This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book considers yet a possible factor that first entered the environment in the 1940s: man-made radioactive chemicals produced from atomic bomb tests, nuclear power production, and nuclear waste. It brings considerable new information that figures strongly in the discussion. The book examines the history of the atomic age. It looks at the types and amounts of radioactive chemicals introduced into the US environment as a result of these policies. The book speculates on what may happen to the low-level nuclear threat in the future. It discusses the generation born after 1983, who are virtually all children and grandchildren of Baby Boomers. The book examines medical and statistical information describing each of these phenomena, we must not forget that the health and well-being of real people are at stake.