Poison

From Wikinfo

In the context of biology, poisons are substances that cause injury, illness, or death to organisms, usually by chemical reaction or other activity on the molecular scale. Some poisons are also toxins, and a distinction between the two terms is not always observed, even among scientists. The derivative forms "toxic" and "poisonous" are synonomous. Within chemistry and physics, a poison is a substance that obstructs or inhibits a reaction, for example by binding to a catalyst.

Biological poisoning

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 almost instantly starves the body of energy by poisoning mitochondria and 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 heart by eliminating the cell potential necessary for muscle contraction. Such rapid reactions are often called acute poisoning.

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 mercury, lead, and asbestos.

Many substances regarded as poisons are toxic only indirectly. An example is "wood alchohol" or methanol, which is not poisonous itself, but is chemically converted to toxic formaldehyde 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 one individual and the next.

The study of the symptoms, mechanisms, treatment and diagnosis of biological poisoning is known as toxicology. Poisons are used deliberately as pesticides and herbicides. Such poisons in order to be safe should not damage the environment, bystanders, or the ultimate user of a product.

Examples of biological poisons

Non-radioactive inorganic poisons

Elemental metals
Elemental metalloids
- arsenic
Elemental nonmetals
Arsenic compounds
- arsenic trioxide
- Fowler's solution
ammonia

Radioactive inorganic poisons

Elemental gases
- Radon
Elemental metals
- Plutonium
- Polonium
- Radium
- Strontium 90 - See Nuclear fallout
- Uranium
- Americium

Organic poisons

cyanides
- potassium cyanide
- hydrogen cyanide (prussic acid)
carbon monoxide
ethanol
methanol
formaldehyde

Naturally produced posions and toxins

Microorganisms
- botulin toxin
- Tetrodotoxin
alkaloids
snake and spider venoms
curare
digitoxin
digoxin
domoic acid (or Amnesic Shellfish Poison, ASP)
Mushroom toxins
- amanita toxin, see Amanita phalloides
muscarine
ricin
Ciguatera poisoning
Shellfish toxins (PSP, DSP, NSP, ASP )
Scombroid poisoning
Aflatoxins
oubain
Pyrrolizidine alkaloids
Phytohaemagglutinin (Red kidney bean poisoning)
Grayanotoxin (Honey intoxication)

Famous poisonings

Charles Darwin (Claimed only by rumor: self-medication with Fowler's solution, one percent potassium arsenite)
Jamestown colonists Standard historical accounts claim deaths by starvation, but the possibility of arsenic poisoning by rat poison (or of death by Bubonic plague) has also been reported (see http://www.pbs.org/wnet/secrets2/case3_clues.html).
Jonestown inhabitants died from a poisoned drink in a mass sucide/murder: see Jonestown mass suicide
Clare Boothe Luce (Did not die of her poisoning) See Arsenic
Georgi Markov (Assassinated in London by KGB agents with ricin)
Napoleon Bonaparte (Claimed only by rumor: killed by someone on his staff; however, arsenic was measured but not found in his hair after his death)
Socrates According to Plato, killed by drinking Hemlock (water hemlock, not hemlock the evergreen tree)
Alan Turing Apparently committed suicide by painting apple with Cyanide and taking a bite.