Toxicology is the scientific study of the adverse effects of chemical substances on living organisms. It encompasses a broad range of disciplines, including biology, chemistry, pharmacology, and environmental science, and is essential for understanding the impact of toxins on human health and the environment. The origins of toxicology can be traced back to ancient civilizations, where herbal remedies and poisons were used in medicine and warfare. Over the centuries, this field has evolved significantly, particularly with advancements in analytical techniques and a greater understanding of biological systems.

The fundamental principle of toxicology is that the effect of a substance depends not only on its inherent toxicity but also on the dose, duration of exposure, and the route by which it enters the body. This is often summarized by the phrase "the dose makes the poison," attributed to the Swiss physician Paracelsus in the 16th century. Paracelsus emphasized that even substances considered beneficial can be harmful in excessive amounts, highlighting the importance of understanding dosage in toxicological assessments.