the unknown samples before quantification. The repeat human milk quality control sample was used as an ongoing measure of laboratory precision and reliability.

Results

Table 1 lists 13 major PBDE congeners, the sum of all the PBDE congeners (ZPBDE), percentage of lipid in each of the 47 individual milk samples, age of each mother, and length of nursing. Table 1 further shows that the range for the [SIGMA]PBDE varied from 6.2 to 419 ng/g lipid, with a mean of 73.9 ng/g and a median 34.0 ng/g. The table is arranged by increasing levels of PBDE congeners. We should note the presence of BDE-209 in 6 of 23 clinic samples, indicating that despite a lower bioavailability compared with the other lower brominated congeners, some of it is absorbed and is present in human milk samples. BDE-17, BDE-77, and BDE-209 measured in the clinic samples in addition to 10 congeners measured in both milk bank and clinic samples contributed < 1% to the [SIGMA]PBDE; therefore, we present only one [SIGMA]PBDE including all 13 congeners, where available.

The milk bank participants were on average about 4 years older than clinic participants (mean age, 30.5 vs. 26.6 years). [SIGMA]PBDE levels were not correlated with age in the whole sample (r = -0.04) or in the milk bank or clinic samples. The median and mean [SIGMA]PBDE levels in the milk bank samples were 45.8 ng/g and 85.7 ng/g, respectively. In the clinic samples, the median was 20.4 ng/g and the mean was 61.6 ng/g. BDE-47 contributed most to the [SIGMA]PBDE (54%), followed by BDE-99 (16.8%), BDE-100 (8.5%), and BDE-153 (5.9%).

We do not know the ethnicity of participants in the milk bank samples, but information obtained from the staff at the milk bank suggests that the majority of women were white. In the clinic samples, 13 women were born in Mexico and have been living in the United States on average 5.3 years, with a range from 6 months to 12 years. We did not observe any substantial difference between PBDE levels in women born outside the United States and the rest of the clinic samples. Hispanic women had similar PBDE levels, with a median [SIGMA]PBDE of 20.4 ng/g compared with 22.7 ng/g in non-Hispanic women.

The length of time nursing in weeks also did not seem to correlate with the [SIGMA]PBDE concentrations (r = -0.07) in the whole sample or in the milk bank or clinic samples. The length of the most recent nursing was shorter in the clinic group (26.6 vs. 30.6 weeks), but six of the clinic sample participants had been nursing only for about 2 weeks when milk was collected. The correlation did not change substantially when the total length of lactation for all children was used in calculations. The number of children of subjects did not correlate with the PBDE concentrations (data not shown).

In Figure 1, the [SIGMA]PBDE concentrations are shown in quartiles, from minimum to maximum. Figure 2 shows the [SIGMA]PBDE concentrations for each of the 47 women. Fifteen of the samples (32%) contain [SIGMA]PBDE > 50 ng/g, and the highest 10 samples contain [greater than or equal to] 100 ng/g; the highest level of [SIGMA]PBDE in milk in these samples is 419 ng/g. Figure 3 shows a comparison of levels of BDE-47, BDE-99, and BDE-153 in human milk between several countries. Values for Germany (Schroeter-Kermani et al 2000), Canada (Ryan et al 2002; Ryan and Patry 2001), Sweden (Noren and Merionyte 2000), and Finland (Strandman et al. 2000) are compared with the U.S. data, showing higher levels for each in the U.S. milk.

[FIGURES 1-3 OMITTED]

Discussion

This is the first study of PBDEs in individual U.S. mothers' milk. Up to 13 PBDE congeners were analyzed in human milk from 47 individual women in the general population from two sources in Texas, a milk bank in Austin and community women's health clinics in Dallas. The findings show extremely elevated levels (10-100 times) in many participants compared with contemporaneous levels reported in Europe (Darnerud et al. 2001; Meironyte Guvenius et al. 1999; Schroeter-Kermani et al. 2000; Strandman et al. 2000; Thomsen et al. 2002). They also show very elevated levels in many of the women with no known occupational exposure. The women were white, African American, and Hispanic in origin. We found no apparent difference in concentrations between age groups or ethnic groups, but even though this is the largest individual U.S. human milk study for PBDEs, it is still a relatively small sample. The milk bank and clinic samples were analyzed by two experienced laboratories that had participated in numerous interlaboratory dioxin and dibenzofuran quality control studies (International Comparisons on Dioxins 2001; WHO 1991), but some of the differences observed could be due to different methodologies used. A human milk interlaboratory study conducted by the Canadian and German laboratories after our study was completed reported almost identical congener levels when using a pooled milk sample (Papke O, Ryan JJ. Personal communication).

Two recent U.S. studies in California (Petreas et al. 2003) and Indiana (Mazdai et al. 2003) have measured PBDE levels in blood samples and adipose tissue and in fetal and maternal serum samples. Levels found in these two studies were also reported on a lipid basis and are similar in range to those found in the present study. These results suggest that there appears to be a similar range in different parts of the United States and that U.S. PBDE levels are at least 10 times and up to 100 times higher than those found in Europe. Data on potential sources of exposure indicate that PBDEs are present in food (Asplund et al. 1999; Huwe et al. 2000; Jacobs et al. 2001; Johnson and Olson 2001; Lind et al. 2002; Ohta et al. 2002; Zegers et al. 2001), land sludge (Pardini et al. 2001), and dust (Knoth et al. 2002; Leonards et al. 2001). It remains to be shown whether or not food represents a major source of PBDEs as it does with dioxins (Schecter 1994; Schecter and Gasiewicz 2003; Startin 1994; U.S. EPA 1984). In a recently published paper, Sjodin et al. (2003) reviewed human exposure to brominated flame retardants, especially PBDEs.

At present, only one study (n = 15) examined the partitioning ratio of PBDE congeners between adipose tissue, milk, and blood (Meironyte Guvenius et al. 2003). The results suggest that partitioning is close to 1:1. The partitioning previously reported for dioxin and dibenzofuran congeners varied in blood and adipose tissue from approximately 1:1 for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), to 2:1 for octachlorinated dibenzodioxin (Schecter et al. 1991, 1998). The partitioning of persistent lipophilic compounds, including dioxins, between human milk and blood lipid was recently reviewed by Aylward et al. (2003). Schecter et al. (1989) have also shown that the partitioning of dioxins and related compounds in various organs of the human body is not always 1:1. Further studies should be conducted to more precisely estimate the partitioning for PBDE congeners and to increase confidence in using different matrices to estimate body burden.

The purpose of this study was to determine whether U.S. women have higher, equal, or lower milk PBDE levels than women in other countries. The answer is striking: the 47 individual U.S. women studied here had markedly higher levels in their breast milk compared to Europeans. This survey clearly indicates that high levels of PBDEs are found in U.S. women and can be transferred to the nursing infants, as shown recently by Mazdai et al. (2003) and Meironyte Guvenius et al. (2003). The effects of age, previous nursing, and food on levels of PBDEs in humans needs to be determined. This study, like the California study (Petreas et al. 2003) and the Swedish (Darnerud et al. 1998) and Norwegian (Thomsen et al. 2002) studies, did not show a positive association with age as has been found with dioxins, PCBs, and other POPs. Even though this association was not tested on a sufficiently large sample to draw a definitive conclusion, data from this and other studies appear to support a lack of increase in PBDE levels with age. Similar to age, and again unlike dioxins and PCBs, length of lactation did not seem to be associated with the PBDE levels. Whether this is because of the relatively short history of intensive PBDE use remains to be determined.

It should be noted that the current use of brominated flame retardants is the result of a need for safer consumer products, that is, products that are less likely to burn in fires. It is estimated that many deaths are avoided in the United States each year by the use of brominated flame retardants, and children are at special risk of death and injury in fires.

Further studies need to be conducted on PBDE levels in milk and blood, in women from different locations, of ethnic groups and different ages, and with different nursing histories, as well as in males and children. Health consequences to the nursing infant as well as the adult from PBDEs at the levels found need further study. There are particular concerns especially about infant health because the fetus and the developing child are more sensitive than adults to the effects of exogenous chemical compounds, including PBDEs in breast milk or diet. Measurement of PBDE levels in meat, fish, dairy products, air, and dust should help determine routes of exposure, adding to the limited data available today (Asplund et al. 1999; Huwe et al. 2000; Jacobs et al. 2001; Johnson and Olson 2001; Knoth et al. 2002; Leonards et al. 2001; Lind et al. 2002; Ohta et al. 2002; Zegers et al. 2001). Occupational health studies of potentially exposed workers may also be helpful in identifying the source of these persistent and toxic halogenated organics. Clearly, much further research is needed to determine the levels and distribution of PBDEs in the U.S. population, routes of intake, and their health effects.

Table 1. Concentrations of PBDE congeners in breast milk from
nursing mothers in Texas in 2001 (ng/g lipid).

                                                 PBDE congener

Sample       Percent     Mother's      Nursing    17      28
no.           lipid     age (years)    (weeks)

 1 (a)         4.8          31           3        ND      0.2
 2 (a)         1.3          29           3        ND      0.3
 3 (a)         2.1          23          74        ND      0.2
 4 (b)         4.8          32          21        --      0.3
 5 (a)         2.6          22          40       0.01     0.3
 6 (a)         3.6          36         109        ND      0.4
 7 (a)         1.9          32          20        ND      0.7
 8 (a)         6.3          25           2        ND      0.4
 9 (b)         2.1          35          29        --      0.7
10 (a)         5.5          32          30        ND      0.4
11 (a)         5.0          20           2       0.01     1.1
12 (a)         3.4          23           3       0.01     0.4
13 (b)         1.3          32          16        --      0.8
14 (a)         3.4          25           NA      0.02     1.1
15 (a)         2.9          21          29       0.03     0.5
16 (b)         3.5          30          30        --      0.7
17 (a)         1.0          23           2        ND      0.9
18 (b)         3.7          23          19        --      0.7
19 (a)         3.2          26           2        ND      1.3
20 (b)         3.5          34          22        --      1.0
21 (b)         3.1          33          60        --      1.4
22 (b)         4.9          38          26        --      1.2
23 (a)         3.4          30           2       0.01     0.7
24 (a)         5.1          28          53       0.01     1.1
25 (b)         4.7          35           NA       --      1.3
26 (a)         1.1          41          38       0.02     1.5
27 (b)         6.1          37          25        --      7.6
28 (b)         3.0          27          51        --      1.4
29 (b)         4.8          25           NA       --      1.8
30 (b)         2.2          39          11        --      1.1
31 (b)         5.6          34           NA       --      2.7
32 (b)         3.4          27          10        --      2.6
33 (a)         2.8          20          13       0.02     1.1
34 (b)         4.0          20          13        --      3.4
35 (b)         3.3          26          17        --      1.4
36 (b)         2.2          20          16        --      1.4
37 (a)         1.1          22          51       0.04     2.2
38 (b)         4.3          29          38        --      5.2
39 (a)         1.0          26          22       0.02     1.7
40 (b)         4.9          32          38        --      3.4
41 (b)         3.4          30           9        --      3.9
42 (a)         1.2          21           2       0.10    10.1
43 (b)         1.2          33          15        --      8.0
44 (a)         1.0          23           2       0.06     3.6
45 (b)         2.1          34          13        --      7.5
46 (a)         1.7          33          47       0.18     6.1
47 (b)         5.1          29          28        --     16.1
  Mean                      28.64       24.56    0.02     2.4
  Median                    29          20       0.01     1.2
  SD                         5.70       22.26    0.04     3.1
  Minimum                   20           2        ND      0.2
  Maximum                   41         109       0.18    16.1

                           PBDE congener

Sample         47      66      77      85       99
ND.

 1 (a)         2.9    0.02     ND     0.08      0.7
 2 (a)         3.5     ND      ND     0.08      0.7
 3 (a)         3.9    0.06     ND     0.11      1.5
 4 (b)         3.5    0.14     --     0.08      1.6
 5 (a)         6.3    0.05     ND     0.23      2.8
 6 (a)         7.8    0.09     ND     0.23      2.4
 7 (a)         8.2    0.04     ND     0.22      1.3
 8 (a)         7.9    0.02     ND     0.38      2.3
 9 (b)         8.8    0.19     --     0.17      1.5
10 (a)         8.0    0.01     ND     0.44      2.9
11 (a)        10.9    0.05     ND     0.18      2.0
12 (a)         8.0    0.03     ND     0.35      3.1
13 (b)        10.5     ND      --     0.35      2.5
14 (a)        12.0    0.13     ND     0.23      2.5
15 (a)        10.7    0.09     ND     0.27      5.5
16 (b)         6.9     ND      --     0.12      1.3
17 (a)        14.2    0.11     ND     0.37      3.7
18 (b)        13.2    0.57     --     0.29      3.7
19 (a)        17.4    0.19     ND     0.35      4.0
20 (b)        14.3    0.29     --     0.46      5.7
21 (b)        18.4     ND      --     0.25      4.1
22 (b)        17.4     ND      --     0.34      7.1
23 (a)        15.2    0.06     ND     0.42      4.2
24 (a)        20.0    0.18     ND     0.53      5.1
25 (b)        20.9    0.56     --     0.31      6.3
26 (a)        19.5    0.11     ND     0.41      3.4
27 (b)        17.2    1.19     --     0.35      6.1
28 (b)        28.2     ND      --     0.51      7.5
29 (b)        21.6    0.94     --     0.50      9.4
30 (b)        26.8     ND      --     0.75      8.9
31 (b)        31.8     ND      --     0.42      7.8
32 (b)        30.1    0.75     --     0.57      5.9
33 (a)        31.3    0.17     ND     0.13     10.2
34 (b)        33.5    2.32     --     0.49      5.8
35 (b)        32.3    0.70     --     0.66      9.6
36 (b)        25.5    0.75     --     0.76      8.0
37 (a)        44.3    0.55    0.03    0.64     10.8
38 (b)        34.8    0.61     --     1.94      9.8
39 (a)        54.7    0.54     ND     1.63     23.6
40 (b)        49.7    1.21     --     1.20      7.7
41 (b)        63.1    3.13     --     2.81     30.1
42 (a)       120.9    1.68    0.06    2.64     30.3
43 (b)       139.6     ND      --     4.12     44.6
44 (a)       172.4    1.14     ND     6.28     69.8
45 (b)       199.6    6.67     --     7.73    108.5
46 (a)       196.2    2.07    0.16    6.46    111.0
47 (b)       271.5    3.16     --     6.29     50.4
  Mean        40.8    0.65    0.01    1.15     14.0
  Median      18.4    0.14     NA     0.41      5.7
  SD          59.4    1.19    0.04    1.89     24.6
  Minimum      2.9     ND      ND     0.08      0.7
  Maximum    271.5    6.67    0.16    7.73    111.0

                        PBDE congener

Sample       100     138      153    154     183
ND.

 1 (a)        0.7     ND      1.5    0.06     ND
 2 (a)        0.5     ND      0.9    0.06    0.06
 3 (a)        0.6     ND      0.4    0.08     ND
 4 (b)        0.7    0.09     1.4    0.09    0.04
 5 (a)        1.2     ND      0.7    0.20    0.05
 6 (a)        1.1    0.01     0.4    0.11     ND
 7 (a)        1.7     ND      0.9    0.12    0.08
 8 (a)        2.7     ND      0.8    0.15    0.06
 9 (b)        1.7    0.16     2.0    0.06    0.03
10 (a)        2.0     ND      0.9    0.14    0.24
11 (a)        2.4     ND      1.3    0.17    0.04
12 (a)        2.7     ND      2.0    0.21    0.61
13 (b)        2.2    0.19     2.0    0.12    0.03
14 (a)        1.8     ND      1.3    0.15    0.08
15 (a)        2.1     ND      0.9    0.35    0.07
16 (b)        4.6    0.41     8.5    0.19    0.06
17 (a)        2.6     ND      1.3    0.24    0.09
18 (b)        2.5    0.29     1.9    0.17    0.06
19 (a)        2.1     ND      0.7    0.18     ND
20 (b)        3.6    0.25     1.4    0.20    0.10
21 (b)        1.8    0.09     2.1    0.16    0.06
22 (b)        2.3    0.14     0.6    0.30    0.12
23 (a)        2.3     ND      3.0    0.22    0.03
24 (a)        3.9    0.01     2.7    0.32    0.11
25 (b)        2.9    0.14     1.2    0.22    0.17
26 (a)        3.3     ND      7.7    0.18     ND
27 (b)        2.3    0.18     1.7    0.27    0.05
28 (b)        2.9    0.25     0.7    0.20    0.75
29 (b)        4.4    0.47     5.8    0.60    0.06
30 (b)        5.3    0.58     2.0    0.45    0.10
31 (b)        3.1    0.09     0.8    0.22    0.10
32 (b)        6.5    0.32     2.5    0.34    0.09
33 (a)        5.9    0.02     1.5    0.48    0.11
34 (b)        5.8    0.27     2.6    0.32    0.06
35 (b)        5.7    0.46    12.4    0.51    0.05
36 (b)       18.3    1.75    18.3    0.94    0.08
37 (a)        8.1    0.02    14.7    0.56     ND
38 (b)       29.2    1.20    14.5    0.96    0.10
39 (a)       10.0     ND      4.8    1.15    0.07
40 (b)       21.1    1.40    16.3    0.93    0.15
41 (b)       16.2    3.29    17.2    1.94    0.08
42 (a)       20.1    0.13    16.4    2.07     ND
43 (b)       23.0    4.47    21.8    2.76    0.18
44 (a)       31.9    0.08     8.4    3.07    0.16
45 (b)       31.7    4.12     6.9    3.62    0.36
46 (a)       31.0    0.27    15.5    7.21    1.32
47 (b)       47.4    6.86    14.1    2.87    0.12
  Mean        8.2    0.60     5.3    0.76    0.13
  Median      2.9    0.09     2.0    0.22    0.07
  SD         10.8    1.37     6.1    1.30    0.23
  Minimum     0.5     ND      0.4    0.06     ND
  Maximum    47.4    6.86    21.8    7.21    1.32

              PBDE congener

Sample       209      [SIGMA]
ND.                    PBDE

 1 (a)        ND         6.2
 2 (a)        ND         6.2
 3 (a)        ND         6.9
 4 (b)        --         8.0
 5 (a)        ND        11.8
 6 (a)        ND        12.5
 7 (a)        ND        13.3
 8 (a)        ND        14.7
 9 (b)        --        15.2
10 (a)       0.48       15.6
11 (a)        ND        18.1
12 (a)       0.93       18.3
13 (b)        --        18.6
14 (a)       1.85       21.1
15 (a)       2.74       22.4
16 (b)        --        22.8
17 (a)        ND        23.5
18 (b)        --        23.5
19 (a)        ND        26.2
20 (b)        --        27.3
21 (b)        --        28.3
22 (b)        --        29.6
23 (a)       3.97       30.1
24 (a)        ND        34.0
25 (b)        --        34.1
26 (a)        ND        36.1
27 (b)        --        36.8
28 (b)        --        42.4
29 (b)        --        45.5
30 (b)        --        46.0
31 (b)        --        47.0
32 (b)        --        49.6
33 (a)       2.96       53.9
34 (b)        --        54.6
35 (b)        --        63.8
36 (b)        --        75.8
37 (a)        ND        81.9
38 (b)        --        98.2
39 (a)        ND        98.2
40 (b)        --       103.1
41 (b)        --       141.6
42 (a)        ND       204.3
43 (b)        --       248.5
44 (a)        ND       296.9
45 (b)        --       376.7
46 (a)       8.24      385.5
47 (b)        --       418.8
  Mean       0.92       73.9
  Median      NA        34.0
  SD         1.96      103.3
  Minimum     ND         6.2
  Maximum    8.24      418.8

Abbreviations: NA, not available; ND, not detected. [SIGMA]PBDE
includes 10 BDE congeners for the Austin samples (BDE-28, BDE-47,
BDE-66, BDE-85, BDE-99, BDE-100, BDE-138, BDE-153, BDE-154, and
BDE-183) and three additional congeners for the Dallas samples
(BDE-17, BDE-66, and BDE-209).

(a) Dallas samples. (b) Austin samples.

REFERENCES

Asplund L, Hornung M, Peterson RE, Turesson K, Bergman A. 1999. Levels of polybrominated diphenyl ethers (PBDEs) in fish from the Great Lakes and Baltic Sea. Organohalogen Compounds 40:351-354.

ATSDR. 1994. Toxicological Profile for Chlorodibenzofurans. Atlanta, GA:Agency for Toxic Substances and Disease Registry.

--. 1998. Toxicological Profile for Chlorinated Dibenzo-p-dioxins. Atlanta, GA:Agency for Toxic Substances and Disease Registry.

--. 2000. Toxicological Profile for Polychlorinated Biphenyls (PCBs). Atlanta, GA:Agency for Toxic Substances and Disease Registry.

Aylward LL, Hays SM, LaKind JS, Ryan JJ. 2003. Rapid communication: partitioning of persistent lipophilic compounds, including dioxins, between human milk lipid and blood lipid: an initial assessment. J Toxicol Environ Health A 66:1-5.

Betts KS. 2002. Rapidly rising PBDE levels in North America. Environ Sci Technol 36:50-52A.

Branchi I, Alleva E, Costa L6. 2002. Effects of perinatal exposure to a polybrominated diphenyl ether (PBDE 99) on mouse neurobehavioural development. Neurotoxicology 23:375-384.

BSEF. 2001. Major Brominated Flame Retardants Volume Estimates. Total Market Demand by Region in 2001. Brussels:Bromine Science and Environmental Forum. Available: http://www.bsef-site.com/docs/BFR_vols_ 2001.doc [accessed 27 August 2003].

Darnerud PO, Atuma S, Aune M, Cnattingius S, Wernroth ML, Wicklund GA. 1998. Polybrominated diphenyl ethers (PBDEs) in breast milk from primiparous women in Uppsala County, Sweden. Organohalogen Compounds 35:411-414.

Darnerud PO, Aune M, Atuma S, Becker W, Bjerselius R, Cnattingius S, et al. 2002. Time trend of polybrominated diphenyl ether (PBDE) levels in breast milk from Uppsala, Sweden, 1996-2001. Organohalogen Compounds 58:233-236.

Darnerud PO, Eriksen GS, Johannesson T, Larsen PB, Viluksela M. 2001. Polybrominated diphenyl ethers: occurrence, dietary exposure, and toxicology. Environ Health Perspect 109(suppl 1):49-68.

Darnerud PO, Thuvander A. 1999. Effects of polybrominated diphenyl ether (PBOE) and polychlorinated biphenyl (PCB) on some immunological parameters after oral exposure in rats and mice. Toxicol Environ Chem 70:229-242.

de Wit CA. 2002. An overview of brominated flame retardants in the environment. Chemosphere 46:583-624.

Eriksson P, Jakobsson E, Fredriksson A. 1998. Developmental neurotoxicity of brominated flame-retardants, polybrominated diphenyl ethers and tetrabromo-bis-phenol A. Organohalogen Compounds 35:375-377.

--. 2001. Brominated flame retardants: a novel class of developmental neurotoxicants in our environment. Environ Health Perspect 109:903-908.

Eriksson P, Viberg H, Jakobsson E, Orn U, Fredriksson A. 1999. PBDE, 2,2',4,4',5-pentabromodiphenyl ether, causes permanent neurotoxic effects during a defined period of neonatal brain development. Organohalogen Compounds 40:333-336.

--. 2002. A brominated flame retardant, 2,2',4,4',5-pentabromodiphenyl ether: uptake, retention, and induction of neurobehavioral alterations in mice during a critical phase of neonatal brain development. Toxicol Sci 67:98-103.

European Parliament. 2002. Directive of the European Parliament and of the Council Amending for the 24th Time Council Directive 76/769/EEC Relating to Restrictions on the Marketing and Use of Certain Dangerous Substances and Preparations (Pentabromodiphenyl Ether, Octabromodiphenyl Ether), PE-CONS 3664/2002--C5-0500/2002--2001/0018(CDD). Brussels:European Union. Available: http://www2.europarl.eu.int/omk/sipade2?PUBREF=-//EP// NONSGML+DOC-C+C5-2002-0500+0+DOC+PDF+VO//EN&L= EN&LEVEL=2&NAV=S&LSTDOC=Y [accessed 27 August 2003].

Fowles JR, Fairbrother A, Baecher-Steppan L, Kerkvliet NI. 1994. Immunologic and endocrine effects of the flame-retardant pentabromodiphenyl ether (DE-71) in C57BL/6J mice. Toxicology 86:49-61.

Furst P. 2001. Organochlorine pesticides, dioxins, PCBs and polybrominated biphenylethersin human milk from Germany in the course of time. Organohalogen Compounds 52:185-188.

Furst P, Furst C, Wilmers K. 1994. Human milk as a bioindicator for body burden of PCDDs, PCDFs, organochlorine pesticides, and PCBs. Environ Health Perspect 102(suppl 1):187-193.

Furst P, Papke O. 2002. PCDDs, PCDFs, and dioxin-like PCBs in human milk and blood from Germany. Organohalogen Compounds 55:251-254.

Gillner M, Jakobsson E. 1996. Structure-affinity relationships for thyroid and dioxin receptor binding of halogenated naphthalenes and diphenylethers. Organohalogen Compounds 29:220-221.

Hale RC, La Guardia MJ, Harvey E, Mainor TM. 2002. Potential role of fire retardant treated polyurethane foam as a source of brominated diphenyl ethers to the US environment. Chemosphere 46:729-735.

Hallgren S, Darnerud PO. 1998, Effects of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and chlorinated paraffins (CPs) on thyroid hormone levels and enzyme activities in rats. Organohalogen Compounds 35:391-394.

--. 2002. Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and chlorinated paraffins (CPs) in rats-testing interactions and mechanisms for thyroid hormone effects. Toxicology 177:227-243.

Hallgren S, Sinjari T, Hakansson H, Darnerud PO. 2001. Effects of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) on thyroid hormone and vitamin A levels in rats and mice. Arch Toxicol 75:200-208.

Hardy ML. 2002a. A comparison of the properties of the major commercial PBDPO/PBDE product to those of major PBB and PCB products. Chemosphere 46:717-728.

--. 2002b. The toxicology of the three commercial polybrominated diphenyl oxide (ether) flame retardants. Chemosphere 46:257-777.

Howie L, Dickerson R, Davis D, Safe S. 1990, Immunosuppressive and monooxygenase induction activities of polychlorinated diphenyl ether congeners in C57BL/6N mice: quantitative structure-activity relationships. Toxicol Appl Pharmacol 105:254-263.

Huwe JK, Lorentzsen M, Thuresson K, Bergman A. 2000. Polybrominated diphenyl ethers in chickens. Organohalogen Compounds 47:429-432.

IARC. 1997. Polychlorinated Dibenzo-para-dioxins and Polychlorinated Dibenzofurans. Monogr Eval Carcinog Risk Hum 69.

Institute of Medicine. 1996. Veterans and Agent Orange: Update 1996. Washington, DC:National Academy Press.

--. 1998. Veterans and Agent Orange: Update 1998. Washington, DC:National Academy Press.

--. 2002. Veterans and Agent Orange: Update 2000. Washington, DC:National Academy Press.

International Comparisons on Dioxins. 2001. Final Report 2001:4. Folkehelsa, Norway:National Institute of Public Health.

International Program on Chemical Safety (IPCS). 1994. Brominated Diphenyl Ethers. Environ Health Criteria 162. Geneva:World Health Organization.

Jacobs M, Covaci A, Schepens P. 2001. Investigation of polybrominated diphenyl ethers in Scottish and European farmed Atlantic salmon (Salmo salar), salmon aquaculture feed and fish oils. Organohalogen Compounds 51:239-242.

Jakobsson K, Thuresson K, Rylander L, Sjodin A, Hagmar L, Bergman A. 2002. Exposure to polybrominated diphenyl ethers and tetrabromobisphenol A among computer technicians. Chemosphere 46:709-716.

Johnson A, Olson N. 2001. Analysis and occurrence of polybrominated diphenyl ethers in Washington State freshwater fish. Arch Environ Contain Toxicol 41:339-344.

Knoth W, Mann W, Meyer R, Nebhuth J. 2002. Polybrominated diphenylether in house dust. Organohalogen Compounds 58:213-216.

Leonards PEG, Santillo D, Brigden K, van der Veen I, Hesselingen JV, de Boer J, et al. 2001. Brominated flame retardants in office dust samples. In: Proceedings of the Second International Workshop on Brominated Flame Retardants, 14-16 May 2001, Stockholm, Sweden. Stockholm:Swedish Chemical Society, 299-302.

Lichtensteiger W, Ceccatelli R, Faass O, Fleischmann I, Schlumpf M. 2003. Effects of polybrominated diphenylethers (PBDE) on reproductive organ and brain development and gone expression in rats [Abstract]. Toxicologist 72:133-134.

Liem AKD, Albers JMC, Baumann RA, van Beuzekom AC, den Hartog RS, Hoogerbrugge R, etal. 1995. PCBs, PCDD/PCDFs and organochlorine pesticides in human milk in the Netherlands. Levels and trends. Organohalogen Compounds 26:69-74.

Lind Y, Aune M, Atuma S, Becker W, Bjerselius R, Glynn A, et al. 2002. Food intake of the brominated flame retardants PBDEs and HBCD in Sweden. Organohalogen Compounds 58:181-184.

Mazdai A, Dodder NG, Abernathy MP, Hites RA, Bigsby RM. 2003. Polybrominated diphenyl ethers in maternal and fetal blood samples. Environ Health Perspect 111:1249-1252; doi:10.1289/ehp.6146 [Online 10 March 2003].

McDonald TA. 2002. A perspective on the potential health risks of PBDEs. Chemosphere 46:745-755.

Meerts IA, Assink Y, Cenijn PH, Van Den Berg JH, Weijers BM, Bergman A, et al. 2002. Placental transfer of a hydroxylated polychlorinated biphenyl and effects on fetal and maternal thyroid hormone homeostasis in the rat. Toxicol Sci 68:361-371.

Meerts IA, Letcher RJ, Hoving S, Marsh G, Bergman A, Lemmen JG, et al. 2001. In vitro estrogenicity of polybrominated diphenyl ethers, hydroxylated PDBEs, and polybrominated bisphenol A compounds. Environ Health Perspect 109:399-407.

Meerts IATM, Luijks EAC, Marsh G, Jakobsson E, Bergman A, Brouwer A. 1998. Polybrominated diphenylethers (PBDEs) as Ah-receptor agonists and antagonists. Organohalogen Compounds 37:147-150.

Meironyte Guvenius D, Aronsson A, Ekman-Ordeberg 6, Bergman A, Noren K. 2003. Human prenatal and postnatal exposure to polybrominated diphenyl ethers, polychlorinated biphenyls, polychlorobiphenylols and pentachlorophenol. Environ Health Perspect 111:1235-1241; doi:10.1289/ehp.5946 [Online 21 January 2003].

Meironyte Guvenius D, Noren K, Bergman A. 1999. Analysis of polybrominated diphenyl ethers in Swedish human milk. A time-related trend study, 1972-1997. J Toxicol Environ Health A 58:329-341.

Morse DC, Groen D, Veerman M, van Amerongen CJ, Koeter HBWM, Smits van Proije, et al. 1993. Interference of polybrominated biphenyls in hepatic and brain thyroid hormone metabolism in fetal and neonatal rats. Toxicol Appl Pharmacol 122:27-33.

Noren K, Meironyte D. 1998. Contaminants in Swedish human milk. Decreasing levels of organochlorine and increasing levels of organobromine compounds. Organohalogen Compounds 38:1-4.

--. 2000. Certain organochlorine and organobromine contaminants in Swedish human milk in perspective of past 20-30 years. Chemosphere 40:1111-1123.

NTP. 1986. Toxicology and Carcinogenesis Studies of Decabromodiphenyl Oxide (CAS No 1163-19-5)in R344/N Rats and B6C3[F.sub.1] Mice (Feed Studies). Technical Report 309. Research Triangle Park, NC:National Toxicology Program.

Ohta S, Ishizuka D, Nishimura H, Nakao T, Aozasa O, Shimidzu Y, et al. 2002. Comparison of polybrominated diphenyl ethers in fish, vegetables and meats and levels in human milk of nursing mothers in Japan. Chemosphere 46:689-696.

Olsman H, Gavel B, Kalbin G, Pettersonn A, Seetnlund S, Strid A. 2002. Formation of dioxin-like compounds as photoproducts of decabrominated diphenyl ether (DEBDE) during UV-irradiation. Organohalogen Compounds 58: 41-44.

Papke O. 1998. PCDD/PCDF: human background data for Germany, a 10-year experience. Environ Health Perspect 106(suppl 2):723-731.

Papke O, Bathe L, Bergman A, Furst P, Meironyte-Guvenius D, Herrmann T, et al. 2001. Determination of PBDEs in human milk from the United States--comparison of results from three laboratories. Organohalogen Compounds 52:197-200.

Pardini A, Jones C, Noble L, Kreiser B, Malcom H, Bruce B, et al. 2001. Persistent pollutants in land-applied sludges. Nature 412:140-141.

Petreas M, She J, Brown FR, Winkler J, Windham G, Rogers E, et al. 2003. High body burdens of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47)in California women. Environ Health Perspect 111:1175-1179.

Pijnenburg AMCM, Everts JW, de Boer J, Boon JP. 1995. Polybrominated biphenyl and diphenylether flame retardants: analysis, toxicity, and environmental occurrence. In: Reviews of Environmental Contamination and Toxicology, Vol 141 (Ware GW, ed). New York:Springer-Verlag, 1-20.

Ryan JJ, Patry B. 2000. Determination of brominated diphenyl ethers(BDEs) and levels in Canadian human milk. Organohalogen Compounds 47:57-60.

--. 2001. Body burdens and food exposure in Canada for polybrominated diphenyl ethers (BDEs). Organohalogen Compounds 51:226-229.

Ryan JJ, Parry B, Mills P, Beaudoin G. 2002. Recent trends in levels of brominated diphenyl ethers in human milks from Canada. Organohalogen Compounds 58:173-176.

Schecter AJ, ed. 1994. Dioxins and Health. New York:Plenum Press.

Schecter AJ, Gasiewicz TA. 2003. Dioxins and Health. 2nd ed. New York:John Wiley and Sons.

Schecter AJ, Kassis I, Papke O. 1998. Partitioning of dioxins, dibenzofurans, and coplanar PCBs in blood, milk, adipose tissue, placenta and cord blood from five American women. Chemosphere 37:1817-1823.

Schecter AJ, Mes J, Davies D. 1989. Polychlorinated biphenyl (PCB), DOT, DDE and hexachlorobenzene (HCB) and PCDD/F isomer levels in various organs in autopsy tissue from North American patients. Chemosphere 18:811-818.

Schecter AJ, Papke O, Ball M, Ryan JJ. 1991. Partitioning of dioxins and dibenzofurans: whole blood, blood plasma and adipose tissue. Chemosphere 23:1913-1919.

Schecter AJ, Papke O, Piskac AL. 2000. Dioxin levels in milk and blood from Germany and the USA. Are dioxin blood levels decreasing in both countries? Organohalogen Compounds 48:68-71.

Schroeter-Kermani C, Hel D, Hermann T, Papke O. 2000. The German environmental specimen bank--application in trend monitoring of PBDEs in human blood. Organohalogen Compounds 47:49-52.

She J, Petreas M, Winkler J, Visita P, McKinney M, Jones R, Kopec D. 2000. Harbor seals as indicators of halogenated contaminants in San Francisco Bay. Organohalogen Compounds 49:422-425.

She J, Petreas M, Winkler J, Visita P, McKinney M, Kopec D. 2002. Polybrominated diphenyl ethers (PBDEs) in the San Francisco Bay Area: measurements in harbor seal blubber and human breast adipose tissue. Chemosphere 46:697-707.

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, Patterson DG, Bergman A. 2001. Brominated flame retardants in serum from US blood donors. Environ Sci Technol 35:3830-3833.

--. 2003. A review on human exposure to brominated flame retardant-particularly polybrominated diphenyl ethers. Environ Int 29: 829-839.

Smith D. 1999. Worldwide trends in DDT levels in human breast milk. Int J Epidemiol 28:179-188.

Startin JR. 1994. Dioxins in food. In: Dioxins and Health (Schecter AJ, ed). New York:Plenum Press, 115-138.

Stoker TE, Ferrell J, Hedge JM, Crofton KM, Cooper RL, Laws SC. 2003. Assessment of DE-71, a commercial polybrominated dibyenyl ether (PBDE) mixture, in the EDSP male pubertal protocol [Abstract]. Toxicologist 72:135-136.

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

Thomsen C, Lundanes E, Becher 6. 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.

U.S. EPA. 1984. Health and Environmental Effects Profile for Brominated Diphenyl Ethers. EPA/600/X-84/133. Washington, DC:U.S. Environmental Protection Agency.

van Bavel B, Hardell L, Kitti A, Lijedahl M, Karlsson M, Pettersson A, et el. 2002. High levels of PBDEs in 5% of 220 blood samples from the Swedish population. Organohalogen Compounds 58:161-164.

Viberg H, Fredriksson A, Eriksson P. 2002. Neonatal exposure to the brominated flame retardant 2,2',4,4',5-pentabromodiphenyl ether causes altered susceptibility in the cholinergic transmitter system in the adult mouse. Toxicol Sci 67:104-107.

WHO. 1991. Levels of PCBs, PCDDs and PCDFs in Human Milk and Blood: Second Round of Quality Control Studies. Environment and Health in Europe 37. Copenhagen:FADL 1-76.

Zegers BN, Lewis WE; Tjoen-A-Choy MR, Smeenk C, Siebert U, Boon J. 2001. Levels of some polybrominated diphenyl ether (PBDE) flame-retardants in animals of different trophic levels of the North Sea food web. Organohalogen Compounds 52:18-21.

Arnold Schecter, (1) Marian Pavuk, (1) Olaf Papke, (2) John Jake Ryan, (3) Linda Birnbaum, (4) and Robin Rosen (5)

(1) University of Texas Health Sciences Center, School of Public Health, Dallas Regional Campus, Dallas, Texas, USA; (2) ERGO Research, Hamburg, Germany; (3) Health Canada, Ottawa, Ontario, Canada; (4) Environmental Toxicology Research Laboratories, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA; (5) University of Texas Southwestern Medical Center, Department of Obstetrics and Gynecology, Dallas, Texas, USA

Address correspondence to A. Schecter, University of Texas Health Sciences Center, School of Public Health, Dallas Regional Campus, 5323 Harry Hines Blvd., V8.112, Dallas, TX 75390 USA. Telephone: [phone]. Fax: [phone]. E-mail: [e-mail]

We thank the study participants in Dallas and Austin. We "also thank our collaborators, S. Heartwell, B. Schwarz, L. Flores, K. Collins, and B. Moses (University of Texas Southwestern Medical Center, Dallas, TX); and G. Flatau, S. Landers, and J. Cote (Austin Mothers' Milk Bank, Austin, TX).

This study was supported in part by the CS Fund, Warsh-Mott Legacy, the Kundstadter Family Foundation, and the Samuel Rubin Foundation.

This document does not constitute U.S. EPA policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

The authors declare they have no conflict of interest.

Received 16 May 2003; accepted 6 August 2003.