Risk Assessment

• joint probabilities of an occurence of an event and its consequences
• Risk = Likelihood of occurrence x Consequences

• 1) Perceived through science. (ie. cholera)
• 2)Perceived directly. (ie. climing a tree)
• 3) Virtual risk. (ie. global warming)

• Asks the questions:
• what can go wrong?
• What is the likelihood that it will go wrong?
• What are the consequences?

• Asks the questions:
• What can be done?
• What options are available?
• What are the impacts on the future?

A situation, which poses a level of threat to life, health, property, or environment.

• 1) Dormant - nothing is currently affected
• 2) Active - Hazard is certain to effect without intervention
• 3) Mitigated - hazards are identified and prevented
• 4) Potential - hazard is in the position to affect

The probability that exposure to a hazard will lead to negative consequences such as cancer.

• 1) Hazard identification
• 2) Toxicity Assessment
• 3) Exposure assessment
• 4) Risk Characterization

The process of determining whether or not a particular chemical is linked to a particular health effect

Determin pathways for the toxic agent and find the concentrations of the toxic agent in the pathways.

Quantify the relationships between the intesity of the activity in question and the adverse effects.

Dosage that will kill 50% of organisms. Higher the better.

• Non-cancer risk has a thresh hold.
• Cancer has an estimated outcome.
• Non- cancer risk is calculated over the period being exposed, not over lifetime.

Used for non cancer risk assessment.

No Observed Adverse Effects Level.

Low Observed Adverse Effects Level.

A 2X2 matrix with exposed, not exposed, with disease, without disease. helps find the relationship between exposure and disease.

• Shows an association between risk and exposure
• RR > 1, there is a causal link between exposure and disease

• Shows an association between exposure and risk
• AR = 0, no association between exposure and risk

• Shows the association between risk and exposure.
• OD > 1 means there is an association between risk and exposure.

Used to calculate cancer risk. EP has tabulated the Potency factor of some carcenagens.

Is the dose of the contaminant averaged over an entire lifetime.

HQ = ADD / Rfd

• HQ<1 no risk of adverse effects
• HQ>1 adverse effects may occur

• The fraction of concentration of toxin in an animal(fish) divided by the concentration of toxin in its environment(water).
• The smaller the better.
• BCF = Cf/Cw

• 1) Risk Identification
• 2) Risk Assessment - likelihood and consequense
• 3) Risk Planning - avoid, minimize, backup plan
• 4) Risk Monitoring - assess each risk over time

failure analysis in which an undesired state of a system is analyzed using boolean logic to combine a series of lower level events.

• 1) identify faults
• 2) identify causes
• 3) find root of cause
• 4) identify countermeasures for each root

a system safety analytical technique

A diagram consisting of hazards on the left, Critical Event in the cenre, and consequences on the right.