Throughout human history, intentional application of poison has been used as a method of murder, pest-control,suicide, and execution. As a method of execution, poison has been ingested, as the ancient Athenians did (see Socrates), inhaled, as with carbon monoxide or hydrogen cyanide (see gas chamber), or injected (see lethal injection). Many languages describe lethal injection with their corresponding words for “poison shot”. Poison’s lethal effect can be combined with its allegedly magical powers; an example is theChinese gu poison. Poison was also employed in gunpowder warfare. For example, the 14th century Chinese text of the Huolongjing written by Jiao Yu outlined the use of a poisonous gunpowder mixture to fill cast irongrenade bombs.
The term poison with regard to biology and chemistry is often misused due to lack of a universal definition. Biologically speaking, any substance, if given in large enough amounts, is poisonous and can cause death. For instance, while botulinum toxin is lethal on the level of nanograms, a person would have to ingest kilograms worth of water to receive a lethal dose. While there may be a large disparity in this example, there are many substances used as medications where the LD50 is only one order of magnitude greater than the ED50 such asfentanyl. A better definition would distinguish between lethal substances that provide a therapeutic value and those that do not. The lack of a mathematical definition for the term poison impedes a universal definition.
