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Risk Assessment

Ecological Risk Assessment

An ecological risk assessment ological risk assessmentThe application of a formal process to (1) estimate the effects of human action(s) on a natural resource, and (2) interpret the significance of those effects in light of the uncertainties identified in each phase of the assessment the process for evaluating how likely it is that the environment might be impacted as a result of exposure to one or more environmental stressors, such as chemicals, land-use change, disease, and invasive species.

An ecological risk assessment includes three phases, but begins with Planning:

  • Planning - EPA begins an ecological risk assessment by planning the overall approach with dialogue between the risk manager(s), risk assessor(s), and other interested parties or stakeholders. Members of the team:
    • identify risk management goals and options;
    • identify the natural resources of concern;
    • reach agreement on scope and complexity of the assessment; and
    • decide on team member roles.
  • Phase 1 - Problem Formulation
    The risk assessor(s) gathers information to determine which plants and animals are or might be at risk and in need of protection. Based on the Planning results, they specify:
    • the scope of the assessment in time and space;
    • the environmental stressors of concern;
    • the endpoints to be evaluated (e.g., continued existence of a fishery population, fish species diversity in lakes, sustainable forest habitat); and
    • which measures, models, and type of data will be used to assess risks to those endpoints.

       Problem formulation concludes with an Analysis plan.

  • Phase 2 - Analysis
    Two components of the analysis phase are exposure and effects assessments. In the exposure assessment, the risk assessor determines which plants and animals are or are likely to be exposed to each environmental stressor and to what degree. In the effects assessment, the risk assessor reviews available research on the relationship between exposure level and possible adverse effects on plants and animals. They may also review evidence of existing harmful ecological effects.
  • Phase 3 - Risk Characterization
    Risk characterization includes two major components—risk estimation and risk description.

           "Risk estimation" compares:

    • the estimated or measured exposure level for each stressor and plant or animal population, community, or ecosystem of concern; and
    • the data on expected effects for that group for the exposure level.

           "Risk description" provides information important for interpreting the risk results. This includes:

    • whether harmful effects are expected on the plants and animals of concern;
    • relevant qualitative comparisons; and
    • how uncertainties (data gaps and natural variation) might affect the assessment.

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Uses of Ecological Risk Assessments

Every day, people face questions about environmental concerns, many of them related to how we interact with plants, animals, and ecosystems as a whole. These questions may be about potential impacts on a place’s aesthetic value, effects of pollution on endangered species, or the consequences of long-term release of contaminants to an ecosystem. For example:

  • How would the construction of a dam impact fish populations in nearby water bodies?
  • Can residential or agricultural application of an insecticide harm endangered bird species?
  • Do contaminants in the environment from an abandoned industrial or mining facility significantly reduce the value of the area as wildlife habitat?
  • What is the risk to native oyster populations of introducing a non-native oyster to an estuary?
  • How much does existing or likely fertilizer runoff reduce oxygen levels in a given lake (or bay) and how might key fish populations respond?

A key part of EPA’s mission is understanding the potential effects of environmental stressors created by human activities. As legislatively mandated, EPA pursues options to manage risks from those stressors to protect the health of the natural environment.  Ecological risk management protects resources and the ecological services they provide (e.g., soil productivity, sustainable fisheries, flood control).

Ecological risk assessments can be used:

  • to predict the likelihood of future effects (prospective); or
  • to evaluate the likelihood that observed effects are caused by past or ongoing exposure to specific stressors (retrospective).

At EPA, ecological risk assessments are used to support many types of actions, including:

  • Regulation of hazardous waste sites, industrial chemicals, and pesticides.
  • Watershed management.
  • Protection of ecosystems from chemical, physical, or biological stressors.

Information from ecological risk assessments can be used by risk managers to:

  • communicate with interested parties and the general public;
  • limit exposure to the ecological stressor;
  • negotiate remediation options with stakeholders; or
  • develop monitoring plans to confirm risk reduction and ecosystem recovery.

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