OIDD 261 Lecture Notes - Lecture 5: Saccharin, Food Additives Amendment Of 1958, Confirmation Bias
1 Jun 2018
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Notes for Slides 7:
Estimating Probabilities of Accidents and Their Consequences
• Fault Trees--Always starts with the definition of undesired effect and reasons how it may
have happened (how)
• Event Trees--Proceeds forward in time from a failure to their accident implications (what)
Normal Accidents--Produced by complexity and tight coupling
• Events are not independent--interactive complexity
• Processes are tightly coupled--no organizational slack
• example : Three Mile Island
Notes for Slides 8:
Differences in Probability Values between Pruned and unpruned Trees (?)
• unpruned trees: more info, more accurate
Three Supreme Court Cases judging Science:
1. Daubert--is Bendectin a carcinogen?
2. Joiner--do PCBs cause lung cancer?
3. Kimho Tire--is automobile tire explosion due to manufacturing defect?
Attributes for determining whether association means causality
• Strength of association
• Consistency across studies
• Specificity to a particular organ or group of people
• Temporality
• Does effect increase with dose?
• Plausibility
• Is relationship coherent with other data?
• Did effect vanish when cause was removed?
Steps in risk assessment process for carcinogens
1. Collection of toxicity information about the substation
2. Identifying whether substance represents a carcinogenic risk
3. Degree of risk substance might pose to humans
4. Extrapolation from animal risk estimates to potential human risk
Methods of risk assessments used by agencies
• Overstate risk posed by carcinogens for the following reasons:
• Chemical which causes cancer in animals will do so in humans
• Assume greatest risk at lowest dose
• Use mathematical models that yield highest prediction of risk at low doses
• Do not assume threshold for any carcinogen
Maintaining integrity of risk assessment process:
• Make explicit all assumptions and uncertainties
• Peer review of risk assessments
• Agencies separate risk assessment from risk management
Assessing Risk: Role of Epidemiology
Definition: Study of the occurrence and causes of disease (and health) in human populations
Goals: disease prevention
Layperson V Expert Disagreement of Cancer Cluster
• Layperson seeks explanation, fears cancer
• Similarities between state cancer rate and block cancer rate is reassuring to
epidemiologists but alarming to laypersons
• Confirmation bias is used by laypersons but not experts
• Leads to the Delaney Clause
• 1958 ban of all carcinogens from any processed food
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Estimating probabilities of accidents and their consequences: fault trees--always starts with the definition of undesired effect and reasons how it may have happened (how, event trees--proceeds forward in time from a failure to their accident implications (what) Normal accidents--produced by complexity and tight coupling: events are not independent--interactive complexity, processes are tightly coupled--no organizational slack, example : three mile island. Differences in probability values between pruned and unpruned trees (?: unpruned trees: more info, more accurate. Steps in risk assessment process for carcinogens: collection of toxicity information about the substation, identifying whether substance represents a carcinogenic risk, degree of risk substance might pose to humans, extrapolation from animal risk estimates to potential human risk. Maintaining integrity of risk assessment process: make explicit all assumptions and uncertainties, peer review of risk assessments, agencies separate risk assessment from risk management. Definition: study of the occurrence and causes of disease (and health) in human populations.
