Agent Orange and other chemicals in the Vietnam War


The United States (US) military used Agent Orange herbicide during the Vietnam War. Its defoliant action stripped the leaves from trees. The US used it to clear vegetation used as shelter by Viet Cong and North Vietnamese soldiers, destroy enemy food crops and clear vegetation around US army bases.

US forces sprayed almost 80 million litres of chemicals on Vietnam between 1962 and 1971. More than half of this was Agent Orange. Roughly 2.9 million hectares of Vietnamese farmland and forests were affected. Some 20,000 Vietnamese villages were sprayed, exposing up to 4 million Vietnamese people to toxins. Ecological impacts include long-lasting chemical residues in Vietnam's soil, water and food chain.

Australian, US and New Zealand soldiers were exposed to chemical agents during the war. Many veterans believed their exposure led to cancers and other serious illnesses. They also believed their exposure risked birth defects in their children. Intense debates have continued about the effects of Agent Orange on veterans' lives.

History of herbicidal warfare

The use of biological and chemical weapons goes back at least 2,500 years. One of the most notable examples of early chemical warfare was the Spartans' use of sulfur in 429 BCE at the Siege of Plataea.

The use of chemicals in war developed over many centuries. Forms of chemical warfare were used in the Middle Ages and the American Civil War. Around the turn of the 20th century, several international treaties banned the use of poisons and chemicals in war. But, this did not stop both sides from using poisonous gases in World War I.

During World War II, Britain and the US investigated using herbicides. Neither nation carried out plans to use the chemicals, but the US developed the defoliant herbicides 2,4,5-T and 2,4-D as part of its biological warfare program.

A rubberised fabric face mask connected by a fabric covered rubber hose to a chemical absorbent canister made of tin plate.

A British-made small box respirator (gas mask) issued in 1918 to Australian soldier Lieutenant George Leslie 'Les' Dolan DCM, serving with the 53rd Australian Infantry Battalion on the Western Front. AWM REL32946.001

Agent Orange herbicide

First made in the 1940s, Agent Orange was used in the US as an industrial farm herbicide and to control weeds along powerlines and railways in forests.

The British Army first used a herbicide very similar to Agent Orange between 1951 and 1953, during the Malayan Emergency. Details of the defoliant CMU 'trioxone' were not released to the public until the 1980s. At that time, New Scientist reported that it was used to thin out jungle vegetation and poison food crops and livestock.

Making and handling CMU 'trioxone' exposed workers and military personnel to dioxin, now known to cause cancers, birth defects and skin conditions. The International Agency for Research on Cancer (IARC) classified dioxin as a known human carcinogen in 1997.

6 men dressed in army uniforms and cloth caps carry rifles and walk along a dirt track in a forest clearing, watched by a man in a dark beret peering from the top of an armoured vehicle.

A Daimler Ferret armoured car which has just escorted these unidentified soldiers from 'stand by' platoon, B Company, 2nd Battalion, The Royal Australian Regiment, (2RAR), to a rubber plantation, Perak, Malaya, 1956. The vehicle keeps guard as the patrol heads off through a rubber plantation and into the jungle after a reported sighting of a gang of communist terrorists during the Malayan Emergency. AWM HOB/56/0751/MC

Testing an effective defoliant

In 1961, South Vietnam asked the US to spray an aerial herbicide against communist guerrilla forces in the country.

US President John F Kennedy did not approve the request straight away. A policy debate considered how the public might see the country's involvement in the military use of herbicides in South Vietnam. Some argued that aerial herbicide spraying was a cost-effective way of targeting Vietnamese communist fighters, by destroying their access to shelter and food. Others were concerned that the US would be criticised and accused of chemical warfare.

In late 1961, Kennedy approved the military use of herbicides in South Vietnam as a limited experiment.

A tactical aerial herbicide spraying program called Operation Ranch Hand began in January 1962. The first major operation was not until September 1962 when US pilots targeted mangrove forests in the Mekong Delta.

Hundreds of black chemical drums with a central orange stripe piled up on a depot tarmac.

Drums filled with Agent Orange (note the orange strip). No date. Image: VA020611, Admiral Elmo R. Zumwalt, Jr. Collection, The Vietnam Center and Sam Johnson Vietnam Archive, Texas Tech University

Spraying in South Vietnam

Agent Orange was the most used herbicide in the Vietnam War. Some 61% of herbicides used in the military defoliation program were Agent Orange.

Other herbicide and defoliants were used at different stages of the war, for different purposes. Like Agent Orange, each one had a colour name. The chemical storage drums had a colour strip to match. The so-called 'rainbow herbicides' included, according to a 1994 US report:

  • Agent Purple, one of the earliest defoliants used in the war
  • Agent Blue, used to kill enemy rice crops
  • Agent Pink
  • Agent Green
  • Agent White.

US planes and helicopters sprayed the chemicals onto the land. Sometimes wind and helicopter blades swept flurries of herbicide back into the planes and onto the crew.

Australian troops were involved in the use of herbicides and insecticides. They sprayed chemicals from trucks and on foot. Insecticides were widely sprayed in Phuoc Tuy province, particularly at Nui Dat, the 1st Australian Task Force (1 ATF) base.

Veterans' advocates, like Graham Walker, said 'significant' amounts of Agent Orange and other chemicals were used in areas where Australian soldiers were based.

Most spraying took place between 1966 and 1969. By late 1969, there was growing public unease about the herbicidal program. Research linked 2,4-D and 2,4,5-T with deformities in animals. By February 1971, the program had ended.

Environmental effects

3 men in army uniforms, one is shirtless, in an open-top military vehicle spraying liquid onto tall vegetation, with a military helicopter spraying from above and another military vehicle with 4 people watching from the other side.

A United States Army helicopter and soldiers in a jeep carry out a river bank defoliation mission in South Vietnam. No date. Image: VA042083. Vietnam Center and Archive. No Date, Admiral Elmo R. Zumwalt, Jr. Collection: Agent Orange Subject Files, Vietnam Center and Sam Johnson Vietnam Archive, Texas Tech University.

Dioxin is a long-lasting toxic chemical found in Agent Orange. It is a known carcinogen, linked with causing cancer in humans.

Some 170 kg of dioxin is believed to have been dumped on land during the Vietnam War, affecting:

  • almost 3 million hectares of land
  • 18% of Vietnamese forests
  • some 20,000 Vietnamese villages.

The wartime herbicidal program had a devastating effect on the Vietnamese environment. Evidence of dioxin is still found in Vietnam's soil, water and food chain.

Pathology samples show dioxin is also found in the Vietnamese population because it is:

  • absorbed through the skin
  • breathed in via contaminated dust
  • consumed via contaminated crops and livestock.

Other environmental impacts include the destruction of forests during the war, leading to a loss of habitat for many animals. Some habitats never recovered.

Dioxin levels in the soil continue to affect regrowth and cause soil erosion, leading to increased flooding incidents.

Impact on Vietnamese people

It's been estimated that 3 million Vietnamese have had health conditions related to herbicide exposure, including:

  • cancers
  • heart conditions
  • infertility and miscarriages
  • liver diseases
  • neurological conditions.

Media reports have highlighted Vietnamese families' suffering, for example:

Vietnamese Red Cross Society said many children had been born with deformities and health problems due to wartime chemical exposure. But, research into links between parental exposure to Agent Orange and birth defects in children has been less clear.

A 2006 meta-study, published in the International Journal of Epidemiology, said Vietnamese parents were at greater risk of having children born with abnormalities. But it also highlighted the '... inconsistent findings in the literature'.

The Vietnamese believe Agent Orange is responsible for damaging the health of people who were exposed to it. US veterans can claim compensation for many medical conditions associated with dioxin in Vietnam. But, the US maintains no proof of the link between Agent Orange exposure and health problems. The issue is still debated in courtrooms around the world.

A man dressed in an army uniform with a cloth cap sits on the grass talking to a group of 7 children, some of who are laughing.

1411070 Private David George Johnson of 5th Battalion, The Royal Australian Regiment (5RAR) makes friends with some Vietnamese children, October 1966. AWM CUN/66/0910/VN

Impact on veterans

Australians returned from South Vietnam between 1970 and 1973. During the 1970s, veterans' stories were no longer popular with a public that wanted to forget the war.

US veterans faced a similar experience on their return, but the situation began to change towards the end of the 1970s. Articles like one published in 1978 by Rolling Stone magazine highlighted the worrying effects of the herbicide program on veterans' health.

Around the same time, Australian veterans started speaking out about their own health issues and those of their families. There were reports of birth defects in veterans' children, cancer and other health issues. Veterans blamed their exposure to Agent Orange and other chemicals used in South Vietnam.

The Whitlam and Fraser governments denied Australian troops had been exposed to chemical defoliants. Subsequent governments later retracted that position in the face of contrary evidence.

In 1998, an Australian Government study found Vietnam War veterans were more likely to suffer some cancers. The study also found veterans' children had higher rates of birth defects.

Silouettes of 4 military planes spraying yellow chemicals, with the phrases 'Yesterday crimes', 'Monsanto', 'GMO' and 'Today outcome?

A poster produced for the Vietnam Association for Victims of Agent Orange (VAVA) in Australia 2012. Monsanto was one of the biggest producers of Agent Orange for the United States Army. It has been the subject of legal battles by veterans seeking recognition of the harmful effects of the chemical. AWM ARTV10317

Vietnam Veterans Association of Australia

By the late 1970s, Australian veterans were seeking help for themselves and their families. The repatriation rules administered by the Department of Veterans' Affairs (DVA) would need to change to access government health services and pensions.

There was some resistance to change in both the RSL and DVA. In 1979, the Vietnam Veterans Action Association was formed in response to the resistance. The next year, it became the Vietnam Veterans Association of Australia (VVAA).

The VVAA lobbied hard on behalf of its members. It believed it had a strong case, particularly as more veterans came forward with similar stories. But the VVAA used a lot of anecdotal material rather than clear evidence, and it faced opposition from many politicians and scientists.

In 1982, the VVAA published a list of symptoms associated with exposure to Agent Orange. More veterans came forward to repatriation clinics, recognising at least one or more signs of illness.

Royal Commission

A royal commission was set up in 1983 to examine the evidence linking herbicide exposure to veterans' health problems.

The Australian Government and Monsanto helped fund a legal defence against the VVAA's case. By 1985, the VVAA had run out of money for legal advice. Veteran Phill Thompson spoke on the association's behalf. Phil told the Royal Commission of the 'great imbalance' of resources available to the Vietnam veterans.

Phil claimed 'virtually all' Australian servicemen were exposed to chemicals during their Vietnam service. He also said Vietnam veterans suffered a variety of health issues, including:

  • cancers
  • heart problems
  • immune system ailments
  • kidney problems
  • liver issues
  • loss of libido
  • mental health issues.

Phill Thompson was later awarded an Order of Australia medal for his advocacy for Vietnam veterans. He died in 1986. John Schumann, of the Australian band Redgum, wrote a song in Phil's honour, Safe behind the wire.

Commission's findings

On 22 August 1985, the Commission published its final report. The Sydney Morning Herald reported Royal Commissioner Justice Phillip Evatt's findings.

CANBERRA: The Agent Orange Royal Commission has made a clear finding there is no link between chemical defoliants sprayed over Vietnam and the health problems suffered by veterans of the war.
[Sydney Morning Herald, 23 August 1985]

Evatt admitted the existence of health problems but found no link to the use of defoliants in Vietnam. Instead, the Commission blamed 'acute stress'. The report did acknowledge certain chemicals could cause some cancers. It also said a connection to illness in Vietnam veterans was unlikely but 'not fanciful'.

Read Evatt's final report to Cabinet dated July 1985.

Continued efforts for recognition

Controversy surrounded the findings of the Royal Commission. In 1988, the Canberra Times reported claims of false evidence. There were also claims in the final report that chemical company information had been quoted without acknowledgement.

The Royal Commission's findings were disappointing for Vietnam veterans. The VVAA needed a different approach to continue the fight for recognition. The Royal Commission conceded a link between certain cancers, dioxins and insecticides. Using this information, the VVAA appealed individual cases in the courts.

In 1992, US research linked chemical use in Vietnam with cancers and neurological damage. The American National Academies of Sciences examined evidence about the effects of veterans' exposure to chemicals. In 1994, it published its report, Veterans and Agent Orange. This report found 'sufficient' and 'limited evidence' linking herbicide exposure to various cancers and other conditions.

The Keating government acknowledged a link between Agent Orange and cancer in October 1994.

The Australian War Memorial commissioned an independent history of veterans' experiences in 2015. Dr Peter Yule's book, The Long Shadow, was published 5 years later. It describes the post-war health experiences of Vietnam veterans from their own perspectives.


  • 1985 'Agent Orange commission nears end', The Canberra Times (ACT : 1926 - 1995), 15 June, p 7, accessed 23 Oct 2023,
  • 1985, 'Royal Commission findings clear Agent Orange', Sydney Morning Herald, 22 August 1985, accessed 21 Jan 2021,
  • 1985 'Agent Orange commission nears end', The Canberra Times (ACT : 1926 - 1995), 15 June, p 7,accessed 23 Oct 2023,
  • 1992, 'Agent Orange, cancer linked', The Canberra Times (ACT : 1926 - 1995), 20 April, p 5
  • 1988 'Swedish scientists accuse Agent Orange commission', The Canberra Times (ACT : 1926 - 1995), 19 February, p 3, accessed 23 Oct 2023,
  • Australian Institute of Health and Welfare (1999), Morbidity of Vietnam veterans: a study of the health of Australia's Vietnam veteran community, AIHW cat. no. PHE 20,
  • Australian War Memorial (undated), 'Vietnam, 1962-1975', Conflict,, accessed 8 Apr 2021.
  • Arnold R Isaacs, Vietnam shadows: the war, its ghosts and its legacy, John Hopkins University Press, 2000.
  • Aschwanden, Christie and Lerner, George (2007), 'Vietnam: war's lasting legacy', Pulitzer Centre, 27 April,, accessed 18 Oct 2022.
  • Banout, Jan et al. (2014), 'Agent Orange Footprint Still Visible in Rural Areas of Central Vietnam', Journal of Environmental and Public Health,
  • Britannica, T. Editors of Encyclopaedia (2021), 'Agent Orange', Encyclopedia Britannica,, accessed 8 Apr 2021.
  • Britannica, T. Editors of Encyclopaedia (2020) 'Indochina wars', Encyclopedia Britannica,, accessed 9 Apr 2021.
  • Britannica, T. Editors of Encyclopaedia (2020), 'Viet Minh', Encyclopedia Britannica,, accessed 9 Apr 2021.
  • Buckingham, William A, Jnr (1982), Operation Ranch Hand, The Air Force and Herbicides in Southeast Asia 1961–1971, Office of Air Force History, United States Air Force,, accessed 8 Apr 2021.
  • Casten, Liane Clorfene and Ford-Martin, Paula Anne (2018, 18 May), 'Agent Orange', Environmental Encyclopedia,, accessed 8 Apr 2021.
  • Connor, S and Thomas, A (1984), 'How Britain Sprayed Malaya With Dioxin', Special Collections, USDA National Agricultural Library,, accessed 8 Apr 2021.
  • Dainton, Deborah (2015), 'The Vietnamese Association for Victims of Agent Orange', Medical and Scientific Aid for Vietnam, Laos and Cambodia,
  • DVA (Department of Veterans' Affairs) (2018), 'Graham Walker (Australian Army), Agent Orange', Veterans' Stories oral history interview,
  • DVA (Department of Veterans' Affairs) (2021), The Malayan Emergency 1948 to 1960, DVA Anzac Portal,, accessed 21 August 2021.
  • DVA (Department of Veterans' Affairs) (2019), Vietnamese victims, DVA Anzac Portal,, accessed 8 Apr 2021.
  • DVA (Department of Veterans' Affairs) (2021), Tactics in warfare during World War I, DVA Anzac Portal,, accessed 23 Aug 2021.
  • Everts, Sarah (2015), 'A brief history of chemical war', Distillations magazine, 11 May,
  • Garton, Stephen (2012), 'Thompson, Phillip Cecil (1944–1986)', Australian Dictionary of Biography, National Centre of Biography, Australian National University,, published first in hardcopy 2012, accessed 21 Aug 2021.
  • History, 'Vietnam War', 29 October 2009 (last updated 19 August 2020),, accessed 8 Apr 2021.
  • History, 'Vietnam War Timeline', last updated 29 April 2020,, accessed 8 Apr 2021.
  • Institute of Medicine; Committee to Review the Health Effects in Vietnam Veterans of Exposure to Herbicides (1994), Veterans and Agent Orange: Health Effects of Herbicides Used in Vietnam, National Academies Press, Washington DC,
  • Irvine, Lachlan (1998), 'The decade of silence: Vietnam veterans in the 1970s', original thesis,, accessed 8 Apr 2021.
  • Kohn, Howard (1978), 'The poison harvest: Agent Orange and the legacy of Vietnam', Rolling Stone, 24 August,
  • Kohn, Richard H (1982), 'Foreword', in William A Buckingham Jr, Operation Ranch Hand: The air force and herbicides in South-East Asia 1961-1971, Office of Air Force History, United States Air Force, Washington DC,
  • Livius (2005), Thucydides on the Siege of Plataea, last modified on 16 July 2020,, accessed 8 Apr 2021.
  • Lawrence, Mark Atwood (2010), The Vietnam War: a concise international history, Oxford University Press, Oxford,
  • Mayor, Adrienne (2009), Greek fire, poison arrows & scorpion bombs: biological and chemical warfare in the ancient world, Duckworth, London, 2009,
  • National Archives of Australia: TITLE: Vietnam war - Australian troops returned from Vietnam march through Brisbane, Queensland, 12 November 1970 CATEGORY: Photograph FORMAT: Colour Transparencies STATUS: Preservation material; A1500, K26968; 1970 - 1970,
  • Ngo, Anh D et al. (2006), 'Association between Agent Orange and birth defects: systematic review and meta-analysis', International Journal of Epidemiology 35(5), pp 1220–1230,
  • Olsen, Kenneth Ray and Morton, Lois Wright (2019), 'Long-Term Fate of Agent Orange and Dioxin TCDD Contaminated Soils and Sediments in Vietnam Hotspots', Open Journal of Soil Science 9 (1),
  • Payton, Philip (2018), Repat: a concise history of repatriation in Australia, Department of Veterans' Affairs,
  • SBS Dateline (2018), 'The Children of Agent Orange', series 2, episode 8,
  • Schuler, Karl (2004), 'Disabled and destitute', Red Cross International Magazine,
  • The American Cancer Society medical and editorial content team (2021), 'Agent Orange and cancer risk',, accessed 8 Apr 2021.
  • Turkish Radio and Television Corporation (2020), 'French court hears landmark case against manufacturers of Agent Orange', TRTC Magazine,, accessed 9 Apr 2021.
  • von Meding, Jason (2017), 'Agent Orange exposed: how US chemical warfare in Vietnam unleashed a slow-moving disaster', The Conversation, 4 October,
  • World Health Organization (2016), 'Dioxins and their effects on human health', Newsroom Fact Sheets,, accessed 8 Apr 2021.
  • Wikipedia contributors. (2021), 'Agent Orange', Wikipedia, The Free Encyclopedia,, accessed 11 Feb 2021.
  • Wikipedia contributors. (2021), 'Herbicidal warfare', Wikipedia, The Free Encyclopedia,, accessed 8 Apr 2021.
  • Wikipedia contributors. (2021), 'Viet Minh', Wikipedia, The Free Encyclopedia,, accessed 9 Apr 2021.
  • Xu, J. et al. (2016). Association between dioxin and cancer incidence and mortality: a meta-analysis. Scientific reports, 6, 38012,
  • Yule, Peter (2020), The Long Shadow: Australia's Vietnam veterans since the war, NewSouth Publishing, Sydney,

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DVA (Department of Veterans' Affairs) ( ), Agent Orange and other chemicals in the Vietnam War, DVA Anzac Portal, accessed 23 July 2024,
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