Editing Poison (section)

=== Acute ===
Acute poisoning is exposure to a poison on one occasion or during a short period of time. Symptoms develop in close relation to the exposure. Absorption of a poison is necessary for systemic poisoning. Furthermore, many common household medications are not labeled with skull and crossbones, although they can cause severe illness or even death. Poisoning can be caused by excessive consumption of generally safe substances, as in the case of [[water intoxication]].

Agents that act on the [[nervous system]] can paralyze in seconds or less, and include both biologically derived [[neurotoxin]]s and so-called [[nerve gas]]es, which may be synthesized for [[chemical warfare|warfare]] or industry.

Inhaled or ingested [[cyanide]], used as a method of [[execution]] in [[gas chamber]]s, or as a [[suicide method]], almost instantly starves the body of energy by [[enzyme inhibitor|inhibiting]] the [[enzyme]]s in [[mitochondria]] that make [[Adenosine triphosphate|ATP]]. Intravenous injection of an unnaturally high concentration of [[potassium chloride]], such as in the execution of prisoners in parts of the United States, quickly stops the [[heart]] by eliminating the [[Membrane potential|cell potential]] necessary for [[muscle contraction]].

Most biocides, including [[pesticide]]s, are created to act as acute poisons to target organisms, although acute or less observable chronic poisoning can also occur in non-target organisms ([[secondary poisoning]]), including the [[human]]s who apply the biocides and other [[beneficial organism]]s. For example, the herbicide [[2,4-D]] imitates the action of a plant hormone, which makes its lethal toxicity specific to plants. Indeed, 2,4-D is not a poison, but classified as "harmful" (EU).

Many substances regarded as poisons are toxic only indirectly, by [[toxication]]. An example is "wood alcohol" or [[methanol]], which is not poisonous itself, but is chemically converted to toxic [[formaldehyde]] and [[formic acid]] in the [[liver]]. Many [[Medication|drug]] molecules are made toxic in the liver, and the genetic variability of certain liver [[enzyme]]s makes the toxicity of many compounds differ between individuals.

Exposure to radioactive substances can produce [[radiation poisoning]], an unrelated phenomenon.

Two common cases of acute natural poisoning are [[theobromine poisoning]] of [[dog]]s and [[cat]]s, and [[mushroom poisoning]] in humans. Dogs and cats are not natural herbivores, but a chemical defense developed by ''[[Theobroma cacao]]'' can be incidentally fatal nevertheless. Many omnivores, including humans, readily consume edible [[fungi]], and thus many fungi have evolved to become [[Amanita phalloides|decisively inedible]], in this case as a direct defense.