Understanding Agent Orange: History, Impacts, and Environmental Justice

This herbicide from the Vietnam War continues to impact our environment today.

A U.S. Air Force plane spraying Agent Orange over Vietnam, May, 1970

Dick Swanson / Getty Images

Agent Orange is an herbicide primarily known for its use by the U.S. military in the war in Vietnam. Its main ingredient is dioxin, which the United Nations calls “one of the most toxic compounds known to humans.” It is a persistent organic pollutant (POP) that the U.S. Environmental Protection Agency has labeled as highly carcinogenic.

The creation and use of Agent Orange are part of the explosion of chemical fertilizers, insecticides, and herbicides after World War II—one of the main contributors to the alarming loss of biodiversity in the past half-century. Just as American veterans and people of Southeast Asia still struggle today with the long-term effects of exposure to Agent Orange, so too do the many species of the Southeast Asian forests stripped of their vegetation.

How Agent Orange Was Used

Agent Orange was developed by the U.S. Department of the Army Advanced Research Project Agency (ARPA) and used as a defoliant in Vietnam and parts of Laos and Cambodia from 1962 to 1971. It is considered the most well-known, most widely used toxic defoliants in Operation Ranch Hand, as the program was called.

The goal of the operation was to defoliate the countryside and, as a result, flush out members of the National Liberation Front of North Vietnam and deprive them of access to food supplies. Agent Orange was used by the United States for nine years until the program ceased in 1971.

For nearly a decade during the war in Vietnam, the air forces of the United States and the South Vietnamese government sprayed approximately 12 million gallons of Agent Orange over the country. The toxic defoliant was spread by C-123 Provider aircraft on some 6,000 missions. An estimated 2.6 to 4.3 million American servicemen and women were exposed to it by touching it, inhaling its dust, or by eating water or food contaminated by it.

Nearly 10% of Vietnam was sprayed with Agent Orange—many multiple times, directly exposing up to 4.8 million people. After the end of the use of Agent Orange in Vietnam, 34 dioxin-contaminated C-123 planes were reassigned to reserve units for missions in the United States until 1982, whose service members were also exposed.

Environmental Impacts

Agent Orange devastated the ecology of Vietnam, causing deforestation, soil erosion, flooding, widespread loss of mangrove forests, the emergence of invasive plants and animals, loss of the region's ability to store carbon, and even changes in the local climate.

Between 1965 and 1970, 30% of the mangrove forests of southern Vietnam were destroyed. The dense forests of southern Vietnam were replaced by grasslands and shrubby bamboo as a result of Agent Orange spraying, “with most or all large trees lost and with no recruitment [of new trees] occurring.” As late as 2002, a map of the most degraded forests in Vietnam overlapped with areas impacted by the war.

Deforestation in Lam Dong province in southern Vietnam
Some forests in Vietnam have yet to recover.

Khanh Bui / Getty Images

Unlike dense forests, grasslands and shrublands have lower rates of evapotranspiration. They take up less water from the soil and release less of it through their leaves. Less water uptake by plants increases runoff and erosion, sending more silt and pollution into waterways. Less evaporation means less cloud cover, less rain, and drier air, which increases ambient temperatures and warms the planet. And forests, including mangrove forests, are important carbon sinks—and among the world's most threatened ecosystems.

Agent Orange's environmental legacy is a long one. While the compound itself has a half-life of only a few weeks after application, the dioxin it contains persists in surface soils for one to 15 years and in subsurface soils for up to 100 years. Without adequate tree cover or deep root systems, erosion helps distribute dioxin in soils further than the initial source of contamination.

Fish from lakes and ponds near the former U.S. airbases of Bien Hoa and Da Nang, where Agent Orange was stored during the war, have been shown to carry unsafe levels of dioxin. Dioxin, like many persistent organic pollutants, is hydrophobic, meaning it repels water. It binds easily to sediment and gets deposited in riverbeds and lake bottoms, where it can remain for decades. Fishing is still banned in waters near Bien Hoa and Da Nang.

Long-Term Health Consequences

Exposure to Agent Orange has been linked to a host of diseases in humans and other vertebrates—health effects that continue to impact people today. Organizations such as the War Legacies Project and the Vietnamese Association for Victims of Agent Orange continue to raise awareness about and help the victims of Agent Orange.

Agent Orange and the Environmental Justice Movement

While the impact of Agent Orange on the environment has been enormous, it's also important to recognize the impact of environmentalists on ending the spraying of Agent Orange.

The defoliant was first used in the same year that Rachel Carson's Silent Spring raised alarm bells about the dangers of toxic chemicals, especially the pesticide DDT. Her book helped launch the awakening of the modern environmental movement.

After public outrage about Agent Orange, by April 1970—the month of the first Earth Day—the United States made the sale and transport of Agent Orange illegal in the United States. Within a year, the military discontinued its use in Vietnam, and DDT was banned a year later. Historians have noted the role that opposition to the Vietnam War and to Agent Orange, in particular, contributed to the growth of the environmental movement.

Environmental Racism

In the mid- to late- 1960s, tests of the effects of dioxin were conducted on inmates of the (now-closed) Holmesburg Prison in Pennsylvania, despite the already known risks of the toxin. Many of the prisoners upon whom dioxin was tested were African American.

The element of racial injustice was not lost on minority journalists, and the experiment is still being protested today. In 2021, amid the Black Lives Matter movement, calls were made to remove scholarships and professorships named in honor of the University of Pennsylvania dermatologist who conducted the Holmesburg experiments.

Moreover, in the late 1960s, the Chicano/a newspaper El Grito del Norte linked Agent Orange's environmental destruction to the health impacts it had on people of color in the developing world, and especially women. Already sensitized by the opposition to pesticides in the United Farm Workers' grape boycott, which began in 1965, the newspaper published images comparing women working in the fields of Vietnam with those working the fields of New Mexico.


A wooden boat in the Mekong River delta, Vietnam
Restoring mangroves and coastal ecosystems like the Mekong delta is central to Vietnam's recovery.

alxpin / Getty Images

Agent Orange's effects will be with us for a long time. Faced with public pressure, the U.S. Veterans Administration has expanded its medical aid to affected veterans. It offers no similar aid to Vietnamese victims, however.

Seeking to establish closer ties, in 2007, the United States appropriated money for the cleanup of dioxin at three former U.S. air bases in Vietnam, including Bien Hoa and Da Nang. Two of the three airbases have been remediated, while work on the third began in 2019.

Vietnam has engaged in programs to restore the mangrove swamps and “bare hills” of the country, often with financial support from the United States. Between the end of the war in 1975 and 1998, more than half of the acreage of mangroves lost during the war were restored, mostly with state funding. In the early 1990s, Vietnam went from net deforestation to net reforestation.

On Earth Day, 2021, the completion of the Vietnam Forests and Deltas project was announced. In addition, two other projects began to help restore Vietnam's forests and mangroves by creating carbon sinks, providing coastal protection, and increasing the country's climate resilience.

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