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Agent Orange—or Herbicide Orange (HO)—is one of the herbicides and defoliants used by the U.S. military as part of its herbicidal warfare program, Operation Ranch Hand,〔(【引用サイトリンク】title=The Air Force and Herbicides )〕 during the Vietnam War from 1961 to 1971.〔(Agent Orange Linked To Skin Cancer Risk )〕 It was a mixture of equal parts of two herbicides, 2,4,5-T and 2,4-D. During the late 1940s and 1950s, the US and British collaborated on development of herbicides with potential applications in warfare. Some of those products were brought to market as herbicides. The British were the first to employ herbicides and defoliants to destroy the crops, bushes, and trees of communist insurgents in Malaya during the Malayan Emergency. These operations laid the groundwork for the subsequent use of Agent Orange and other defoliant formulations by the US. In mid-1961, President Ngo Dinh Diem of South Vietnam asked the United States to conduct aerial herbicide spraying in his country. In August of that year, the South Vietnamese Air Force initiated herbicide operations with American help. But Diem's request launched a policy debate in the White House and the State and Defense Departments.〔 However, U.S. officials considered using it, pointing out that the British had already used herbicides and defoliants during the Malayan Emergency in the 1950s. In November 1961, President John F. Kennedy authorized the start of Operation Ranch Hand, the codename for the U.S. Air Force's herbicide program in Vietnam. Agent Orange was manufactured for the U.S. Department of Defense primarily by Monsanto Corporation and Dow Chemical.〔"Agent Orange" entry in Encyclopedia of United States National Security, edited by Richard J. Samuel. SAGE Publications, 2005. ISBN 9781452265353〕 It was given its name from the color of the orange-striped barrels in which it was shipped, and was by far the most widely used of the so-called "Rainbow Herbicides".〔 The 2,4,5-T used to produce Agent Orange was contaminated with 2,3,7,8-Tetrachlorodibenzodioxin (TCDD), an extremely toxic dioxin compound. In some areas, TCDD concentrations in soil and water were hundreds of times greater than the levels considered safe by the U.S. Environmental Protection Agency.〔Fawthrop, Tom; ("Vietnam's war against Agent Orange" ), BBC News, June 14, 2004〕〔Fawthrop, Tom; ("Agent of Suffering" ), ''Guardian'', February 10, 2008〕 In the absence of specific customary or positive international humanitarian law regarding herbicidal warfare, a draft convention, prepared by a Working Group set up within the Conference of the Committee on Disarmament (CCD), was submitted to the UN General Assembly in 1976. In that same year, the First Committee of the General Assembly decided to send the text of the draft convention to the General Assembly, which adopted Resolution 31/72 on December 10, 1976, with the text of the Convention attached as an annex thereto. The convention, namely the Environmental Modification Convention, was opened for signature and ratification on May 18, 1977, and entered into force in October 5, 1978. The convention prohibits the military or other hostile use of environmental modification techniques having widespread, long-lasting or severe effects. Many states do not regard this as a complete ban on the use of herbicides and defoliants in warfare but it does require case-by-case consideration.〔(Convention on the Prohibition of the Military or Any Other Hostile Use of Environmental Modification Techniques )〕 Although in the Geneva Disarmament Convention of 1978, Article 2(4) Protocol III to the weaponry convention has "The Jungle Exception", which prohibits states from attacking forests or jungles "except if such natural elements are used to cover, conceal or camouflage combatants or military objectives or are military objectives themselves" this voids any protection of any military or civilians from a napalm attack or something like agent Orange and is clear that it was designed to cater to situations like U.S. tactics in Vietnam. This clause has yet to be revised.〔Detter, Ingrid. (Law of War ), (pub. 2013 ) pg. 255.〕 ==Chemical description and toxicology== Chemically, Agent Orange is an approximately 1:1 mixture of two phenoxyl herbicides – 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) – in iso-octyl ester form.〔IOM, 1994: (p. 90 )〕 Numerous studies have examined health effects linked to Agent Orange, its component compounds, and its manufacturing byproducts.〔Frumkin, 2003: (pp.245–255 )〕 In 1969 it was revealed to the public that the 2,4,5-T was contaminated with a dioxin, 2,3,7,8-tetrachlorodibenzodioxin (TCDD), and that the TCDD was causing many of the previously unexplained adverse health effects which were correlated with Agent Orange exposure.〔Young, 2009: (p. 6 )〕 TCDD has been described as "perhaps the most toxic molecule ever synthesized by man".(Galston 1979, cited in〔Schuck, 1987: (p. 18 )〕) Internal memoranda revealed that Monsanto (a major manufacturer of 2,4,5-T) had informed the U.S. government in 1952 that its 2,4,5-T was contaminated.〔Schuck, 1987: (p. 17 )〕 In the manufacture of 2,4,5-T, accidental overheating of the reaction mixture easily causes the product to condense into the toxic self-condensation product TCDD. At the time, precautions were not taken against this unintended side reaction, which also caused the Seveso disaster in Italy in 1976. In 1979, Yale biologist Arthur Galston, who specialized in herbicide research, published a review of what was known at the time about the toxicity of TCDD. Even "vanishingly small" quantities of dioxin in the diet caused adverse health effects when tested on animals.〔 Since then, TCDD has been comprehensively studied. It has been associated with increased neoplasms in every animal bioassay reported in the scientific literature.〔Dwyer and Flesch-Janys, ("Editorial: Agent Orange in Vietnam" ), American Journal of Public Health, April 1995, Vol 85. No. 4, p. 476〕 The National Toxicology Program has classified TCDD as "known to be a human carcinogen", frequently associated with soft-tissue sarcoma, non-Hodgkin's lymphoma, Hodgkin's lymphoma and chronic lymphocytic leukemia (CLL).〔NTP, 2006: 〕 Of the two herbicides that make up Agent Orange, 2,4-D and 2,4,5-T, the latter is considered to be less biodegradable.〔("2,4,5-Trichlorophenoxyacetic Acid Pathway Map" ) by Brian Hill and Jiangbi Liu (accessed 2013-06-18)〕 While degradation of 2,4,5-T with a half-life on a scale of days can be achieved by adding bacteria of a special strain, "no substantial degradation" was observed in the same soil without addition of bacteria.〔("Biodegradation of 2,4,5-trichlorophenoxyacetic acid in soil by a pure culture of Pseudomonas cepacia" ) by D K Chatterjee, J J Kilbane and A M Chakrabarty in ''Appl. Environ. Microbiol.'' 1982, 44(2):514. (accessed 2013-06-18)〕 The half-life of dioxins in soil is more than 10 years,〔Centre for Ecological Sciences, Indian Institute of Science: ("Dioxins" ) (accessed 2013-06-18)〕 and that of TCDD in human fat tissue is about 7 years.〔Umweltbundesamt: ("Chemikalienpolitik und Schadstoffe, REACH - Dioxine" ) (accessed 2013-07-24)〕 A 1969 report authored by K. Diane Courtney and others found 2,4,5-T could cause birth defects and stillbirths in mice.〔Buckingham, 1992: ''Chapter IX – Ranch Hand Ends''〕 Several studies have shown an increased rate of cancer mortality for workers exposed to 2,4,5-T. In one such study, from Hamburg, Germany, the risk of cancer mortality increased by 170% after working for 10 years at the 2,4,5-T-producing section of a Hamburg manufacturing plant.〔 Three studies have suggested prior exposure to Agent Orange poses an increased risk of acute myelogenous leukemia in the children of Vietnam veterans.〔 It has often been claimed〔on this and (3) other pages of en.Wikipedia〕〔(''Agent Orange revelations raise Futenma stakes'' ) by Jon Mitchell, Japan Times (accessed 2013-07-21)〕〔(''Agent Orange and the Removal of Dioxin in Da Nang Airport'' ) by Tony Thanh, October 16, 2011, Da Nang, Vietnam (accessed 2013-07-21)〕〔(''In Support of the Vietnamese Victims of Agent Orange'' ) June 18th, 2012, (accessed 2013-07-21)〕〔(''Agent Orange and Other Herbicides'' ) 2013 (accessed 2013-07-21)〕〔(''Agent Orange still 'killing' Vietnam War veterans'' ) March 22, 2013 (accessed 2013-07-07)〕〔(''Agent Orange Exposure In Vietnam: A Spokane Woman’s Battle'' ) by Kelsey Watts, KHQ Local News Anchor/Reporter, May 23, 2013 (accessed 2013-07-21)〕〔(... and elsewhere, certainly thousands of times, likely more than 100,000 times ) (accessed 2013-07-21)〕 that the contamination with dioxin was discovered only ''later''. However, prior to Operation Ranch Hand (1962-1971), health-risks had become apparent, from several accidents in 2,4,5-T-production in the U.S. and in Europe.〔(Table TCDD-UNFÄLLE - Eine Bilanz des Schreckens ) pp. 54-59 in ''Seveso ist überall - Die tödlichen Risiken der Chemie'' by Egmont R. Koch, Fritz Vahrenholt; 1978, ISBN 3 462 012908 (accessed: 2013-07-21)〕 The causes had been investigated, and results published〔(Berufliche Akne (sog. Chlorakne) durch chlorierte aromatische zyklische Äther ) Von J. Kimmig und K. H. Schulz in ''Dermatologica'' Vol. 115, 1957, p.540-6 (German; with English and French summaries; cited in CA 1958:22227) (accessed: 2013-07-21)〕 in 1957, specifically stating "tetrachlordibenzodioxine proved very active". Additionally "Boehringer, which used the relatively safer low-temperature-process since 1957, in the same year warned the other producers of 2,4,5-TCP, which were using the high-temperature-process, pointing out the risk and providing suggestions how to avoid them."〔p. 49 in ''Seveso ist überall - Die tödlichen Risiken der Chemie'' by Egmont R. Koch, Fritz Vahrenholt; 1978, ISBN 3 462 012908〕 Starting in 1991, Congress asked the Institute of Medicine to review the scientific literature on Agent Orange and the other herbicides used in Vietnam, including their active ingredients and the dioxin contaminant. The IOM found an association between dioxin exposure and diabetes.〔IOM, 2000〕〔("Data Suggest a Possible Association Between Agent Orange Exposure and Hypertension" ), ''(Office of News and Public Information )'', National Academy of Sciences. Quote: "the report also concluded that there is suggestive but limited evidence that AL amyloidosis is associated with herbicide exposure" (accessed:19 May 2008)〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Agent Orange」の詳細全文を読む スポンサード リンク
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