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Soil Screening Guidance for Radionuclides

Topics for Key Radiation Guidances and Reports

These calculations are based on the U.S. Environmental Protection Agency's (EPA) Soil Screening Guidance for Radionuclides. The guidance must be read before attempting to calculate values. The guidance is available through:

Soil Screening Guidance for Radionuclides: User's Guide
EPA Document Number: EPA/540-R-00-007

Soil Screening Guidance for Radionuclides: Technical Background Document
EPA Document Number: EPA/540-R-00-006, October 2000

Highlight 1: Key Attributes of the Soil Screening Guidance for Radionuclides

  • Standardized equations are presented to address human exposure pathways in a residential setting consistent with Superfund's concept of "Reasonable Maximum Exposure" (RME).

  • Source size (area and depth) can be considered on a site-specific basis.

  • Parameters are identified for which site-specific information is needed to develop site-specific SSLs.

  • Default parameter values are provided to calculate generic SSLs where site-specific information is not available.

  • SSLs are generally based on a 10-6 lifetime cancer risk. SSLs for migration to ground water are based on maximum contaminant levels (MCLs), proposed MCLs (Uranium), or health based levels.

  • Radiation risk coefficients used to calculate SSLs represent the average risk per unit exposure to members of a population exposed throughout life to a constant concentration of a radionuclide in a specific environmental medium. They assume no radioactive decay, however, radioactive decay is accounted for in this electronic version.

Usage and Limitations:

thumbtack SSLs are not national cleanup standards.
thumbtack Radionuclide SSLs are based on a target risk of one-in-a-million (10-6), or, for the ground water migration pathway, a maximum contaminant level (MCL), where available.
thumbtack Although the application of SSLs during site investigations is not mandatory at sites being addressed by CERCLA or RCRA, EPA recommends the use of SSLs as a tool to facilitate prompt identification of radionuclides and exposure areas of concern.
thumbtack In addition, this guidance presents methodologies to address the leaching of radionuclides through soil to an underlying potable aquifer. This pathway should also be addressed in the development of PRGs.
thumbtack The Soil Screening Guidance is a tool for screening at National Priorities List (NPL) sites.
thumbtack Some NPL sites will not meet all the conditions necessary for use of this tool; consequently, EPA does not expect this tool to be applicable for all NPL sites.
thumbtack The guidance is intended to be used to screen out areas of sites, exposure pathways, or chemicals of concern from further consideration, assuming certain conditions are present, or to determine that further study is warranted at a site.
thumbtack Generally, areas of a site which fall below the screening levels may be eliminated from further assessment. Areas above the screening levels generally warrant further evaluation.
thumbtack The levels should not be interpreted to represent cleanup standards for a site, and concentrations in soil above screening levels do NOT automatically designate a site as dirty.
thumbtack SSLs do not supersede existing federal or state ARARs and use of the guidance is not legally binding.
thumbtack An ecological assessment should also be performed as part of the RI/FS to evaluate potential risks to ecological receptors.
thumbtack Although SSLs are "risk-based," they do not eliminate the need to conduct a site-specific risk assessment for those areas identified as needing further investigation.
thumbtack Exposure Pathways are as follows:
  • Direct ingestion of soil
  • Inhalation of fugitive dusts
  • External radiation exposure from photon-emitting radionuclides in soil
  • Ingestion of homegrown produce that has been contaminated via plant uptake
  • Ingestion of contaminated ground water caused by migration of radionuclides through soil to an underlying potable aquifer
thumbtack This guidance addresses the carcinogenic effects of radionuclides. For systemic toxicity of metals such as Uranium, please see the Soil Screening Calculations for chemicals.
thumbtack The Soil Screening Guidance for Radionuclides should NOT be used for chemical contaminants. Please see Soil Screening Calculations for chemicals.


I accept the Usage and Limitations and am fully informed about using the Soil Screening Guidance.
Begin Calculations for Radionuclides

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This site is maintained and operated through an Interagency Agreement between the EPA Office of Superfund and Oak Ridge National Laboratory. For questions or comments please contact Stuart Walker at the Office of Superfund Remediation and Technology Innovation.

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