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In the context of biology, poisons
are substances that can cause disturbances to organisms, [1] usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism. Legally and in hazardous chemical labelling, poisons are especially toxic substances; less toxic substances are labelled "harmful", "irritant", or not labelled at all.
In medicine (particularly veterinary) and in zoology, a poison is often distinguished from a toxin and a venom. Toxins are poisons produced via some biological function in nature, and venoms are usually defined as biologic toxins that are injected by a bite or sting to cause their effect, while other poisons are generally defined as substances which are absorbed through epithelial linings such as the skin or gut.
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POISON TICKETS
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Terminology
Some poisons are also
toxins, usually referring to naturally produced substances, such as the
bacterial proteins that cause
tetanus and
botulism. A distinction between the two terms is not always observed, even among scientists.
Animal toxins that are delivered subcutaneously (e.g. by
sting or
bite) are also called
venom
. In normal usage, a poisonous organism is one that is harmful to consume, but a venomous organism uses poison to defend itself while still alive. A single organism can be both venomous and poisonous.
The derivative forms "toxic" and "poisonous" are synonymous.
Within
chemistry and
physics, a poison is a substance that obstructs or inhibits a reaction, for example by binding to a
catalyst. For an example, see
nuclear poison.
Paracelsus, the father of
toxicology, once wrote: "Everything is poison, there is poison in everything. Only the dose makes a thing not a poison." The phrase "poison" is often used colloquially to describe any harmful substance, particularly
corrosive substances,
carcinogens,
mutagens,
teratogens and harmful
pollutants, and to exaggerate the dangers of chemicals. The legal definition of "poison" is stricter. A medical condition of poisoning can also be caused by substances that are not legally required to carry the label "poison".
Uses of poison
Throughout human history, intentional application of poison has been used as a method of
assassination,
murder,
suicide, and
execution.
[2] [3] 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 the
Chinese gu
poison. Poison was also employed in
gunpowder warfare. For example, the 14th century Chinese text of the
Huo Long Jing
written by
Jiao Yu outlined the use of a poisonous gunpowder mixture to fill
cast iron grenade bombs.
[4]
On the whole, however, poisons are usually not used for their toxicity, but may be used for their other properties. The property of toxicity itself has limited non-lethal applications: mainly for controlling pests and weeds, cleaning and maintenance, and for preserving building materials and food stuffs. Where possible, specific agents which are less poisonous to humans have come to be preferred, but exceptions such as
phosphine continue in use.
Most poisonous materials still in use are used for their chemical or physical properties other than being poisonous. Many over-the-counter medications, such as
aspirin and
Tylenol, are quite toxic if ingested in sufficiently large quantities.
Alcohol is also toxic if too much is ingested in a short enough time. In laboratory environments, where specific chemical properties are often required, the most effective, easiest, safest, or cheapest option for use in a
chemical synthesis may be a poisonous material. If a toxic substance possesses these properties more exactly than a non-toxic one, the toxic substance is superior.
Chromic acid is an example of such a "simple to use" reagent, but reactivity, in particular, is important.
Hydrogen fluoride (HF), for example, is both poisonous and extremely corrosive. However, it has a high
affinity (
free energy) for
silicon, which is exploited by using HF to
etch glass or to manufacture silicon semiconductor chips.
On the other hand, certain medical treatments actually make deliberate use of the toxicity of certain substances.
Antibiotics (originally harvested from organisms but now artificially produced in laboratories) are highly disruptive to the biochemistry of micro-organisms while having almost no direct effect upon humans. Similarly, the drugs used in
chemotherapy are quite toxic; the reason chemotheraputic drugs have far more severe side effects than antibiotics is that their toxicity is not as narrowly tailored. Their benefit arises from the fact that they are—hopefully—more toxic to cancerous cells than normal ones. Such substances could be classified as poisons under the categories defined above, as they are generally artificial in nature, but are not generally discussed as such.
Biological poisoning
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. In contrast, substances that destroy tissue but do not absorb, such as
lye, are classified as
corrosives rather than poisons.
Chronic poisoning is long-term repeated or continuous exposure to a poison where symptoms do not occur immediately or after each exposure. The patient gradually becomes ill, or becomes ill after a long latent period. Chronic poisoning most commonly occurs following exposure to poisons that
bioaccumulate such as
mercury and
lead.
Contact or absorption of poisons can cause rapid death or impairment. Agents that act on the
nervous system can paralyze in seconds or less, and include both biologically derived
neurotoxins and so-called
nerve gases, which may be synthesized for
warfare or industry.
Inhaled or ingested
cyanide, used as a method of
execution in
gas chambers, almost instantly starves the body of energy by
inhibiting the
enzymes in
mitochondria that make
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
cell potential necessary for
muscle contraction.
Most biocides, including
pesticides, are created to act as poisons to
target organisms, although acute or less observable chronic poisoning can also occur in non-target organism, including the
humans who apply the biocides and other
beneficial organisms. For example, the herbicide
2,4-D imitates the action of a plant hormone, to the effect that the lethal toxicity is 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
drug molecules are made toxic in the liver, and the genetic variability of certain liver
enzymes makes the toxicity of many compounds differ between individuals.
The study of the symptoms, mechanisms, treatment and diagnosis of biological poisoning is known as
toxicology.
Exposure to radioactive substances can produce
radiation poisoning, an unrelated phenomenon.
Poisoning management
- Poison Control Centers (reachable at 1-800-222-1222 in the US ) provide immediate, free, and expert treatment advice and assistance over the telephone in case of suspected exposure to poisons or toxic substances.
Initial management
- Initial management for all poisonings includes ensuring adequate cardiopulmonary function and providing treatment for any symptoms such as seizures, shock, and pain.
Decontamination
- If the toxin was recently ingested, absorption of the substance may be able to be decreased through gastric decontamination. This may be achieved using activated charcoal, gastric lavage, whole bowel irrigation, or nasogastric aspiration. Routine use of emetics (syrup of Ipecac), cathartics or laxatives are no longer recommended.
- * Activated charcoal is the treatment of choice to prevent absorption of the poison. It is usually administered when the patient is in the emergency room or by a trained emergency healthcare provider such as a Paramedic or EMT. However, charcoal is ineffective against metals, Na, K, alcohols, glycols, acids, and alkalis.
- * Whole bowel irrigation cleanses the bowel, this is achieved by giving the patient large amounts of a polyethylene glycol solution. The osmotically balanced polyethylene glycol solution is not absorbed into the body, having the effect of flushing out the entire gastrointestinal tract. Its major uses are following ingestion of sustained release drugs, toxins that are not absorbed by activated charcoal (i.e. lithium, iron), and for the removal of ingested packets of drugs (body packing/smuggling). [5]
- * Gastric lavage, commonly known as a stomach pump, is the insertion of a tube into the stomach, followed by administration of water or saline down the tube. The liquid is then removed along with the contents of the stomach. Lavage has been used for many years as a common treatment for poisoned patients. However, a recent review of the procedure in poisonings suggests no benefit. [6] It is still sometimes used if it can be performed within 1 h of ingestion and the exposure is potentially life threatening.
- * Nasogastric aspiration involves the placement of a tube via the nose down into the stomach, the stomach contents are then removed via suction. This procedure is mainly used for liquid ingestions where activated charcoal is ineffective, e.g. ethylene glycol.
- * Emesis (i.e. induced by ipecac) is no longer recommended in poisoning situations. [7]
- * Cathartics were postulated to decrease absorption by increasing the expulsion of the poison from the gastrointestinal tract. There are two types of cathartics used in poisoned patients; saline cathartics (sodium sulfate, magnesium citrate, magnesium sulfate) and saccharide cathartics (sorbitol). They do not appear to improve patient outcome and are no longer recommended. [8]
Antidotes
Some poisons have specific
antidotes:
Poison/Drug
| Antidote
|
paracetamol (acetaminophen)
| N-acetylcysteine
|
vitamin K anticoagulants, e.g. warfarin
| vitamin K
|
opioids
| naloxone
|
iron (and other heavy metals)
| desferrioxamine, Deferasirox or Deferiprone
|
benzodiazepines
| flumazenil
|
ethylene glycol
| ethanol, fomepizole or Thiamine
|
methanol
| ethanol or fomepizole
|
cyanide
| amyl nitrite, sodium nitrite & sodium thiosulfate
|
Organophosphates
| Atropine & Pralidoxime
|
Magnesium
| Calcium Gluconate
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Calcium Channel Blockers (Verapamil, Diltiazem)
| Calcium Gluconate
|
Beta-Blockers (Propranolol, Sotalol)
| Calcium Gluconate and/or Glucagon
|
Isoniazid
| Pyridoxine
|
Atropine
| Physostigmine
|
Thallium
| Prussian Blue
|
Enhanced excretion
- In some situations elimination of the poison can be enhanced using diuresis, hemodialysis, hemoperfusion, hyperbaric medicine, peritoneal dialysis, or exchange transfusion.
Further treatment
- In the majority of poisonings the mainstay of management is providing supportive care for the patient, i.e. treating the symptoms rather than the poison. :))
See also
- Antidote
- Biosecurity
- Food taster
- LD50
- Lethal injection
- List of extremely hazardous substances
- List of fictional toxins
- List of poisonings
- List of poisonous plants
- List of types of poison
- Toxicity
- Toxicology
- Toxics use reduction
- Venom
- Mr. Yuk
References
- {{DorlandsDict|six/000084583|poison}}
- Kautilya suggests employing means such as seduction, secret use of weapons, poison etc. S.D. Chamola, ''Kautilya Arthshastra and the Science of Management: Relevance for the Contemporary Society'', p. 40. ISBN 8178711265.
- Kautilya urged detailed precautions against assassination—tasters for food, elaborate ways to detect poison. "Moderate Machiavelli? Contrasting The Prince with the Arthashastra of Kautilya". ''Critical Horizons'', vol. 3, no. 2 (September 2002). Brill Academic Publishers. ISSN 1440-9917 (Print) 1568-5160 (Online). DOI: 10.1163/156851602760586671.
- Needham, Joseph (1986). ''Science and Civilization in China: Volume 5, Part 7''. Taipei: Caves Books, Ltd. Page 180.
- Position paper: whole bowel irrigation
- Position paper: gastric lavage
- Position paper: Ipecac syrup
- Position paper: cathartics