CIREEHwiki | Main / Exposure to PBDEs--Research at Boston University School of Public Health

The PBDE/SVOC Research Group at Boston University School of Public Health, Dept. Environmental Health
Our principal focus is the investigation of human exposure to PBDEs in the indoor environment. We have broadened this work to include other semivolatile organic compounds (SVOCs), including new and alternative flame retardants and perfluoroalkyl chemicals (PFCs).

Polybrominated diphenyl ethers (PBDEs)
PBDEs are a class of compounds commonly used as fire retardants in furniture containing polyurethane foam (PUF) and consumer products such as televisions. As shown by their generic chemical structure below, PBDEs are structurally related to their better known cousins: PCBs, polybrominated biphenyls (PBBs), and polychorinated dioxins/dibenzofurans. These compounds are persistent organic pollutants (POPs) and semivolatile organic compounds (SVOCs). Human body burdens and environmental concentrations of PBDEs have increased for several decades and vary geographically, with the highest values reported in the USA. Major questions include impacts on human health and the environment and major routes of human exposure.

Exposure to PBDEs
PBDEs are persistent and bioaccumulative, suggesting exposure via diet, particularly animal products. Given their use in consumer products, it is very likely that the indoor environment also causes exposure. We found associations between PBDE concentrations in people and i) consumption of dairy products and meat, ii) house dust sampled from participant’s homes (Wu et al 2005, 2007); see the figure below. The latter finding--in first time mothers from the Greater Boston area--is particularly important because of the very large uncertainty in adult exposure to dust. It supports the hypothesis that exposure to PBDEs in dust is an important route of exposure.

People are exposed to PBDEs via dust and diet. See: Wu N, Herrmann T, Paepke O, Tickner J, Hale R, Harvey E, La Guardia M, McClean MD, Webster TF. Human exposure to PBDEs: Associations of PBDE body burdens with food consumption and house dust concentrations. Environ Sci Technol 2007; 41(5): 1584-1589. Web release date: 17 Jan 2007. Abstract and full text (for ES&T subscribers): doi=10.1021/es0620282]. See also the accompanying ES&T news report by Kellyn Betts.

The correlation between concentrations of PBDEs in people and in dust cannot, by itself, distinguish between direct exposure to dust (via incidental ingestion or dermal exposure) and inhalation, if the concentrations in air and dust are correlated. Exposure estimates by ourselves (Webster et al 2005) and others suggest that ingestion/dermal exposure to dust is more important than inhalation of indoor air. However, most such calculations rely on indoor air measurements made in rooms using passive air monitors, a method that should underestimate personal exposure. We therefore carried out a second study comparing personal air measurements with room air measurements, using active air pumps (Allen et al., 2007). We found higher concentrations of PBDEs in 'personal air' (sampled near the breathing zone) than in rooms, particularly for decaBDE which is bound to particulate. This is indicative of a personal dust cloud, also known as the Pigpen effect.

We all have our little dust clouds. Read about it in our article: Allen JG, McClean MD, Stapleton HM, Nelson JW, Webster TF. Personal exposure to polybrominated diphenyl ethers (PBDEs) in residential indoor air. Environ Sci Technol 2007; 41(13): 4574-4579. Abstract and full text (for ES&T subscribers): doi=10.1021/es0703170.

Charles Schulz

Sources of PBDEs in the Indoor Environment
PBDEs in indoor air and dust are thought to originate with consumer products such as foam-containing furniture and electronics. However, most earlier research including our own (Wu et al 2007, Allen et al 2007) finds no association between indoor PBDE concentrations and counts of foam-containing furniture and electronics. This could be caused by non-differential exposure misclassification (e.g. large differences in PBDE content between otherwise similar objects), producing a bias toward the null. To deal with this problem, we have used X-ray fluorescence (XRF), providing an easy and quick surrogate measure of the bromine content of household products. This work was published in Environmental Science and Technology in 2008.

News: Read the news story in Environmental Science &Technology about our work with XRF, as presented at BFR07.

"This handheld X-ray fluorescence analyzer allows Joseph Allen of Boston University to detect in seconds the presence of bromine in household products such as televisions."

photo by M. Kenda

Dust sampling: What is to be done?
Dust appears to be an important source of exposure for PBDEs. But there are several important questions about sampling dust:

Is it better to examine the concentration of PBDEs in dust or the amount of PBDEs per area of floor?
How much do PBDE dust concentrations change over time in homes? Is a single snap-shot good enough?
Do PBDE concentrations in dust vary between rooms within the same home?
It's easy to collect vacuum cleaner bags from homes. How well does this match dust collected by more standardized methods?
Do the PBDE concentrations in dust correlate with those in indoor air?

If you'd like to know more about these issues, read our recent paper: Allen JG, McClean MD, Stapleton HM, Webster TF. Critical Factors in Assessing Exposure to PBDEs via House Dust. Environ Intern 2008; 34: 1085-1091. [Online 5 May 2008]. Abstract and full text (for EI subscribers): doi: 10.1016/j.envint.2008.03.006.

New and alternative BFRs: Deja vu all over again?

Penta and octa have been banned in the US but is the problem solved? There is still enormous amounts of this stuff in people's homes as well as being thrown out. In addition, we've been finding new and alternative brominated flame retardents in dust. Pictured at left is a recently identified component of Firemaster 550, a brominated form of the phthalate DEHP. For more information on FM550, look here.

DBDPE: Another alternative BFR in house dust

Decabromodiphenyl ethane (DBDPE) is another new flame retardant we found in house dust, in collaboration with Heather Stapleton. This and other work was recently profiled in ES&T by Kellyn Betts.

How do PBDEs get from products into dust? Do they off-gas or is the plastic breaking down into little bits? To find out, read our new paper and the accompanying news story "CSI-style tools offer clues about flame retardants in dust."

TDCPP (chlorinated tris): A replacement for pentaBDE

Wonder what is being used in polyurethane foam as a flame retardant now that production of the Penta form of PBDE has been banned? Firemaster 550 is one alternative (above). Another is TDCPP, also known as chlorinated tris. This compound, along with its more famous cousin (brominated tris), were used for a while in kids' pajamas before being removed about 30 years ago. See our new paper.

News & Awards (For details, look here)

October 2009. News article by Naomi Lubick in Environmental Health Perspectives ''PBDEs in Diet: Meat Fat a Leading Source" on our recent PBDE and diet paper, Fraser et al 2009.
18 August 2009: News article by Kellyn Betts, Discontinued pajama flame retardant detected in baby products and house dust, discusses our new paper on TDCPP (chlorinated tris).
17 July 2009: News article in Wired about our new paper on diet as a source of exposure to PBDEs.
18 March 2009: News article by Kellyn Betts, CSI-style tools offer clues about flame retardants in dust, in ES&T discusses our new paper on the use of scanning electron microscopes and other "CSI" tools to investigate PBDEs in dust.
3 December 2008: News article by Kellyn Betts in ES&T discusses decabromodiphenyl ethane (DBDPE), another new flame retardant we found in house dust.
23 July 2008: See our paper on alternative brominated flame retardants in dust, including components of Firemaster 550, the replacement for penta in Environmental Science and Technology. See also the accompanying story by Kellyn Betts. For more information on FM550, look here.
July 2008: Our PBDE work was featured in the Summer 2008 edition of Bostonia magazine, Art Jahnke's article "Trouble at Home."
1 May 2008: Work by our PBDE group heavily featured in a news story in today's Environmental Health Perspectives.
18 April 2008: Our PBDE work featured on Nature Network Boston.
27 March 2008: Three new papers on exposure to PBDEs are in press: on PBDEs in handwipes, measuring PBDEs in dust, linking PBDEs in dust to household products via XRF. See publications below.
19 March 2008: News story about our work with Heather Stapleton on measuring PBDEs on handwipes.
6 March 2008: Paper on PBDEs by doctoral student Nerissa Wu one of the most cited papers published in ES&T in 2007.
10 December 2007: Doctoral student Joe Allen defended his dissertation!
13 June 2007: News story "Finding PBDEs in couches and TVs" in ES&T
24 May 2007: What do PBDEs have to do with the the cartoon character Pigpen?
27 April 2007: Doctoral student Joseph Allen wins award at BFR 2007
17 January 2007: News story by Kellyn Betts, "The risk of PBDEs in dust" in ES&T

Publications

Nelson JW, Hatch EE, Webster TF. Exposure to Polyfluoroalkyl Chemicals and Cholesterol, Body Weight, and Insulin Resistance in the General U.S. Population. Environ Health Perspect. In press. [Online 2 November 2009]. The full text is freely available doi:10.1289/ehp.0901165.
Stapleton HM, Klosterhaus S, Eagle S, Fuh J, Meeker JD, Blum A, Webster TF. Detection of Organophosphate Flame Retardants in Furniture Foam and U.S. House Dust. Environ Sci Technol 2009; 43:7490–7495. [Online 13 August 2009]. Abstract and full text (for ES&T subscribers): DOI: 10.1021/es901401.
Fraser AJ, Webster TF, McClean MD. Diet contributes significantly to the body burden of PBDEs in the general U.S. population. Environ Health Perspect 2009; 117:1520-1525. [Online 18 June 2009]. The full text is freely available doi:10.1289/ehp.0900817.
Webster TF, Harrad S, Millette JR, Holbrook RD, Davis JM, Stapleton HM, Allen JG, McClean, MichaeI MD, Ibarra C, Abdallah M, Covaci A. Identifying transfer mechanisms and sources of decabromodiphenyl ether (BDE 209) in indoor environments using environmental forensic microscopy. Environ Sci Technol 2009; 43(9): 3067–3072. [Online 18 March]. Abstract and full text (for ES&T subscribers): doi: 10.1021/es803139w.
Wu N, McClean MD, Brown P, Aschengrau A, Webster TF. Participant Experiences in a Breastmilk Biomonitoring Study: A qualitative assessment. Environmental Health; 2009, 8:4. [Online 18 February 2009]. The full text is freely available doi:10.1186/1476-069X-8-4.
Stapleton HM, Kelly SM, Allen JG, Watkins DJ, Heiger-Bernays WJ, Mcclean MD, Webster TF,Konstantinov A, Klosterhaus S. Response to Comment on "Alternate and New Brominated Flame Retardants in US House Dust." Environ Sci Technol 2008; 42: 9455-6. [Online 14 November 2008]. Full text (for ES&T subscribers): doi: 10.1021/es802619.
Stapleton HM, Allen JG, Kelly S, Konstantinov A, Klosterhaus S, Watkins D, Mcclean MD, Webster TF. Alternate and New Brominated Flame Retardants Detected in US House Dust. Environ Sci Technol 2008; 42 (18), 6910–6916. [Online 23 July 2008]. Abstract and full text (for ES&T subscribers): doi: 10.1021/es702964a.
Allen JG, McClean MD, Stapleton HM, Webster TF. Critical Factors in Assessing Exposure to PBDEs via House Dust. Environ Intern 2008; 34: 1085-1091. [Online 5 May 2008]. Abstract and full text (for EI subscribers): doi: 10.1016/j.envint.2008.03.006.
Allen JG, McClean MD, Stapleton HM, Webster TF. Linking PBDEs in House Dust to Consumer Products using X-ray Fluorescence (XRF). Environ Sci Technol 2008; 42 (11): 4222–4228. [Online April 30, 2008]. Abstract and full text (for ES&T subscribers): doi: 10.1021/es702964a.
Stapleton HM, Kelly SM, Allen JG, McClean MD, Webster TF. Measurement of Polybrominated Diphenyl Ethers on Hand Wipes: Estimating Exposure from Hand to Mouth Contact. Environ Sci Technol 42(9): 3329-34. [Web release date: 19 March 2008]. DOI: 10.1021/es7029625. See also the accompanying ES&T news story by Kellyn Betts.
Allen JG, McClean MD, Stapleton HM, Webster TF. PBDEs in dust: between- and within-home variation linked to XRF characterization of consumer products. Organohalogen Compounds 2007; 69:1002-1004.
Allen JG, McClean MD, Stapleton HM, Nelson JW, Webster TF. Personal exposure to polybrominated diphenyl ethers (PBDEs) in residential indoor air. Environ Sci Technol 2007; 41(13): 4574-4579. Web release date: 24 May 2007. Abstract and full text (for ES&T subscribers): doi=10.1021/es0703170.
Wu N, Herrmann T, Paepke O, Tickner J, Hale R, Harvey E, La Guardia M, McClean MD, Webster TF. Human exposure to PBDEs: Associations of PBDE body burdens with food consumption and house dust concentrations. Environ Sci Technol 2007; 41(5): 1584-1589. Web release date: 17 Jan 2007. Abstract and full text (for ES&T subscribers): doi=10.1021/es0620282. See also the accompanying ES&T news report by Kellyn Betts.
Allen JG, McClean MD, Stapleton HM, Nelson JW, Sanchez G, Fraser AJ, Webster TF. Personal and indoor air exposure to PBDEs in US urban residences. Organohalogen Compounds 2006; 68:2198-2201.
Webster TF. Pharmacokinetics of POPs: Simple models with different implications for halflives and steady state levels. Organohalogen Compounds 2006; 68:344-347. The full text is freely available here.
Wu N, Webster T, Herrmann T, Paepke O, Tickner J, Hale R, Harvey E, La Guardia M, Jacobs E. Associations of PBDE Levels in Breast Milk with Diet and Indoor Dust Concentrations. Organohalogen Compounds 2005; 67: 654-657.
Webster T, Vieira V, Schecter A. Estimating Exposure to PBDE-47 via Air, Food and Dust Using Monte Carlo Methods. Organohalogen Compounds 2005; 67: 505-8. The full text is freely available here,

Upcoming conference and seminar presentations:

BFR 2010: The Fifth International Conference on Brominated Flame Retardants (Kyoto, 7-9 April 2010)

Recent conference and seminar presentations:

Webster T. More Exposure Surprises. International Society of Exposure Science. Minneapolis, 1-5 November 2009. link
Webster, T. Human Exposure to PBDEs From Product to Person. American Chemical Society, Northeastern Regional Meeting (NERM). Hartford, CT, 7 October 2009.
Webster, T. The Fate of PBDEs in the Indoor Environment. Fire Retardants and their Potential Impact on Fire Fighter Health. National Institute of Standards and Technology, 30 September 2009.
Fraser A, McClean M, Webster TF. Diet contributes significantly to the body burden of PBDEs in the general U.S. population. Presented at ISEE 2009. Dublin, Ireland, 26-29 August 2009.
Watkins D, Stapleton HM, Chan S, McClean MD, Webster TF. PBDE Exposure: Which Is More Important, Homes or Offices? Presented at the 29th International Symposium on Halogenated Persistent Organic Compounds (Dioxin 2009) (Beijing, China, 23-28 August 2009)
Stapleton HM, Klosterhaus S, Eagle S, Fuh J, Meeker JD, Blum A, Watkins D, McClean MD, Webster TF. Identification of Tris(1,3-Dichloro-2-Propyl) Phosphate and Other Organophosphate Flame Retardants in U.S. Indoor Environments. Presented at the 29th International Symposium on Halogenated Persistent Organic Compounds (Dioxin 2009) (Beijing, China, 23-28 August 2009).
Webster, T. Exposure to Flame Retardants From Product to Person. 'The Fire Retardant Dilemma.' Green Science Policy Institute. Beijing, China. 22 August, 2009.
Webster, T. Epidemiology of Flame Retardants. 'The Fire Retardant Dilemma.' Green Science Policy Institute. Beijing, China. 22 August, 2009.
Webster, T. Exposure to Flame Retardants From Product to Person. 'The Fire Retardant Dilemma.' Green Science Policy Institute. Beijing, China. 22 August, 2009.
Webster TF. Exposure to PBDEs: From Product to Person. Norwegian Institute of Public Health, Oslo, Norway. 28 May 2009.
Webster TF, Harrad S, Millette JR, Holbrook RD, Davis JM, Stapleton HM, Allen JG, McClean, MichaeI MD, Ibarra C, Abou-Elwafa AM, Covaci A. How does BDE209 get from products into dust? Insights from environmental forensic microscopy. Presented at 11th Annual Workshop on Brominated Flame Retardants (Ottawa, Canada, 19-20 May 2009)
Stapleton HM, Klosterhaus S, Fuh J, Eagle S, Meeker J, Blum A, Webster T. Detection of Chlorinated Phosphate Flame Retardants in Furniture Foam and Ambient Measurements of Phosphate Flame Retardants in US House Dust. Presented at 11th Annual Workshop on Brominated Flame Retardants (Ottawa, Canada, 19-20 May 2009)
Webster T. Frontiers in Environmental Health: Toxics in your Sofa? Boston University School of Public Health 2009 Alumni Symposium. 4 April 2009.
Webster T. Residential Exposure to PBDEs: From product to person. ESF Exploratory Workshop on INDOOR CONTAMINATION WITH PERSISTENT ORGANIC COMPOUNDS: AN IMPORTANT EXPOSURE PATHWAY FOR PEOPLE? Stockholm (Sweden), 23-25 March 2009.
Webster T. Identifiying sources of DecaBDE in indoor environments using forensic microscopy. ESF Exploratory Workshop on INDOOR CONTAMINATION WITH PERSISTENT ORGANIC COMPOUNDS: AN IMPORTANT EXPOSURE PATHWAY FOR PEOPLE? Stockholm (Sweden), 23-25 March 2009.
Webster, T. Exposure to PBDEs: From Product to Person. 'The Fire Retardant Dilemma.' Green Science Policy Institute. University of California Berkeley. 30 January, 2009.
Webster T. Exposure to PBDEs: Characterizing Sources. National Institute of Standards. Gaithersburg, MD. 6 January 2009.
Webster T. PBDE Exposure: From Product to Person. Environmental Health Colloquium. Harvard School of Public Health. 11 December 2008.
Allen JG, McClean MD, Stapleton HM, Webster TF. Sources of DecaBDE in House Dust. Presented at ISEE-ISEA 2008 (Pasadena, CA, 12-16 October 2008)
Webster T. From Product to Person: Exposure to PBDEs (and Beyond). Environmental Health Research Seminar, Boston University School of Public Health, 1 October 2008.
Webster TF, Harrad S, Millette JR, Holbrook RD, Davis JM, Stapleton HM, Allen JG, McClean, MichaeI MD, Ibarra C, Abou-Elwafa AM, Covaci A. Identifying sources of decaBDE in indoor environments using forensic microscopy. Presented at Dioxin 2008: 28th International Symposium on Halogenated Persistent Organic Compounds (Birmingham UK, 17-22 August 2008).
Webster TF, McClean MD, Allen JG, Stapleton HM. Residential exposure to PBDEs: From product to person. Presented at Dioxin 2008: 28th International Symposium on Halogenated Persistent Organic Compounds (Birmingham UK, 17-22 August 2008).
Stapleton HM, Allen JG, Kelly SM, McClean MD, Klosterhaus S, Konstantinov A, Watkins D, Webster TF. Alternative and new brominated flame retardants detected in house dust. Presented at BFR 2008: 10th Annual Workshop on Brominated Flame Retardants (Victoria BC, 3-4 June 2008).
Fraser AJ, McClean MD, Webster TF. Diet predicts serum PBDE concentrations in the United States population. Presented at BFR 2008: 10th Annual Workshop on Brominated Flame Retardants (Victoria BC, 3-4 June 2008).
Allen JG, McClean MD, Stapleton HM, Webster TF. Televisions as sources of decaBDE: XRF-measured bromine in televisions is associated with decaBDE dust concentrations. Presented at BFR 2008: 10th Annual Workshop on Brominated Flame Retardants (Victoria BC, 3-4 June 2008).
Webster, T. Exposure to Polybrominated Diphenyl Ether flame retardants (PBDEs): From Product to Person. 2 June 2008. University of British Columbia.
Webster, T. Human Exposure to DecaBDE. 47th Annual Meeting of the Society of Toxicology. 16-20 March 2008. Seattle, WA.
Stapleton HM, Allen JG, Kelly SM, McClean MM, Webster TF. Exposure and Fate of a New Class of POPs, PBDEs: A Case-Study for Indoor Exposure to POPs. SETAC North America 28th Annual Meeting. Milwaukee, 11-15 November.
Stapleton HM, Kelly S, Allen JG, Webster TF. Characterizing Exposure to Brominated Flame Retardants Based on Hand Wipe Measurements. 17th Annual Conference of the International Society of Exposure Analysis, Durham, NC, 14-18 October.
Allen JG, MD McClean Stapleton HM, Webster TF. Human Exposure to PBDEs: From Product to Person. 17th Annual Conference of the International Society of Exposure Analysis, Durham, NC, 14-18 October
Allen JG, McClean MD, Stapleton HM, Webster TF. PBDEs in dust: between- and within-home variation linked to XRF characterization of consumer products. 27th International Symposium on Halogenated Persistent Organic Pollutants (Dioxin 2007), Tokyo, 2-7 September.
Webster, T. Fireproof women & other tales of human exposure to PBDEs. University of New Hampshire. 4 May 2007.
Allen JG, McClean MD, Stapleton HM, Nelson JM, Fraser AJ, Sanchez G, Webster TF. Characterization of PBDEs in Household Dust: Comparison of Collection Methods and Relationship to Indoor Air. Fourth International Workshop on Brominated Flame Retardants (BFR 2007), Amsterdam, 24-27 April 2007.
Allen JG, McClean MD, Stapleton HM, Fraser AJ, Cichanowski B, Palmisano J, Webster TF. Linking PBDEs in House Dust to Consumer Products using X-ray Fluorescence. Presented at the Fourth International Workshop on Brominated Flame Retardants (BFR 2007), Amsterdam, 24-27 April 2007.
Stapleton HM, Kelly S, Allen JG, Webster TF. Exposure to PBDEs from Hand to Mouth Contact: Measurements of PBDEs on Hand Wipes from Individuals in the United States. Presented at the Fourth International Workshop on Brominated Flame Retardants (BFR 2007), Amsterdam, 24-27 April 2007.
Allen J, McClean M, Stapleton H, Webster T. Exposure to PBDEs and BTBPE in the Indoor Environment. Society of Toxicology Annual Meeting. 25-29 March 2007, Charlotte, NC.
Webster TF. The Epidemiology of Human Exposure to POPs. NERC Persistent Organic Pollutants Network. 10 January 2007. University of Birmingham, UK. program
Allen JG, McClean MD, Stapleton HM, Nelson JW, Sanchez G, Fraser AJ, Webster TF. PBDE levels in indoor air and dust collected in US urban residences. Presented at ISEE/ISEA, 2-6 September 2006, Paris, France. Epidemiology 2006; 17(6) Suppl:S375

Recent & Forthcoming conferences

PBDE/SVOC Research Group at Boston University School of Public Health, Department of Environmental Health

Alicia Fraser, doctoral student
Courtney Walker, doctoral student
Colleen Makey, Research Assistant
Deborah Watkins, doctoral student
Nerissa Wu, doctoral student
Joe Allen, D.Sc. (former doctoral student), currently at Environmental Health & Engineering, Inc, Newton, MA
Wendy Heiger-Bernays, Ph.D.
Veronica Vieira, D.Sc.
Mike McClean, Sc.D., head of the BUSPH Exposure Biology Lab
Tom Webster, D.Sc. (my unofficial site at CIREEH) or my official site at BUSPH

Links (Collaborators, etc.)

For more information:
email: Dr. Tom Webster

return to Tom Webster