Lecture 2 and 3: Risk Flashcards
What is risk?
The potential for realization of unwanted consequences to human life, health, property or the environment
What are the 3 parameters of risk?
- PROBABILITY of harm
- SEVERITY of harm
- SCALE of time or extent
Define probability of harm
The probability or likelihood of a harmful event occurring (aka Quantity)
What is severity of harm?
The impact of an event occurring (the end point)
Name the 3 regions of risk
- Broadly Acceptable Region
- As Low As Reasonably Practicable (ALARP) Region
- Intolerable Region
What are the 2 types of risk?
- Absolute risk
- Relative risk
What is Absolute Risk?
The risk of an event occurring (eg. developing some disease over a certain period of time)
Eg: “1 in 10”, “10%”, etc
What is Relative Risk?
The risk of an event relative to exposure to certain factors
NB: Compares risk in two different groups of people (exposed versus non-exposed)
What are the 3 types of relative risk ?
- Detrimental: RR > 1
- No correlation: RR = 1
- Beneficial: RR < 1
List 5 factors that influence the perception of risk
- Familiarity vs Lack of familiarity with the technology
- Personal control vs lack of control
- Voluntary vs Involuntary exposure
- Direct vs Indirect benefits from use of the technology
- Fairness of exposure (only some neighbourhoods are exposed)
List the top 5 relative risk activities
- Motor Vehicles
- Smoking
- Alcoholic beverages
- Handguns
- Surgery
“Safe” is not the same as risk-free
True
What are the 2 biological effects of ionizing radiation?
- Somatic effects
- Hereditary (genetic) effects
What is somatic effect?
A health effect limited to the exposed individual and not carried to offspring from a parent
What is hereditary/genetic effect?
A health effect in a descendant resulting from a modification of genetic material in a parent
Name 5 somatic effects
- Leukemia
- Tumours
- Radiation skin burns
- Loss of organ function
- Death
Name 4 hereditary effects
- Congenital cataracts
- Anemia
- Epilepsy
- Diabetes
What are the 2 types of Somatic Effects?
- Deterministic effects
- Stochastic effects
What is deterministic effect?
A radiation-induced health effect with a threshold dose, increasing in severity.
What is stochastic effect?
A health effect where the “risk” of occurrence (probability) increases as dose increases
What is the main difference between deterministic and stochastic effects?
With deterministic, the person will get it after a certain threshold is reached, but with stochastic, we can’t predict when or if the effect will occur in any particular person.
Deterministic vs Stochastic Effects
What is the Linear No-Threshold Model?
This assumes that any radiation dose, no matter how small, increases cancer risk proportionally.
NB: It is used to determine a “safe” level of radiation exposure for stochastic effects. It is suggested that this model overestimates the risk at low doses
What is radiation hormesis?
This is the suggestion that low-dose radiation exposure may have beneficial health effects by stimulating biological defenses.
What is the value given by the ICRP as estimate for an increase in risk for hereditary effects?
0.2% per Seivert
List 4 stochastic effects
Fatal cancer
Non-fatal cancer
Tumour
Genetic/hereditary effects
How is ionizing radiation harmful?
It either breaks DNA directly, or creates free radicals (usually OH molecules) that cause chemical damage.
Mutations in somatic cells =
somatic or non-heritable effects
Mutations in germ cells (sperm and ova) =
Genetic/heritable effects
