2003 Progress Report: Polybrominated Diphenyl Ethers (Flame Retardants) in Babies, Sediment Cores, and Fishes

EPA Grant Number: R830397
Title: Polybrominated Diphenyl Ethers (Flame Retardants) in Babies, Sediment Cores, and Fishes
Investigators: Hites, Ronald A. , Bigsby, Robert M.
Current Investigators: Hites, Ronald A.
Institution: Indiana University
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 2003 through December 31, 2004
Project Period Covered by this Report: January 1, 2003 through December 31, 2004
Project Amount: $228,760
RFA: Futures Research in Natural Sciences (2001) RFA Text |  Recipients Lists
Research Category: Land and Waste Management , Ecological Indicators/Assessment/Restoration , Hazardous Waste/Remediation


Polybrominated diphenyl ethers (PBDEs) are flame-retardants that are added to plastics, particularly those used in furniture and in consumer electronics. Their use currently is unregulated, and their concentrations in the environment are increasing. For example, concentrations of PBDEs are increasing exponentially (with a doubling time of 5 years) in human milk in Sweden. It seems likely that children in the United States are receiving the same level of exposure before birth. This research project has two main objectives:

1. We have measured the concentration of PBDEs in umbilical-cord blood obtained from approximately 20 newborn infants and in vein blood from their mothers. This tells us if the fetus is exposed to these compounds, the variability in exposure among individuals, and if the degree of exposure is increasing with time.

2. To determine trends of these compounds in the United States environment as a function of time, we have studied lake sediment cores and fishes from around the Great Lakes to assess the long-term trends of these compounds in the environment. Sediment cores are widely used to determine the historical input of pollutants into the environment. We also have used collections of Great Lakes fish (primarily lake trout) that date back to 1980 and have been collected biennially ever since. By analyzing fish from this historical collection, we have obtained retrospective information on the input of PBDEs into the Great Lakes ecosystem.

Progress Summary:

One aim of our study was to determine the human fetal and maternal serum concentrations of PBDE in central Indiana. Although based on only a small sample set, our findings indicate that women in Indiana are exposed to levels even higher than those which were considered a reason for banning the use of PBDE in products sold in Sweden. Our data indicate large-scale studies will be needed to assess exposure levels across a broader population, to identify the sources of exposure in the United States and to examine possible neurodevelopment deficits associated with high levels of exposure during fetal development.

We obtained Institutional Review Board approval for these studies involving humans. Patients over 18 years of age, presenting in labor to Indiana University Hospital or Wishard Memorial County Hospital in Indianapolis during August to December 2001, were asked to participate. Pregnancies were full-term, and no other major medical problems were noted in the mothers. Patients were asked to fill out a survey to determine age, race, smoking habits, potential occupational exposures to PBDE (such as working in computer or electronics manufacturing, repair, or dismantling plants), and any other chemical exposures. Maternal blood was obtained when the patient was admitted to the labor and delivery suite, and fetal blood was obtained from the umbilical cord vein after delivery. The weight and presence of any congenital defects were noted for each baby.

Fifteen paired maternal and fetal samples were analyzed for PBDE; three pairs of these samples are not reported because they did not meet quality-control specifications. None of the mothers reported any work-related potential for exposure to PBDE, and all denied smoking exposure. No birth defects were documented. Six different congeners of PBDE were measured in the serum samples. Of the six congeners detected, BDE-47 accounted for the majority (53-64 percent) of all PBDE; BDE-99 was the next most abundant congener, at 15-19 percent. The concentrations of total PBDE found in maternal sera ranged from 15-580 ng/g lipid, and the concentrations found in fetal samples ranged from 14-460 ng/g lipid. The PBDE concentrations were highly correlated between maternal and fetal blood, with a coefficient of determination, r2, of 0.986.

To date, there are only a few studies documenting the concentrations of PBDE in human blood. Plasma samples in Norway contained concentrations of BDE-47, the most abundant congener, in the range of 0.43-15 ng/g lipid. Among Swedish workers, those employed in electronics dismantling facilities showed the highest exposure, with blood serum concentrations as high as approximately 40 ng/g lipid. Samples collected from U.S. blood donors in 1988 had sum concentrations of PBDE of 0.12-0.65 ng/g lipid. In the present study, we found much higher concentrations of PBDE, 14-580 ng/g lipid. Further investigation is required to determine if the high human concentrations reported here represent a regional or a national trend. In a review of the currently available data, however, Ryan observed that concentrations of PBDE in breast milk of North American women were 40-50 times greater than concentrations previously described in Swedish breast milk samples. Similarly, a recent study of PBDE in breast fat of women in San Francisco found concentrations averaging 86 ng/g lipid. Together with our study, these observations indicate that women in North America are exposed to much higher levels of PBDE than are Europeans.

It is apparent that PBDEs cross the placenta into the fetal circulation. It is likely that lipophilic compounds such as PBDE move into fetal circulation along with maternal lipids. Studies examining the concentration of serum lipids in the umbilical vein versus the umbilical artery show a significantly higher level of serum lipids in the umbilical vein. This indicates an influx of lipids from maternal and placental sources. There is a dramatic mobilization of maternal fat stores during the third trimester of gestation, a period critical to brain development; the biological significance and bioavailability of PBDE in fetal circulation during this period of gestation are yet to be determined.

The other focus of the project this last year was determining the temporal trends and spatial distributions of brominated flame retardants in archived fishes from the Great Lakes. We used fish collected in 1980, 1984, 1990, 1992, 1994, 1996, 1998, and 2000. Each sample analyzed was a composite made by grinding and regrinding five fishes together. For 1980 and 1984, we analyzed one composite for each lake. For other years, we analyzed three composites for each lake, except for Lake Huron in 2000, where two samples were analyzed. Lake trout (Salvelinus namaycush) were used for all lakes, for all years, except for Lake Erie, where only walleye (Stizostedion vitreum vitreum) were available. There are few lake trout in Lake Erie, presumably because of its relatively high water temperature.

The year 2000 SPBDE concentrations (in ng/g lipid) in the five lakes are: Michigan, 1,400; Superior, 990; Erie, 600; Ontario, 550; and Huron, 370. Lake Michigan and Lake Superior had the highest year 2000 SPBDE concentrations, which is surprising given that Lake Superior generally is considered the most pristine of the Great Lakes. Perhaps the relatively high PBDE concentrations in Lake Superior are a result of atmospheric deposition of PBDE into that lake. Our finding that trout from Lake Michigan and Lake Ontario are generally the most contaminated with PBDE is expected, given the large human population residing on the shores of these lakes, and given the intense industrial processes associated with these large urban regions.

The rate at which PBDE concentrations have increased in the environment and in humans has been of considerable interest. Temporal trend studies from Europe have indicated that PBDE levels in human milk increased markedly from 1972 to 1997, approximately doubling every 5 years. After that, the PBDE levels in human milk decreased somewhat. A similar rate of increasing PBDE concentrations also was observed in the Japanese population. In this study, we found that the sigma2PBDE levels in the fishes from all five of the Great Lakes increased exponentially as a function of time, doubling every 3-4 years. There are some indications that the sigma2PBDE concentrations have leveled off in Lake Huron and in Lake Michigan since 1998, and especially in Lake Ontario since 1994. Similar trends were observed for herring gull eggs studied by Norstrom, et al., who reported that sigma2PBDE levels increased exponentially in eggs collected from colonies on Lake Michigan, Lake Huron, and Lake Ontario and that the doubling times were approximately 3 years. Norstrom, et al., also observed the leveling-off of sigma2PBDE concentrations in herring gull eggs from Lake Michigan after 1998, and from Lake Ontario after 1999. It is not yet clear what has caused this leveling in recent years. Other studies have found that PBDE levels in biota and humans from North America have increased with doubling times of 4-6 years. The differences in doubling times among all of these results are not statistically significant. Suffice it to say that the concentrations of sigma2PBDE in the Great Lakes environment have rapidly increased since 1980, but there are signs that these increases have slowed.

Future Activities:

Next year, we will focus on the sediment core work. We already have a very good core from Lake Erie, and next summer we will obtain cores from one or two other Great Lakes. We also may measure PBDE in matched male/female partners to investigate PBDE exposure issues (home or workplace). We also have begun to consider PBDE metabolites and will measure concentrations of hydroxylated metabolites in rat-feeding studies. We also want to begin looking at the concentrations of hexabromocyclododecane in paired neonatal/mother samples.

Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other project views: All 8 publications 8 publications in selected types All 8 journal articles
Type Citation Project Document Sources
Journal Article Hites RA. Polybrominated diphenyl ethers in the environment and in people: A meta-analysis of concentrations. Environmental Science & Technology 2004;38(4):945-956. R830397 (2003)
R830397 (Final)
  • Abstract from PubMed
  • Other: ACS PDF
  • Journal Article Mazdai A, Dodder NG, Abernathy MP, Hites RA, Bigsby RM. Polybrominated diphenyl ethers in maternal and fetal blood samples. Environmental Health Perspectives 2003;111(9):1249-1252. R830397 (2003)
    R830397 (Final)
  • Abstract from PubMed
  • Full-text: Environmental Health Perspectives Full Text
  • Other: Environmental Health Perspectives PDF
  • Journal Article Zhu LY, Hites RA. Determination of polybrominated diphenyl ethers in environmental standard reference materials. Analytical Chemistry 2003;75(23):6696-6700. R830397 (2003)
    R830397 (Final)
  • Abstract from PubMed
  • Journal Article Zhu LY, Hites RA. Temporal trends and spatial distributions of brominated flame retardants in archived fishes from the Great Lakes. Environmental Science & Technology 2004;38(10):2779-2784. R830397 (2003)
    R830397 (Final)
  • Abstract from PubMed
  • Supplemental Keywords:

    polybrominated diphenyl ether, PBDE, human blood, Great Lakes, fish, lake trout, sediment, Lake Michigan, Lake Erie, Lake Huron, Lake Ontario, Lake Superior., RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, INTERNATIONAL COOPERATION, Geographic Area, Waste, Water, Contaminated Sediments, Environmental Chemistry, Health Risk Assessment, Risk Assessments, Biochemistry, Physical Processes, Children's Health, Ecological Risk Assessment, Ecology and Ecosystems, Environmental Policy, Great Lakes, neonates, fish borne toxicant, chemical exposure, infants, blood samples, exposure, contaminated sediment, flame retardants, PBDE, children, environmental sampling, human exposure, exposure pathways, fish-borne toxicants, human health risk, polybrominated diphenal ethers

    Progress and Final Reports:

    Original Abstract
  • Final Report