Pronunciations (4)
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/daɪˈɒksɪn/
Pronunciation notes
- Received-Pronunciation
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/daɪˈɑksən/
Pronunciation notes
- General-American
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daɪˈɒksɪn
Pronunciation notes
- GB
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daɪˈɑksən
Pronunciation notes
- US
Noun
The unsaturated six-membered heterocycle having four carbon atoms, two oxygen atoms, and two double bonds (molecular formula C₄H₄O₂); 1,2-dioxin and 1,4-dioxin.
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Dioxin is a specific organic unsaturated non-antiaromatic six-membered ring compound with a chemical formula of C4H4O2. However, the term dioxin is used generically by most authorities to include chlorinated dioxins with furans and many derivative compounds as a complex of at least 75 ubiquitous and environmentally persistent organochlorine compounds, of variable toxicity.
The parent compound dibenzo-1,4-dioxin or dibenzo-p-dioxin (molecular formula C₁₂H₈O₂), in which two benzene rings are connected through two oxygen atoms; dibenzodioxin, oxanthrene.
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Dioxins are not a single chemical. They are a family of chemicals that contain two benzene rings connected by a pair of oxygen molecules. When chlorine atoms are connected to the benzene rings, we have a chlorinated dioxin. The particular chlorinated dioxin of greatest interest and concern is 2,3,7,8-tetrachlorodibenzo-p-dioxin (generally abbreviated TCDD).
Any of a broad range of toxic or carcinogenic halogenated polycyclic compounds that occur as byproducts of herbicides.
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The detection of dioxin (specifically, the 2,3,7,8-tetrachlorodibenzo-pdioxin TCDD) in 2,4,5-T raised the question whether dioxin might be present in other herbicides.
Poisonous residues carelessly treated today can produce calamities miles away and decades later. One example is dioxin, a waste left behind in factories after the production of hexachlorophene, a potent antiseptic. Dioxins are lethal, capable of killing people in concentrations as diluted as one part in a million. Oils containing discarded dioxins have been sprayed on horse farms in Missouri to control dust. Horses subsequently died.
Dioxins are polychlorinated isomers that form as by-products either during combustion of waste products or afterward in the incinerator stack. They include dibenzo-dioxins (PCDD), dibenzofurans (PCDF), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). 2,3,7,8-TCDD is one of the extremely carcinogenic groups of dioxin compounds. A risk of exposure to humans occurs once dioxin compounds are released from the stack of the incinerator and are transported by the wind elsewhere.
[page 6] Dioxins in food and the environment hae been intensively studied over the past twenty years [...]. The term ‘dioxins’ has come to be used for polychlorinated dibenzo-p-dioxins and in some cases also polychlorinated dibenzofurans. [...] [page 7] The sources of food contamination with dioxins are now known to be many more than was originally asserted when claims were made that incinerators were the main source of dioxins in the environment. Indeed known sources of dioxins now include vehicle exhausts, domestic coal fires, manufacture and use of organic chemicals, and metallurgical processors.
EPA [the Environmental Protection Agency] characterizes 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as a Human Carcinogen based on weight of evidence and characterizes other dioxins, furans, and PCBs [polychlorinated biphenyls] as Likely Human Carcinogens. The toxicity of all of the dioxin, furan, and PCB congeners considered in this analysis is based on the toxicity of the most highly characterized congener, 2,3,7,8-TCDD [...].
Any of a broad range of toxic or carcinogenic halogenated polycyclic compounds that occur as byproducts of herbicides. The compound 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; molecular formula C₁₂H₄Cl₄O₂), a persistent organic pollutant of the environment which is generally produced as a byproduct of organic synthesis or when organic materials are burned.
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The 2,4,5-T used by Courtney and co-workers [...] was contaminated with approximately 30 ppm of 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin). [...] The present work describes the results of our teratogenic studies on hamsters with samples of 2,4,5-T containing varying amounts of dioxin and with samples of 2,4-D from different manufacturers.
When manufacture of 2,4,5-T is controlled carefully, dioxin contamination is less than 1 ppm. Dioxin was identified in 1962 as the culprit of damage and death in 1957 of uncounted numbers of chicks. Dioxin produces neurological disturbances and is teratogenic.
Dioxin—2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)—is not manufactured commercially but is present as an impurity in 2,4,5-trichlorophenol (TCP). Minute traces may be present in the herbicide 2,4,5-T and in the antibacterial agent hexachlorophene, which are produced from trichlorophenol.
Dioxin or TCDD is a chemical contaminant that occurs as chlorine byproduct of the paper bleaching manufacturing process. Although it is useless on its own, dioxin is a common environmental contaminant. Dioxin was also released as a contaminant of the pesticide Agent Orange, which was used as a defoliant by U.S. forces in Vietnam. The highest concentrations of dioxin result from the incineration of medical waste.
Noun
any of several toxic or carcinogenic hydrocarbons that occur as impurities in herbicides
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