The Nature of a Chemical

The second rule of toxicology helps to explain why some chemicals are easily excreted from the body, while others are not. It also goes to the heart of why different toxic agents affect us in different ways. The second rule was first posed by Ambroise Pare, a sixteenth-century French surgeon, who realized that “Poison … kills by a certain specific antipathy contrary to our nature.” In other words, a chemical’s particular action depends on its inherent chemical nature.