Radiation safety and risk management, a critical issue in the nuclear age, is an ongoing concern in the field of radiation health risk sciences. It is the particular mission and task of the Nagasaki University Global COE program to explore human health risks from radiation on a global scale and to come up with measures for overcoming its negative legacies. Ionizing radiation is a well-documented human cancer risk factor, and long-term health consequences in individuals exposed at a young age to such events as the Hiroshima and Nagasaki atomic bombing are now being followed up. Unique and comprehensive, this book introduces updated radiation health-related issues, including