Polybrominated and mixed brominated/chlorinated dibenzo-p-dioxins in sponge (Ephydatia fluviatilis) from the Baltic Sea.

Polybrominated dibenzo-p-dioxins (PBDDs) have recently been found in the Baltic Sea at concentrations 1000 times above that of the chlorinated analogs (PCDDs), yet their sources are undefined. Marine production of organobrominated compounds by sponges is well documented. The objective of the current study was to investigate the potential for an aquatic sponge (Ephydatia fluviatilis), common to the Baltic Sea, to produce PBDDs and other organobromine compounds in the field. Mono- to pentaBDDs as well as several mixed brominated/chlorinated dibenzo-p-dioxins (Br/Cl-DDs), PCDDs and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) were quantified in sponge from the SW Baltic. Concentrations of individual PBDDs in the range 1-80 ng per g extractable organic matter were similar as in blue mussels from the Baltic Sea and about 25 000 times higher than 2,3,7,8-tetraCDD. To the best of our knowledge, this is the first time Br/Cl-DDs are reported in biota from a background environment. While this study does not point out sponges as a dominant source, the concentrations of PBDDs in sponge relative to related anthropogenic compounds such as PBDEs and PCDDs as well as the relative abundance of brominated dioxins and furans strengthens the idea of natural production.