Agent Orange is a chemical herbicide and defoliant. During the Vietnam War, the United States Armed Forces along with the South Vietnamese military used it in Operation Ranch Hand (1962–1971), part of a broader herbicidal warfare campaign intended to deprive the People's Army of Vietnam/Viet Cong of vegetation cover. It was one of a group of tactical-use herbicides, known as Rainbow Herbicides. Agent Orange was earlier used by the British during the Malayan Emergency which influenced its later use by the U.S. Primarily a mixture of equal parts of two herbicides, 2,4,5-T and 2,4-D, it contained trace amounts of 2,3,7,8-TCDD, a dioxin compound established as a carcinogen and persistent organic pollutant.
Agent Orange was produced in the United States beginning in the late 1940s and was used in industrial agriculture, and was also sprayed along railroads and power lines to control undergrowth in forests. During the Vietnam War, the U.S. military procured over 20,000,000 U.S. gal (76,000,000 L; 17,000,000 imp gal). Nine chemical companies produced it, including Dow Chemical Company and Monsanto Company.
Agent Orange exposure is linked to increased rates of birth defects, malignancies, cardiovascular diseases, and diabetes. The science on the causality between exposure and health problems remains incomplete. The U.S. government has documented cases of leukemia, Hodgkin's lymphoma, and various kinds of cancer in exposed U.S. veterans, but not concluded a causal relationship or a plausible biological carcinogenic mechanism. The U.S. Centers for Disease Control and Prevention identified an increase in the rate of birth defects of the children of exposed U.S. veterans.
The impact of Agent Orange in Vietnam includes health and ecological effects. The government of Vietnam says that up to four million people in Vietnam were exposed to the defoliant, and as many as three million people have suffered illness because of Agent Orange, while the Vietnamese Red Cross estimates that up to one million people were disabled or have health problems as a result of exposure to Agent Orange. The government of Vietnam defined victims of Agent Orange by looking at where they live, their family history, and if the health problems have been linked to Agent Orange. The U.S. government has described these figures as unreliable.
Agent Orange has also caused enormous environmental damage in Vietnam. This has been described by numerous lawyers, historians and other academics as ecocide. Over 7,700,000 acres (3,100,000 ha) or 12,000 sq mi (31,000 km2) of tropical forest were defoliated. Defoliants eroded tree cover and seedling forest stock, making reforestation difficult in numerous areas. Animal species diversity is sharply reduced in contrast with unsprayed areas.
The use of Agent Orange in Vietnam resulted in numerous legal actions. The United Nations ratified General Assembly Resolution 31/72 in 1976 and the Environmental Modification Convention in 1977. Under the Organisation for the Prohibition of Chemical Weapons (OPCW) definition, Agent Orange is not considered a chemical weapon as it was not used to cause intentional death or harm to humans through its toxic properties. Lawsuits have been filed on behalf of both U.S. and Vietnamese veterans and civilians seeking compensation for damages.
Chemical composition
The active ingredient of Agent Orange was an equal mixture of two phenoxy herbicides – 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) – in iso-octyl ester form, which contained traces of the dioxin 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD was a trace, but significant, contaminant of Agent Orange (typically 2–3 ppm, ranging from 50 ppb to 50 ppm).
Toxicology
TCDD is the most toxic of the dioxins and is classified as a human carcinogen by the U.S. Environmental Protection Agency (EPA). The fat-soluble nature of TCDD causes it to accumulate easily in the food chain, and can enter the body readily through physical contact or ingestion. When TCDD binds to cytoplasmic aryl hydrocarbon receptor (AhR), a transcription factor, the protein translocates to the cell nucleus, where it influences gene expression.
According to U.S. government reports, if not bound chemically to a biological surface such as soil, leaves or grass, Agent Orange dries quickly after spraying and breaks down within hours to days when exposed to sunlight and is no longer harmful.
Development
Several herbicides were developed as part of efforts by the United States and the United Kingdom to create herbicidal weapons for use during World War II. These included 2,4-D, 2,4,5-T, MCPA (2-methyl-4-chlorophenoxyacetic acid, 1414B and 1414A, recoded LN-8 and LN-32), and isopropyl phenylcarbamate (1313, recoded LN-33).
In 1943, the United States Department of the Army contracted botanist (and later bioethicist) Arthur Galston, who discovered the defoliants later used in Agent Orange, and his employer University of Illinois Urbana-Champaign to study the effects of 2,4-D and 2,4,5-T on cereal grains (including rice) and broadleaf crops. While a graduate and post-graduate student at the University of Illinois, Galston's research and dissertation focused on finding a chemical means to make soybeans flower and fruit earlier. He discovered both that 2,3,5-triiodobenzoic acid (TIBA) would speed up the flowering of soybeans and that in higher concentrations it would defoliate the soybeans. From these studies arose the concept of using aerial applications of herbicides to destroy enemy crops to disrupt their food supply. In early 1945, the U.S. Army ran tests of various 2,4-D and 2,4,5-T mixtures at the Bushnell Army Airfield in Florida. As a result, the U.S. began a full-scale production of 2,4-D and 2,4,5-T and would have used it against Japan in 1946 during Operation Downfall if the war had continued.
In the years after the war, the U.S. tested 1,100 compounds, and field trials of the more promising ones were done at British stations in India and Australia, in order to establish their effects in tropical conditions, as well as at the U.S. testing ground in Florida. Between 1950 and 1952, trials were conducted in Tanganyika, at Kikore and Stunyansa, to test arboricides and defoliants under tropical conditions. The chemicals involved were 2,4-D, 2,4,5-T, and endothall (3,6-endoxohexahydrophthalic acid). During 1952–53, the unit supervised the aerial spraying of 2,4,5-T in Kenya to assess the value of defoliants in the eradication of tsetse fly.
Early use
In Malaya, the local unit of Imperial Chemical Industries researched defoliants as weed killers for rubber plantations. Roadside ambushes by the Malayan National Liberation Army were a danger to the British Commonwealth forces during the Malayan Emergency, several trials were made to defoliate vegetation that might hide ambush sites, but hand removal was found cheaper. A detailed account of how the British experimented with the spraying of herbicides was written by two scientists, E. K. Woodford of Agricultural Research Council's Unit of Experimental Agronomy and H. G. H. Kearns of the University of Bristol.
After the Malayan Emergency ended in 1960, the U.S. considered the British precedent in deciding that the use of defoliants was a legal tactic of warfare. Secretary of State Dean Rusk advised President John F. Kennedy that the British had established a precedent for warfare with herbicides in Malaya.
Use in the Vietnam War
In mid-1961, President Ngo Dinh Diem of South Vietnam asked the United States to help defoliate the lush jungle that was providing cover to the North Vietnamese army and Viet Cong. In August of that year, the Republic of Vietnam Air Force conducted herbicide operations with American help. Diem's request launched a policy debate in the White House and the State and Defense Departments. Many U.S. officials supported herbicide operations, pointing out that the British had already used herbicides and defoliants in Malaya during the 1950s. In November 1961, Kennedy authorized the start of Operation Ranch Hand, the codename for the United States Air Force's herbicide program in Vietnam. The herbicide operations were formally directed by the government of South Vietnam.
During the Vietnam War, between 1962 and 1971, the United States military sprayed nearly 20,000,000 U.S. gal (76,000,000 L; 17,000,000 imp gal) of various chemicals – the "rainbow herbicides" and defoliants – in Vietnam, eastern Laos, and parts of Cambodia as part of Operation Ranch Hand, reaching its peak from 1967 to 1969, including around 43,300,000 L or rounded 11438600 U.S. gal. As the British did in Malaya, the goal of the U.S. was to defoliate rural/forested land, depriving guerrillas of food and concealment and clearing sensitive areas such as around base perimeters and possible ambush sites along roads and canals. Samuel P. Huntington argued that the program was also part of a policy of forced draft urbanization, which aimed to destroy the ability of peasants to support themselves in the countryside, forcing them to flee to the U.S.-dominated cities, depriving the guerrillas of their rural support base.
Agent Orange was usually sprayed from helicopters or from low-flying C-123 Provider aircraft planes, fitted with sprayers and "MC-1 Hourglass" pump systems and 1,000 U.S. gal (3,800 L; 830 imp gal) chemical tanks. Spray runs were also conducted from trucks, boats, and backpack sprayers. Altogether, over 21,000,000 U.S. gal (79,000,000 L; 17,000,000 imp gal) of Agent Orange were applied.
The first batch of herbicides was unloaded at Tan Son Nhut Air Base in South Vietnam on January 9, 1962. U.S. Air Force records show that at least 6,542 spraying missions took place throughout Operation Ranch Hand. By 1971, 12 percent of the total area of South Vietnam had been sprayed with defoliating chemicals, at an average concentration of 13 times the recommended U.S. Department of Agriculture application rate for domestic use. In South Vietnam alone, an estimated 39,000 sq mi (100,000 km2) of agricultural land was ultimately destroyed. In some areas, TCDD concentrations in soil and water were hundreds of times greater than the levels considered safe by the EPA.
The campaign destroyed 7,700 sq mi (20,000 km2) of upland and mangrove forests and thousands of square kilometres of crops. Overall, more than 20% of South Vietnam's forests were sprayed at least once over the nine years. 3.2% of South Vietnam's cultivated land was sprayed at least once between 1965 and 1971. 90% of herbicide use was directed at defoliation.
The U.S. military began targeting food crops in October 1962, primarily using Agent Blue; the American public was not made aware of the crop destruction programs until 1965 (and it was then believed that crop spraying had begun that spring). In 1965, 42% of all herbicide spraying was dedicated to food crops. In 1965, members of the U.S. Congress were told, "crop destruction is understood to be the more important purpose ... but the emphasis is usually given to the jungle defoliation in public mention of the program." The first official acknowledgment of the programs came from the State Department in March 1966.
When crops were destroyed, the National Liberation Front would compensate for the loss of food by confiscating more food from local villages. Some military personnel reported being told they were destroying crops used to feed guerrillas, only to later discover, most of the destroyed food was actually produced to support the local civilian population. Wil Verwey wrote in 1977 that ecologist Arthur H. Westing, during a 1969 visit to the Quang Ngai province, had been told that 15 crop destruction missions had been approved in the province for 1970. According to Verwey, these missions would have been enough to cover 85% of crop lands in the province and would have caused famine and left hundreds of thousands of people without food or malnourished although it was unclear if all the approved missions were actually carried out. According to a report by the American Association for the Advancement of Science, the herbicide campaign had disrupted the food supply of more than 600,000 people by 1970.
Many experts at the time, including plant physiologist and bioethicist Arthur Galston, opposed herbicidal warfare because of concerns about the side effects to humans and the environment from indiscriminately spraying the chemical over a wide area. As early as 1966, resolutions were introduced to the United Nations charging that the U.S. was violating the 1925 Geneva Protocol, which regulated the use of chemical and biological weapons in international conflicts. The U.S. defeated most of the resolutions, arguing that Agent Orange was not a chemical or a biological weapon as it was considered an herbicide and a defoliant and it was used in effort to destroy plant crops and to deprive the enemy of concealment and not meant to target human beings. The U.S. delegation argued that a weapon, by definition, is any device used to injure, defeat, or destroy living beings, structures, or systems, and Agent Orange did not qualify under that definition. It also argued that if the U.S. were to be charged for using Agent Orange, then the United Kingdom and its Commonwealth nations should be charged since they also used it widely during the Malayan Emergency in the 1950s. In 1969, the United Kingdom commented on the draft Resolution 2603 (XXIV):
The evidence seems to us to be notably inadequate for the assertion that the use in war of chemical substances specifically toxic to plants is prohibited by international law.
A study carried out by the Bionetic Research Laboratories between 1965 and 1968 found malformations in test animals caused by 2,4,5-T, a component of Agent Orange. The study was later brought to the attention of the White House in October 1969. Other studies reported similar results and the Department of Defense began to reduce the herbicide operation. On April 15, 1970, it was announced that the use of Agent Orange was suspended. Two brigades of the Americal Division in the summer of 1970 continued to use Agent Orange for crop destruction in violation of the suspension. An investigation led to disciplinary action against the brigade and division commanders because they had falsified reports to hide its use. Defoliation and crop destruction were completely stopped by June 30, 1971.
Health effects
There are various types of cancer associated with Agent Orange, including chronic B-cell leukemia, Hodgkin's lymphoma, multiple myeloma, non-Hodgkin lymphoma, prostate cancer, respiratory cancer, lung cancer, and soft tissue sarcomas. Some literature claims that neither Agent Orange nor its contaminants are carcinogenic in humans.
Vietnamese people
The government of Vietnam states that 4 million of its citizens were exposed to Agent Orange, and as many as 3 million have suffered illnesses because of it; these figures include their children who were exposed. The Red Cross of Vietnam estimates that up to 1 million people are disabled or have health problems due to Agent Orange contamination. The United States government has challenged these figures as being unreliable.
According to a study by Dr. Nguyen Viet Nhan, children in the areas where Agent Orange was used have been affected and have multiple health problems, including cleft palate, mental disabilities, hernias, and extra fingers and toes. In the 1970s, high levels of dioxin were found in the breast milk of South Vietnamese women, and in the blood of U.S. military personnel who had served in Vietnam. The most affected zones are the mountainous area along Truong Son (Long Mountains) and the border between Vietnam and Cambodia. The affected residents are living in substandard conditions with many genetic diseases.
In 2006, Anh Duc Ngo and colleagues of the University of Texas Health Science Center published a meta-analysis that exposed a large amount of heterogeneity (different findings) between studies, a finding consistent with a lack of consensus on the issue. Despite this, statistical analysis of the studies they examined resulted in data that the increase in birth defects/relative risk (RR) from exposure to agent orange/dioxin "appears" to be on the order of 3 in Vietnamese-funded studies, but 1.29 in the rest of the world. There is data near the threshold of statistical significance suggesting Agent Orange contributes to stillbirths, cleft palate, and neural tube defects, with spina bifida being the most statistically significant defect. The large discrepancy in RR between Vietnamese studies and those in the rest of the world has been ascribed to bias in the Vietnamese studies.
Twenty-eight of the former U.S. military bases in Vietnam, where the herbicides were stored and loaded onto airplanes, may still have high levels of dioxins in the soil, posing a health threat to the surrounding communities. Extensive testing for dioxin contamination has been conducted at the former U.S. airbases in Da Nang, Phù Cát District and Biên Hòa. Some of the soil and sediment on the bases have extremely high levels of dioxin, requiring remediation. The Da Nang Air Base has dioxin contamination up to 350 times higher than international recommendations for action. The contaminated soil and sediment continue to affect the citizens of Vietnam, poisoning their food chain and causing illnesses, serious skin diseases and a variety of cancers in the lungs, larynx, and prostate.
U.S. and allied veterans
While in Vietnam, U.S. and Free World Military Assistance Forces soldiers were told not to worry about Agent Orange and were persuaded that the chemical was harmless. After returning home, Vietnam veterans from all countries that served began to suspect their ill health or the instances of their wives having miscarriages or children born with birth defects might be related to Agent Orange and the other toxic herbicides to which they had been exposed in Vietnam.
U.S veterans
U.S. Veterans began to file claims in 1977 to the Department of Veterans Affairs for disability payments for health care for conditions they believed were associated with exposure to Agent Orange, or more specifically, dioxin, but their claims were denied unless they could prove the condition began when they were in the service or within one year of their discharge.
In order to qualify for compensation, U.S. veterans must have served on or near the perimeters of military bases in Thailand during the Vietnam Era, where herbicides were tested and stored outside of Vietnam, veterans who were crew members on C-123 planes flown after the Vietnam War, or were associated with Department of Defense (DoD) projects to test, dispose of, or store herbicides in the U.S.
By April 1993, the Department of Veterans Affairs had compensated only 486 victims, although it had received disability claims from 39,419 soldiers who had been exposed to Agent Orange while serving in Vietnam.
In a November 2004 Zogby International poll of 987 people, 79% of respondents thought the U.S. chemical companies that produced Agent Orange defoliant should compensate U.S. soldiers who were affected by the toxic chemical used during the war in Vietnam, and 51% said they supported compensation for Vietnamese Agent Orange victims.
Australian and New Zealand veterans
Several official investigations in Australia failed to prove otherwise even though extant American investigations had already established that defoliants were sprayed at U.S. airbases including Bien Hoa Air Base where Australian and New Zealand forces first served before being given their own Tactical area of responsibility (TAOR.) Even then, Australian and New Zealand non-military and military contributions saw personnel from both countries spread over Vietnam such as the hospitals at Bong Son and Qui Nhon, on secondments at various bases, and as flight crew and ground crew for flights into and out of Da Nang Air Base – all areas that were well-documented as having been sprayed.
It wasn't until a group of Australian veterans produced official military records, maps, and mission data as proof that the TAOR controlled by Australian and New Zealand forces in Vietnam had been sprayed with the chemicals in the presence of personnel that the Australian government was forced to change its stance. Only in 1994 did the Australian government finally admit that it was true that defoliants had been used in areas of Vietnam where Australian forces operated, and the effects of these may have been detrimental to some Vietnam veterans and their children.
It was only in 2015 that the official Australian War Memorial accepted rewriting the official history of Australia's involvement in the Vietnam War to acknowledge that Australian soldiers were exposed to defoliants used in Vietnam.
New Zealand was even slower to correct its error, with the government going as far as to deny the legitimacy of the Australian reports in a report called the "McLeod Report," published by Veterans Affairs NZ in 2001, thus infuriating New Zealand veterans and those associated with their cause.
In 2006 progress was made in the form of a Memorandum of Understanding signed between the New Zealand government, representatives of New Zealand Vietnam veterans, and the Royal New Zealand Returned and Services' Association (RSA) for monetary compensation for New Zealand Vietnam veterans who have conditions as evidence of association with exposure to Agent Orange, as determined by the United States National Academy of Sciences. In 2008, the New Zealand government finally admitted that New Zealanders had been exposed to Agent Orange while serving in Vietnam, and the experience was responsible for detrimental health conditions in veterans and their children. Amendments to the memorandum made in 2021 meant that more veterans were eligible for an ex gratia payment of NZ$40,000.
National Academy of Medicine (Institute of Medicine)
Starting in the early 1990s, the federal government directed the Institute of Medicine (IOM), renamed the National Academy of Medicine, to issue reports every 2 years on the health effects of Agent Orange and similar herbicides. First published in 1994 and titled Veterans and Agent Orange, the IOM reports assess the risk of both cancer and non-cancer health effects. Each health effect is categorized by evidence of association based on available research data. The last update was published in 2016, entitled Veterans and Agent Orange: Update 2014.
The report shows sufficient evidence of an association with soft tissue sarcoma; non-Hodgkin lymphoma (NHL); Hodgkin disease; Chronic lymphocytic leukemia (CLL); including hairy cell leukemia and other chronic B-cell leukemias. Limited or suggested evidence of an association was linked with respiratory cancers (lung, bronchus, trachea, larynx); prostate cancer; multiple myeloma; and bladder cancer. Numerous other cancers were determined to have inadequate or insufficient evidence of links to Agent Orange.
The National Academy of Medicine has repeatedly concluded that any evidence suggestive of an association between Agent Orange and prostate cancer is "limited because chance, bias, and confounding could not be ruled out with confidence."
At the request of the Veterans Administration, the Institute of Medicine evaluated whether service in these C-123 aircraft could have plausibly exposed soldiers and been detrimental to their health. Their report Post-Vietnam Dioxin Exposure in Agent Orange-Contaminated C-123 Aircraft confirmed it.
U.S. Public Health Service
Publications by the United States Public Health Service have shown that Vietnam veterans, overall, have increased rates of cancer, and nerve, digestive, skin, and respiratory disorders. The Centers for Disease Control and Prevention notes that in particular, there are higher rates of acute/chronic leukemia, Hodgkin's lymphoma and non-Hodgkin's lymphoma, throat cancer, prostate cancer, lung cancer, colon cancer, ischemic heart disease, soft tissue sarcoma, and liver cancer. Except liver cancer, these are the same conditions the U.S. Veterans Administration has determined may be associated with exposure to Agent Orange/dioxin and are on the list of conditions eligible for compensation and treatment.
Military personnel who were involved in storage, mixture and transportation (including aircraft mechanics), and actual use of the chemicals were probably among those who received the heaviest exposures. Military members who served on Okinawa also claim to have been exposed to the chemical, but there is no verifiable evidence to corroborate these claims.
Some studies have suggested that veterans exposed to Agent Orange may be more at risk of developing prostate cancer and potentially more than twice as likely to develop higher-grade, more lethal prostate cancers. However, a critical analysis of these studies and 35 others consistently found that there was no significant increase in prostate cancer incidence or mortality in those exposed to Agent Orange or 2,3,7,8-tetracholorodibenzo-p-dioxin.
U.S. Veterans of Laos and Cambodia
During the Vietnam War, the United States fought the North Vietnamese, and their allies, in Laos and Cambodia, including heavy bombing campaigns. They also sprayed large quantities of Agent Orange in each of those countries. According to one estimate, the U.S. dropped 475,500 U.S. gal (1,800,000 L; 395,900 imp gal) in Laos and 40,900 U.S. gal (155,000 L; 34,100 imp gal) in Cambodia. Because Laos and Cambodia were both officially neutral during the Vietnam War, the U.S. attempted to keep secret its military operations in those countries, from the American population and has largely avoided compensating American veterans and CIA personnel stationed in Cambodia and Laos who suffered permanent injuries as a result of exposure to Agent Orange there.