Large-scale environmental problems remind us the link that intimately binds human health and environmental health together. Although primarily designed to serve humankind, industrial and economical activities are also promoting detrimental impacts on humans themselves and the environment, leading to an ever stronger finding that human health requires a healthy environment. In this context, the health effects of environmental radioactivity, both on humans and biota, are currently particularly debated. This is especially boosted by the civil use of nuclear energy in view of fulfilling future societies energetic needs, and the experience of the Chernobyl accident that yielded catastrophic consequences. This book tackles the health effects of environmental radioactivity on both humans and biota in a integrated manner, therefore strengthening the fact that life, whether human, animal or vegetal, is always bound to an ecosystem hosting a complex network of interactions.