Agent Orange is a 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 . 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 or 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.New Scientist, 19 April 1985, p. 34, https://books.google.com/books?id=q7v_rDK0uOgC&pg=PA34
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 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 chemical tanks. Spray runs were also conducted from trucks, boats, and backpack sprayers. Altogether, over of Agent Orange were applied.Vietnam War: French court to hear landmark Agent Orange case , BBC News, January 25, 2021
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 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 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.