Chapter 6 Environmental Risk Analysis 2004 Thomson LearningSouthWestern

Chapter 6 Environmental Risk Analysis © 2004 Thomson Learning/South-Western

Concept of Risk l Risk – the chance of something bad happening ¡ ¡ Dealing with risk involves two tasks: l Identifying the degree l Responding to it Policymaker must use a systematic assessment of risk before devising a policy response 2

Concept of Risk l Classifying Risk: Voluntary and Involuntary Risk ¡ ¡ Voluntary risk – a risk that is deliberately assume at an individual level Involuntary risk – a risk beyond one’s control and not the result of a willful decision 3

Concept of Risk l Defining Environmental Risk ¡ ¡ ¡ Environmental risk – the probability that damage will occur due to exposure to an environmental hazard Hazard – the source of the environmental damage Exposure – the pathways between the source of the damage and the affected population or resource 4

Risk Assessment in Environmental Decision Making l Risk assessment – qualitative and quantitative evaluation of the risk posed to health or the ecology by an environmental hazard ¡ Hazard identification – scientific analysis to determine whether a causal relationship exists between a pollutant and any adverse effects 5

Risk Assessment in Environmental Decision Making Figure 6. 1 Risk Assessment Process 6

Risk Assessment in Environmental Decision Making ¡ Methods of identifying environmental hazards l Case clusters – study based on observation of abnormal patters of health patterns within some population group l Animal bioassay – a study based on the comparative results of laboratory experiments on living organisms both before and after exposure to a given hazard l Epidemiology – the study of the causes and distribution of disease in human populations based on characteristics such as age, gender, occupation, and economic status 7

Risk Assessment in Environmental Decision Making l Dose-Response Analysis – a quantitative relationship between doses of a contaminant and the corresponding reactions ¡ ¡ Threshold – the level of exposure to a hazard up to which no response exists Two types of extrapolations l High-to-low dose extrapolation – adjusts for the high exposure levels used in laboratory or other test conditions l Laboratory-to-natural extrapolation – infers how the effects observed in the laboratory would differ under conditions existing in nature 8

Risk Assessment in Environmental Decision Making Figure 6. 2 Hypothetical Dose-Response Relationships 9

Risk Assessment in Environmental Decision Making l Exposure Analysis – characterizes the sources of an environmental hazard, concentration levels at that point, pathways, and any sensitivities ¡ Risk Characterization – description of risk based upon an assessment of a hazard and exposure to that hazard l Quantitatively identifies magnitude of the risk and a way to compare one risk to another l Qualitatively gives context to the numerical risk value 10

Risk Management in Environmental Decision Making: Responding to Risk l Risk Management – the decision-making process of evaluating and choosing from alternative responses to environmental risk ¡ Two major tasks: l Determining what level of risk is “acceptable” to society l Evaluating and selecting the “best” policy instrument to achieve that risk level 11

Risk Management in Environmental Decision Making: Responding to Risk l Tasks of Risk Management ¡ ¡ Determining Acceptable Risk l “Acceptable” risk – the amount of risk determined to be tolerable for society l De minimis risk – a negligible level of risk such that reducing it further would not justify the costs of doing so Evaluating and Selecting a Policy Instrument 12

Risk Management in Environmental Decision Making: Responding to Risk l Risk Management Strategies ¡ ¡ Considerations in selection of risk management strategy: l The level of risk established l The benefits that accrue to society from adopting the policy l The associated costs of implementing the policy Prevalent risk management strategies: l Comparative risk analysis l Risk-benefit analysis l Benefit-cost analysis 13

Risk Management in Environmental Decision Making: Responding to Risk ¡ ¡ ¡ Comparative risk analysis – an evaluation of relative risk Risk-benefit analysis – an assessment of risks of a hazard along with the benefits to society of not regulating that hazard Benefit-cost analysis – a strategy that compares the MSB of a risk reduction policy to the associated MSC 14