Dictionary:

poison

  (poi'zən)

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1. A substance that causes injury, illness, or death, especially by chemical means.
2. Something destructive or fatal.
3. Chemistry & Physics. A substance that inhibits another substance or a reaction: a catalyst poison.

1. To kill or harm with poison.
2. To put poison on or into: poisoning arrows; poisoned the drink.
3. 1. To pollute: Noxious fumes poison the air. See synonyms at contaminate.
   2. To have a harmful influence on; corrupt: Jealousy poisoned their friendship.
4. Chemistry & Physics. To inhibit (a substance or reaction).

Poisonous.

[Middle English, from Old French, from Latin pōtiō, pōtiōn-, drink.]

WORD HISTORY   The phrase poison potion, besides being alliterative, also consists of doublets, that is, two words that go back ultimately to the same source in another language. The source for both words is Latin pōtiō (stem form pōtiōn-), which meant “the act of drinking, a drink, or a draft, as of a medicine or poison.” Our word potion, which retains the sense “dose,” passed through Old French (pocion) on its way to Middle English (pocion), first recorded in a work composed around 1300. In Old French pocion is a learned borrowing, one that was deliberately taken from Latin in a form corresponding to the Latin form. Our spelling potion is the result of a similar impulse toward Latinization; in the late Renaissance and Enlightenment, numerous English words that had been borrowed from Old French were respelled according to the shape of their Latin ancestors. Pocion thus was changed to potion on the model of Latin pōtiō. But the Latin word had also passed through Vulgar Latin into Old French in the different form poison. This word meant “beverage,” “liquid dose,” and also “poison beverage, poison.” The word poison is first recorded in Middle English in a work composed around 1200.

A substance which by chemical action and at low dosage can kill or injure living organisms. Broadly defined, poisons include chemicals toxic for any living form: microbes, plants, or animals. In common usage the word is limited to substances toxic for humans and mammals, particularly where toxicity is a substance's major property of medical interest. Because of their diversity in origin, chemistry, and toxic action, poisons defy any simple classification. Almost all chemicals with recognized physiological effects are toxic at sufficient dosage.

Origin and chemistry

Many poisons are of natural origin. Some bacteria secrete toxic proteins (for example, botulinus, diphtheria, and tetanus toxins) that are among the most poisonous compounds known. Lower plants notorious for poisonous properties are ergot (Claviceps purpurea) and a variety of toxic mushrooms. See also Ergot and ergotism; Mushroom; Toxin.

Higher plants, which constitute the major natural source of drugs, contain a great variety of poisonous substances. Many of the plant alkaloids double as drugs or poisons, depending on dose. These include curare, quinine, atropine, mescaline, morphine, nicotine, cocaine, picrotoxin, strychnine, lysergic acid, and many others. See also Atropine; Cocaine; Quinine.

Poisons of animal origin (venoms) are similarly diverse. Toxic marine animals alone include examples of every phylum. Insects and snakes represent the best-known venomous land animals, but on land, too, all phyla include poison-producing species. Among mammalian examples are certain shrews with poison-producing salivary glands. See also Poison gland.

Poisons of nonliving origin vary in chemical complexity from the toxic elements, for example, the heavy metals, to complex synthetic organic molecules. Most of the heavy metals (gold, silver, mercury, arsenic, and lead) are poisons of high potency in the form of their soluble salts. Strong acids or bases are toxic largely because of corrosive local tissue injury.

The chemically reactive gases hydrogen sulfide, hydrocyanic acid, chlorine, bromine, and ammonia are also toxic, even at low concentration, both because of their corrosiveness and because of more subtle chemical interaction with enzymes or other cell constituents.

Many organic substances of synthetic origin are highly toxic and represent a major source of industrial hazard. Most organic solvents are more or less toxic on ingestion or inhalation. Many alcohols, such as methanol, are much more toxic. Many solvents (for example, carbon tetrachloride, tetrachloroethane, dioxane, and ethylene glycol) produce severe chemical injury to the liver and other viscera, sometimes from rather low dosage.

Physiological actions

The action of poisons is generally described by the physiological or biochemical changes which they produce. For most poisons, a descriptive account can be given which indicates what organic system (for example, heart, kidney, liver, brain, and bone marrow) appears to be most critically involved and contributes most to seriously disordered body function or death. In many cases, however, organ effects are multiple, or functional derangements so generalized that a cause of death cannot be localized.

More precise understanding of the mechanism of poisons requires detailed knowledge of their action in chemical terms. Information of this kind is available for only a few compounds, and then in only fragmentary detail. Poisons that inhibit acetylcholinesterase have toxic actions traceable to a single blocked enzyme reaction, hydrolysis of normally secreted acetylcholine. Detailed understanding of the mechanism of chemical inhibition of cholinesterase is not complete, but allows some prediction of chemical structures likely to act as inhibitors. See also Acetylcholine.

Carbon monoxide toxicity is also partly understood in chemical terms, since formation of carboxyhemoglobin, a form incapable of oxygen transport, is sufficient to explain the anoxic features of toxicity.

Heavy metal poisoning in many cases is thought to involve inhibition of enzymes by formation of metal mercaptides with enzyme sulfhydryl groups, the unsubstituted form of which is necessary for enzyme action. This is a general reaction that may occur with a variety of sulfhydryl-containing enzymes in the body. Specific susceptible enzymes whose inhibition explains toxicity have not yet been well documented.

Metabolic antagonists active as poisons function by competitive blocking of normal metabolic reactions. Some antagonists may act directly as enzyme inhibitors, others may be enzymatically altered to form derivatives which are even more potent inhibitors at a later metabolic step. See also Enzyme inhibition.

Where poison mechanisms are relatively well understood, it has sometimes been possible to employ rationally selected antidotes.

Potency

The strength or potency of poisons is most frequently measured by the lethal dose, potency being inversely proportional to lethal dose. From statistically treated dose-response data, the dose killing 50% of the sample population can be determined, and is usually designated the MLD (median lethal dose) or LD50. This is the commonest measure of toxic potency. See also Lethal dose 50; Toxicology.

noun

1. Anything that is injurious, destructive, or fatal: bane, canker, contagion, toxin, venom, virus. See help/harm/harmless.
2. One that contaminates: adulterant, adulterator, contaminant, contamination, contaminator, impurity, pollutant. See clean/dirty.

verb

1. To make physically impure: contaminate, defile, foul, pollute. See clean/dirty.
2. To have a destructive effect on: canker, envenom, infect. Archaic empoison. See help/harm/harmless.

adjective

Capable of injuring or killing by poison: mephitic, mephitical, poisonous, toxic, toxicant, venomous, virulent. See help/harm/harmless.

Idioms beginning with poison:
poison-pen letter

In addition to the idiom beginning with poison, also see one man's meat is another man's poison.

Definition: substance which causes harm, death
Antonyms: antidote

v

Definition: contaminate, pollute
Antonyms: purify, sterilize

A substance that, when ingested, inhaled, absorbed, injected into, or developed within the body, will cause damage to structures of the body and impair or destroy their function.

For more information on poison, visit Britannica.com.

Any substance dangerous to living organisms that if applied internally or externally, destroy the action of vital functions or prevent the continuance of life.

Economic poisons are those substances that are used to control insects, weeds, fungi, bacteria, rodents, predatory animals, or other pests. Economic poisons are useful to society but are still dangerous.

The way a poison is controlled depends on its potential for harm, its usefulness, and the reasons for its use. The law has a right and a duty pursuant to the police power of a state to control substances that can do great harm.

In the past, an individual who was harmed by a poison that had been handled in a careless manner could institute a lawsuit for damages against the person who had mishandled the chemical. As time went on, state statutes prescribed the circumstances under which someone was legally liable for injuries caused by a poison. For example, a sale to anyone under sixteen years of age was unlawful, and a seller was required to ensure that the buyer understood that the chemical was poisonous. It was not unusual for all poisons, drugs, and narcotics to be covered by the same statutory scheme.

Specialized statutes currently regulate poisons. Pesticides must be registered with the federal government, and those denied registration cannot be used. The Environmental Protection Agency (EPA) has issued a number of regulations governing the use of approved pesticides. Federal law also prohibits unauthorized adulteration of any product with a poisonous substance and requires clear labeling for anything sold with a poisonous ingredient. It might not be sufficient to list all the chemicals in a container or even to put the word POISON on the label. The manufacturer should also warn of the injuries that are likely to occur and the conditions under which the poison will cause harm. Stricter standards are applied to household products than to poisonous products intended to be used in a factory, on a farm, or by a specially trained person. Poisonous food products are banned. Under other federal regulations, pesticide residues on foods are prohibited above certain low tolerance levels.

Certain provisions under federal law seek to protect children from poisoning. Special packaging is required for some household products so that a child will not mistake them for food or will not be able to open containers. Federal funds are available for local programs to reduce or eliminate the danger of poisoning from lead-based paint. Under the Hazardous Substances Act (15 U.S.C.A. § 1261 et seq.), toys containing poisonous substances can be banned or subjected to recall.

A substance that, on ingestion, inhalation, absorption, application, injection or development within the body, in relatively small amounts, may cause structural damage or functional disturbance.
Corrosives are poisons that destroy tissues directly. They include the mineral acids, such as nitric acid, sulfuric acid and hydrochloric acid, and the caustic alkalis, such as ammonia, sodium hydroxide (lye), sodium carbonate and sodium hypochlorite; and carbolic acid (phenol).
Irritants are poisons that inflame the mucous membranes by direct action. These include copper sulfate, salts of lead, cantharidin, oxalate raphides, and many plant and insect poisons.
Nerve toxins act on the nerves or affect some of the basic cell processes. This large group includes the narcotics, such as opium, heroin and cocaine, and the barbiturates, anesthetics and alcohols.
Blood toxins act on the blood and deprive it of oxygen. They include carbon monoxide, carbon dioxide, hydrocyanic acid and the gases used in chemical warfare. Some blood toxins destroy the blood cells or the platelets.
See also poisoning and names of individual poisons.

• p. bean — sesbania spp., thermopsis montana.
• berry p. — gastrolobium parvifolium.
• box p. — gastrolobium parviflorum.
• bullock p. — gastrolobium trilobum.
• p. bush — thesium namaquense.
• bushman's p. — acokanthera spp.
• p. buttercup — ranunculus scleratus.
• camel p. — erythrophleum chlorostachys.
• candyup p. — stypandra glauca.
• Champion Bay p. — gastrolobium oxyloboides.
• clover-leaf p. — goodia lotifolia.
• cluster p. — gastrolobium bennettsianum.
• p. Control Center — public facility set up to provide information around the clock to provide information on toxicity of substances and current information of correct first aid methods and antidotes for poisoning emergencies.
• crinkle-leaf p. — gastrolobium villosum.
• desert p. bush — gastrolobium grandiflorum.
• p. elder — toxicodendron vernix.
• Gilbernene p. — gastrolobium rotundifolium.
• granite p. — gastrolobium graniticum.
• heart-leaf p. bush — gastrolobium bilobum or G. grandiflorum.
• p. hemlock — conium maculatum.
• Hill River p. — gastrolobium polystachyum.
• hook-point p. — gastrolobium hamulosum.
• horned p. — gastrolobium polystachyum.
• Hutt River p. — gastrolobium propinquum.
• insect p. — see bee sting, epicauta vittata, tick paralysis.
• p. ivy — toxicodendron radicans.
• kite-leaf p. — gastrolobium laytonii.
• lamb p. — isotropis cuneifolia.
• p. leaf — dichapetalum cymosum.
• p. lobelia — lobelia pratioides.
• mallet p. — gastrolobium densifolium.
• marlock p. — gastrolobium parviflorum.
• p. morning glory — ipomoea muelleri.
• narrow-leaf p. — gastrolobium stenophyllum.
• net-leaf p. — gastrolobium racemosum.
• p. oak — toxicodendron diversilobum, T. quercifolium.
• p. onion — dipcadi glaucum.
• pea-blossom p. — isotropis spp.
• p. peach — trema tomentosa. Called also peach-leaf poison bush.
• p. pimelea — pimelea pauciflora.
• p. pod albizia — albizia versicolor.
• prickly p. — gastrolobium spinosum.
• rigid-leaf p. — gastrolobium rigidum.
• river p. — gastrolobium forrestii.
• river p. tree — excoecaria dallachyana.
• rock p. — gastrolobium callistachys.
• Roe's p. — gastrolobium spectabile.
• round-leaf p. — gastrolobium pycnostachyum.
• runner p. — gastrolobium ovalifolium.
• p. sage — isotropis atropurpurea.
• sandplain p. — gastrolobium microcarpum.
• scale-leaf p. — gastrolobium appressum.
• p. sedge — schoenus asperocarpus.
• slender p. — gastrolobium heterophyllum.
• slender lamb p. — isotropis juncea.
• spike p. — gastrolobium glaucum.
• Stirling Range p. — gastrolobium velutinum.
• p. suckleya — suckleya suckleyana.
• p. sumac — toxicodendron vernix.
• thick-leaf p. — gastrolobium crassifolium.
• p. vetch — astragalus spp., oxytropis spp.
• wallflower p. — gastrolobium grandiflorum.
• p. walnut — cryptocarya pleurosperma.
• wodjil p. — gastrolobium floribundum.
• woolly p. — gastrolobium tomentosum.
• York Road p. — gastrolobium calycinum.