Toxin
A toxin (Greek: τοξικόν, toxikon) is a poisonous substance produced by living cells or organisms[1][2] (although humans are technically living organisms, man-made substances created by artificial processes usually aren't considered toxins by this definition).
For a toxic substance not produced by living organisms, "toxicant" is the more appropriate term, and "toxics" is an acceptable plural.
Toxins can be small molecules, peptides, or proteins that are capable of causing disease on contact with or absorption by body tissues interacting with biological macromolecules such as enzymes or cellular receptors. Toxins vary greatly in their severity, ranging from usually minor and acute (as in a bee sting) to almost immediately deadly (as in botulinum toxin).
Terminology
Toxins are often distinguished from other chemical agents by their method of production - the word toxin does not specify method of delivery (compare with venom and (the narrower meaning of) poison). It simply means it is a biologically produced poison. There was an ongoing dispute between NATO and the Warsaw Pact over whether to call a toxin a biological or chemical agent, in which the former opted for the latter, and vice versa.
According to a International Committee of the Red Cross review of the Biological Weapons Convention, "Toxins are poisonous products of organisms; unlike biological agents, they are inanimate and not capable of reproducing themselves." and "Since the signing of the Convention, there have been no disputes among the parties regarding the definition of biological agents or toxins..."[3]
According to Title 18 of the United States Code, "...the term "toxin" means the toxic material or product of plants, animals, microorganisms (including, but not limited to, bacteria, viruses, fungi, rickettsiae or protozoa), or infectious substances, or a recombinant or synthesized molecule, whatever their origin and method of production..."[4]
A rather informal terminology of individual toxins relate them to the anatomical location where their effects are most notable:
- Hemotoxin, causes destruction of red blood cells (hemolysis)
- Phototoxin, causes dangerous photosensitivity
On a broader scale, toxins may be classified as either exotoxins, being excreted by an organism, and endotoxins, that are released mainly when bacteria are lysed.
Related terms are:
Biotoxins
The term "biotoxin" is sometimes used to explicitly confirm the biological origin.[5][6]
Toxins produced by microorganisms are important virulence determinants responsible for microbial pathogenicity and/or evasion of the host immune response[7].
Biotoxins vary greatly in purpose and mechanism, and can be highly complex (the venom of the cone snail contains dozens of small proteins, each targeting a specific nerve channel or receptor), or relatively small protein.
Biotoxins in nature have two primary functions:
- Predation (spider, snake, scorpion, jellyfish, wasp)
- Defense (bee, ant, termite, honeybee, wasp, poison dart frog)
Some of the more well known types of biotoxins include:
- Cyanotoxins, produced by cyanobacteria
- Hemotoxins target and destroy red blood cells, and are transmitted through the bloodstream. Organisms that produce hemotoxins include:
- Pit vipers, such as rattlesnakes
- Necrotoxins cause necrosis (i.e., death) in the cells they encounter and destroy all types of tissue[citation needed]. Necrotoxins spread through the bloodstream[citation needed]. In humans, skin and muscle tissues are most sensitive to necrotoxins[citation needed]. Organisms that possess necrotoxins include:
- The brown recluse or "fiddle back" spider
- The "Puff Adder" - Bitis arietans
- Necrotizing fasciitis (the "flesh eating" bacteria)
- Neurotoxins primarily affect the nervous systems of animals. Organisms that possess neurotoxins include:
- The Black Widow and other widow spiders
- Most scorpions
- The box jellyfish
- Elapid snakes
- The Cone Snail
- Cytotoxins are toxic at the level of individual cells, either in a non-specific fashion or only in certain types of living cells:
- Ricin is a plant toxin found in the castor bean plant
- Apitoxin, the honey bee venom
Environmental toxins
The term "environmental toxin" is often used.[8][9][10]
In these contexts, it can sometimes explicitly include contaminants that are man-made, [11] which contradicts most formal definitions of the term "toxin". Because of this, when encountering the word "toxin" outside of microbiological contexts, it is important to confirm what the researcher means by the use of the term. The toxins that are specific dangerous to biological species include:
- Paralytic shellfish poisoning (PSP) [12], [13], [14]
- Amnesic shellfish poisoning (ASP) [15], [16]
- Diarrheal shellfish poisoning (DSP) [17], [18]
Non-technical usage
When used non-technically, the term "toxin" is often applied to any toxic substances. Toxic substances not of biological origin are more properly termed poisons. Many non-technical and lifestyle journalists also follow this usage to refer to toxic substances in general, though some specialist journalists at publishers such as the BBC[citation needed] and The Guardian[19] maintain the distinction that toxins are only those produced by living organisms.
In the context of alternative medicine the term is often used non-specifically to refer to any substance claimed to cause ill health, ranging anywhere from trace amounts of pesticides to common food items like refined sugar or additives like artificial sweeteners and MSG.[citation needed]
See also
- Brevetoxin
- Insect toxins
- List of fictional toxins
- List of highly toxic gases
- Microbial toxins
- Toxicophore, feature or group within a chemical structure that is thought to be responsible for the toxic property
Notes & references
- ^ "toxin" at Dorland's Medical Dictionary
- ^ "toxin - Definition from the Merriam-Webster Online Dictionary". Retrieved 2008-12-13.
- ^ "The Biological Weapons Convention - An overview". Retrieved 2008-12-13.
- ^ "U.S. Code". Retrieved 2008-12-13.
- ^ "biotoxin - Definition from the Merriam-Webster Online Dictionary". Retrieved 2008-12-13.
- ^ "biotoxin" at Dorland's Medical Dictionary
- ^ Proft T (editor) (2009). Microbial Toxins: Current Research and Future Trends. Caister Academic Press. ISBN 978-1-904455-44-8.
{{cite book}}
:|author=
has generic name (help) - ^ Lanphear BP, Vorhees CV, Bellinger DC (2005). "Protecting children from environmental toxins". PLoS Med. 2 (3): e61. doi:10.1371/journal.pmed.0020061. PMC 1069659. PMID 15783252.
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ignored (help)CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link) - ^ Grollman AP, Jelaković B (2007). "Role of environmental toxins in endemic (Balkan) nephropathy. October 2006, Zagreb, Croatia". J. Am. Soc. Nephrol. 18 (11): 2817–23. doi:10.1681/ASN.2007050537. PMID 17942951.
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ignored (help) - ^ Cohen M (2007). "Environmental toxins and health--the health impact of pesticides". Aust Fam Physician. 36 (12): 1002–4. PMID 18075622.
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ignored (help) - ^ Grigg J (2004). "Environmental toxins; their impact on children's health". Arch. Dis. Child. 89 (3): 244–50. PMC 1719840. PMID 14977703.
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ignored (help) - ^ Vale, Carmen; et al. (2008). "In Vitro and in Vivo Evaluation of Paralytic Shellfish Poisoning Toxin Potency and the Influence of the pH of Extraction". Analytical chemistry. 80 (5). American Chemical Society: 1770–1776. doi:10.1021/ac7022266.
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(help) - ^ Oikawa, Hiroshi; et al. (2008). "Difference in the level of paralytic shellfish poisoning toxin accumulation between the crabs Telmessus acutidens and Charybdis japonica collected in Onahama, Fukushima Prefecture". Fisheries Science. 73 (2). Springer: 395–403. doi:10.1111/j.1444-2906.2007.01347.x.
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(help) - ^ Abouabdellah, Rachid; et al. (2008). "Paralytic shellfish poisoning toxin profile of mussels Perna perna from southern Atlantic coasts of Morocco". Toxin. 51 (5). Elsevier: 780–786. doi:10.1016/j.toxicon.2007.12.004.
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(help) - ^ Wang, Lin; et al. (2009). "Amnesic shellfish poisoning toxin stimulates the transcription of CYP1A possibly through AHR and ARNT in the liver of red sea bream Pagrus major". Marine Pollution Bulletin. 58 (11). Elsevier: 1643–1648. doi:10.1016/j.marpolbul.2009.07.004.
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(help) - ^ Wang, Lin; et al. (2001). "Optimization of conditions for the liquid chromatographic-electrospray lonization-mass spectrometric analysis of amnesic shellfish poisoning toxins". Chromatographia. 53 (1). Vieweg Verlag: S231–S235. doi:10.1007/BF02490333.
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(help) - ^ Mouratidou, Theoni; et al. (2006). "Detection of the marine toxin okadaic acid in mussels during a diarrhetic shellfish poisoning (DSP) episode in Thermaikos Gulf, Greece, using biological, chemical and immunological methods". Science of The Total Environment. 366 (2–3). Elsevier: 894–904. doi:10.1016/j.scitotenv.2005.03.002.
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(help) - ^ Doucet, Erin; et al. (2007). "Enzymatic hydrolysis of esterified diarrhetic shellfish poisoning toxins and pectenotoxins". Analytical and Bioanalytical Chemistry. 389 (1). Springer: 335–342. doi:10.1007/s00216-007-1489-3.
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(help) - ^ Corrections and clarifications, The Guardian, 30 May 2005.