Novel Natural and Synthetic Organobromine Compounds in the Environment: Toxic or Therapeutic?

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Organobromine compounds can be natural or synthetic. Brominated flame retardants (BFRs), such as polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs) are of concern due to high production volume, widespread use, ubiquitous occurrence in the environment, and toxicity. Concentrations of hydroxylated and methoxylated PBDEs in aquatic ecosystems are often greater than those of PBDEs. Synthetic BRPs have also been produced and widely used as flame retardants. While PBDE formulations are being phased out, as many as 75 new classes of synthetic BFRs are being substituted. It is expected that these new compounds will begin to enter the environment. In addition to the known synthetic bromine (Br)-containing compounds in the environment, there are a number of unidentified organobromine (OBrs) in the environment. While EOBrs have been investigated in some environmental samples, few studies have determined the proportion of EOBr that can be identified and what proportion of EOBr is composed of natural products or synthetic compounds. Preliminary studies have shown that less than 1% of extractable organic Br compounds (EOBr) and total Br (TBr) in environmental samples could be identified. The proposed research will: 1) identify and quantify novel EOBrs in a range of marine and freshwater organisms; 2) use a mass balance (on Br) approach to determine what additional EOBrs might be present; An extraction and cleanup method for TBr, EOBr and five classes of identified EOBrs, based on molecular size and polarity has been developed and will be applied so that appropriate subsequent identification procedures can be applied and 3) use bioassays to determine the toxicity and potential beneficial effects of novel EOBrs will be subjected to a range of bioassays to determine: 1) their toxic mode of action and threshold for effects and 2) their potential as therapeutic agents. If compounds are determined to be too toxic, they will not be tested further for therapeutic properties.