EPA's Risk Assessment Program develops and uses computer models to assess risk to humans from radioactively contaminated sites and from air emissions. These models are also used to demonstrate compliance with National Emissions Standards for Hazardous Air Pollutants for Radionuclides.
Risk Assessment Tools
The models are used for demonstrating compliance or assessing dose and risk. Certain models may be used to demonstrate compliance with 40 CFR 61, Subpart H and I.
- Dose and Risk Calculation Software
The software calculates dose per unit intake of over 800 radionuclides, combines results with risk models to develop average lifetime risk estimates for a unit intake of a radionuclide.
Radionuclide (HEAST) Tables
The Radionuclide Table, formerly HEAST Table 4, lists ingestion, inhalation and external exposure cancer slope factors (risk coefficients for total cancer morbidity) for radionuclides in conventional units of picocuries (pCi).
News & Information
The publications list provides access to and descriptions of reports and other publications on developing and using EPA's risk assessment models.
- Relative Biological Effectiveness of Low-Energy Electrons and Photons (PDF) (25 pp, 689 K, About PDF)
In this work, relative biological effectiveness values were derived for electrons and photons as a function of energy. There is growing evidence that low-energy electrons and photons may exhibit RBEs greater than one. Consideration of the potentially greater effectiveness of these radiation is important to improve the quality of risk assessments.
provides links to other federal and state Web sites with related information.