Environ. Sci. Technol. 2007, 41, 1584-1589
Human Exposure to PBDEs: Associations of PBDE Body Burdens with Food Consumption and House Dust Concentrations NERISSA WU,† THOMAS HERRMANN,‡ OLAF PAEPKE,‡ JOEL TICKNER,§ ROBERT HALE,⊥ ELLEN HARVEY,⊥ MARK LA GUARDIA,⊥ MICHAEL D. MCCLEAN,† AND T H O M A S F . W E B S T E R * ,† Department of Environmental Health (Talbot 2E), Boston University School of Public Health, 715 Albany Street, Boston, Massachusetts 02118, EurofinssERGO Research, Geierstr. 1, D-22305 Hamburg, Germany, Center for Sustainable Production, University of MassachusettssLowell, 3 Solomont Way Suite 3, Lowell, Massachusetts 01854-5127, and Virginia Institute of Marine Science, Rt. 1208, Greate Road, P.O. Box 1346, Gloucester Point, Virginia 23062
This study was designed to determine the body burden of polybrominated diphenyl ethers (PBDEs) among firsttime mothers in the Greater Boston, Massachusetts area and to explore key routes of exposure. We collected breast milk samples from 46 first-time mothers, 2-8 weeks after birth. We also sampled house dust from the homes of a subset of participants by vacuuming commonly used areas. Data on personal characteristics, diet, home furniture, and electrical devices were gathered from each participant using a questionnaire. Breast milk and dust samples were analyzed for PBDEs using gas chromatography/ mass spectrometry. PBDE concentrations were lognormally distributed in breast milk and dust. We found statistically significant, positive associations between PBDE concentrations in breast milk and house dust (r ) 0.76, p ) 0.003, not including BDE-209), as well as with reported dietary habits, particularly the consumption of dairy products (r ) 0.41, p ) 0.005) and meat (r ) 0.37, p ) 0.01). Due to low detection rates, it was not possible to draw conclusions about the association between BDE-209 in milk and dust. Our results support the hypothesis that the indoor environment and diet both play prominent roles in adult human exposure to PBDEs.
Introduction Polybrominated diphenyl ethers (PBDEs) are commonly used as fire retardants in consumer products such as foam cushions, carpets, and televisions. PBDEs are structurally similar to polychlorinated biphenyls (PCBs) and appear to act similarly in the environment, persisting over long periods of time and bioaccumulating in various species (1). While * Corresponding author phone: (617) 638-4620; fax: (617) 6384857; e-mail:
[email protected]. † Boston University. ‡ EurofinssERGO Research. § University of Massachusetts. ⊥ Virginia Institute of Marine Science. 1584
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there are virtually no data on the effects of PBDEs on human health, results of animal studies suggest reproductive/ developmental effects, neurotoxicity and endocrine disruption (1-3). Interest in PBDEs increased following the publication of a 1999 Swedish study of PBDEs in breast milk. Analysis of samples stored since 1972 indicated a steep increase in PBDE concentration with a doubling time of 5 years (4). Additional studies have observed this trend in the United States (U.S.) and showed that concentrations in the U.S. are at least an order of magnitude higher than in Europe and display considerable between-subject variability (5-7). Given the lipophilicity of PBDEs and their presence in consumer products and house dust, suspected routes of human exposure include both diet and the indoor environment. Several studies measured PBDEs in common food products or aggregated diets (8-10), while others examined PBDEs in house dust (11-18). Previous estimates of PBDE exposure suggest that incidental ingestion of dust may be important, particularly for children (15-20), but calculations were based on very uncertain exposure factors for dust ingestion, especially for adults (21). Few studies have empirically examined the association between an individual’s body burden and dietary habits (22-24), while only one small study has explored the link between an individual’s PBDE body burden and house dust concentrations, finding no association (13). The primary objectives of our study were to characterize PBDE levels in breast milk collected from first time mothers in the Greater Boston (Massachusetts) area and determine whether diet and/or dust are significant determinants of the total absorbed dose of PBDEs.
Materials and Methods Recruitment of Study Participants. Eligibility for participation was based on a World Health Organization (WHO) protocol for breast milk monitoring (25), although we reduced the WHO’s 5 year residency requirement to facilitate recruitment. Participants were first-time mothers, 18 years or older, who had lived in the Greater Boston area for at least 3 years at delivery. Participants spoke English or Spanish and had pregnancies that were healthy and singlet. To provide diversity, we recruited participants at three sites: a health center in Lowell, Massachusetts that serves an ethnically diverse, working class community; a private obstetrics office in Cambridge, Massachusetts; and a maternity center in Brookline, Massachusetts. The Cambridge and Brookline facilities serve similar populations, predominantly white and highly educated. Participants were given information about PBDEs and biomonitoring as well as breastfeeding support and education. We provided a small stipend to participants in exchange for milk samples. At the Lowell facility, where existing breastfeeding rates were low, lactation support and manual breast pumps were also distributed to boost breastfeeding rates. The study protocol was approved by the Institutional Review Boards (IRB) at Boston University Medical Center and University of Massachusetts Lowell. All participants gave informed consent prior to enrollment. Sampling and Analysis of Breast Milk. A single 50 mL breast milk sample was collected from participants 2-8 weeks post-partum between April 2004 and January 2005. Most women used an electric or manual breast milk pump to collect the sample, pumping directly into glass storage jars that had been rinsed with analytical grade solvents and fitted with a Teflon cap liner. Samples were frozen at -20 °C and shipped to ERGO Research Laboratory. 10.1021/es0620282 CCC: $37.00
2007 American Chemical Society Published on Web 01/17/2007
All analyses were performed following the isotope dilution method. Twelve native standards (12C labeled BDE 17, 28, 47, 66, 77, 85, 99, 100, 138, 153, 154, 183) were obtained from Cambridge Isotope Laboratories (Andover, MA); BDE-209 was obtained from Wellington Laboratories (Guelph, Canada). Six internal 13C labeled standards were obtained from Wellington (BDE 28, 47, 99, 153, 154, 183); BDE-209 was obtained from Cambridge Isotope Laboratories. Solvents were obtained from Merck (n-pentane), Baker (diethyl ether), and Mallinckrodt (ethanol, toluene). Silica gel, alumina oxide, sodium sulfate, and potassium oxalate of the highest purity commercially available were obtained from Merck. Before extraction, the mixture of 7 internal PBDE standards was added to the sample. 5-10 mL of human milk was extracted three times with pentane, after adding 5 mL of 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 alumina oxide columns. The final extract was reduced in volume under a stream of nitrogen. The final volume was 50 uL containing 13C labeled BDE-139 for a recovery standard. The measurements were performed using gas chromatography/highresolution mass spectrometry (HP 5890 coupled with VG Autospec) at RP ) 10 000 using a DB 5 (30 m, 0.25 mm ID, 0.1 um film) column for gas chromatographic separation. Solvents and reagents were tested before the laboratory procedures. All glassware was rinsed by analytical grade solvents prior to use. Silica gel and sodium sulfate were prewashed. Rotary evaporators were not used to reduce the risk of contamination. No plastic equipment was used. For quality control, a laboratory blank and a QC pool of human milk was run with each batch of ten samples. Quantification was only done if sample level was at least twice the blank level. For statistical analysis, half of the detection limit was used for nondetected congeners. Methodologies and QC/QA have been described elsewhere (26, 27). Sampling and Analysis of House Dust. We recruited Cambridge and Brookline participants for dust sampling. We collected dust as soon after milk sampling as was convenient for participants (1-43 days, median ) 18 days). Based on Rudel et al. (11), we used a Eureka Mighty-Mite canister vacuum cleaner with a cellulose thimble inserted into a Teflon crevice tool. Study staff vacuumed commonly used rooms, recording the vacuumed surface area (24.7 95.9 m2; median ) 62.3 m2). Pre-extracted soil was run through the vacuum to estimate PBDE levels contributed from the sample collection procedure. Dust samples were transferred to sample jars, frozen at -20 °C and shipped to the Virginia Institute of Marine Science. Dust samples were sieved to
