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PIE word
The skeletal formula for 1,4-dioxin, one form of dioxin (sense 1).
The skeletal formula for dibenzo-1,4-dioxin (sense 2).
The skeletal formula for 2,3,7,8-tetrachlorodibenzo-p-dioxin, known as TCDD or just dioxin (sense 3.1).

From di- (prefix meaning ‘double; two’) +‎ ox(ygen) +‎ -in (suffix indicating a neutral chemical compound),[1] a reference to the fact that the compound has two oxygen atoms.



dioxin (uncountable)

  1. (countable, organic chemistry) 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.
    • 2011, Peter Stride, “Limited Bio-diversity and Other Defects of the Immune System in the Inhabitants of the Islands of St Kilda, Scotland”, in Oscar Grillo and Gianfranco Venora, editors, Biodiversity Loss in a Changing Planet, Rijeka, Croatia: InTech, →ISBN, section 11 (Dioxin), page 236:
      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.
  2. (countable, organic chemistry) 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.
    • 1992, Ronald E. Gots, “Dioxins and Agent Orange”, in Toxic Risks: Science, Regulation, and Perception, Boca Raton, Fla.; London: Lewis Publishers, CRC Press, →ISBN, page 173:
      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).
  3. (countable, organic chemistry) Any of a broad range of toxic or carcinogenic halogenated polycyclic compounds that occur as byproducts of herbicides.
    • 1974 May, Hazardous Materials Advisory Committee, “Chemistry and Analysis”, in Herbicide Report: Chemistry and Analysis, Environmental Effects, Agricultural and Other Applied Uses (EPA-SAB; 74-001), Washington, D.C.: Science Advisory Board, U.S. Environmental Protection Agency, OCLC 16729652, page 17:
      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.
    • 1986, Benjamin Walter; Malcolm Getz, “Social and Economic Effects of Toxic Waste Disposal”, in Sheldon Kamieniecki, Robert O’Brien, and Michael Clarke, editors, Controversies in Environmental Policy (SUNY Series in Environmental Public Policy), State University of New York Press, →ISBN, page 223:
      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.
    • 1992, Merrie G. Klapp, “Bargaining with Uncertainty”, in Bargaining with Uncertainty: Decision-making in Public Health, Technological Safety, and Environmental Quality, Westport, Conn.: Auburn House, Greenwood Publishing Group, →ISBN, page 12:
      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.
    • 2001, D[avid] Waston, “Introduction”, in David H. Watson, editor, Food Chemical Safety (Woodhead Publishing in Food Science and Technology), volume 1 (Contaminants), Abington, Cambridgeshire: Woodhead Publishing; Boca Raton, Fla.: CRC Press, published 2005, →ISBN, section 1.4 (Persistent Environmental Chemicals), pages 6 and 7:
      [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.
    • 2002 May, Center for Environmental Analysis, RTI, “Hazard Identification/Dose-response Assessment”, in Exposure Analysis for Dioxins, Dibenzofurans, and CoPlanar Polychlorinated Biphenyls in Sewage Sludge: Technical Background Document: Draft, Washington, D.C.: Office of Water, U.S. Environmental Protection Agency, OCLC 1222828536, page 2-1:
      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 [...].
    1. (uncountable, specifically, loosely) 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.
      • 1971 November–December, T. F. X. Collins; C. H. Williams, “Teratogenic Studies with 2,4,5-T and 2,4-D in the Hamster”, in Bulletin of Environmental Contamination and Toxicology, volume 6, number 6, New York, N.Y.: Springer-Verlag, DOI:10.1007/BF01796866, OCLC 22747612, PMID 5317286, page 559; reprinted in Selected Technical Publications: July–December 1971, Washington, D.C.: Food and Drug Administration, Public Health Service, U.S. Department of Health, Education, and Welfare, 1971, ISSN 0888-9945, OCLC 436646057, page 163:
        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.
      • 1973 September, James Edward Huff; John S. Wassom, “Chlorinated Dibenzodioxins and Dibenzofurans”, in Douglas H. K. Lee and Hans L. Falk, editors, Environmental Health Perspectives (DHEW Publication; no. (NIH) 74-218), experimental issue number 5, Research Triangle Park, N.C.: National Institute of Environmental Health Science, National Institutes of Health, U.S. Department of Health, Education, and Welfare, OCLC 78146106, page 307, column 1:
        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.
      • 1998, “Guide to Chemicals”, in Jeanne Mager Stellman, editor, Encyclopaedia of Occupational Health and Safety, volume IV, 4th edition, Geneva, Switzerland: International Labour Office, →ISBN, section 104.286 (Hydrocarbons, Halogenated Aromatic), page 287, column 2:
        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.
      • 2002, Elaine A. Moore, “Environmental Triggers of Autoimmune Disease”, in Autoimmune Diseases and Their Environmental Triggers, Jefferson, N.C.; London: McFarland & Company, →ISBN, page 82:
        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.



  1. ^ dioxin, n.”, in Lexico, Dictionary.com; Oxford University Press, 2019–present; compare “dioxin, n.”, in OED Online Paid subscription required, Oxford, Oxfordshire: Oxford University Press, 1989.

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