About Health Risk Assessment
The following information describes health risk assessment, which is a form of risk assessment often used to evaluate environmental health hazards.
Health risk assessment is the characterization of potential adverse health effects from human exposures to environmental hazards. It is one of several tools that scientists, government agencies, and the public may use to make decisions about how to prevent and reduce exposures to harmful or toxic substances. Health risk assessment also is used to identify vulnerable populations (e.g., infants, children, elderly) who may be at increased risk from exposure to environmental health hazards, and to identify the hazards that pose the greatest risks to public health. For more information about health risk assessment, see the four-step process (below) and Health Risk Assessment Programs/Services.
The Four-Step Process
Health risk assessment is typically described as consisting of four basic steps: hazard identification, exposure assessment, dose-response assessment, and risk characterization.
Step 1: Hazard Identification: In the first step, hazard identification, scientists examine peer-reviewed studies of effects in humans, and laboratory animals, to determine the types of health problems a chemical can cause. Depending on the chemical, these health effects may include short-term (acute) aliments, such as headaches, rashes, and ear, nose and throat irritation; or chronic diseases, such as cancer. An important part of this step is an evaluation of the nature and strength of the evidence of causation between a chemical and an effect.
Step 2: Exposure Assessment: In exposure assessment, scientists estimate the amount, frequency, and duration of exposure to a chemical. They often use environmental monitoring data and mathematical models to estimate exposures. In this step, scientists also evaluate the route of exposure (i.e., inhalation, ingestion, dermal contact, transplacental transfer) and any other scenario-specific exposure information.
Step 3: Dose-Response Assessment: In dose-response assessment, scientists use the data gathered in Step 1 to estimate the amount of a chemical that is likely to result in a particular health effect. Dose-response assessment is the characterization of the relationship between exposure or dose and the incidence and severity of the adverse health effect. This step includes the evaluation of factors that influence dose-response relationships, such as intensity and pattern of exposure, and age and lifestyle variables that could affect susceptibility.
Step 4: Risk Characterization: Based on the information gathered during steps 1-3, scientists estimate the probability or likelihood of risk(s) to the exposed population. An important part of this step is a discussion of the uncertainties and limitations associated with risk estimates.
Health risk assessments often have a considerable degree of uncertainty because of the limitations of available human exposure and toxicity data. When limited data are available, scientists use conservative assumptions based on the best available scientific information to protect public health. As new data become available, scientists incorporate new information, as appropriate, by conducting refined assessments to improve risk estimates.
How Health Risk Assessment is Used in Minnesota
Health risk assessment is used by state and local agencies in Minnesota to evaluate environmental health hazards, develop risk assessment and environmental health policy, and to communicate information about health risks to the public.
For example, the Minnesota Department of Health uses health risk assessment to:
- Develop health-based Values/Guidance for groundwater, air and other environmental media;
- Develop Fish Consumption Advice;
- Evaluate exposures to contaminants near Superfund and other Hazardous Sites;
- Assess air emissions from facilities undergoing permit review by the Minnesota Pollution Control Agency;
- Issue Drinking Water Well Advisories and Special Well Construction Areas;
- Evaluate chemical exposures of potentially vulnerable populations (e.g., children, elderly);
- Conduct Studies and Assessments of Environmental Health Hazards;
- Provide consultation to the public and government agencies about Chemicals and Hazards and Reducing Exposures to contaminants.
Risk managers in regulatory agencies (e.g., Minnesota Pollution Control Agency, Minnesota Department of Agriculture) use the results of health risk assessments for setting environmental clean-up goals, issuing permits, and other environmental decision-making. Risk managers are responsible for protecting public health, but also consider public acceptance, as well as technological, economic, social, and political factors when making their decisions.
For more information about health risk assessment, see the Minnesota Department of Health, Health Risk Assessment Programs/Services and the links below.
U.S. Environmental Protection Agency, Risk Assessment Portal
California Environmental Protection Agency, A
Guide to Health Risk Assessment (PDF: 237KB/12 pages)