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Arctic Marine Predators and the Ability to Metabolize Brominated Flame Retardants

2011-10-17

Mother and cub on the ice in Scoresby Sound, East Greenland, March 3, 2011 | © EC, Robert LetcherScientists have used a more sophisticated liver microsomal assay design to better identify how top Arctic marine predators biotransform certain new-to-the-market brominated flame retardants (BFRs).

New decabromodiphenyl ethanes (DBDPEs) are a replacement for established environmental contaminants, such as polybrominated diphenyl ethers (PBDEs), a type of BFR used in various consumer products to meet fire safety standards. The European and North American markets banned or phased out penta- and octa-brominated diphenyl etther (BDE) use, but little is known about how replacement chemicals, such as DBDPE, are metabolized and changed into other chemicals/compounds within the bodies of various Arctic wildlife.

Scientists compared the ability of polar bears, beluga whales, ringed seals, and laboratory rats to metabolize higher (BDE209 and DBDPE) and older lower (BDE99, BDE100, and BDE154) brominated PBDEs. The new assay allowed them refined insight into the possible first step of the metabolic process.

All species were more able to rapidly metabolize and deplete higher brominated chemicals (44 to 74% depletion of DBDPE and 14 to 25% of BDE209) than lower brominated chemicals (only 0 to 3% depletion). This may be attributable to greater molecular flexibility of DBDPE, which better facilitates enzyme-mediated metabolism.

Scientists caution that rapid metabolism of BDE209 should not underestimate the burden it places on the ecosystem. They suggest further research to identify and assess the persistence and toxicity of major BDE209 metabolites.

They warn that DBDPE may also be a similar cause for concern due to similar physico-chemical and environmental behaviour, rapid biotransformation, and the apparently increasing use of DBDPE as a replacement for BDE209.

Read more about the Organic Contaminants Research Laboratory, where this study was conducted.

Source: McKinney, M.A., R. Dietz, C. Sonne, S. De Guise, K. Skirnisson, K. Karlsson, E. Steingrímsson and  R.J. Letcher. 2011. Comparative hepatic microsomal biotransformation of selected polybrominated diphenyl ether, including decabromodiphenyl ether, and decabromodiphenyl ethane flame retardants in arctic marine-feeding mammals. Environ. Toxicol. Chem. 30:1506-1514.

Contact: Robert Letcher 613-998-6696/Ecotoxicology and Wildlife Health