The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

Radiation ¹

Added text ² to state that radiation is energy in the form of high-speed particles or electromagnetic waves.

Added text ³ about the characteristics of ionizing radiation and the epidemiologic and biologic lines of evidence that link exposure to it to lethal cancer; also stated that the National Research Council of the National Academies, Committee to Assess the Health Risks from Exposure to Low Levels of Ionizing Radiation, the Biologic Effects of Ionizing Radiation VII report concluded that no dose of radiation should be considered completely safe, and attempts should be made to keep radiation doses as low as possible (cited National Research Council et al. as reference 6).

Added text ⁴ to state that the major sources of population exposure to ionizing radiation are medical radiation and its overuse and naturally occurring radon gas in the basements of homes (cited National Council on Radiation Protection and Measurements as reference 7 and Mettler et al. as reference 8).