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Interface Between Risk Assessment and Economics: Economic Valuation Methods Presentation to IRAC Conference Risk Assessment, Economic Analysis, and Foodborne.

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Presentation on theme: "Interface Between Risk Assessment and Economics: Economic Valuation Methods Presentation to IRAC Conference Risk Assessment, Economic Analysis, and Foodborne."— Presentation transcript:

1 Interface Between Risk Assessment and Economics: Economic Valuation Methods Presentation to IRAC Conference Risk Assessment, Economic Analysis, and Foodborne Illness Regulations Al McGartland, USEPA November 16, 2007 The opinions in this presentation do not necessarily represent those of EPA.

2 2 1990s Evolution of Risk Assessment at EPA 1970s  beginnings of the field of risk assessment  emphasis on oral route per FDA precedent 1980 s  adopt RA/RM paradigm  guidelines & basic methodologies  data bases (IRIS)  new tools/data bases  refinement of existing tools  understanding mechanisms of action/interactions  ecological assessment 2000s  complex mixtures  sensitive subpopulations  non-linear dose-response  input into economic analysis

3 3 Roles of Risk Assessment Risk Assessment - cancer - non-cancer Policy Decision - standards - information Risk AssessmentRisk Management Protective

4 4 Roles of Risk Assessment Risk Assessment - cancer - non-cancer Policy Decision - standards - information Risk Assessment Economic Analysis - benefit-cost analysis - cost effectiveness - economic impacts Risk Management Protective Predictive

5 5 Damage Function Approach Benefits analysis draws upon results of other disciplines Simplified linear process of benefits analysis, but there may be feedback loops –For example, changes in individual behaviors evaluated in the benefits “box” may have implications for emissions or exposure Emissions Environmental Concentrations Exposure Effects (dose-response) Benefits ($ for each effect)

6 6 From Risk Assessment to Economics Should focus on well-defined health endpoints that have an effect on individual sense of well-being. –“hormone level” vs. hypothyroidism Should be probabilities to represent the expected changes in risk to an individual –probabilities not thresholds –upper bound risk estimates Should provide information on when risks change due to exposure changes –substantial lags between exposure and cancer

7 7 Health Science Inputs and Economic Valuation Epidemiological data are preferred for valuation in policy analysis –observed health effects in humans –incorporates behavioral responses Results from animal studies may be used –Cancer dose-response: risk estimates are still usable although their applicability can be a concerns (e.g, upper-bound estimates) –Non-cancer risk assessment: Reference doses and other measures that don’t estimate probabilities cannot be utilized in benefits analysis

8 8 Cancer vs. Non-Cancer Benefits

9 9 Economic Analysis Predictive Risk Assessment Data Cost of Illness Willingness to Pay Quality Adjusted Life Years Disability Adjusted Life Years Cost- Effectiveness Analysis Benefit-Cost Analysis Analytic Approach Health Value Measure

10 10 Economic Analysis Predictive Risk Assessment Data Cost of Illness Willingness to Pay Quality Adjusted Life Years Disability Adjusted Life Years Cost- Effectiveness Analysis Benefit-Cost Analysis Analytic Approach Health Value Measure

11 11 Benefit-Cost Analysis Simulates the private market test for public goods –BCA quantifies all benefits and costs of producing environmental protection –Consistent with private markets, the efficient outcome is the option that maximizes net benefits –BCA is, therefore, an efficiency test for the production of environmental protection.

12 12 Benefits Rules for determining the benefit, or value, of environmental protection are the same as those in the private market – quantify the willingness to pay for the environmental commodity Value is determined by what consumers are willing to pay for a commodity, not what the analyst believes the value to be –Economists look to see what values society places on environmental goods –Analysts do not assign their own values Because environmental protection it is a public good, the benefits of a policy are the sum total of each affected individual’s willingness to pay for the policy

13 13 Values for use in Benefit-Cost Analysis Cost of illness ($) Each avoided health effect converted to $-equivalent based on lost production and health care costs –lost production may include household production Clearly defined and measurable Limited measure –not necessarily based on individual preferences –incomplete, does not include pain and suffering –price of health care may not equal costs –generally, loosely, characterized as a lower bound on willingness to pay

14 14 Willingness to Pay Willingness to Pay for risk reduction ($) Each avoided health effect converted to $ based on preferences of the individuals affected Well-being is expressed in a general utility function: Utility=(health, all other goods) Willingness to pay is... One’s own WTP for one’s own risk reduction –WTP for others may be included under strict conditions Affected and constrained by income –willingness to pay includes “ability to pay” Willingness to pay is not… A measure of on ex post compensation experiencing health effect –WTP is measured ex ante for risk reductions

15 15 Health Benefits & Methods Methods are based on where people appear to tradeoff risk and wealth: –Hedonics: Wage-risk: how much additional wages to workers require to take risky jobs? Housing prices: extra housing price for “safer” area or higher env. quality? –Averting Behaviors: how much do individuals pay for safety devices and safer vehicles, etc.? –Stated Preference (Surveys): how much do individuals state they will pay for a specified risk reduction

16 16 Value of a Statistical Life (VSL) The value of mortality risk reductions is often summarized by calculating the value of a statistical life or VSL What is a “statistical life”? –Suppose a public policy were to reduce mortality risk by 1 in 10,000 If 10,000 were affected by this policy then, statistically, 1 death would be avoided –We have no idea before we implement the policy which life will be “saved.” What is the Value of a Statistical Life (VSL)? –Derived from the value or WTP individuals place on a small change in risk

17 17 VSL Key Points VSL estimates do NOT capture the value of an identifiable person VSL estimates do NOT capture how much an individual would be willing to pay to save his own life with certainty or the life of a loved one Instead, VSL estimates represent (or are derived from) individual willingness to pay for a SMALL change in the probability of dying

18 18 Example VSL Calculations Suppose that each of 10,000 people were willing to pay $500 each for the 1 in 10,000 risk reduction –The value of that statistical life is the sum of the total of the individual amounts the 10,000 people would pay for the risk reduction Put more generally, the value of a statistical life is calculated: –VSL = WTP* (1/risk reduction) In our case this would amount to… –VSL $500*(1/(1/10,000)) = $5,000,000

19 19 Issue: VSL and Life Expectancy

20 20 Morbidity (illness): ”value of statistical illness” based on WTP to reduce risks or avoid illness We lack WTP estimates for many non-fatal illnesses each illness is unique to some extent (severity, frequency, duration) –requires unique research or systematic extrapolation from others EPA policy and practice –No set values for particular illness –Often use WTP values for similar illnesses Non-fatal bladder cancer use range based on WTP per statistical chronic bronchitis ($600,000) to non-fatal lymphoma ($3 million) Cost-of-illness methods can be difficult –Reporting is censored. Likely that many minor illnesses are never seen by physician. Valuing changes in morbidity risk

21 21 Additional Considerations (WTP) Equity Considerations –WTP is related to income –What if studies demonstrate the elderly have lower VSL? –recent results suggest health status has little effect on valuing mortality risks Economic criticisms –sensitive to risk perceptions –does not include people’s WTP for risk reductions to other people Dollar terms can be compared directly to costs Very flexible theoretically... –incorporates broad range of health effects –can incorporate context (source of risk)

22 22 Issue: Timing of Exposure changes and risk reductions The timing of risk reductions matters for the value of benefits Generally, risk reduction like any economic good is preferred sooner rather than later (time discounting) Also, the shorter the cessation lag: The more cases are avoided (or lives saved) over the life of the rule or the analysis The fewer deaths from other causes before the benefit is realized These data are not often part of the risk assessment

23 23 Impact of Cessation Lags on Benefits A B C D Alternative Cessation Lag“cases” avoided Benefits ($m) 3% Benefits ($m) 7% Immediate Benefits (A+B+C+D)120$ 429$ 257 Exponential Decay (A+B+C)100$ 330$ 176 Lagged Step Function (A+B)60$ 162$ year fixed lag (A)30$ 65$ 18

24 24 Cost Effectiveness Analysis Benefits are not measured in non-monetary units Ranks alternatives by $ per unit, –may determine the best alternative, but cannot determine if any of the alternatives should be done. For mortality risks typical “units” –Lives saved => rank by $ per life saved –Life years =>rank by $ per life-year saved Neither of these measures accomodates non-fatal illnesses Cost-effectiveness cannot accommodate mortality and morbidity unless they are combined into some common measure –Quality Adjusted Life Years (QALYs) combine fatal and non-fatal illnesses into one measure

25 25 QALYs for Cost-Effectiveness Quality-Adjusted Life Years (QALYs) health conceptualized as having two dimensions –longevity (years) –health-related quality of life –outcome is total years weighted by quality in each year well-being is defined by health profile over time –Utility = U(Quality, longevity) wealth does not enter into this framework

26 26 Quality-Adjusted Life Years (QALYs) Assume a policy extends the baseline health profile (white) The gain in QALYs is shown in gray –Quality * years at that quality Note the risk assessment requirements: a profile of expected future health outcomes and time in each health state

27 27 Additional Considerations (QALYs) Equity considerations –interventions for young preferred to interventions for old Young have more life years remaining –life extensions for healthy preferred to life extensions to less-healthy Healthy have a higher quality than chronically ill Economic criticisms –assumptions are restrictive and may not reflect actual preferences –concern about quality of surveys (data) –How to deal with non-health effects (e.g., environmental) from the policy in a cost-effectiveness framework

28 28 WTPQALY Type of Analysis Benefit-Cost Analysis Cost-Effectiveness Analysis Tradeoff basis money and risks to health health and longevity Endowment / Comparison individual wealthhealth profile Social Goal Max. self-assessed welfare Sum (individual WTP ($) values) Max. health - weighted longevity Sum (quality * years) WTP & QALY: Some Conceptual Comparisons

29 29 Concluding Thoughts Economics offers tools for risk management –Risk assessment must be predictive to support economic analysis This kind of risk assessment is being actively pursued –There are two widespread economic approaches to valuing changes to health and risk: benefit-cost analysis and cost-effectiveness analysis –Benefit-cost analysis and cost-effectiveness analysis approaches use very different metrics to assess the value of risk changes BCA and CEA will not necessarily point to the same policy or standard.


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