Developing a Sustainable Method for the Determination of Bioaccessibility of Organic Contaminants from Polluted Sites
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DEVELOPING A SUSTAINABLE METHOD FOR THE DETERMINATION OF BIOACCESSIBILITY OF ORGANIC CONTAMINANTS FROM POLLUTED SITES Thesis submitted for the Degree of Doctor of Engineering (EngD) Technologies for Sustainable Built Environments Centre School of Construction Management and Engineering Stephen Richard Lowe June 2017 Declaration I confirm that this is my own work and the use of all material from other sources has been properly and fully acknowledged. Name: Stephen Richard Lowe Date: June 2017 Abstract The United Kingdom has an abundance of brownfield sites which can play a pivotal role in addressing the ever growing crisis of supply in the housing sector. However, many otherwise attractive sites are afflicted by the legacy pollutants of former industrial activities. Historically, contaminated land has been viewed as an issue which can only be addressed in the bluntest of ways. A contaminant is present, therefore risk is present, and developers either seek remediation or choose to build on a greenfield alternative. The result is an approach that sees brownfield land as a burden rather than opportunity. This project aims to explore other approaches. Bioaccessibility is increasingly being seen as a viable method for assessing contaminant risk in humans, as part of an approach that is more physiologically relevant and less conservative than traditional methods, with methods such as the Unified Bioaccessibility Method (UBM), human gastrointestinal based bioaccessibility extraction method, gaining increasing traction and acceptance as a viable testing method for the determination of bioaccessibility in inorganics such Arsenic, Lead, Zinc and Cadmium. However, currently no standard method exists for the determination of bioaccessibility in organic contaminants, despite the development of several methodologies designed to assess bioaccessibility in these compounds. In the following thesis, oral bioaccessibility in PCBs is assessed using the FOREhST (Fed ORganic Estimation human Simulation Test) and CE-PBET (Colon Extended Physiologically Based Extraction Test) methods in 34 industrially contaminated soils. ∑ICES 7 (the International Council for the Exploration of the Sea designated indicator congeners) bioaccessibility was recorded as 39.63% using the FOREhST method, though it was found that PCB 180 was consistently underestimated due to a saponification step included in the protocol. CE-PBET resulted in a significantly lower ∑ICES 7 bioaccessibility of 15.21%. Although results varied, both methods demonstrated that the total contaminant approach is overly-conservative in the assessment of PCB contaminated soils. As part of the thesis, a survey of PCB concentrations in the urban soils Central London was completed. The survey demonstrated low background levels of PCBs (15.1 µg/kg) dominated by isolated hotspots of elevated concentration (148.7 µg/kg), which may be attributed to re-emission events. Acknowledgements Thanks must be paid to those who provided the essential support required in the production of this thesis. First and foremost I would like to thank my supervisors, both at Reading and BGS for such support and understanding: Chris and Tom at Reading, and Chris and Mark at BGS. I would like to thank the Engineering and Physical Sciences Research Council and BGS for funding my research, studies and conference attendance. For technical and academic support at BGS I am indebted to the skills of Alex Kim and Darren Beriro, without your efforts and patience I could not have completed this work, along with Matthieu Delannoy, Cyril Feidt and Agnes Fournier at the University of Lorraine for the provision of soils and in vivo data. At the TSBE Centre, I would like to thank Emma and Jenny for running the centre, the conferences and support. Especially Jenny, whose reassurances towards the end kept me going. Also at the TSBE I would like to thank the many new friends I’ve made, especially Nick, Tom, Dan, Alan and Josh. Our friendships will long outlast our time at Reading. At BGS I would like to acknowledge the friendship of Olivier, Elliott, Dan, Naomi, Tef and so many more. I would like to thank my family, Mum and Dad, this is for you. I wouldn’t have got through the last few years without the support of my friends, including Dave and David, for endless train chats and trips to Bristol to keep my spirits up, and my long suffering flatmate, Dan, who somehow managed to motivate me to run the Reading half marathon. For keeping me sane over the past few years, I acknowledge the invaluable input of Shigeru Miyamoto, BBC 6 Music, Public Service Broadcasting and Bethesda Softworks. CONTENTS LIST OF FIGURES ................................................................................................................................................ I LIST OF TABLES .............................................................................................................................................. IV CONFERENCE ATTENDANCE AND OUTREACH................................................................................................. VI CHAPTER 1: INTRODUCTION ............................................................................................................................ 1 1.1 A REFOCUSING ON SUSTAINABILITY IN REMEDIATION ......................................................................................... 1 1.2 INDUSTRIAL CONTEXT ......................................................................................................................................... 3 1.2.1 Sponsorship organisation ...................................................................................................................... 3 1.3 STATEMENT OF PROJECT AIMS....................................................................................................................... 4 1.3.1 Research objectives ........................................................................................................................... 5 1.4 STRUCTURE OF THESIS ................................................................................................................................. 5 CHAPTER 2: APPROACHES TOWARDS CONTAMINATED LAND ......................................................................... 7 2.1 BROWNFIELD LAND, CONTAMINATED LAND AND THE REMEDIATION PROCESS ................................................................. 7 2.2 PERSISTENT ORGANIC POLLUTANTS ........................................................................................................................ 8 2.3 SPATIAL DISTRIBUTION OF CONTAMINANTS ............................................................................................................. 9 2.4 POLLUTANT LINKAGES ...................................................................................................................................... 10 2.5 CURRENT UK POLICY ON CONTAMINATED SITES .................................................................................................... 11 2.6 THE BIOAVAILABILITY/ BIOACCESSIBILITY QUESTION ................................................................................................ 16 2.7 IN VITRO TECHNIQUES FOR ORAL BIOACCESSIBILITY ASSESSMENT ............................................................................... 18 2.7.1 The requirement for validation ........................................................................................................... 23 2.8 RECENT TRENDS IN BIOACCESSIBILITY RESEARCH .................................................................................................... 23 2.10 REFERENCES ................................................................................................................................................ 26 CHAPTER 3: THE UNIQUE CHALLENGE OF PCBS .............................................................................................. 32 3.1 DISTRIBUTION ................................................................................................................................................. 32 3.2 ENVIRONMENTAL FATE AND FOOD CHAIN TRANSFER ............................................................................................... 33 3.2.1 The 1999 Belgian PCB incident ............................................................................................................ 34 3.3 COMMON USES AND APPLICATIONS .................................................................................................................... 35 3.4 PHYSICOCHEMICAL PROPERTIES .......................................................................................................................... 40 3.5 NOMENCLATURE ............................................................................................................................................. 41 3.6 HUMAN HEALTH IMPACTS ................................................................................................................................. 44 3.7 REFERENCES ................................................................................................................................................... 48 CHAPTER 4: POLYCHLORINATED BIPHENYLS (PCBS) IN THE URBAN SOILS OF CENTRAL LONDON, A EUROPEAN MEGACITY...................................................................................................................................................... 53 4.1 INTRODUCTION..............................................................................................................................................