Browsing by Author "Skinner, Daniel J. C."
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Item Open Access Identifying uncertainty in environmental risk assessments: the development of a novel typology and Its implications for risk characterisation(Taylor & Francis, 2014-12-31T00:00:00Z) Skinner, Daniel J. C.; Rocks, Sophie A.; Pollard, Simon J. T.; Drew, Gillian H.Environmental risk analysts need to draw from a clear typology of uncertainties when qualifying risk estimates and/or significance statements about risk. However, categorisations of uncertainty within existing typologies are largely overlapping, contradictory, and subjective, and many typologies are not designed with environmental risk assessments (ERAs) in mind. In an attempt to rectify these issues, this research provides a new categorisation of uncertainties based, for the first time, on the appraisal of a large subset of ERAs, namely 171 peer-reviewed environmental weight-of-evidence assessments. Using this dataset, a defensible typology consisting of seven types of uncertainty (data, language, system, extrapolation, variability, model, and decision) and 20 related sub-types is developed. Relationships between uncertainties and the techniques used to manage them are also identified and statistically evaluated. A highly preferred uncertainty management option is to take no action when faced with uncertainty, although where techniques are applied they are commensurate with the uncertainty in question. Key observations are applied in the form of guidance for dealing with uncertainty, demonstrated through ERAs of genetically modified higher plants in the European Union. The presented typology and accompanying guidance will have positive implications for the identification, prioritisation, and management of uncertainty during risk characterisation.Item Open Access A novel approach for indentifying uncertainties within environmental risk assessments(Cranfield University, 2012-10) Skinner, Daniel J. C.; Rocks, S.Uncertainties can manifest within the different aspects of environmental risk assessments, affecting the validity of the risk estimate and, in turn, weakening the basis for risk management actions. This research investigated the issues associated with uncertainty characterisation and identification in environmental risk assessments. This led to the creation of a defensible typology of uncertainties, and the creation and validation of a novel uncertainty identification system (UnISERA), based on the elicited views of experts regarding the levels (i.e. magnitudes), natures (i.e. reason for existence) and locations (i.e. where manifest) of uncertainties present within different risk domains. The developed typology, drawn from an analysis of existing assessments, contained seven locations of uncertainty (data, language, system, extrapolation, variability, model and decision), with 20 related sub-types. The output from UnISERA, based on 19 aggregated elicitations across three risk domains (genetically modified higher plants, particulate matter and pesticides), showed that: the risk characterisation phase of assessments contained the highest magnitudes of uncertainty (the level dimension); uncertainties across all four phases of assessments existed primarily through a combination of lack of knowledge and randomness (the nature dimension); and data uncertainty was dominant in the first three phases, and extrapolation uncertainty in the final phase (the location dimension). In comparing the output from UnISERA to similarly produced results in the risk domain of engineered nanomaterials, the nature of uncertainty showed the highest degree of validation (90%), followed by the location (80%) and level (55%) dimensions. The novel approach to uncertainty characterisation and identification presented here will be of use during environmental risk assessments and uncertainty analyses, promoting an understanding of potential uncertainties, and allowing risk analysts to perform assessments with prioritised uncertainties in mind.Item Open Access A review of uncertainty in environmental risk: characterising potential natures, locations and levels(Taylor and Francis, 2013-06-10) Skinner, Daniel J. C.; Rocks, Sophie A.; Pollard, Simon J. T.Uncertainties, whether due to randomness or human or system errors, are inherent within any decision process. In order to improve the clarity and robustness of risk estimates and risk characterisations, environmental risk assessments (ERAs) should explicitly consider uncertainty. Typologies of uncertainty can help practitioners to understand and identify potential types of uncertainty within ERAs, but these tools are yet to be reviewed in earnest. Here, we have systematically reviewed 30 distinct typologies and the uncertainties they communicate and demonstrate that they: (1) use terminology that is often contradictory; (2) differ in the frequencies and dimensions of uncertainties that they include; (3) do not uniformly use systematic and robust methods to source information; and (4) cannot be applied, on an individual basis, to the domain of ERA. On the basis of these observations, we created a summary typology – consisting of seven locations (areas of occurrence) of uncertainty across five distinct levels (magnitude of uncertainty) – specifically for use with ERAs. This work highlights the potential for confusion, given the many versions of uncertainty typologies which exist for closely related risk domains and, through the summary typology, provides environmental risk analysts with information to form a solid foundation for uncertainty analysis (based on improved understanding) to identify uncertainties within an ERA.Item Open Access Where do uncertainties reside within environmental risk assessments? Expert opinion on uncertainty distributions for pesticide risks to surface water organisms(Elsevier, 2016-08-01) Skinner, Daniel J. C.; Rocks, Sophie A.; Pollard, Simon J. T.A reliable characterisation of uncertainties can aid uncertainty identification during environmental risk assessments (ERAs). However, typologies can be implemented inconsistently, causing uncertainties to go unidentified. We present an approach based on nine structured elicitations, in which subject-matter experts, for pesticide risks to surface water organisms, validate and assess three dimensions of uncertainty: its level (the severity of uncertainty, ranging from determinism to ignorance); nature (whether the uncertainty is epistemic or aleatory); and location (the data source or area in which the uncertainty arises). Risk characterisation contains the highest median levels of uncertainty, associated with estimating, aggregating and evaluating the magnitude of risks. Regarding the locations in which uncertainty is manifest, data uncertainty is dominant in problem formulation, exposure assessment and effects assessment. The comprehensive description of uncertainty described will enable risk analysts to prioritise the required phases, groups of tasks, or individual tasks within a risk analysis according to the highest levels of uncertainty, the potential for uncertainty to be reduced or quantified, or the types of location-based uncertainty, thus aiding uncertainty prioritisation during environmental risk assessments. In turn, it is expected to inform investment in uncertainty reduction or targeted risk management action.Item Open Access Where do uncertainties reside within environmental risk assessments? Testing UnISERA, a guide for uncertainty assessment(Elsevier, 2017-03-08) Skinner, Daniel J. C.; Rocks, Sophie A.; Pollard, Simon J. T.A means for identifying and prioritising the treatment of uncertainty (UnISERA) in environmental risk assessments (ERAs) is tested, using three risk domains where ERA is an established requirement and one in which ERA practice is emerging. UnISERA's development draws on 19 expert elicitations across genetically modified higher plants, particulate matter, and agricultural pesticide release and is stress tested here for engineered nanomaterials (ENM). We are concerned with the severity of uncertainty; its nature; and its location across four accepted stages of ERAs. Using an established uncertainty scale, the risk characterisation stage of ERA harbours the highest severity level of uncertainty, associated with estimating, aggregating and evaluating expressions of risk. Combined epistemic and aleatory uncertainty is the dominant nature of uncertainty. The dominant location of uncertainty is associated with data in problem formulation, exposure assessment and effects assessment. Testing UnISERA produced agreements of 55%, 90%, and 80% for the severity level, nature and location dimensions of uncertainty between the combined case studies and the ENM stress test. UnISERA enables environmental risk analysts to prioritise risk assessment phases, groups of tasks, or individual ERA tasks and it can direct them towards established methods for uncertainty treatment.