Risk Assessment & The Four Steps

The Four Steps of Risk Assessment

1) Hazard Identification; (2) Dose-response Assessment; (3) Exposure Assessment; (4) Risk Characterization

The Red Book

1983, Risk Assessment in the Federal Government: Managing the Process. Report by the National Research Council of the National Academy of Sciences (NAS) that brought principles for evaluating environmental chemical risks to human health together, presented them in a framework that formalized the risk assessment process.

The Silver Book

2009, Science and Decisions: Advancing Risk Assessment. Updated design and methods of risk assessment. Added "Problem Formulation" as first step.

Problem Formulation

Step 1. A systematic planning step linked to the regulatory and policy context. It IDs major factors to be considered in RA. What adverse health effects and associated environmental conditions are of concern in the population of interest? What policy and other risk management options exist to reduce risk of health effects? What types of analysis are necessary to evaluate these risk management options?

Hazard Identification

Step 2. The process of examining the evidence for adverse health effects due to human exposures to an environmental contaminant. The type and extent of harm caused by a specific agent or contaminant. What adverse health effects are demonstrated to be associated with the environmental contaminant of concern?

Dose-Response Assessment

Step 3. Characterizes the relationship between the dose of a chemical administered or received and the resulting incidence of an adverse affect. Quantifies how much harm may be caused at any given level of exposure. What is the relationship between dose of the contaminant and the probability of adverse health effects?

Exposure Assessment

Step 4. Produces a description of a population's exposure--how much, over what time period, by what pathways--to the contaminant of concern. Potential exposures in the population are calculated or estimated. Diagnoses the population exposure to, or dose from, a particular stressor. What are the current exposures or doses of the contaminant in the populations of interest?

Risk Characterization

Step 5. Provides a synthesis of the risk level for the particular health effect of a particular chemical contaminant in a particular population. Brings all the prior steps together to synthesize the view on overall population risk. What is the nature and magnitude of risk to human health from the contaminant in the population of interest, and what are the main uncertainties associated with this risk? Leads to "Risk Management."

Risk Management

The process of identifying, evaluating, prioritizing, and choosing among policy options. Taking into account the findings of risk characterization, what are the main risk management options? How does each policy option address the problem, given acceptable level of risk, net cost and benefits, ease of implementation, existing legislation, stakeholder perceptions, and acceptable level of risk? What is the best policy option? How should this decision be communicated to the population of interest?