Polybrominated diphenyl ethers (PBDEs), widely used as flame retardants, were previously poorly characterized, but significant information on their distributions and impacts have been collected in recent decades. However, the distributions and impacts of their degradation and by-products remain relatively poorly known. A study led by researchers at the University of Minnesota, in collaboration with the San Francisco Estuary Institute, Science Museum of Minnesota’s St. Croix Watershed Research Station, ETH Zurich, and Pace Analytical, provided an opportunity to investigate the distribution of potential by-products of PBDEs in surface sediments and cores from San Francisco Bay, Drakes Estero at Point Reyes, and compared their distributions to those in Minnesota lakes. Results from that study, titled “Quantification of Hydroxylated Polybrominated Diphenyl Ethers (OH-BDEs), Triclosan, and Related Compounds in Freshwater and Coastal Systems,” have been recently published in the online journal PLOS ONE.
Hydroxylated polybrominated diphenyl ethers (OH-BDEs) and polybrominated dibenzo-dioxins and furans (PBDD/Fs) can be formed by the degradation of PBDEs or other brominated synthetic compounds, and like PBDEs can be toxic hormone-disrupting chemicals. However, there are also natural pathways of OH-BDE and PBDD/F formation, so the study examined these chemicals in a range of environments, together with total PBDEs as a potential source, and triclosan (a common anti-bacterial agent) as a general indicator of recent anthropogenic influence. Surprisingly, the study found no measurable OH-BDEs in Minnesota lakes, despite the presence of PBDEs. Furthermore, OH-BDEs were found in SF Bay cores in sediment dating prior to WWII, long before widespread use of PBDEs as flame retardants. These findings suggest primarily natural formation pathways for the OH-BDEs found. However the higher concentrations found in SF Bay as compared to Point Reyes suggest there may still be some indirect anthropogenic influences on their distributions. See the study by following this link to the PLOS ONE website.
The NSF primarily funded the study, with the UMN team as lead investigators and SFEI staff providing support in selection of core and surface sediment sites and interpretation of results. The UMN press relese on the study can be viewed here.
The Regional Monitoring Program for Water Quality in San Francisco Bay provided support by collecting samples during ongoing cruises to monitor priority pollutants and other contaminants in in San Francisco Bay.