Poison

Image:Skull and crossbones.svg Image:HAZCHEM T.jpg

This article is about the dangerous substance. for other uses of the term see Poison (disambiguation)

In the context of biology, poisons are substances that cause injury, illness, or death to organisms, usually by chemical reactionor other activity on the molecularscale.

Terminology

Some poisons are also toxins, usually referring to naturally produced substances, such as the bacterialproteinsthat cause tetanusand botulism. A distinction between the two terms is not always observed, even among scientists.

Animal toxins that are delivered subcutaneously (e.g. by stingor 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 chemistryand physics, a poison is a substance that obstructs or inhibits a reaction, for example by binding to a catalyst.

Lay use

The phrase "poison" is often used colloquially to describe other categories of substances:

• Carcinogens, such as some artificial sweeteners, Asbestos, Benzene, Carbon tetrachloride, Dioxin, and tobacco
• Mutagens, such as Ultravioletrays (Long term exposure may cause skin cancer such as Melanoma) and other Ionizing Radiation(causes radiation sicknessand cancer)
• Teratogens, such as Thalidomide
• Pollutantscan be poisonous, or they can be non-poisonous but harmful in other ways.

Warning symbols

Poisons have been known to be symbolized by the skull and crossbones(shown beside), although since this attracts children (being linked to pirates) it is gradually being replaced by Mr. Yukin the United States. In the United Kingdomand some parts of Europe, irritantpoisons are symbolised by a large "X" on an orange background.

Uses of poison

Deliberate application of poison has throughout the ages been used as method of murder, suicideand execution. As a method of execution, the poison can be administered as ingested, as the ancient Athenians did (see Socrates), breathed, such as carbon monoxideor hydrogen cyanide(see gas chamber) or intravenously (see lethal injection). Many non-English languages call lethal injection with their corresponding words for "poison shot".

Biological poisoning

Contact or absorption of poisons can cause rapid death or impairment. Agents that act on the nervous systemcan paralyze in seconds or less, and include both biologically derived neurotoxinsand so-called nerve gases, which may be synthesized for warfareor industry. Inhaled or ingested cyanideas used as method of executionon US gas chambersalmost instantly starves the body of energy by poisoning mitochondriaand the synthesis of 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 heartby eliminating the cell potentialnecessary for muscle contraction. Such rapid reactions are often called acute poisoning.

Most (but not all) pesticidesare created to act as poisons to target organisms, although acute or less observable chronic poisoning can also occur to non-target organism, including the humanswho apply the pesticides and other beneficial organisms.

A poison may also act slowly. This is known as chronic poisoning and is most common for poisons that bioaccumulate. Examples of these types of poisons are mercuryand lead.

Many substances regarded as poisons are toxic only indirectly. An example is "wood alcohol" or methanol, which is not poisonous itself, but is chemically converted to toxic formaldehydein the liver. Many drugmolecules are made toxic in the liver, and the genetic variability of certain liver enzymesmakes the toxicity of many compounds differ between one individual and the next.

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 in children

Background

• Poisoning is the fourth most common cause of accidents in children.
• Children less than 5 years of age and adolescent are prone to poisoning.
• Accidental ingestions are most common in children less than 5 years old.
• Adolescent ingestions are more typically a result of suicidalattempts or experimentation with illicit drugs.
• 90% of all poisonings occur at home, the most common site being the kitchenand the bathroom.
• Accidental poisonings occur most frequently when routines are disrupted, for example moving and vacations.
• Child safety caps have helped decrease the number of poisonings; however they are not 100% effective and should not give a false sense of security.
• All potential poisons should be properly labeled, stored out of reach of children, and locked.
• Medications should not be taken in front of small children.
• Parents should receive anticipatory guidance regarding poisonings and should have the number for Poison Control.
• If the poisoning occurs at home, Poison control should be called first!
• If the poison is an inhalant, remove the patient from the area.
• If the poisoning is affecting the skin, remove the clothing and wash the skin thoroughly unless a dry powder is the cause of the poisoning.
• If the patient has swallowed the poison, induce vomiting if appropriate and take the patient to the hospital.
• If the poison is in the eye, flush the eye thoroughly.
• When caring for poisoning in the emergency room center doctors will focus on the ABC's, airway, breathing, and circulation.
• Reviewing the patient's history and performing a pertinent, focused physical examination is a must.

Management

• Treat the patient for shock, burns, and pain
• If a narcoticis suspected, give naloxone
• The goal is to prevent absorption. This may be done using emesisin the first 4 hours, gastric lavage, activated charcoal, cathartics, and diuresis. Ipecacis no longer recommended.
  • Indications for gastric lavageinclude comaor impending coma, seizures, or a depressed gag reflex. Gastric lavage is most effective within 1 h of ingestion, and the largest possible orogastric tubeshould be used. Gastric lavage should be done only in older children.
  • Activated charcoalhas no real contraindicationsand is the treatment of choice to prevent absorption of the poisoning when the patient is in the emergency room. However charcoal is ineffective against cyanides, metals, Na, K, Cl, acids, and bases.
  • Catharticsdecrease absorption by increasing the rate of excretion.
  • Magnesium sulfateshould not be used if the patient has renal failure.
  • Diuresismay be done using hemodialysis, hemoperfusion, and peritoneal dialysis.
• Exchange transfusionshould only be performed if the patient is unresponsive to appropriate care.

Types of poisons

The majority of this section is sorted by ICD-10code, which classifies poisons based upon the nature of the poison itself. However, it is also possible to classify poisons based upon the effect the poison has (for example, "Metabolic poisons" such as Antimycin, Malonate, and 2,4-Dinitrophenolact by adversely disrupting the normal metabolismof an organism.)

(T36-T50) Poisoningby drugs, medicamentsand biological substances

(T36) Poisoningby systemic antibiotics

(T37) Poisoningby other systemic anti-infectivesand antiparasitics

(T38) Poisoningby hormonesand their synthetic substitutes and antagonists, not elsewhere classified

(T39) Poisoningby nonopiod analgesics, antipyreticsand antirheumatics

(T40) Poisoningby narcoticsand psychodysleptics(hallucinogens)

(T41) Poisoningby anaestheticsand therapeutic gases

(T42) Poisoningby antiepileptic, sedative-hypnoticand antiparkinsonismdrugs

(T43) Poisoningby psychotropic drugs, not elsewhere classified

(T44) Poisoningby drugs primarily affecting the autonomic nervous system

Neurotoxinsinterfere with nervous systemfunctions and often lead to near-instant paralysisfollowed by rapid death. They include most spiderand snakevenoms, as well as many modern chemical weapons. One class of toxins of interest to neurochemical researchers are the various cone snailtoxins known as conotoxins.

• Atropine
• Poison hemlock

Anticholinesterases (T44.0)

• Fasciculin
• Nerve agents

Acetylcholine antagonists

• Curare
• Pancuronium

Cell membrane disrupters

Others

• Nicotine- not strictly a neurotoxin, but capable in large doses of causing heart attack

(T45) Poisoningby primarily systemicand haematological agents, not elsewhere classified

• Phytohaemagglutinin(Red kidney beanpoisoning)

(T46) Poisoningby agents primarily affecting the cardiovascular system

• Digitoxin
• Digoxin
• Ouabain

(T47) Poisoningby agents primarily affecting the gastrointestinal system

• Solanine
• Hyoscyamine

(T48) Poisoningby agents primarily acting on smooth and skeletal musclesand the respiratory system

• Strychnine
• Aconite

(T49) Poisoningby topical agentsprimarily affecting skinand mucous membraneand by opthalmological, otorhinolaryngologicaland dentaldrugs

(T50) Poisoningby diureticsand other unspecified drugs, medicaments and biological substances

(T51-T65) Toxic effectsof substances chiefly nonmedicinal as to source

(T51) Toxic effect of alcohol

• (T51.0) Ethanol
• (T51.1) Methanol

(T52) Toxic effect of organic solvents

(T53) Toxic effect of halogen derivatives of aliphaticand aromatic hydrocarbons

(T54) Toxic effect of corrosivesubstances

Corrosivesmechanically damage biological systems on contact. Both the sensation and injury caused by contact with a corrosive resembles a burn injury.

• Acids and bases, corrosives
  • Various light metal oxides, hydroxides, superoxides
  • Bleach, some pool chemicals, other hypochlorates (acidic and oxydizing effect)
  • Hydrofluoric acid

Acids (T54.2)

Strong inorganic acids, such as concentrated sulfuric acid, nitric acidor hydrochloric acid, destroy any biological tissuewith which they come in contact within seconds.

Bases (T54.3)

Strong inorganic bases, such as lye, gradually dissolve skin on contact but can cause serious damage to eyes or mucous membranesmuch more rapidly. Ammoniais a far weaker base than lye, but has the distinction of being a gas and thus may more easily come into contact with the sensitive mucous membranes of the respiratory system. Quicklime, which has household uses, is a particularly common cause of poisoning. Some of the light metals, if handled carelessly, can not only cause thermal burns, but also produce very strongly basic solutions in sweat.

(T55) Toxic effect of soapsand detergents

(T56) Toxic effect of metals

A common trait shared by heavy metalsis the chronic nature of their toxicity (a notable exception would be bismuth, which is considered entirely non-toxic). Low levels of heavy metal salts ingested over time accumulate in the body until toxic levels are reached.

Heavy metals are generally far more toxic when ingested in the form of soluble saltsthan in elemental form. For example, metallic mercurypasses through the human digestive tract without interaction and is commonly used in dental fillings—even though mercury saltsand inhaled mercury vapor are highly toxic.

Examples:

• (T56.0) Lead poisoning
• (T56.1) Mercury
• (T56.2) Chromium
• (T56.3) Cadmium
• (T56.7) Beryllium(a highly but subtly toxic light metal)
• Antimony
• Barium
• Thallium
• Uranium

(T57) Toxic effect of other inorganic substances

• (T57.0) Arsenic(see arsenic poisoning)
  • Arseniccompounds
    • Arsenic trioxide
    • Fowler's solution

Reducing agents

• (T57.1) The most notable substance in this class is phosphorus.

(T58) Toxic effect of carbon monoxide

• (T58) By far the most notable metabolic poison is carbon monoxide, which blocks the ability of red blood cellsto transport oxygen.

(T59) Toxic effect of other gases, fumesand vapours

• Formaldehyde(T59.2)
• Phosgene
• Phosphine
• Hydrogen sulfide

Oxidizers

Poisons of this class are generally not very harmful to higher life forms such as humans (for whom the outer layer of cells are more or less disposable), but lethal to microorganismssuch as bacteria. Typical examples are ozoneand chlorine(T59.4), either of which is added to nearly every municipal water supplyin order to kill any harmful microorganisms present.

All halogensare strong oxidizing agents, fluorine(T59.5) being the strongest of all.

See also: Free radical

(T60) Toxic effect of pesticides

• Pesticide poisoning
• Fluoroacetateis a metabolic poison that blocks a vital step in the citric acid cycle.
• Rotenoneis a metabolic poison that disrupts electron transport in cellular respiration.

(T61) Toxic effect of noxioussubstances eaten as seafood

• Ciguatera poisoning
• Scombroid poisoning
• Shellfish toxins(PSP, DSP, NSP, ASP)
• Domoic acid(or Amnesic Shellfish Poison, ASP)
• Tetrodotoxin

(T62) Toxic effect of other noxioussubstances eaten as food

• Food poisoning
• Botulintoxin
• Hemlock water dropwort
• Grayanotoxin(Honeyintoxication)
• Tetanospasmin(Tetanos Toxin)

(T63) Toxic effect of venomous animals

• Snakeand spidervenoms

(T64) Toxic effect of aflatoxinand other mycotoxinfood contaminants

• Fungaltoxins
  • Amanitatoxin, see Amanita phalloides
  • Muscarine
  • Aflatoxins

(T65) Toxic effect of other and unspecified substances

• (T65.0) Cyanide is a metabolic poison that bonds with an enzyme involved in ATPproduction.

See also

• Antidote
• Biosecurity
• Food taster
• LD50
• Lethal injection
• List of poisonings
• List of fictional toxins
• Toxicity

External links

• Agency for Toxic Substances and Disease Registrycs:Jed

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It uses material from the http://en.wikipedia.org/wiki/Poison Wikipedia article Poison.