page title goes here Risk Assessment
Welcome to the EPA's "Dose Compliance Concentrations for Radionuclides on Outdoor Surfaces at Superfund Sites" (SDCC) Download and Calculator website. The recommended SDCCs on this website are dose levels for contaminated outdoor hard surfaces such as building slabs, outside building walls, sidewalks, and roads.
This tool presents recommended dose-based SDCCs calculated using default input parameters and the latest dose conversion factors. In addition, users are able to modify the input parameters to create site-specific SDCCs to meet specific site needs, considering factors related to the underlying exposure scenarios, pathways, and routes. To learn more about the use of these recommended SDCCs, please see further guidance located in the "User's Guide", "What's New", 'FAQ", and "Download Area" links. Below is a general description of how SDCCs can be used for situations involving radionuclides. The EPA has prepared a fact sheet for the general public that describes SDCC uses, SDCC calculator operation, and land uses available for assessment. Additionally, this fact sheet describes the SPRG and SDCC calculators in greater detail for EPA staff. The OSWER Directive, Superfund Radiation Risk Assessment: A Community Toolkit was also developed by the EPA to help the public understand more about the risk assessment process used at Superfund sites with radioactive contamination.
The SDCC calculator results were previously verified. The documentation from these may be seen on the Internal Verification and External Verification pages. The SDCC calculator was largely developed based on the SPRG calculator and benefited from its peer reviews, which may be seen here. A comparison review that focused on describing the default parameters in various models may be found here.
The primary purpose of this recommended SDCC calculation tool is to assist risk assessors, remedial project managers, and others involved with dose assessment and decision-making at sites with contaminated outdoor hard surfaces.
This website was updated after new EPA guidance was issued. The website was initially made available for use in a transmittal memo entitled " Distribution of Superfund ARAR Dose Compliance Concentrations Goals for Radionuclides in Buildings (BDCC) and ARAR Dose Compliance Concentrations Goals for Radionuclides in Surfaces (SDCC) Electronic Calculator", January 4, 2010.
ARAR Dose Compliance Concentrations
Dose conversion factors (DCFs), or "dose coefficients", for a given radionuclide generally represent the dose equivalent per unit intake (i.e., ingestion or inhalation) or external exposure of that radionuclide. These DCFs normally are used to convert a radionuclide concentration in soil, air, water, or foodstuffs to a radiation dose. DCFs may be specified for specific body organs or tissues of interest or as a weighted sum of individual organ dose, termed the effective dose equivalent. These DCFs may be multiplied by the total activity of each radionuclide inhaled or ingested per year, or the external exposure concentration to which a receptor may be exposed, to estimate the dose equivalent to the receptor.
This website provides SDCCs calculated using the dose conversion factors from International Commission on Radiological Protection (ICRP) 30, ICRP 60, and ICRP 107. This website does not address the calculation of SDCCs for ARARs based on ICRP 2 dose conversion factors (e.g., 40 CFR 141.66(d), 10 CFR 61.41).
It is EPA's recommendation that dose assessments should only be conducted under CERCLA when necessary to demonstrate ARAR compliance. Further, dose recommendations in guidance should generally not be used as to-be-considered material. For more information on this issue, please see questions 33 and 36 on pages 27 to 29 of "Radiation Risk Assessment At CERCLA Sites: Q & A" (EPA 540-R-012-13, May 2014).
Also, EPA generally does not use ARARs greater than 12 mrem/yr to establish cleanup levels at CERCLA sites. Cleanup levels not based on an ARAR should be based on the carcinogenic risk range (generally 10-4 to 10-6, with 10-6 as the point of departure and 1 x 10-6 used for SPRGs). For further guidance on this issue, refer to question 35 on page 28 of "Radiation Risk Assessment At CERCLA Sites: Q & A" (EPA 540-R-012-13, May 2014).
It should also be noted that calculating a SDCC does not address human cancer risk or noncancer toxicity or potential ecological risk. Of the radionuclides generally found at CERCLA sites, only uranium has potentially significant noncancer toxicity. When assessing sites with uranium as a contaminant, it may also be necessary to consider the noncancer toxicity of uranium using other tools, such as EPA's Regional Screening Levels (RSLs) for Chemical Contaminants at Superfund Sites electronic calculator for uranium in soil, water, or air and the WTC for uranium inside buildings. EPA's DCC Calculator should be used to assess radionuclide dose in soil, water, and air, and the BDCC Calculator for radionuclide dose inside buildings. EPA's PRG Calculator should be used to assess radionuclide cancer risk for soil, water, and air, BPRG Calculator for radionuclide cancer risk inside buildings, and the SPRG Calculator for radionuclide cancer for hard outside surfaces. Similarly, some sites with radiological contaminants in sensitive ecological settings may also need to be evaluated for potential ecological risk. EPA's guidance "Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessment" contains an eight step process for using benchmarks for ecological effects in the remedy selection process.