Abstract/Summary

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.