Environmental Risk Analysis

1. Environmental Risk Analysis Chapter 6

2. Overview of Risk • Risk is the chance of something bad happening • Risk is inevitable if we want to do anything • Need to: • Describe and assess the risk • Manage or respond to the risk

3. 1. Describing Risk • Classifying risk: • Voluntary risk: deliberately assumed by individuals • Involuntary risk: not the result of willful decision • Environmental risk is the involuntary risk of exposure to an environmental hazard • Hazard: source of environmental damage • Exposure: pathways between the hazard and the affected population or natural resource • Risk groups: • Humans • Environment/ecology

4. Risk Assessment Qualitative and quantitative evaluation of risk of an environmental hazard to health or the environment National Center for Environmental Assessment

5. Hazard Identification • Use of scientific data to determine if a pollutant causes adverse effects on health or the environment • Scientific methods to identify health hazards • Case cluster: Look at abnormal patterns of health effects in some population group • Animal bioassay: Compare findings of lab experiments on living organisms before and after exposure to some hazard • Epidemiology: Study causes and distribution of disease in human populations based on characteristics like age, gender, occupation, etc.

6. Dose-Response Assessment • Get a profile of the pollutant’s effects • Dose-response relationship gives the quantitative relationship between doses of the contaminant and corresponding reactions • Thresholdis the level of exposure up to which no response exists • Reference dose (RfD) is exposure to a hazard that can be tolerated over a lifetime without harm • Example: milligrams of pollutant per body weight per day

7. Hypothetical Dose-Response Functions response response response 0 0 dose 0 dose dose Dt DO What does each figure mean?

8. EPA’s IRIS • Integrated Risk Information System: Information on health risks of environmental contaminants • Risks to both humans and ecology • Ecological risk assessment evaluates the probability of changes to the natural environment linked to such stressors as pollution exposure or climate change

9. 2. Risk Management • Risk management is the decision-making process of evaluating and choosing from alternative responses to environmental risk • Tasks: • Determining what level of risk is “acceptable” to society • Evaluating and selecting the “best” policy instrument to achieve that risk level

10. Determining “Acceptable” Risk • The extent of risk reduction determines the level of exposure and stringency of policy • Should exposure be set to zero? If not, what positive level is appropriate? • Might use minimum risk as baseline • Might use comparative risk analysis to compare risk of environmental hazard to other risks faced by society

11. Risk Management Strategies • Evaluate policy options in a systematic way • Common risk management strategies: • Comparative risk analysis – compare risks against each other • Risk-benefit analysis – compare risks with benefits of allowing risk (pesticide rules) • Benefit-cost analysis – compare costs of risk with benefits of allowing risk

12. Key Ideas • Risk is inevitable • Assess risk – knowledge of chemistry, biology • Manage risk – policy decision based on economics