 Guidance
Ecological Risk Assessment Methods
Place-Based Risk Assessments
Development of guidelines, assessments, and methods that quantify risks
to ecosystems from multiple stressors at multiple scales and multiple endpoints.
Since the 1970's, EPA has implemented a host of environmental statutes (e.g., Clean Air Act,
Clean Water Act, Toxic Substances Control Act). Using an "end of the pipe" regulatory approach,
releases to the environment have been significantly reduced from smokestacks, wastewater treatment
facilities, and solid and hazardous wastes. As a result EPA has made significant strides in reducing
"end of the pipe" pollutant releases, to such an extent that regional and global scale problems,
including habitat alteration, loss of biodiversity and non-point source pollution, are now recognized
as greater risks to ecosystems than site specific problems.
The early 1980s saw both the emergence of risk assessment as a regulatory paradigm and the
first wide-spread use of ecological impacts to influence regulatory and policy decisions. The use
of ecological information for decision making has expanded slowly through the 1980s as illustrated
by the regulation of diazinon based on impacts to birds, the adverse impacts of acid deposition on
lakes and forests and the damaging effects of ozone on crops. In the middle to late 1980s, tools
and methods for conducting ecological risk assessments began to be standardized with the publication
of the Ambient Water Quality Criteria methodology, the pesticides program's Standard Evaluation
Procedures, and Superfund's Environmental Evaluation Manual.
The EPA's Science Advisory Board (SAB) report, titled Future Risk: Research Strategies for
the 1990's, emphasized the need for a fundamental shift in EPA's approach to environmental protection
and challenged ORD to provide leadership in the area of ecosystem science. This report provided the
impetus to shift the approach previously used in ecological assessments by focusing on the resources
at risk and their composition within a landscape, multiple stressors and multiple assessment endpoints.
In 1992, the Agency published the Ecological Risk Assessment Framework as the first statement of principles
for ecological risk assessment, and in 1996 published the first draft Ecological Risk Assessment Guidelines.
These documents not only describe methods for conducting the more conventional single-species, chemical-based
risk assessment, they describe techniques for assessing risks to ecosystems from multiple stressors and
multiple endpoints. With the publication of these important documents came the need to create an organization
that will focus on enhancing EPA's ability to do better ecological assessments. This is the goal of the
National Center for Environmental Assessment (NCEA) within ORD.
NCEA's goal is to advance the science of multiple-scale, multiple-stressor and multiple-endpoint
ecological assessments. This will be accomplished by emphasizing research in three areas:
- Developing risk assessment guidance.
- Performing risk assessments, and
- Conducting research on methods.
The ability to assess risks to ecosystems must be based on a knowledge of ecosystem behavior and herein
may lie the greatest risk to ecosystems: lack of knoweldge of how ecosystems respond to multiple stressors.
Short-lived stressors may produce transient and frequently immeasuable effects. We are just now only beginning
to understand the ecological impact of stressors like acid precipitation and global warming and our ability to
assess the impacts to ecosystems requires that there be research on ecosystem behavior. Thus, other elements
of ORD - effects research, research on ecological exposure, models and monitoring - are necessary components of
ecosystem-level assesssments. Likewise, the problem formulation phase of the risk assessment helps direct the
scope and nature of the research being conducted by the other ORD laboratories. The outcome of the risk
assessment - what's at risk and the level it should be protected to ensure ecological sustainability - is an
essential element of risk management research.
What Is Ecological Risk Assessment?
An ecological risk assessment evaluates the potential adverse effects that human activities have on the
plants and animals that make up ecosystems. The risk assessment process provides a way to develop, organize
and present scientific information so that it is relevant to environmental decisions. When conducted for a
particular place such as a watershed, the ecological risk assessment process can be used to identify vulnerable
and valued resources, prioritize data collection activity, and link human activities with their potential effects.
Risk assessments can also provide a focal point for cooperation among local communities and state and federal
government agencies. Risk assessment results provide a basis for comparing different management options, enabling
decision makers and the public to make better informed decisions about the management of ecological resources.
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