Agent Orange: herbicide, wartime use, and long-term impacts

Between 1962 and 1971, more than 6,000 sorties with various defoliants were conducted by the U.S. Air Force in the Vietnam War during Operation Ranch Hand, authorized by John F. Kennedy in 1961. Agent Orange was sprayed from planes and helicopters from January 1965 to April 1970. The
first area-wide deployment took place on 7 February 1967. The aim was to defoliate forests in order to uncover hiding places and supply routes of the enemy (Ho Chi Minh Trail) and, on the other hand, to expand own military bases and airfields in the dense jungle. In addition, arable land was sprayed to deprive the enemy of food.

Agent Orange was manufactured and supplied by, among others, the US companies Dow Chemical and Mobay, a joint venture between Monsanto and Bayer AG. Due to the enormous demand, there were supply difficulties. Intermediates were also supplied by the German company Boehringer Ingelheim and the Czechoslovakian company Spolana. According to a 1991 article in the news magazine Der Spiegel, Boehringer Ingelheim supplied 720 tons of trichlorophenolate lye to Dow Chemical in 1967. The use of Agent Orange reached its peak in 1967 and 1968.

The bulk of Agent Orange contained a mixture of the n-butyl esters of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4-dichlorophenoxyacetic acid (2,4-D) in equal proportions. The active ingredient content was 1033 grams per liter, expressed as ester-free 2,4,5-T and 2,4-D. Probably starting in 1968, "Agent Orange II" was also used, which consisted of a 50:50 mixture of the iso-octyl ester of 2,4,5-T and the n-butyl ester of 2,4-D. It had an active ingredient content of 910 grams per liter. 3,591,000 liters of "Agent Orange II" were delivered to Vietnam. US forces sprayed a total of 45,677,937 liters of Agent Orange. If the other herbicides are added, the number almost doubles to 80 million liters. By 1971, this had defoliated nearly a quarter of Vietnam.

A mixture called "Modified Orange", which also contained the active ingredient picloram, was only used on a trial basis.

The last spray plane carrying Agent Orange took off on January 7, 1971. In 1973, the U.S. Air Force still had stocks of 2,338,900 gallons (8,853,672 liters) with an acquisition value of $16,540,000. Since a restriction on the use of 2,4,5-T was issued in the U.S. in 1970 and upheld by the EPA in 1971, consideration was given to selling the excess Agent Orange as herbicide in South America. Stockpiles of Agent Orange were stored on Johnston Island and at the Naval Construction Battalion Center in Gulfport, Mississippi. Only now were dioxin levels beginning to be determined. Dioxin concentrations varied widely from drum to drum. In Gulfport, 28 samples were found to have TCDD concentrations ranging from 6.2 to 14.3 ppm, with a mean of 13.25 ppm. In another study, TCDD levels ranged from 0.05 to 13.3 ppm. From this, a mean value of 2.99 ppm (mgL-1) was derived. For 200 samples from the Johnston Island repository, the mean value for Agent Orange was 1.91 ppm ± 20% TCDD. This did not include four samples with the highest levels (17, 22, 33, and 47 ppm) because they may have been Agent Purple. The remaining stocks were incinerated on the high seas aboard the incinerator ship Vulcanus in 1977. Estimates of the amounts of dioxin released in Vietnam in association with the herbicides range from 106 to over 366 kg.

The main cause of the immense damage to humans and nature is the by-product TCDD, which is formed during the production of trichlorophenoxyacetic acid. The long-lived TCDD is formed during synthesis between 300 and 600 degrees Celsius. It is the most toxic of the 300 or so dioxins (known as the "Seveso toxin" since the 1976 Seveso disaster in Italy). Even the smallest amounts can cause severe organ damage and cancer. It disrupts hormonal signalling pathways and causes severe malformations in children.

According to the Vietnamese Association of Victims of Agent Orange, more than three million victims of Agent Orange suffer from late effects of Agent Orange, especially deformities such as cleft lip and palate and immune deficiencies. Many newborns are born with severe deformities even three generations after the use of Agent Orange. Cancer is also one of the late effects. So far, there is a lack of studies on the connection between exposure to Agent Orange and the development of tumours, but dioxin is known to be carcinogenic.

Agricultural scientists from Illinois and Iowa predicted in early 2019 in the scientific journal "Open Journal of Soil Science" that Vietnam would suffer from the late effects for decades to come. On the surface, TCDD decays in one to three years; in soil and in river and ocean sediments, it can persist for more than 100 years. TCDD spread via rivers, wind and soil erosion during the monsoon season and entered food chains.

Since the 'Pivot to Asia' announced by US President Obama, the US needs new allies against China. Therefore, since 2012, the US government has been involved in the soil decontamination around the former US base Da Nang, which was a main distribution point for Agent Orange. Forty-three million dollars have been made available for this purpose. In 2016, the US Agency for International Development (USAID) estimated that for contamination in the megacity of Bien Hoa alone, a comprehensive dioxin cleanup would cost 126 to 600 million US dollars.

Furthermore, severely malformed and sick children are born. Most of the victims cannot receive adequate medical care, if at all. Vietnam's government invests mainly in the economic development of the country. Individuals are building homes and health stations for victims of Agent Orange with donations they have collected themselves. In 1998, the Village of Friendship, built with the help of US war veterans, was opened as a treatment centre for victims of the defoliant.