Polybrominated diphenyl ethers as indicators of environmental DecaBDE exposure

The two polybrominated diphenyl ether commercial products, PentaBDE and OctaBDE, were phased out in Europe in August 2004 and a major U.S. producer has ceased the production of these PBDE products as well. However, DecaBDE is still on the market with an annual production volume of 50-60.000 tons. DecaBDE is almost entirely made up by one PBDE congener, BDE-209, the perbrominated diphenyl ether. However, BDE-209 is a source for lower brominated diphenyl ethers, polybrominated dibenzofurans (PBDFs) and hydroxylated and/or methoxylated PBDEs as formed via abiotic processes and/or via metabolism.

The objective of this project is to identify and characterize DecaBDE degradation products. It is particularly important to identify DecaBDE marker compounds that can be assessed in environmental abiotic and biological samples to better, more reliably and easily show DecaBDE exposure than yet possible.

The project is divided into the following specific aims (deliverables):
1. Identification of photochemical degradation products of BDE-209: The product profile determinations and identifications of potential PBDEs and PBDFs formed from laboratory UV-degradation of BDE-209 will be performed by GC/MS and GC-ECD.

2. Identificaton of PBDE congeners formed via reductive reaction pathways of BDE-209: BDE-209 has been shown to undergo metabolic reductive debromination in fish and has also been indicated in an experimental study in rats and in humans occupationally exposed to DecaBDE but no metabolites have hitherto been identified. Experimental work and further studies of human plasma are planed for analysis and comparison to authentic reference PBDEs substituted with 7-9 bromine atoms. Laboratory debromination reaction using sodium borohydride will provide hepta-octaBDEs.

3. Identification of potential hydroxylated metabolites of BDE-209: There is not much known about the metabolites formed from decaBDE. Blood from humans exposed to BDE-209 have been sampled but not yet studied for potentially retained oxygen containing metabolites. The metabolites indicated hitherto contain a hydroxy- or a methoxy-group, and/or two substituents, both a hydroxy- and a methoxygroup. The aim includes determination of potential BDE-209 marker metabolites to be assessed in wildlife and in humans as a measure of DecaBDE exposure.

4. Chemical synthesis of heptaBDE and octaBDE congeners to be applied as standards for the aims 1-2, above, and for neurodevelopmental studies by Prof. Per Eriksson (UU). Synthesis of OH-PBDEs and MeO-PBDEs are included in this effort.