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  • PBDEs in the Environment Time trends, bioaccumulation and the identification

    of their successor, decabromodiphenyl ethane

    Amelie Kierkegaard

    Doctoral thesis

    Department of Applied Environmental Science

    Stockholm University

    Stockholm 2007

  • ii

    © Amelie Kierkegaard, Stockholm 2007 ISBN 91-7155-410-6 Typesetting: Intellecta Docusys Printed in Sweden by Intellecta Docusys, Västra Frölunda 2007 Distributor: Stockholm University Library

  • iii

    Abstract

    Polybrominated diphenyl ethers (PBDEs) are important chemical flame re- tardants, but also environmental pollutants. Their behaviour in the environ- ment is a function of their inherent molecular properties, largely governed by the number and character of the bromine atoms substituted, and the micro- environment where they reside. In this thesis different aspects of importance for the understanding of the behaviour of lower brominated and higher bro- minated PBDEs in the environment are addressed.

    The contamination of a Swedish freshwater system with lower bromi- nated BDEs was assessed by a retrospective study of pike from Lake Bol- men covering the time period 1967 to 2000. The concentrations of tetra- to hexaBDEs increased exponentially up to the mid-1980s and then leveled off/decreased slowly, possibly reflecting the voluntary reduction in produc- tion and usage of lower brominated BDEs in Europe. Methoxylated PBDEs were found to be present in similar concentrations to the PBDEs. However, there was no correlation between the levels of the two substance groups, and it was therefore concluded that they originated from different sources. To understand the low abundance of higher brominated BDEs in wildlife despite their extensive use and high levels in e.g. sediment, the dietary up- take of the fully brominated BDE, BDE209, was studied in fish. Although it was not expected to be taken up due to its large size and hydrophobicity, it was absorbed to a small extent via the diet. Once absorbed, BDE209 was reductively debrominated to nona- to hexa-brominated BDE congeners.

    Reductive debromination in vivo was also demonstrated in dairy cows ex- posed to higher brominated BDEs in their natural diet. The transfer of BDE209 to milk was low (< 0.2 %). In contrast to PCBs and lower bromi- nated BDEs, there was no equilibrium between adipose tissues and milk fat, and for congeners with a log Kow > 7 a progressively smaller fraction of the ingested PBDEs was transferred to the milk. The results indicate that while lower brominated BDEs are excreted in the milk of dairy cows exposed to PBDEs, the higher brominated BDEs are accumulated in the meat.

    At the same time that PBDEs were receiving increasing regulatory atten- tion, the next generation of brominated flame retardants was introduced. In this thesis decabromodiphenyl ethane, a replacement for the technical BDE209 formulation, was identified for the first time in the environment.

    This thesis identified differences in uptake, metabolism and excretion for brominated compounds compared to the previously thoroughly characterized organochlorines. This knowledge will be useful for future risk assessments given the ongoing use of these brominated aromatic compounds.

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    “To dare is to lose one's footing momentarily. Not to dare is to lose oneself.”

    Sören Kierkegaard

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    List of papers

    This thesis is based upon the following papers which are referred to in the text by their Roman numerals.

    I Polybrominated diphenyl ethers (PBDEs) and their methoxy-

    lated derivatives in fish from Swedish waters with emphasis on temporal trends, 1967-2000. Amelie Kierkegaard, Anders Bignert, Ulla Sellström, Mats Olsson, Lillemor Asplund, Bo Jansson and Cynthia A. de Wit Environ. Pollut., 2004, 130, 187-198.

    II Dietary uptake and biological effects of decabromodiphenyl

    ether in the rainbow trout (Oncorhynchus mykiss). Amelie Kierkegaard, Lennart Balk, Ulla Tjärnlund, Cynthia de Wit and Bo Jansson Environ. Sci. Technol., 1999, 33, 1613-1617.

    III Fate of higher brominated diphenyl ethers in lactating cows.

    Amelie Kierkegaard, Lillemor Asplund, Cynthia A. de Wit, Michael S. McLachlan, Gareth O. Thomas, Andrew J. Sweetman, and Kevin C. Jones Environ. Sci. Technol., 2007, 41, 417-423

    IV Identification of the flame retardant decabromodiphenyl ethane

    in the environment. Amelie Kierkegaard, Jonas Björklund and Ulrika Fridén. Environ. Sci. Technol., 2004, 38, 3247-3253.

    The papers are reprinted with the kind permission of the publishers, paper I by Elsevier and papers II-IV by the American Chemical Society. I, Amelie Kierkegaard, made the following contributions: in Papers I and IV, I was responsible for the planning, chemical analysis, data evaluation, and writing the manuscript. In papers II and III, I took part in the planning of the project, was re- sponsible for the chemical analysis, data evaluation and manuscript writing. The exposure, sampling and biological part of paper II was performed by Lennart Balk and his co-workers. The mass balance study that provided the samples in paper III was planned and conducted by Gareth Thomas and his co-workers. The other co- authors each made valuable contributions to the planning, data evaluation, and/or writing of the manuscripts.

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  • vii

    Contents

    Abstract .......................................................................................................... iii List of papers...................................................................................................v Contents........................................................................................................ vii Abbreviations ............................................................................................... viii Introduction .....................................................................................................1 Objectives .......................................................................................................2

    Brominated flame retardants...........................................................................4 PBDEs ........................................................................................................5

    Properties and usage.................................................................................................5 Environmental occurrence .........................................................................................8 Toxicity .......................................................................................................................8

    Next generation BFRs ................................................................................9 Decabromodiphenyl ethane.......................................................................................9

    BFR Look alikes .......................................................................................10 Methoxy-PBDEs.......................................................................................................10

    Analytical procedure......................................................................................12 Sample matrices.......................................................................................12 Extraction..................................................................................................13 Clean-up ...................................................................................................15 Instrumental analysis................................................................................16

    Gas chromatography ...............................................................................................16 Mass spectrometry...................................................................................................18

    Identification & quantification....................................................................20 Quality of the analysis ..............................................................................23

    Results and Discussion.................................................................................27 Environmental levels - Temporal trends...................................................27

    PBDEs......................................................................................................................27 Methoxy-BDEs .........................................................................................................30

    Bioaccumulation .......................................................................................33 Dietary absorption....................................................................................................33 Biotransformation.....................................................................................................36 Aquatic versus terrestrial environment ....................................................................43

    Risk assessment / Implications for exposure characterisation ................44 Decabromodiphenyl ethane – a next generation BFR .............................47

    Conclusions...................................................................................................50 Acknowledgements .......................................................................................52 References..........................................................................