The book describes the environmental consequences of the Chernobyl disaster, the radionuclide environmental pollution, migration of radionuclides through the Dnieper and the cascade of its reservoirs to the Black Sea, the dynamics of accumulation of radionuclides, irradiation doses and organic disturbances in the flora and fauna of terrestrial and aquatic ecosystems. The results of research carried out by experts from Ukraine, Belarus, Russia and other countries are summarized for early and long-term effects of ionizing exposure of the human body. The expansion of the use of nuclear technology and ionizing radiation sources not only expands the power of countries, but also creates risks for the atomic age civilization. Testing of nuclear and thermonuclear weapons, disasters at Chernobyl and Fukushima-1 NPPs have led to the formation of previously unknown in the biosphere unsuitable for permanent human habitation man-made radionuclide anomalies. The book is aimed at a wide range of readers.