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Risk Perception

Risk Perception. What It Is and What It Should Never Be. Definitions. Hazard evaluation – inherent biological effects X exposure (toxicity) (fate) Note: above = risk assessment = what agencies do

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Risk Perception

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  1. Risk Perception What It Is and What It Should Never Be

  2. Definitions Hazard evaluation – inherent biological effects X exposure (toxicity) (fate) Note: above = risk assessment = what agencies do Risk – hazard X probability of hazardous conditions (use certain assumptions/model i.e. 1/500 – 1/1000) Risk management - set acceptable levels of an occurrence Note: what is acceptable varies N.C. Q7 – 20 weekly mean flow every 20 years (more restrictive) A.R. Q7 – 10 weekly mean flow every 10 years (less restrictive) Note: real risks may be governed by other probabilities e.g. Could have two 100 year low flows in three years (severe drought years) • USDA Designates Entire State of Arkansas a Disaster Area – GRAINNET Oct. 17, 2005

  3. Management of Risk A. Acute – TFM (lampricide) kill lampreys in Great Lakes by dosing larvae in streams Free-swimming lamprey eel Suckers! Lake trout parasitized by lamprey • Want to kill lamprey’s (extreme risk to them) without killing lake trout (low risk to them)

  4. Relationship between risk of TFM to lake trout and lamprey 100 % Lamprey Mortality LC99 for lamprey LC1 for lake trout Lake trout 0 LC50 Log [TFM]

  5. Had to screen 45,000 chemicals to come up with TFM • Now TFM is applied to all 320 streams feeding into the Great Lakes where lampreys breed • Note: Other species are ignored  same as killing black flies in a stream even though may be primary food source of fish • Good example of how risk can be managed

  6. B. Chronic Control response Response (growth) Chronic value = highest acceptable risk (level of exposure) Control Log Dose

  7. C. Other • E.g labeling – pesticide labeled with what they are allowed to be used on  fungicide on grapes, insecticides (pyrethroids) on cotton Note: cotton requires some pesticides banned for all other uses

  8. Risk Perception • May differ greatly from true risk = “eye of the beholder” phenomenon • Acceptable risk = f(benefits)3 - if can measure $ value of benefits, acceptability follows cubically from that  people willing to accept risk if it means increasing $ in their pocket (not companies)

  9. Risk reality vs Risk Perception experts psychometrics Collective statistics factor analysis, (but can be slanted other multivariate e.g. safety of airplane statistical techniques (high risk in air) vs car (low risk in air)

  10. Decision making/judgement • The psychometric paradigm  thru trial and error  society has arrived at a balance between risks and benefits associated with any activity • Judgements on the risk associated with a particular hazard are based on: a. Hazards status relative to perceived risk - attitude Note: perceived risk based on voluntariness (skiing vs. food additives), dread, knowledge, controllability b. Benefits that hazard provides to society (chlorination of water) c. Number of deaths caused by a hazard in an average year d. Number of deaths caused by a hazard in a disastrous year

  11. Risks Perceived Hazard League of Women VotersExperts Nuclear power Motor vehicles Smoking Police work Private planes X-rays Electric power Mountain climbing 20 1 2 17 12 7 9 29 1 2 4 8 7 22 18 15 - Have to look at hazards individually (each stands on its own) - Communication problems  public does not care about scientific evidence

  12. Further evaluation of risk perception Unknown Saccharin X-rays Regulated TCE Mirex Individual Nuclear accident Pesticides Lead paint PCBs Hg Controllable Vaccines Uncontrollable dread Nerve gas Smoking Familiar Alcohol Nuclear war Skiing Accidents Auto accident Elec. shock Dynamite Motorcycles Fireworks Known

  13. Conclusions • Can categorize by two things  known/unknown and controllable/uncontrollable • As things get less familiar • Perception of risk increases • Can become “irrational” • Irrationality cannot be controlled by citing facts/probabilities • Activities which have high unknown and dread factors tend to be viewed as more significant no matter what the true risk is

  14. Position Papers • Used by advocay organizations to brief people (briefing documents) • Keep short/sweet  two sides + analysis  get to point • Give balanced treatment (unbiased)  subsequent analysis (opinion) can be as biased as one wants • Congressional staffers, dept. heads • Format and possible topics in writing guide • Remember: using headings will increase chance of a better grade because I will not have to search

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