This document presents new U.S. Environmental Protection Agency (EPA) estimates of cancer incidence and mortality risks due to low doses of ionizing radiation for the U.S. population, as well as their scientific basis. It replaces the 1994 EPA report Estimating Radiogenic Cancer Risks, often referred to as the 'Blue Book'. In 1999, the Agency applied the 1994 Blue Book contents, metabolic models, and usage patterns to publish Federal Guidance Report 13 (FGR-13), Cancer Risk Coefficients for Environmental Exposure to Radionuclides. FGR-13 includes coefficients for calculating estimates of cancer risk for over 800 radionuclides. It is anticipated that results presented here will be applied to update the radionuclide risk coefficients in the next revision of FGR-13. For the most part, estimates of radiogenic risk in this document are calculated using models recommended in the National Academy of Sciencesf report: Health Risks from Exposure to Low Levels of Ionizing Radiation, BEIR VII Phase 2 (NAS 2006). The NAS report, often referred to as BEIR VII, was sponsored by EPA and several other federal agencies. As in BEIR VII, models are provided here for estimating risk as a function of age at exposure, age at risk, gender, and cancer site.