{{Short description|Herbicides used by the US in the Vietnam War}} {{Use American English|date=May 2026}} {{multiple image |direction = vertical |image1 = 'Ranch Hand' run.jpg |caption1 = Four USAF C-123s spraying Rainbow Herbicide over South Vietnam as part of Operation Ranch Hand |image2 = Agent Orange at Johnston Atoll 1976.jpg |caption2 = Agent Orange stored at Johnston Atoll in 1976, following the end of US involvement in Vietnam }}
The '''Rainbow Herbicides''' are a group of tactical-use herbicides used by the United States military in Southeast Asia during the Vietnam War. Success with Project AGILE field tests in 1961 with herbicides in South Vietnam was inspired by the British use of herbicides and defoliants during the Malayan Emergency in the 1950s, which led to the formal herbicidal program Trail Dust (see Operation Ranch Hand). Herbicidal warfare is the use of substances primarily designed to destroy the plant-based ecosystem of an agricultural food production area and/or to destroy dense foliage which provides the enemy with natural tactical cover. Under the Organisation for the Prohibition of Chemical Weapons (OPCW) definition, toxic agents such as rainbow herbicides are not considered chemical weapons as they are not used to cause intentional death or harm to humans through their toxic properties.<ref name="Young2009"/><ref>{{Cite web |title=What is a Chemical Weapon? |url=https://www.opcw.org/our-work/what-chemical-weapon |website=OPCW |language=en}}</ref>
== Background ==
The United States discovered 2,4-dichlorophenoxyacetic acid (2,4-D) during World War II. It was recognized as toxic and was combined with large amounts of water or oil to function as a weed-killer. Army experiments with the chemical eventually led to the discovery that 2,4-D combined with 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) yielded a more potent herbicide.<ref name=Ornitz>Ornitz, Sheri L. "[http://www.bgtha.org/files/Publication/BTHA%20%20Journal%20Volume%2010.pdf#page=3 Agent Orange and its Continuing Effects] {{Webarchive|url=https://web.archive.org/web/20150209122651/http://www.bgtha.org/files/Publication/BTHA%20%20Journal%20Volume%2010.pdf#page=3 |date=2015-02-09 }}". ''British Travel Health Association Journal'', vol. 10. Winter 2007.</ref> Some batches of 2,4,5-T manufactured for Rainbow Herbicide use were later found to have been contaminated with synthesis-byproduct dioxins including 2,3,7,8-tetrachlorodibenzodioxin (TCDD). Work by researcher Alvin Lee Young identifies examples of Agent Pink and Agent Green containing as much as double the TCDD concentrations observed in Agent Purple or Agent Orange.<ref name="Young2009">{{cite book|author=Alvin L. Young|title=The History, Use, Disposition and Environmental Fate of Agent Orange|url=https://books.google.com/books?id=1iCHpk2fZksC&pg=PA34YEAR|publisher=Springer|isbn=978-0-387-87486-9|page=34|date=2009-04-21}}</ref>
== Types ==
This is a list of the different types of agents used, their active ingredients, and the years they were being used during the Vietnam War as follows:<ref>{{cite journal |last1= Stellman |first1= Jeanne |last2= Stellman |first2= Steven D. |last3= Christian |first3= Richard |last4= Weber |first4= Tracy |last5= Tomasallo |first5= Carrie |date= 17 April 2003 |url= http://stellman.com/jms/Stellman1537.pdf |title= The extent and patterns of usage of Agent Orange and other herbicides in Vietnam |journal= Nature |volume= 422 |issue= 6933 |pages= 681–7 |issn= 0028-0836 |doi= 10.1038/nature01537 |pmid=12700752|bibcode= 2003Natur.422..681S |s2cid= 4419223 }}</ref> {| class="wikitable sortable" |- ! Name !! Content !! used |- |Agent Green || 100% ''n''-butyl ester 2,4,5-T || prior to 1963<ref name="Young2009" /> |- |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) || prior to 1964<ref name="Young2009" /> |- |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 || 1961–1965 |- |Agent Blue (Phytar 560G) || 65.6% organic arsenicical (cacodylic acid (Ansar 138) and its sodium salt sodium cacodylate)<ref name="Young2009" /> || 1962–1971<ref name="HerbicidesMedicine1994"/> |- |Agent White (Tordon 101) || 21.2% (acid weight basis) triisopropanolamine salts of 2,4-D and 5.7% picloram || 1966–1971<ref name="Young2009" /><ref name="HerbicidesMedicine1994">{{cite book|author1=Committee to Review the Health Effects in Vietnam Veterans of Exposure to Herbicides|author2=Institute of Medicine|title=Veterans and Agent Orange: Health Effects of Herbicides Used in Vietnam|url=https://books.google.com/books?id=RjCHcoUE3B8C&pg=PA89|year=1994|publisher=National Academies Press|isbn=978-0-309-55619-4|pages=89–90}}</ref> |- |Agent Orange Herbicide Orange (HO) || 50% ''n''-butyl ester 2,4-D and 50% ''n''-butyl ester 2,4,5-T || 1965–1970 |- |Agent Orange II || 50% n-butyl ester 2,4-D and 50% isooctyl ester 2,4,5-T || after 1968<ref name="Bull2004">{{cite book|author=Stephen Bull|title=Encyclopedia of Military Technology and Innovation|year=2004|publisher=Greenwood Publishing Group|isbn=978-1-57356-557-8|page=6}}</ref><ref name="Vallero2011">{{cite book|author=Daniel Vallero|title=Biomedical Ethics for Engineers: Ethics and Decision Making in Biomedical and Biosystem Engineering|year=2011|publisher=Academic Press|isbn=978-0-08-047610-0|page=73}}</ref> |- |Agent Orange III || 66.6% n-butyl 2,4-D and 33.3% n-butyl ester 2,4,5-T.<ref name="Detrick">{{Cite report |publisher=U.S. Army Corps of Engineers St. Louis District |date=4 April 2012 |title=Archives Search Report Findings for Field Testing of 2,4,5-T and Other Herbicides |url=http://www.detrick.army.mil/responsible/ArchivalReport2012.pdf |page=116 |access-date=8 August 2013 |archive-date=22 December 2016 |archive-url=https://web.archive.org/web/20161222092755/https://www.detrick.army.mil/responsible/ArchivalReport2012.pdf }}</ref> || |- |Enhanced Agent Orange, Orange Plus, 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 Company product called Tordon 101, an ingredient of Agent White.<ref name="SuperOrange" /><ref name="DOW">{{Cite report |date=September 9, 1966 |title=DGSC-PI Memorandum for the record: Herbicides reformulation thereof (Operation Guns and Butter meeting) |publisher=Dow Chemical Company }}</ref> || |}
== Use == In Vietnam, the early large-scale defoliation missions (1962–1964) used {{convert|8,208|U.S.gal|abbr=on}} of Agent Green, {{convert|122,792|U.S.gal|abbr=on}} of Agent Pink, and {{convert|14,500|U.S.gal|abbr=on}} of Agent Purple. These were dwarfed by the {{convert|11,712,860|U.S.gal|abbr=on}} of Agent Orange (both versions) used from 1965 to 1970. Agent White started to replace Orange in 1966; {{convert|145,239,853|U.S.gal|abbr=on}} of White were used. The only agent used on a large scale in an anti-crop role was Agent Blue, with {{convert|142,166,656|U.S.gal|abbr=on}} used.<ref>"Herbicides" entry in {{cite book|editor=Spencer C. Tucker|title=The Encyclopedia of the Vietnam War|year=2011|publisher=ABC-CLIO|isbn=978-1-85109-961-0|edition=2nd}}</ref> The bombardment occurred most heavily in the area of the Ho Chi Minh Trail.<ref name="Ornitz" />
The rainbow herbicides damaged the ecosystems and cultivated lands of Vietnam, and led to the buildup of dioxins in the regional food chain.<ref name="Ornitz" /> About 4.8 million people were affected.<ref name="Wright" /> The environmental destruction caused by this defoliation has been described by Swedish Prime Minister Olof Palme, lawyers, historians and other academics as an ecocide.<ref>{{Cite book |last=Zierler |first=David |title=The invention of ecocide: agent orange, Vietnam, and the scientists who changed the way we think about the environment |date=2011 |publisher=Univ. of Georgia Press |isbn=978-0-8203-3827-9 |location=Athens, Ga.}}</ref><ref>{{Cite web |date=2022-12-18 |title=How Imperative Is It To Consider Ecocide As An International Crime? |url=https://www.ijllr.com/post/how-imperative-is-it-to-consider-ecocide-as-an-international-crime |access-date=2023-06-21 |website=IJLLR |language=en}}</ref><ref>{{Cite journal |last=Falk |first=Richard A. |date=1973 |title=Environmental Warfare and Ecocide — Facts, Appraisal, and Proposals |journal=Bulletin of Peace Proposals |volume=4 |issue=1 |pages=80–96 |doi=10.1177/096701067300400105 |jstor=44480206 |s2cid=144885326 |issn=0007-5035}}</ref><ref>{{Cite web |date=2022-02-17 |title=Industrial disasters from Bhopal to present day: why the proposal to make 'ecocide' an international offence is persuasive – The Leaflet |url=https://theleaflet.in/industrial-disasters-from-bhopal-to-present-day-why-the-proposal-to-make-ecocide-an-international-offence-is-persuasive/ |access-date=2023-06-21 |website=theleaflet.in |language=en-US}}</ref><ref>{{Cite SSRN |last=Giovanni |first=Chiarini |date=2022-04-01 |title=Ecocide: From the Vietnam War to International Criminal Jurisdiction? Procedural Issues In-Between Environmental Science, Climate Change, and Law |ssrn=4072727 |language=en}}</ref>
In addition to testing and using the herbicides in Vietnam, Laos, and Cambodia, the US military also tested the "Rainbow Herbicides" and many other chemical defoliants and herbicides in the United States,<ref>{{cite web |url= http://www.publichealth.va.gov/exposures/agentorange/outside_vietnam_usa.asp |title= Herbicide Tests and Storage in the U.S. |publisher= Department of Veterans Affairs |access-date= 16 June 2010}}</ref> Canada, Puerto Rico, Korea, India, and Thailand<ref>{{cite web |url= http://www.publichealth.va.gov/exposures/agentorange/outside_vietnam.asp |title= Herbicide Tests and Storage Outside the U.S. |publisher= Department of Veterans Affairs |access-date= 16 June 2010}}</ref> from the mid-1940s to the late 1960s. Herbicide persistence studies of Agent Orange and Agent White were conducted in the Philippines.<ref>{{cite web |title=Preliminary Proposals for the Study of Persistence of Herbicides in Forest and Mangrove Soil |last1=Fryer |first1=J. D. |last2=Blackman |first2=G. E. |date=January 1972 |work= NAS Committee on the Effect of Herbicides in Vietnam |publisher=National Academy of Science, (NAS) }}</ref> The Philippine herbicide test program was conducted in cooperation with the University of the Philippines College of Forestry, and was also described in a 1969 issue of The Philippine Collegian, the college's newspaper. Super or enhanced Agent Orange was tested by representatives from Fort Detrick and Dow Chemical in Texas, Puerto Rico, Hawaii, and later in Malaysia, in a cooperative project with the International Rubber Research Institute.<ref name="SuperOrange">{{cite web |title= Operational Evaluation of Super-Orange (U)- unclassified|last1=Corcoran |first1=Charles A. |date=December 1968|work=Military Assistance Command Vietnam (MAC-V) to Joint Chief of Staff (JCS) message for CINCPAC, USARPAC Ofc Science Adviser |publisher=National Security Archives at George Washington University }}</ref> Picloram in Agent White and Super-Orange was contaminated by hexachlorobenzene (HCB).{{Citation needed|date=June 2013}} The Canadian government also tested these herbicides and used them to clear vegetation for artillery training.<ref>Pelletier, Richard. "[http://archive.bangordailynews.com/2005/07/01/agent-purple-deadlier-than-agent-orange/ Agent Purple Deadlier than Agent Orange]." ''Bangor Daily News'', 1 July 2005.</ref>
A 2003 study in ''Nature'' found that the military underreported its use of rainbow herbicides by {{convert|2,493,792|U.S.gal|abbr=on}}.<ref name="Wright">Wright, Laura. "[http://www.scientificamerican.com/article/new-study-finds-agent-ora/ New Study Finds Agent Orange Use Was Underestimated]". ''Scientific American'', April 17, 2003.</ref>
== Long-term effects == thumb|Professor Nguyen Thi Ngoc Phuong, at Từ Dũ Obstetrics and Gynecology Hospital is pictured with a group of disabled children in 2004.Vietnam remains heavily contaminated by dioxin-like compounds, which are classified as persistent organic pollutants. These compounds remain in the water table and have built up in the tissues of local fauna. However, the contamination has begun to deteriorate, and the forest canopy has regrown somewhat since the Vietnam War.<ref name="Ornitz" />
Dioxins are endocrine disruptors and may have effects on the children of people who were exposed.<ref name=Ornitz /> Rainbow herbicides and other dioxin-like compounds are endocrine disruptors, and evidence suggests that they continue to have long-term health consequences many years after exposure. Because they mimic, or interfere with, hormonal function, adverse effects can include problems with reproduction, growth and development, immune function, and metabolic function. As an example, dioxins and dioxin-like compounds influence the hormone dehydoepiandosterone (DHEA), which has a role in the determination of male or female sex characteristics. There have been thousands of documented instances of health problems and birth defects associated with rainbow herbicide exposure in Vietnam, where tested levels remain high in the soil, water, and atmosphere, decades after initial exposure.
Soldiers exposed to Rainbow Herbicides in Southeast Asia reported long-term health effects, which led to several lawsuits against the U.S. government and the manufacturers of the chemical.<ref name=Ornitz />
== See also == * U.S. Army Biological Warfare Laboratories
== References== {{Reflist}}
== Further reading == * {{cite book |first=Alvin L. |last=Young |title=The History of the US Department of Defense Programs for the Testing, Evaluation, and Storage of Tactical Herbicides |date=December 2006 |url=http://www.dod.mil/pubs/foi/operation_and_plans/NuclearChemicalBiologicalMatters/TacticalHerbicides.pdf |access-date=2016-09-02 |archive-date=2012-10-07 |archive-url=https://web.archive.org/web/20121007100012/http://www.dod.mil/pubs/foi/operation_and_plans/NuclearChemicalBiologicalMatters/TacticalHerbicides.pdf }}. A more abbreviated version: {{doi|10.1007/978-0-387-87486-9_2}} * [http://www.maine.gov/dvem/bvs/CFB%20Gagetown%20Agent%20Orange%20Information%20Paper%20Update%201.pdf "Update #1 to INFORMATION PAPER Agent Orange/Agent Purple and Canadian Forces Base Gagetown"]. Department of Defense, Veterans and Emergency Management; Maine Veterans' Services. February 9, 2006. * [http://www.oneofmanyfeathers.com/herbicidal_warfare_vietnam_1961-1971.html Herbicidal Warfare Vietnam 1961–1971]; {{Webarchive|url=https://web.archive.org/web/20140714160112/http://www.oneofmanyfeathers.com/herbicidal_warfare_vietnam_1961-1971.html |date=2014-07-14 }}. ''oneofmanyfeathers.com'', 2/1/2014.
==External links== * {{Commons category-inline|Herbicidal warfare}}
{{Rainbow Herbicides}}
Category:Defoliants Category:Military equipment of the Vietnam War Category:Environmental racism Category:Chemical warfare