Urs A. Boelsterli, Ph.D., FAASLD, is an Emeritus Professor of Toxicology at the University of Connecticut School of Pharmacy, where he also held the first Boehringer-Ingelheim Endowed Chair in Mechanistic Toxicology. Prior to this, he was head of the Toxicology Program at the National University of Singapore and ran a research lab at Roche, Basel, Switzerland, and the ETH in Zurich. He is retired and currently lives in Switzerland with his family.

1. Introduction. Part I The Concepts: Hazard and Exposure 2. What Does "Toxic" Mean? 3. Paracelsus Reloaded-The Dose Concept. 4. Exposure-The Key Determinant in Risk Assessment. 5. Natural and Synthetic Chemicals. 6. What Our Body Does to a Chemical. 7. What a Chemical Does to Our Body. 8. Defense Shields. 9. Correlation and Causality. Part II The Chemicals 10. Pesticides-Killers with a License. 11. Toxic Food. 12. Dietary Supplements - The More The Better? 13. Significant Risks: Persistent and Widespread. 14. Drugs. Part III The Risk 15. Safety Assessment. 16. Acceptable Limits, Tolerance, and Red Lines. 17. Risk Assessment. 18. Gauging the Risk Against the Benefit. 19. Risk Communication. Part IV The Future 20. Toxicological Challenges. 21. Conclusions and Outlook.