The development of toxicology began with cave dwellers who recognized poisonous plants and animals, and used their extracts for hunting or war. By 1500 BC, written evidence indicated that hemlock, opium, arrow poisons, and certain metals were used to poison enemies or for state executions. With time, poisons became widely used and were highly sophisticated. By the time of the Renaissance and the Age of Enlightenment, certain fundamental concepts to toxicology began to take shape.The first noteworthy studies of toxicology were from Paracelsus (~1500AD) and Orfila (~1800 AD). Paracelsus determined that specific chemicals were actually responsible for the toxicity of a plant or animal poison. He documented that the body’s response to those chemicals depended on the dose received. His studies revealed that small doses of a substance might be harmless or beneficial whereas larger doses could be toxic. This is now a major concept of toxicology called the “dose-response relationship”.Paracelsus is often quoted for his statement: “All substances are poisons; there is none which is not a poison. The right dose differentiates a poison and a remedy. ” Mathieu Orfila published the first comprehensive work on forensic toxicology in 1813. He was a Spanish physician and is often referred to as the father of toxicology. It was Orfila who first established a systematic connection between the chemical and biological properties of poisons of the time.He demonstrated effects of poisons on specific organs by analyzing autopsy materials for poisons and their associated tissue damage. Aspects Toxicology is the study of the toxic or harmful effects of chemicals. It is concerned with how toxins act, when their harmful effects occur, and what the symptoms and treatments are for poisoning. It also involves the identification of the substances involved.