Founded on the paradox that all things are poisons and the difference between poison and remedy is quantity, the determination of safe dosage forms the base and focus of modern toxicology. In order to make a sound determination there must be a working knowledge of the biologic mechanisms involved and of the methods employed to define these mechanisms. While the vastness of the field and the rapid accumulation of data may preclude the possibility of absorbing and retaining more than a fraction of the available information, a solid understanding of the underlying principles is essential. Extensively revised and updated with four new chapters and an expanded glossary, this fifth edition of the classic text, Principles and Methods of Toxicology provides comprehensive coverage in a manageable and accessible format. New topics include 'toxicopanomics', plant and animal poisons, information resources, and non-animal testing alternatives. Emphasizing the cornerstones of toxicology-people differ, dose matters, and things change, the book begins with a review of the history of toxicology and followed by an explanation of basic toxicological principles, agents that cause toxicity, target organ toxicity, and toxicological testing methods including many of the test protocols required to meet regulatory needs worldwide. The book examines each method or procedure from the standpoint of technique and interpretation of data and discusses problems and pitfalls that may be associated with each. The addition of several new authors allow for a broader and more diverse treatment of the ever-changing and expanding field of toxicology. Maintaining the high-quality information and organizational framework that made the previous editions so successful, Principles and Methods of Toxicology, Fifth Edition continues to be a valuable resource for the advanced practitioner as well as the new disciple of toxicology.