de Boer, J; Allchin, C; Zegers, B; Boon, JP; Brandsma, SH; Morris, S; Kruijt, AW; van der Veen, I; van Hesselingen, JM; Haftka, JJH
Indicative studies had shown that relatively high levels of hexabromocylcododecane (HBCD) could be present in Dutch river sediments and biota. HBCD is used in upholstery textiles and polystyrene foams (e.g. for roof isolation). It was supposed that losses during the impregnation of the flame retardant in these materials would be the cause of environmentally detectable amounts of HBCD. A study on the occurrence of HBCD in sewage sludge, sediments and biota was carried out in order to trace possible sources of HBCD, to study the behaviour of HBCD in sewage treatment plants (STPs), and to study the distribution of HBCD in the aquatic environment In addition to HBCD, tetrabromobisphenol-A (TBSP-A) and its dimethyl derivative (MeTBBP-A) were analysed as well. Occasionally, also polybrominated diphenyl ether (PBDE) concentrations were measured. The study consisted of four sub-projects: i) a method development part, ii) a study on the distribution of HBCD and TBBP-A in the river Scheidt basin in Belgium, iii) a study on the occurrence of HBCD and TBBP-A in sewage treatment plants and landfills, and iv) a study on the levels of HBCD and TBBP-A in various food chains and rivers and North Sea sediments. In addition to these parts and as a separate project, an interlaboratory study on HBCD, TBBP-A, MeTBBP-A and PBDEs was organised. The results of the first four parts are described in this report. The interlaboratory study will be reported separately.
As regards the sampling plan and the analyses, the project has been very successful. Almost all samples planned could be taken. This sampling process was facilitated through the kind collaboration with a number of colleague institutes throughout the world, for which we are very grateful. Some delay was encountered in the method development phase. At the start of the project, methods for HBCD and TBBP-A analysis in environmental samples were neither available in the group of research institutes in charge of this project, nor in the literature. HBCD consists of three different diastereomers (often just called, although not completely correct, isomers). At temperatures above 160-190°C thermal rearrangements can take place. That means that a gas chromatographic (GC) method may be prone to errors as regards the quantification of the total HBCD concentration. A GC separation of the three diastereomers is, at the current state-of-the-art not possible. As it was expected that certain industrial processes applied by the users of HBCD would result in a different isomer profile than that in the technical HBCD mixture, it was highly desirable for this project to develop an high performance liquid chromatographic (HPLC) method for the isomer-specific determination of HBCD. Consequently, a block of time was reserved for the development of methods, including an entire new method for the isomer specific analysis of HBCD. Because more difficulties than expected were met in this phase, the project was delayed by ca. 6 weeks. Apart from this delay, which seems very acceptable given the substantial risk factor of this part of the project, the progress was good and a large and consistent data set has been obtained, from which a lot can be learned about the occurrence and behaviour of HBCD and TBBP-A in the aquatic environment.