Anaerobic Microbial Reductive Debromination of Polybrominated Diphenyl EthersEPA Grant Number: R830251
Title: Anaerobic Microbial Reductive Debromination of Polybrominated Diphenyl Ethers
Investigators: Nies, Loring , Filley, Timothy
Current Investigators: Nies, Loring , Ahn, Mi Youn , Filley, Timothy
Institution: Purdue University
EPA Project Officer: Lasat, Mitch
Project Period: August 12, 2002 through August 13, 2004 (Extended to September 1, 2006)
Project Amount: $230,795
RFA: Futures Research in Natural Sciences (2001) RFA Text | Recipients Lists
Research Category: Land and Waste Management , Ecological Indicators/Assessment/Restoration , Hazardous Waste/Remediation
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.
We will experimentally test our hypotheses by monitoring the fate of different PBDE congeners in controlled laboratory experiments. We will identify any transformation products that appear in sediment microcosms and chemical biomimetic reactions using appropriate reference standards and GC/MS. This approach has been used previously to examine the reductive dehalogenation of PCBs, PBBs, and PCDDs.
We expect to identify the PBDE products that will be produced from the reductive debromination of BDE-209 that is found in sediments. These products will be more mobile, bioavailable, and potentially more toxic than BDE-209. The data from this study can be used to estimate the rate of reductive debromination of BDE-209 in sediments in the environment. This information could contribute to a larger global model used to assess 1) the fate of BDE-209 already in service, and 2) the flux of PBDEs through various environmental compartments under different future use scenarios. Many nations are restricting or eliminating the use of lower brominated PBDEs. The results from this study will provide an important contribution to the body of knowledge that is needed to assess the risk of continued use of highly brominated PBDEs such as BDE-209. Users of the data acquired in this study would be policy makers and regulatory officials (e.g. US EPA) who need sound science on which to base decisions. The ultimate beneficiary of this work will be the public at large.