• Uncertainty: A Risky Business?

    A report on the 2015 SoBRA Summer Workshop, Uncertainty: A Risky Business?

    By Stephen Lowe, EPSRC PhD candidate, University of Reading / British Geological Survey

    Stephen LoweTaking place at the Northern Institute of Mining, Newcastle-upon-Tyne, the 2015 SoBRA (Society of Brownfield Risk Assessment) Summer Workshop took the theme of ‘Addressing Uncertainty in Human Health Risk Assessment’. As is usual with SoBRA events, the attendees represented a cross-section of academics and professionals with an interest in contaminated land management and risk assessment.

    The morning session consisted of a series of informative talks. Andy Hart (FERA) covered the different approaches to uncertainty, including the identification and management of errors, the need for a ‘body of evidence’ approach for human health risk assessment, and the necessity for adequate precaution in decision making. An interesting compromise was discussed, in which the potential deterrence effect on redevelopment caused by over-conservative assessment must be balanced against a potential loss in confidence and trust caused by misrecognition of SPOSH (significant possibility of significant harm, defined by Part 2a of the Environmental Protection Act 1990 [as amended]).

    The concept of uncertainty in risk assessment was covered in greater detail by Jonathan Welch (Aecom). Jonathan’s talk covered the risk of uncertainty in the conceptual site model approach, and the requirement for a robust sampling methodology.

    Simon Firth covered the necessity of DQRA (Detailed Quantitative Risk Assessment) in the application of the CLEA (Contaminated Land Exposure Assessment) model in risk assessment. Emphasis was placed on the need to provide a clear, site specific understanding of contaminant pathways, the physico-chemical properties of the contaminant, and the potential for human harm associated with the contaminant. Once again, the need for conservative assessment, alongside a ‘body of evidence’ approach to potential risks was emphasised.

    Mark Cave (BGS) followed with a talk covering the current position of bioaccessibility testing research, and the minimisation of uncertainty associated with bioaccessibility testing and risk assessment. Mark emphasised the need for strong QA and sampling regimes, and the need to understand the variety of soil types and conditions found in contaminated sites. The talk also highlighted the need for in vivo validation of bioaccessibility tests with a wide range of xenobiotics.

    Camilla Pease (Ramboll Environ) concluded the morning with a talk covering the significance of toxicology to risk assessment. The presentation covered the necessity for PBPK (Physiologically Based Pharmacokinetic) modelling, and the need for confidence in toxicological reports and TEF (Toxic Equivalency Factor) values. The talk explored the role of ‘acceptable risk’, and how this is influenced by methodologies with inherent uncertainty.

    Following lunch, the meeting was split into discussion groups associated with a specific area of discussion: bioaccessibility, conceptual site models, site investigation and exposure parameters.

    The group discussions were lively and informative, and provided a useful opportunity to hear the views of practitioners working with contaminated land and risk assessment on a regular basis. The group sessions concluded with a brief presentation of findings.

    The bioaccessibility group, for which I acted as facilitator, explored the role of bioaccessibility testing in site risk assessment, sampling strategies, cost/ benefit analysis of bioaccessibility testing, progress in the development of new methods and the range of methods available, including methods for the assessment of bioaccessibility in organic compounds, such as PAHs.

    Details of further events and the full findings of each group will be published by SoBRA in due course, and will be available to access at http://www.sobra.org.uk

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