In the decades since the atomic bombing of Hiroshima and Nagasaki, economic and political trends have opened avenues for radiation research while breakthroughs in molecular biology have shed light on radiation's effect on the human body. This volume comprehensively reviews what is now known about human exposure to ionizing radiation, with emphasis on unifying the scientific disciplines that inform this topic. Today's most widely recognized experts in the field examine four broad areas: Physics and dosimetry, including the various systems of A-bomb survivor dosimetry, the effect on survivors of subsequent medical radiation, and chromosome aberrations as biomarkers. Cancer statistics and epidemiology, including a historical review of leukemia risk in A-bomb survivors, the incidence of solid cancer and resulting mortality, and the results of studies of workers exposed to low-level radiation. Genetics, including the path from radiation exposure to cellular effects, carcinogenesis, and mutagenesis. Experts discuss the interaction between radiation and other cancer risk factors, review models of radiation-induced cancer, and report on other aspects of molecular biology. Psychological effects of radiation catastrophesâ€"as seen at Hiroshima and Nagasaki, Three Mile Island, and Chernobylâ€"and consequences of the Atomic Bomb Survivors Relief Law.