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ANAEROBIC MICROBIAL REDUCTIVE DEBROMINATION OF POLYBROMINATED DIPHENYL ETHERS
Description:
Polybrominated diphenyl ether (PBDE) flame retardants have been detected in sediments, sewage sludge, fish, mammals (including humans), and air throughout the northern hemisphere. While concentrations of PCBs, DDT, and PCDDs in biota are generally decreasing, PBDE concentrations are increasing exponentially. Our objective is to determine whether anaerobic reductive debromination of decabromodiphenyl ether (BDE-209) in sediments to 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) is responsible for some portion of the flux of BDE-47 that is accumulating in the biosphere. The specific hypotheses to be tested will determine whether BDE-209 will undergo reductive debromination. Furthermore, we will identify and quantify the products of this biotransformation. Forty million kg of PBDE flame retardants are produced each year, of which 75% is BDE-209 and only 4% is BDE-47. Yet 60-70% of all PBDE detected in the atmosphere, sediments, and biota (including humans) is BDE-47. BDE-47 is a known endocrine disruptor in rats and mice. Based on knowledge acquired over the last three decades about PCBs, PBBs, and PCDDs we would expect PBDEs to slowly undergo microbial reductive debromination in anaerobic sediments. To date no studies have been completed regarding the biotransformation of PBDEs in sediments. This is clearly an area where scientific data is insufficient. Continued use and release of PBDEs could produce serious future environmental problems to humans and ecosystems.