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Waste and Cleanup Risk Assessment

RCRA Risk Assessment: Ecological: Problem Formulation

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Resource and Conservation Recovery Act


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Hazardous Waste Identification

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An initial step of an Ecological Risk Assessment (ERA) is to decide which components of an ecosystem (the sum of all the living organisms and the physical factors in a particular area) should be protected: in other words, what species should be the focus of the ERA. This initial step is part of Problem Formulation, which includes the development of a conceptual model: a representation of how the particular contaminants at a site are expected to behave in the environment.

The conceptual model is based on fate (e.g., does a contaminant break down in the environment or is it persistent?) and transport (how does a contaminant move through the environment and where does it end out?). The purpose of the problem formulation and the conceptual model is used to narrow attention to the animals and/or plants likely to be exposed to the contaminants at the site. In risk assessment language, the species that may be exposed to contaminants are called "receptors".

For this step, the risk assessor gathers information about the site that can help determine the potential risk to plants and animals found at the site being studied. Information can come from a variety of sources, including a site visit, historical information, and data from previous sampling of the area. The following issues should be addressed:

  1. Environmental setting;
  2. Contaminants known or suspected to be at the site;
  3. Contaminant movement physically within the site and through the local food chain;
  4. What plants and animals may be harmed by contaminants at the site;
  5. How the plants or animals come in contact with the contaminants;
  6. What are the effects on the plants and animals that are exposed.

Documents | EPA Links | External Links


  1. Ecological Assessment of Superfund Sites: An Overview (PDF) (8 pp, 67K,  About PDF)
    Eco Update, December 1991
    This EcoUpdate bulletin describes the components of the ecological risk assessment process and how they fit into the Remedial Investigation/Feasibility Study process.

  2. Ecological Risk Assessment and Risk Management Principles for Superfund Sites, (Issuance of Final Guidance) (PDF) (9 pp, 1MB,  About PDF)
    October 7, 1999
    Guidance intended to help Superfund project managers to make ecological assessment decisions that are consistent across the United States and are transparent to the public.

  3. Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments - Interim Final
    June 1997, EPA 540-R-97-006
    These proposed guidelines are EPA's first Agency-Wide Ecological Risk Assessment Guidelines. They are broad in scope, providing general principles and providing numerous examples to show how ecological risk assessment can be applied to a wide range of systems, stressors, and biological spatial/temporal scales.

  4. Ecological Significance and Selection of Candidate Assessment Endpoints, 1996

  5. ECO Update Bulletin Series
    EcoUpdates are a series of bulletins which provide information on various aspects of Ecological Risk Assessments, including toxicity testing, the role of the Biological Technical Assistance Group (BTAG), field studies, and screening level risk assessments.

  6. Guidelines for Ecological Risk Assessment
    These Agency-wide guidelines are provided to improve the quality and consistency of EPA's ecological risk assessments. The Guidelines expand on and replace the 1992 report Framework for Ecological Risk Assessment.

  7. Role of Screening Level ERAs and Refining Contaminants of Concern in Baseline Ecological Risk Assessments (PDF) (4 pp, 364K,  About PDF)
    This EcoUpdate bulletin describes the process and purpose of the screening level ecological risk assessment, which is the first steps in a ecological risk assessment at a site, and how the list of COCs can be refined to include only those contaminants that may pose a risk.

  8. Role of the Ecological Risk Assessment in the Baseline Risk Assessment (PDF) (2 pp, 180MB,  About PDF)
    OSWER Directive 9285.7-17, August 12, 1994
    Describes the process and purpose of baseline ecological risk assessments, which, if required, come after screening level risk assessments.

  9. Screening Level Ecological Risk Assessment Protocol
    This is a guidance document that describes the process used in conducting ecological risk assessments at Hazardous Waste Combustion Facilities.

  10. Selecting and Using Reference Information in Superfund ERAs, 1994

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EPA Links

  1. EPA's Ecological Risk Assessment Support Center (ERASC)
    The ERASC provides technical information and addresses scientific questions of concern or interest on topics relevant to ecological risk assessment at hazardous waste sites for EPA's Office of Solid Waste and Emergency Response (OSWER) personnel and Regional Superfund/Resource Conservation and Recovery Act (RCRA) staff. Requests must be channeled to ERASC through the Ecological Risk Assessment Forum (ERAF). To assess emerging and complex scientific issues that require expert judgment, the ERASC relies on the expertise of scientists and engineers located throughout EPA Office of Research and Development (ORD) labs and centers. ERASC develops responses that reflect the “state of the science” for ecological risk assessment and also provides a communication point for the distribution of the responses to other interested parties.

    For further information, contact Erasc.Ecology@epa.gov or call 513-569-7940 or visit ERASC's website at www.epa.gov/erasc.

  2. EPA Region 5 Ecology Technical Center Ecological Risk Assessment
    Overview of ecological risk assessment process in Superfund, regional case studies, toxicity profiles, and regional contacts.

  3. Greenbook Pesticide Labels and MSDS, EPA's Pesticide Program, PPIS Data, Biopesticides, and RED Pesticide Summaries
    EPA pesticide news stories, summaries, and featured sites.

  4. Provisional Guidance for Quantitative Risk Assessment of Polycyclic Aromatic Hydrocarbons. EPA/600/R-93/C89, July 1993

  5. Revised Interim Soil Lead Guidance for CERCLA Sites and RCRA Corrective Action Facilities 1993, OSWER Directive #9355.4-12
    This document provides an approach for determining protective levels of lead in soil, including recommended screening levels, how to develop preliminary remediation goals, and a description of a clean-up plan for CERCLA (Superfund) and RCRA sites with multiple sources of lead.

  6. SW-846, Test Methods for Evaluating Solid Waste, Physical/Chemical Methods
    SW-846 contains over 200 documents, including the Table of Contents, Disclaimer, Preface, Chapters One through Thirteen, and many different methods for the sampling and analysis of wastes. All of the documents found in the Third Edition of SW-846, as updated by Updates I, II, IIA, IIB, III and IIIA, are located at this site.

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External Links

  1. ATSDR's Toxicological Profiles
    Link to information on toxicological effects caused by hazardous chemicals found at National Priorities List site.

  2. DEQ Information
    Link to U.S. Fish & Wildlife Service's Division of Environmental Quality.

  3. DOE Standard, A Graded Approach for Evaluating Radiation Doses to Aquatic and Terrestrial Biota (PDF) (48 pp, 374K, About PDF)
    and the RAD-BCG Calculator
    Link to Department of Energy’s procedure for investigating radiation exposure to aquatic and land plants and animals.

  4. EC Info and Literature From Region 2 EC Program
    Link to U.S. Fish & Wildlife Service's Environmental Contaminants program.

  5. Guidelines for Interpretation of Residues in Biota, Water, and Sediments from USGS-BRD
    National Irrigation Water Quality Program, U.S. Department of the Interior

  6. National Pesticide Information Center (NPIC) Link to EPA's External Link Disclaimer
    A cooperative effort of Oregon State University and the U.S. Environmental Protection Agency (800-858-7378).

  7. Oak Ridge National Laboratory - Ecological Risk Analysis: Tools and Applications
    Link to guidance, screening benchmarks for various categories of plants and wildlife, and examples of completed ecological risk assessments.

  8. Oak Ridge National Laboratory: Toxicology and Risk Analysis Section
    This EcoUpdate bulletin describes the components of the ecological risk assessment process and how they fit into the Remedial Investigation/Feasibility Study process.

  9. PCB Review by Heidi Fieldler  Link to EPA's External Link Disclaimer
    A general overview of Polychlorinated Biphenyls (PCBs).

  10. TOXNET (including TRI), Extoxnet and Extoxnet-pesticides  Link to EPA's External Link Disclaimer
    Provides a variety of information about pesticides.

  11. USDA Pesticide Info  Link to EPA's External Link Disclaimer
    Each fact sheet (issued by the U.S. Dept. of Agriculture Forest Service) provides information on forest and land management uses, environmental and human health effects, and safety precautions for various pesticides and their formulations.

  12. USGS - Contaminant Reviews
    Contains the 35 reports in the Contaminant Hazard Reviews (CHR) originally published between 1985 and 1999 in the U.S. Dept. of the Interior Biological Report series, which include information on selected inorganic and organic chemicals and ionizing radiation.

  13. USGS Acute Toxicity Database
    This database summarizes the results from aquatic acute toxicity tests conducted by the USGS Columbia Environmental Research Center located in Columbia, Missouri. The acute toxicity test provides a relative starting point for hazard assessment of contaminants and is required for federal chemical registration programs.

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