US ENVIRONMENTAL PROTECTION AGENCY RADIOGENIC RISK MODELS AND PROJECTIONS FOR THE US POPULATION

The U.S. Environmental Protection Agency has updated its 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. For the most part, these estimates were calculated using models recommended in the recent National Academy of Sciences' (BEIR VII) report on health effects from low levels of ionizing radiation. However, a number of modifications and extensions to the BEIR VII approach have been implemented. Most notably, risk estimates are included for: 1) alpha particles; 2) additional cancer sites (basal cell carcinomas, kidney cancer, bone sarcomas); and 3) cancers from prenatal exposures. In addition, unlike in BEIR VII, the primary numerical estimates of lifetime risk are for a stationary population instead of the U.S. census population. For uniform whole-body exposures of low dose gamma radiation to the entire population, the cancer incidence risk coefficient (Gy(-1)) is 1.16 x 10(-1) (5.6 x 10(-2) to 2.1 x 10(-1)), where the numbers in parentheses represent an estimated 90% uncertainty interval. The corresponding coefficient for cancer mortality (Gy(-1)) is about one-half that for incidence: 5.8 x 10(-2) (2.8 x 10(-2) to 1.0 x 10(-1)). In addition, a somewhat altered and expanded analysis of uncertainties in the cancer risk estimates is provided. It is anticipated that results summarized here will be applied to update the Agency's next revision of Federal Guidance Report 13, which tabulates cancer risk coefficients for specific radionuclides. Health Phys. 102(6):646-656;2012