This book explains basic principles in plain language while illuminating the most important issues in contemporary toxicology. The author begins by exploring age-old precepts of the field such as the dose-response relationship and the concept, first introduced by Ambroise Paré in the sixteenth century, that a chemical's particular action depends on its inherent chemical nature. The author goes on to show exactly how chemicals enter the body and elicit their toxic effect, as well as the body's methods of defense. With the fundamentals established, the author digs into advances in toxicology, tracing the field's development from World War II to the present day. The book examines both technical discoveries and their impacts on public policy. Highlights include studies of endocrine-disrupting chemicals in toiletries and prescriptions, the emerging science on prions, and our growing understanding of epigenetics. Readers learn not only how toxic exposure affects people and wildlife, but about the long-term social and environmental consequences of our chemicals. Whether studying toxicology itself, public health, or environmental science, readers will develop a core understanding of-and curiosity about-this fast-changing field.