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For a list of biologically injurious substances, including toxins and other materials, as well as their effects, see poison
Universal warning symbol used to indicate toxic substances or environments
A toxin (Greek: τοξικόν, toxikon) is a poisonous substance produced by living cells or organisms (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).
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..."
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..."
A rather informal terminology of individual toxins relate them to the anatomical location where their effects are most notable:
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:
- Toxoid, weakened or suppressed toxin
- Venom, toxins in the sense of use by certain types of animals
The term "biotoxin" is sometimes used to explicitly confirm the biological origin.
Toxins produced by microorganisms are important virulence determinants responsible for microbial pathogenicity and/or evasion of the host immune response.
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:
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:
- Necrotoxins cause necrosis (i.e., death) in the cells they encounter and destroy all types of tissue. Necrotoxins spread through the bloodstream. In humans, skin and muscle tissues are most sensitive to necrotoxins. Organisms that possess necrotoxins include:
- Neurotoxins primarily affect the nervous systems of animals. Organisms that possess neurotoxins include:
- 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
The term "environmental toxin" is often used.
In these contexts, it can sometimes explicitly include contaminants that are man-made, 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 from food chains which maybe dangerous to human health include:
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 and The Guardian 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.
Notes & references
- ^ toxin at Dorland's Medical Dictionary
- ^ "toxin - Definition from the Merriam-Webster Online Dictionary". http://www.merriam-webster.com/dictionary/toxin. Retrieved 2008-12-13.
- ^ "The Biological Weapons Convention - An overview". http://www.icrc.org/web/eng/siteeng0.nsf/html/57JNPA. Retrieved 2008-12-13.
- ^ "U.S. Code". http://law2.house.gov/uscode-cgi/fastweb.exe?getdoc+uscview+t17t20+235+1++()%20%20AND%20((18)%20ADJ%20USC)%3ACITE%20AND%20(USC%20w/10%20(209))%3ACITE. Retrieved 2008-12-13.
- ^ "biotoxin - Definition from the Merriam-Webster Online Dictionary". http://www.merriam-webster.com/dictionary/biotoxin. 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.
- ^ Lanphear BP, Vorhees CV, Bellinger DC (March 2005). "Protecting children from environmental toxins". PLoS Med. 2 (3): e61. doi:10.1371/journal.pmed.0020061. PMID 15783252.& PMC 1069659. http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0020061.
- ^ Grollman AP, Jelaković B (November 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. http://jasn.asnjournals.org/cgi/pmidlookup?view=long&pmid=17942951.
- ^ Cohen M (December 2007). "Environmental toxins and health--the health impact of pesticides". Aust Fam Physician 36 (12): 1002–4. PMID 18075622. http://www.racgp.org.au/afp/200712/21201.
- ^ Grigg J (March 2004). "Environmental toxins; their impact on children's health". Arch. Dis. Child. 89 (3): 244–50. PMID 14977703.& PMC 1719840. http://adc.bmj.com/cgi/pmidlookup?view=long&pmid=14977703.
- ^ 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 (American Chemical Society) 80 (5): 1770–1776. doi:10.1021/ac7022266.
- ^ 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 (Springer) 73 (2): 395–403. doi:10.1111/j.1444-2906.2007.01347.x.
- ^ Abouabdellah, Rachid et al. (2008). "Paralytic shellfish poisoning toxin profile of mussels Perna perna from southern Atlantic coasts of Morocco". Toxin (Elsevier) 51 (5): 780–786. doi:10.1016/j.toxicon.2007.12.004.
- ^ 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 (Elsevier) 58 (11): 1643–1648. doi:10.1016/j.marpolbul.2009.07.004.
- ^ Wang, Lin et al. (2001). "Optimization of conditions for the liquid chromatographic-electrospray lonization-mass spectrometric analysis of amnesic shellfish poisoning toxins". Chromatographia (Vieweg Verlag) 53 (1): S231 - S235. doi:10.1007/BF02490333.
- ^ 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 (Elsevier) 366 (2 - 3): 894–904. doi:10.1016/j.scitotenv.2005.03.002.
- ^ Doucet, Erin et al. (2007). "Enzymatic hydrolysis of esterified diarrhetic shellfish poisoning toxins and pectenotoxins". Analytical and Bioanalytical Chemistry (Springer) 389 (1): 335–342. doi:10.1007/s00216-007-1489-3.
- ^ Poli, Mark A. et al. (2000). "Neurotoxic shellfish poisoning and brevetoxin metabolites: a case study from Florida". Toxicon (Elsevier) 38 (7): 981–993. doi:10.1016/S0041-0101(99)00191-9.
- ^ Morohashi, Akio et al. (1995). "Brevetoxin B3, a new brevetoxin analog isolated from the greenshell mussel perna canaliculus involved in neurotoxic shellfish poisoning in new zealand". Tetrahedron Letters (Elsevier) 36 (49): 8995–8998. doi:10.1016/0040-4039(95)01969-O.
- ^ Morohashi, Akio et al. (1999). "Brevetoxin B4 isolated from greenshell mussels Perna canaliculus, the major toxin involved in neurotoxic shellfish poisoning in New Zealand". Tetrahedron Letters (Natural Toxins) 7 (2): 45–48. http://www3.interscience.wiley.com/journal/65500591/abstract. Retrieved 15 February 2010.
- ^ Corrections and clarifications, The Guardian, 30 May 2005.
note: some toxins are produced by lower species and pass through intermediate species