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Risk-Screening Environmental Indicators (RSEI) Model

How RSEI Should Be Used

EPA's Risk-Screening Environmental Indicators (RSEI) model should be used for screening-level activities to determine potential for chronic health risks. Federal, state and local officials, and academic and other analysts have used RSEI to investigate:

  • Industry sector- and facility-based targeting for further investigation and strategic planning.
  • Analysis of trends.
  • Impact of regulations on cross-media risk transfers.
  • Environmental justice (EJ) issues.
  • Prioritization for community-based environmental protection.

Understanding RSEI results provides more details on what the results mean. All RSEI results should be followed up with additional analysis if detailed conclusions are desired.

RSEI does not provide a risk assessment, so it is inappropriate to use it to:

  • Conclude that a particular chemical release is causing harm to a specific population or location,
  • Draw conclusions or make decisions about the risk posed by any particular facility, or
  • Draw conclusions about individual risk or generate quantitative risk estimates.

What to do after an analysis using RSEI

Because RSEI uses simplifying assumptions, high RSEI Scores can only indicate the need for further investigation. There are a number of ways to investigate how RSEI assumptions may affect risk-related results. For each facility and release, users are able to review the specific parameters used to generate the estimates. Users may want to research those parameters to determine if they represent the best estimate for a specific facility. Examples of steps one might take include:

  • Verify reported releases (e.g., check EPA's Envirofacts database for corrected TRI reporting forms). Companies occasionally submit corrections to reported releases that may not be reflected in RSEI before the next update.
  • Determine what specific chemical substance is being released when chemicals are reported as categories (metals and metal compounds, diisocyanates, polycyclic aromatic compounds, etc.). For screening-level purposes, RSEI assumes all releases in the category are for the chemical with the greatest chronic toxicity, with some exceptions.
  • Verify other RSEI simplifying assumptions, for example:
    • Parameters related to air releases such as stack heights – If actual stack heights are greater than the modeled stack heights, ambient concentration will be below the RSEI estimated concentration and therefore potential concerns are lessened.
    • Water releases – Is the outfall location correct- on the correct stream or river and on the correct segment?
  • Compare TRI sources of substances of concern with other sources (mobile sources, area sources, non-TRI point sources, indirect exposure to TRI sources) and assess the relative contribution of TRI releases. If the direct exposure to the TRI source is a minimal contributor, further efforts should focus on other sources of those substances. Other sources of environmental information provides links and information to help assess situations of potential concern.
  • Consider more detailed modeling using appropriate air and water dispersion models, or, if resources permit, monitor ambient concentrations (air, water, fish tissue) to see if pollutant levels rise above the level of concern (reference dose or reference concentration, or acceptable cancer risk levels).