© University of Hertfordshire, 2018 7LFS1034 Environmental Management Tools and Methods Environmental Risk Assessment Dr John Tzilivakis Agriculture and Environment Research Unit (AERU) School of Life and Medical Sciences 30 November 2018 © University of Hertfordshire, 2018 Environmental Risk Assessment: Contents • Concepts and terminology • Risk assessment frameworks – Qualitative assessment/risk screening – Quantitative risk assessment (QRA) • Typical steps: – Hazard identification and analysis – Exposure assessment – Risk estimation – Risk communication – Risk management / options appraisal • Example risk assessment • Some general principles for risk assessment © University of Hertfordshire, 2018 Concepts and terminology • Risk is multi-faceted with many overlapping components • Terms are often used either interchangeably and/or confusingly (e.g. 'risk' can often be used instead of 'hazard’, albeit they are connected) • There is also risk perception, which is a field of study of its own – not unrelated, but is more about human interpretation of risks or how people assess risks • Environmental Risk Assessment (ERA) is an 'objective' and scientific process to identify, characterise and quantify (where possible) risks to the environment, i.e. negative impacts. It tends be part of a broader framework of Environmental Risk Management (ERM) © University of Hertfordshire, 2018 Concepts and terminology • Environmental risk assessment is often context specific • Approaches may vary between industry sectors • Approaches may vary between industry and regulators • There are many different models, diagrams, concepts and ideas relating to risk assessment • But there are some fundamental aspects that are common to all… © University of Hertfordshire, 2018 Hazard Exposure Source Probability Receptor Risk Assessment Pathway © University of Hertfordshire, 2018 Types of risk assessment from ranking/scoring systems to probabilistic approaches Toxicity Ranking of concerns in the absence of specific exposure information Toxicity Exposure Assessment of hazard based in a ratio of single deterministic exposure and toxicity values Exposure Hazard Toxicity Hazard Risk Probability Assessment of risk based on the likelihood of exposure and/or toxicity Source: Krieger, R.I. and Krieger, W.C. (eds) (2001) Handbook of Pesticide Toxicology (Second Edition) Chapter 13 © University of Hertfordshire, 2018 Risk assessment frameworks © University of Hertfordshire, 2018 Steps in environmental risk management 1. Establish the context (e.g. river) Environmental Risk Assessment (ERA) 2. Identification of environmental risk sources 3. Prediction of the frequency and consequences 4. Potential risk definition: Acceptable, Tolerable and Intolerable 5. Create the environmental risk plan Environmental Risk Management (ERM) 6. Implementation of the environmental risk plan 7. Review and evaluation of the environmental risk plan Source: Darbra, R. M., Eljarrat, E. and Barcelo, D. (2008) How to measure uncertainties in environmental risk assessment. Trends in Analytical Chemistry, 27(4), 377-385. DOI: 10.1016/j.trac.2008.02.005 © University of Hertfordshire, 2018 Technical framework for environmental risk assessment and management Source: DETR (2000) Guidelines for Environmental Risk Assessment and Management. Department of the Environment, Transport and the Regions, London: HMSO. Available online at: http://webarchive.nationalarchives.gov.uk/20081023145831/http:/www. defra.gov.uk/environment/risk/eramguide/ (Last accessed: 27/11/18) © University of Hertfordshire, 2018 Technical framework for environmental risk assessment and management Source: Defra & Cranfield University (2011) Guidelines for Environmental Risk Assessment and Management. Green Leaves III. Defra, PB13670 https://www.gov.uk/government/uploads/system/uploads/attach ment_data/file/69450/pb13670-green-leaves-iii-1111071.pdf (Last accessed: 27/11/18). © University of Hertfordshire, 2018 Tiers of risk assessment Source: Brooks, A. (2009) Environmental risk assessment and risk management. Chapter 13 in Morris, P. and Therivel, R. (eds.) (2009) Methods of Environmental Impact Assessment. Third Edition. Taylor & Francis, 2009. ISBN 0415441757, 9780415441759. © University of Hertfordshire, 2018 Risk screening • Quantitative risk assessments tend to require large amounts of data, are costly to undertake and/or are very narrow in their perspective • Consequently as a first stage to risk assessment a risk screening exercise is normally undertaken, in order to 'screen out' lesser risks in order to prioritise resources for more detailed risk assessment of more 'important' risks • A common approach is to use expert judgement in combination with risk ranking matrices, in order to codify relative magnitude and probabilities… © University of Hertfordshire, 2018 Simple risk ranking matrix Impact 4 8 12 16 3 6 9 12 2 4 6 8 1 2 3 4 Likelihood Source: IEMA (2006) Risk management for the environmental practitioner. Institute of Environmental Management and Assessment. May 2006. ISSN 1 473-849X © University of Hertfordshire, 2018 Example summary of key pollutant linkages identified from a risk screening exercise Source Pathways of hazard Receptors Probability of Consequences Interim qualitative Justification for interim risk exposure risk characterisation characterisation PCDD/Fs Local residents/workers Medium Severe High Direct pathway, high load, assumes close proximity to site and outdoor exposure, high potency Incidental Local residents, particularly Medium ingestion of soil, children dust Severe High Indirect pathway, low load dispersion but local hot spots, limited intake, high potency Ingestion of Local breast-fed babies maternal breast milk Medium Severe High Indirect pathway, low load, limited uptake and storage by mothers, local hotspots where mother is long-term resident regularly consuming home grown produce, bioaccumulation in fatty tissue and release through breast feeding, high potency Consumption of Residential consumers of contaminated home grown produce fruit produce and vegetables) Low Severe Medium Indirect pathway, low load, removal due to rainfall and washing produce, assumes root crops unpeeled, limited contribution to diet, high potency Consumption of Consumers of locally Medium contaminated produced dairy and meat dairy and meat products (eggs and poultry) Products Severe High Indirect pathway, low load but local hotspots adjacent to site, limited transfer to dairy and meat products, evidence of bioaccumulation in eggs and poultry, high potency Inhalation of airborne dusts As, Pb, Cd, CrVI Inhalation of airborne dust Local residents Medium Severe High Direct pathway, high load, assumes close proximity to site and outdoor exposure, known health effects Incidental Local residents ingestion of soil, dust Medium Severe High Indirect pathway, low load, dispersion but local hotspots, limited intake, known health effects Source: Macleod, C., Duarte-Davidson, R., Fisher, B., Ng, B., Willey, D., Shi, J. P., Martin, I., Drew, G. and Pollard, S. (2006) Modelling human exposures to air pollution control (APC) residues released from landfills in England and Wales. Environment International, 32, 500–509. DOI: 10.1016/j.envint.2005.11.004 © University of Hertfordshire, 2018 Quantitative Risk Assessment (QRA) • QRA can be split into: – Generic QRA: use of generally available and tested models to provide simple quantification of risks – Site specific or tailored QRA: the development of specific models to meet a particular purpose – usually complex and expensive • QRA is usually used for characterising high priority risks and/or those that cannot be resolved or quantified using less sophisticated techniques (e.g. because of the complexities involved) • QRA is usually focused on one particular source-pathwayreceptor (rather than the whole or broader chain of events) © University of Hertfordshire, 2018 Quantifying risk – scope, tools and causality Release Exposure Harm Fault-tree and event tree analysis Distribution modelling Dose-response / surrogate standards Source Pathway Receptor Source Pathway Receptor Source Pathway Receptor Source: IEMA (2006) Risk management for the environmental practitioner. Institute of Environmental Management and Assessment. May 2006. ISSN 1 473-849X © University of Hertfordshire, 2018 ERA and ERM Steps • Although there is a tiered approach to risk assessment, there can be some common steps within each tier • Generally involves the following steps: – Hazard identification and analysis – Exposure assessment (consequences & magnitude) – Risk estimation (probability & significance) – Risk communication – Risk management / options appraisal © University of Hertfordshire, 2018 Hazard identification and analysis Exposure assessment Risk estimation Risk communication Risk management / options appraisal © University of Hertfordshire, 2018 Hazard identification and analysis • A hazard can only be defined in the context of: – The receptor to which the hazard applies; and – How (the pathway by which) that hazard might be realised • For a hazard to result in harm there must be a way in which it can affect a receptor, if not then a risk is non-existent © University of Hertfordshire, 2018 Hazard identification and analysis • Event tree or fault tree analysis is a common and accepted means of identifying hazards • It is generally a qualitative process • The structure should show the combination of preconditions required for a particular undesired outcome © University of Hertfordshire, 2018 Node 1 Node 2 Node 3 Node 4 Ignition? Application of fire water? Primary containment reestablished? Secondary containment failure? Yes No Yes Spill goes offsite No Spill contained onsite Yes Spill contained where released Yes No No Yes Running pool fire going off-site No Pool fire in secondary containment Flammable liquid release Short duration pool fire in vicinity of leak Yes No No Outcome Yes Spill goes offsite No Spill contained onsite Yes Source: IEMA (2006) Risk management for the environmental practitioner. Institute of Environmental Management and Assessment. May 2006. ISSN 1 473-849X Spill contained where released © University of Hertfordshire, 2018 Node 1 Node 2 Node 3 Node 4 Ignition? Application of fire water? Primary containment reestablished? Secondary containment failure? Yes No Yes Spill goes offsite No Spill contained onsite Doh! Yes Spill contained where released Yes No No Yes Running pool fire going off-site No Pool fire in secondary containment Flammable liquid release Short duration pool fire in vicinity of leak Yes No No Outcome Yes Spill goes offsite No Spill contained onsite Yes Source: IEMA (2006) Risk management for the environmental practitioner. Institute of Environmental Management and Assessment. May 2006. ISSN 1 473-849X Spill contained where released © University of Hertfordshire, 2018 Hazard identification and analysis • Often based on real world data, particularly data relevant to the local circumstances • Can also be useful for identifying mitigation options/intervention points • Hazard analysis involves estimating the probability or chance of occurrence of a particular hazard – e.g. by assigning probabilities to each branch of the event tree and can also include quantifying outcomes • Can also involve modelling (more likely to be undertaken as part of a QRA) to provide estimates or assessments, e.g. modelling the fate and transport of pollutants in the environment… (e.g. using dispersion models) which leads into exposure assessment… © University of Hertfordshire, 2018 Exposure assessment • For a hazard to be realised a receptor must be exposed to the hazard • Additionally, the level of exposure may affect the severity of the impact, e.g. concentrations of pollutants © University of Hertfordshire, 2018 Exposure assessment • There are a number of aspects to consider: – A clear definition of the hazard – The characteristics of the local environment, both in terms of how this affects the hazard and also what specific receptors may be exposed and their sensitivity to the hazard – The behaviour of the hazard – Specific 'dose-response' relationships • The effect or consequences of the hazard/exposure also needs to be assessed, e.g. does it… – Affect the health of the receptor, e.g. affect its reproductive capability (use of No Observable Effect Concentration – NOEC) – Kill the receptor, if so what proportion of the population might it affect (use of Lethal Dose or Concentration - LD50 or LC50) © University of Hertfordshire, 2018 Example table of risk consequences Type of consequence Description Very high risk Ecosystem irreversibly altered; no recovery. Over 100 km² affected. High risk Ecosystem altered, but not irreversibly ; recovery may take as long as 50 years. 50-100 km² affected. Moderate risk Only one component of the ecosystem affected; 10 year recovery period. Low risk Temporary alteration; effects confined to less than 0.5 km²; recovery in less than five years. Very low risk Temporary alteration; very localised and minor consequences. © University of Hertfordshire, 2018 Risk estimation • It is probably this aspect of risk assessment in which there are as many techniques as there risk assessments, however some common approaches do exist… • The simplest form of risk estimation is usually a matrix, combining the results of hazard and consequence analyses or hazard and probability/likelihood • Simplified risk matrix: Magnitude Probability or likelihood High Medium Low High Very high risk High risk Moderate risk Medium High risk Moderate risk Low risk Low Moderate risk Low risk Very low risk © University of Hertfordshire, 2018 Risk estimation • Other more sophisticated approaches include: – Using scoring, ranking and weighting methods to ascertain a risk score • Sometimes presented as Multi-Criteria Analysis (MCA) – Calculating/quantifying risks • e.g. use of substance X will result in the death of 50% of fish species Y in areas A and B © University of Hertfordshire, 2018 Risk communication • In many respects, this is a field of study of its own, especially with respect to risk perception and/or communicating risks to the public • However, there a number of basic aspects to consider including: – The target audience/purpose of the risk assessment – Avoid unrealistic levels of precision in risk estimates – Communication of data quality – Communication of uncertainty or unknown risks © University of Hertfordshire, 2018 Risk communication • The target audience/purpose of the risk assessment: – The risk assessment is usually undertaken to aid decision making – ensure that the information is presented in a way to support the decision making process – In some instances, decision makers may require simplified representations of risk, in other instances they may want the full detail (including the ability to view underlying 'raw' data) – so tailor results according to end user needs • Avoid unrealistic levels of precision in risk estimates – Presenting risk numerically can imply precision that simply is not there, more so if presented with decimal places: • e.g. 62.88% might be better presented as 6 out of 10 – Risk is usually presented nominally or ordinally: • e.g. low, medium or high; or I, II, III © University of Hertfordshire, 2018 Risk communication • Communication of data quality – The data on which a risk assessment has been based can vary in quality – Where this is significant it should be communicated to the end user, so that this is known and can be taken into account in any decision making process • Communication of uncertainty or unknown risks – In some instances, data may be missing or unknown, consequently it is not possible to assess risk – Where risk is unknown this needs to be communicated and not simply left out of the results – Need to avoid unknown risk being perceived as being no risk © University of Hertfordshire, 2018 Risk management / options appraisal • Utilises the results of the assessment to mitigate or reduce unacceptable risks • Need to understand the full spectrum of risks and consequences in order to draft responses and interventions that will reduce the risk – in the context of cost versus benefit • Need to assess the potential relative risk reduction of each mitigation option, so that this can be weighed up against the cost of that option • Ideally want low cost options with high mitigation potential rather than high cost options with low mitigation potential © University of Hertfordshire, 2018 QRA Example: Pesticide use © University of Hertfordshire, 2018 FOOT-FS: Risk assessment tool • Developed 2006-2009 as part of the EU FOOTPRINT project • FOOT-FS = Field Scale (FS) risk assessment tool (there were also tools for catchment and national levels) • Helps identify the activities (and pathways) that most contribute to the contamination of water resources with pesticides. The tool: – Models fate and transport of pesticides and predicts concentrations – Calculates ecotoxicity risks – Interprets and communicates the risk – Suggests mitigation options © University of Hertfordshire, 2018 FOOT-FS: Fate and Transport • Drift • Drainage • Run-off & Erosion • Leaching to groundwater © University of Hertfordshire, 2018 FOOT-FS: Predicted Environmental Concentrations - PECs • Inputs from drift, drainage and run-off/erosion • Use STEPS 3 model to calculate PEC • Time-weighted average to obtain the 24 hour period (during 7 days - 168 hours) with the highest concentration... © University of Hertfordshire, 2018 FOOT-FS: Predicted Environmental Concentrations - PECs Hours 166 161 156 151 146 141 136 131 126 121 116 111 106 101 96 91 86 81 76 71 66 61 56 51 46 41 36 31 26 21 16 6 11 1 Concentration © University of Hertfordshire, 2018 FOOT-FS: Ecotoxicity • The PECs and data from the pesticide properties database (PPDB*) are then used to calculate Toxicity Exposure Ratios (TERs) for: – Fish (acute) – Fish (chronic) – Invertebrates (acute) – Invertebrates (chronic) – Algae (acute) – Algae (chronic) – Aquatic plants * PPDB - see: http://sitem.herts.ac.uk/aeru/ppdb/en/ (Last accessed: 27/11/18) © University of Hertfordshire, 2018 FOOT-FS: Risk Interpretation • TERs are converted to a risk score and risk band for each taxa using the following: Algae (chronic and acute), Lemna, Fish (chronic) & Daphnia (chronic) Fish (acute) & Daphnia (acute) High Moderate Low Source: Adapted from: Hart, A., Brown, C. D., Lewis, K. A. and Tzilivakis, J. (2003) p-EMA (II): evaluating ecological risks of pesticides for a farm-level risk assessment system. Agronomie, 23(1), 75-84. DOI: 10.1051/agro:2002075 © University of Hertfordshire, 2018 FOOT-FS: Risk Interpretation • Risk alerts (low, moderate, and high) for each taxa for each active substance applied • Where data are missing (e.g. no ecotoxicity values exist for a substance) an unknown risk is allocated • Results can be displayed in a number of ways © University of Hertfordshire, 2018 FOOT-FS: Results • At a summary level we have a simple indicator bar for each active substance applied, based on the number of low, moderate and high ecotoxicity risk alerts generated: lenacil phenmedipham • Also use icon alerts for different taxa when moderate or high alerts are triggered, e.g.: Fish Invertebrates Algae Plants © University of Hertfordshire, 2018 FOOT-FS: Risk mitigation/management • What can be done to mitigate the risks? – Change application equipment (sprayer and nozzle type) – Change application rates or dates – Change the formulation – Reduce the amount applied – Increase buffer zones – Use physical barriers, grass strips, windbreaks, etc. © University of Hertfordshire, 2018 FOOT-FS: Demonstration © University of Hertfordshire, 2018 Some general principles • Clearly define the problems being addressed, the scope of the assessment and the decisions it supports. • Clearly define any spatial and temporal boundaries • A stepwise and iterative approach aids transparency and communication, building up through qualitative screening processes to more complex quantitative assessments on the key risk areas • Assessments should not be more complex than is needed the level of analysis should be commensurate with the risks © University of Hertfordshire, 2018 Some general principles • Uncertainty is inherent in all environmental risks – so be careful on how much precision is inferred by a risk assessment, and where there is significant uncertainty ensure this is communicated • Models can be incomplete and lack accuracy, so be careful on how they are used and how results are interpreted • A good test for a risk assessment is whether it does actually aid decision making: – Does it add clarity to decision processes or does it add confusion? © University of Hertfordshire, 2018 Any Questions?
