Environmental Factor, June 2009, National Institute of Environmental Health Sciences
Birnbaum is Plenary Lecturer at BFR2009
By Eddy Ball
NIEHS and National Toxicology Program (NTP) Director Linda Birnbaum, Ph.D., was back on very familiar turf when she delivered a plenary lecture at the 11th Annual Workshop on Brominated Flame Retardants (BFR2009) held May 19-20 at the Government Conference Centre in Ottawa. Her talk on "Effects of Brominated Flame Retardants: Health and Regulations" set the stage for the second day of presentations, discussions and poster displays at the workshop.
Jointly sponsored by Health Canada (http://www.hc-sc.gc.ca/ahc-asc/index-eng.php) and Environment Canada (http://www.ec.gc.ca/default.asp?lang=En&n=FD9B0E51-1) , the workshop focused on highlighting innovative research on various aspects of novel and legacy brominated fire retardants (BFRs), including analytical chemistry, toxicology, fate and environmental behavior, monitoring and surveillance, and risk assessment and management. Birnbaum, recognized as a world expert on the toxicology of BFRs, offered an overview of the various compounds that are present in consumer products found in virtually every home and workplace in North America along with a review of research into their potential health effects.
As Birnbaum explained, despite banning or suspending manufacture of the Deca form of polybrominated diphenyl ethers (PBDEs) in recent years, Deca and other PBDEs are ubiquitous in the environment, leading to concerns about continued exposures for people and wildlife that have been linked to endocrine disruption and developmental neurotoxicity. Some environmentalists and scientists, she noted, also question the "safer" alternative BFRs developed to replace them. These chemicals remain unregulated in most places.
Many of the BFRs are bioaccumulative and persistent and can act as endocrine disruptors in animals. BFRs are widely dispersed and have been found in animals living in environments where the compounds are not commonly used, such as the Arctic. Research with animals points to their potential toxicity or mutagenicity in animal studies and their disruption of the estrogen, androgen and thyroid hormone systems, but only one of the compounds, Deca, has been tested in two-year rodent studies. In those studies, Deca was shown to be carcinogenic.
Birnbaum reviewed experimental animals studies and epidemiological studies that have raised concerns about other health effects of PBDE mixtures and cogeners, including hepatotoxicity and the induction of xenobiotic metabolizing enzymes. Few human studies have been performed on newer BFRs, such as tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD), although animal studies and in vitro data suggest similar health effects to those found in PBDE studies. Even less is known about the additive effects of PBDEs and other chemicals.
Birnbaum's talk was followed by three focused sessions that elaborated on the themes of her presentation.
- "Effects of BFRs in Wildlife," chaired by Pamela Martin of Environment Canada
- "Effects of BFRs in Humans and Laboratory Studies," chaired by Thea Rawn, Ph.D., of Health Canada
- "Assessment of BFRs," chaired by Mark Feeley of Health Canada
The workshop concluded with a look forward to BFR2010 (http://www.bfr2010.com/) - the fifth international symposium on BFRs, in Kyoto, Japan. Birnbaum is one of two U.S. representatives on the meeting's International Scientific Committee.