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Operation ''Ranch Hand'' was a U.S. military operation during the Vietnam War, lasting from 1962 until 1971. Largely inspired by the British use of 2,4,5-T and 2,4-D (Agent Orange) during the Malayan Emergency in the 1950s, it was part of the overall herbicidal warfare program during the war called "Operation Trail Dust". ''Ranch Hand'' involved spraying an estimated of defoliants and herbicides over rural areas of South Vietnam in an attempt to deprive the Viet Cong of food and vegetation cover. Areas of Laos and Cambodia were also sprayed to a lesser extent. Nearly 20,000 sorties were flown between 1961 and 1971. The Vietnamese government estimates that 400,000 people were killed or maimed and 500,000 children born with birth defects as a result of this spraying of what were called by the Americans 'rainbow herbicides'.〔()〕 The "Ranch Handers" motto was "Only you can prevent a forest"〔 – a take on the popular U.S. Forest Service poster slogan of Smokey Bear. During the ten years of spraying, over of forest and of crops were heavily damaged or destroyed. Around 20% of the forests of South Vietnam were sprayed at least once.〔Vo Quy, ("Statement to the House Subcommittee on Asia, the Pacific and Global Environment," ) 4 June 2009.〕 The herbicides were sprayed by the U.S. Air Force flying C-123s using the call sign "Hades". The planes were fitted with specially developed spray tanks with a capacity of of herbicides. A plane sprayed a swath of land that was 80 meters wide and 16 km (≈10 miles) long in about 4½ minutes, at a rate of about . Sorties usually consisted of three to five airplanes flying side by side. 95% of the herbicides and defoliants used in the war were sprayed by the U.S. Air Force as part of Operation ''Ranch Hand''. The remaining 5% were sprayed by the U.S. Chemical Corps, other military branches, and the Republic of Vietnam using hand sprayers, spray trucks, helicopters and boats, primarily around U.S. military installations.〔Stellman, Jeanne et al. "(The extent and patterns of usage of Agent Orange and other herbicides in Vietnam. )" ''Nature''. Vol 422. pg 681〕 == Defoliants == The herbicides used were sprayed at up to 50 times the concentration than for normal agricultural use. The most common herbicide used was Herbicide Orange, more commonly referred to as Agent Orange: a fifty-fifty mixture of two herbicides 2,4-D (2,4-dichlorophenoxyacetic acid) and 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) manufactured for the U.S. Department of Defense primarily by Monsanto Corporation and Dow Chemical. The other most common color-coded ''Ranch Hand'' herbicides were Agent Blue (cacodylic acid) that was primarily used against food crops, and Agent White (picloram) which was often used when Agent Orange was not available. The Agents used—known as the Rainbow Herbicides—their active ingredients, and years used were as follows:〔Stellman, Jeanne et al. Page 682〕 *Agent Green: 100% ''n''-butyl ester 2,4,5-T, used prior to 1966〔 *Agent Pink: 100% 2,4,5-T (60% ''n''-butyl ester 2,4,5-T, and 40% iso-butyl ester of 2,4,5-T) used prior to 1966〔 *Agent Purple: 50% 2,4,5-T (30% ''n''-butyl ester of 2,4,5-T, and 20% iso-butyl ester of 2,4,5-T) and 50% ''n''-butyl ester of 2,4-D used 1961–65 *Agent Blue (Phytar 560G): 65.6% organic Arsenicical (cacodylic acid (Ansar 138) and its sodium salt sodium cacodylate)〔 used from 1962–71 in powder and water solution〔 *Agent White (Tordon 101): 21.2% (acid weight basis) triisopropanolamine salts of 2,4-D and 5.7% picloram used 1966–71〔 *Agent Orange or Herbicide Orange, (HO): 50% ''n''-butyl ester 2,4-D and 50% ''n''-butyl ester 2,4,5-T used 1965–70 *Agent Orange II:50% n-butyl ester 2,4-D and 50% isooctyl ester 2,4,5-T used after 1968. *Agent Orange III: 66.6% n-butyl 2,4-D and 33.3% n-butyl ester 2,4,5-T. *Enhanced Agent Orange, Orange Plus, or Super Orange (SO), or DOW Herbicide M-3393: standardized Agent Orange mixture of 2,4-D and 2,4,5-T combined with an oil-based mixture of picloram, a proprietary DOW Chemical product called Tordon 101, an ingredient of Agent White. The herbicides were procured by the U.S. military from Dow Chemical Company (all but Blue), Monsanto (Orange, Purple and Pink), Hercules Inc. (Orange and Purple), Thompson-Hayward Chemical Company (Orange and Pink), Diamond Alkali/Shamrock Company (Orange, Blue, Purple and Pink), United States Rubber Company (Orange), Thompson Chemicals Corporation (Orange and Pink), Agrisect Company (Orange and Purple), Hoffman-Taft Inc. (Orange), and the Ansul Chemical Company (Blue).〔Young, Alvin L. ''The History, Use, Disposition and Environmental Fate of Agent Orange''. Springer, 2009. pg. 44.〕 In April 1967, the USA's entire production of 2,4,5-T was confiscated by the military; foreign sources were also tapped into, including the Imperial Chemical Industries (ICI).〔Der Spiegel, 32/1991: (Der Tod aus Ingelheim ) by Cordt Schnibben (accessed 2013-07-30)〕 65% of the herbicides used contained 2,4,5-trichlorophenoxyacetic acid that was contaminated with 2,3,7,8-tetrachlorodibenzodioxin,〔 a "''known human carcinogen''...by several different routes of exposure, including oral, dermal, and intraperitoneal".〔(Report on Carcinogens, Twelfth Edition (2011) ) (accessed 2013-07-30)〕 About of dioxin-contaminated herbicides were sprayed over Southeast Asia during American combat operations.〔Pellow, David N. ''Resisting Global Toxics: Transnational Movements for Environmental Justice'', ((Google Books )), MIT Press, 2007, p. 159, (ISBN 026216244X).〕 In 2005, a New Zealand government minister was quoted and widely reported as saying that Agent Orange chemicals had been supplied from New Zealand to the United States military during the conflict. Shortly after, the same minister claimed to have been mis-quoted, although this point was less widely reported. From 1962 to 1987, ''2,4,5T'' herbicide had been manufactured at an Ivon Watkins-Dow plant in New Plymouth.〔(【引用サイトリンク】title=NZ admits supplying Agent Orange during war )〕〔(【引用サイトリンク】title=THE POISONING OF NEW ZEALAND )〕 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「Operation Ranch Hand」の詳細全文を読む スポンサード リンク
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