The definition of toxicology is "the science of poisons". It is the study of the opposing effects of physical agents or chemicals on living organisms. As toxicology is an ever-evolving medical science, so too is our understanding of the science. Knowledge of the adverse effects of toxic agents towards the body is progressing with medical knowledge.
Toxicology first began with the cave dwellers. They used poisonous plant extracts for hunting and warfare. Throughout history, hemlock, opium, arrow poisons and certain metals have all been used as used to poison enemies.
Famous poisoning victims include Claudius, Cleopatra and Socrates. The founder of toxicology is thought to have been a Spanish physician named Orifila. He demonstrated the effects of poisons on organs and their associated tissue damage.
Xenobiotic is a term used to describe foreign substances taken into the body. The word is taken from the Greek xeno, meaning "foreigner". Xenobiotics do not just produce toxic effects, but can also produce beneficial ones as in the case of pharmaceuticals. Whereas high doses of certain toxins in the body can lead to death, smaller doses may be harmless or even beneficial. This is known as the dose-response relationship, a major concept in toxicology.
A toxic agent may be biological, physical or chemical in form. An example of a chemical toxin is cyanide, while a biological toxin could be snake venom and a physical toxin could be radiation. Scientists that study and determine the effects of toxicology are called toxicologists.
The effects of toxicity are complex, with many influencing factors. Dosage of the toxin is hugely important. Some chemicals, for example, are intrinsically toxic. Others are not toxic until they are absorbed and chemically changed within the body. Many toxins only affect specific organs. Others, once absorbed, can damage every tissue or cell they come into contact with.
Toxicology is also selective. Toxins can harm different species. Antibiotics are virtually nontoxic to humans but are selectively toxic to microorganisms. Insecticide is a lethal toxin for insects but is relatively nontoxic to animals. Age is also a very important factor in the adverse effects of toxins on the body. Some toxins may be more harmful to young children and the elderly than to adults.
The ability of a substance to absorb into the body is also an important factor in toxicology. Nearly all alcohol is easily absorbed when ingested. The toxins in red wine are thought to have beneficial aspects if taken moderately, but when taken in large quantities the toxins can become harmful and lead to alcohol poisoning. You may end up needing the toxic properties of an aspirin to help soothe the headache from the toxic effects of your wine.