How Agent Orange Worked

A U.S. Department of Veteran Affairs poster created to raise awareness about VA programs for vets exposed to Agent Orange. See more bioweapon pictures.
Image courtesy U.S. Department of Veteran Affairs

­In war, sometimes the greatest tragedies come long after hostilities cease. So it goes with Agent Orange, a potent herbicide used as a defoliant during the Vietnam War. The U.S. military deployed almost 20 million gallons (76 millions liters) of herbicides from 1962 to 1971 [source: Veterans Administration]. Among these substances, Agent Orange was the most used herbicide, around 11 million gallons (42 million liters) deployed from January 1965 through April 1970 [sources: Veterans Administration and Buckingham].

Agent Orange has been linked to many health problems in Vietnam veterans and Vietnamese civilians. Thousands have died from conditions likely brought on by exposure to Agent Orange. The herbicide, and its component dioxin, is considered to be one of the most dangerous substances in the world [source: Glaberson]. Overall, the mass spraying of Agent Orange has been called an "ecocide" because of the devastation that it wrought on the Vietnamese environment and on the health of many residents of that country [source: Hitchens].


The name Agent Orange comes from the containers that it was stored in, which had an orange stripe. In all, the United States used 15 herbicides in Southeast Asia, including Agents Orange, Blue, White, Pink, Purple and Green, all of which were mixtures of various herbicides and defoliants [source: Veterans Administration]. Agent Orange was a mix of two herbicides called 2,4,-D and 2,4,5-T.

­Agent Orange's development came about in part due to work by Dr. Arthur W. Galston, a botanist who researched compounds that boost plant growt­h, known as growth regulators. But after the U.S. military began using Agent Orange in Vietnam, Galston observed its effects and worked to publicize the damage that the defoliant caused to plants, animals, ecosystems and human health. He became one o­f the foremost campaigners against the use of Agent Orange.

Gradually, public protest against the use of Agent Orange grew. Newspaper articles about the ill effects of Agent Orange, particularly against the U.S.-allied South Vietnamese, attracted government attention. Prominent scientists argued that the deployment of herbicides was an immoral use of chemical weapons [source: Buckingham]. When, in 1970, scientific testing showed that Agent Orange produced adverse health effects in rats, President Nixon ordered ­the military to cease spraying.


So why did the U.S. military employ such a toxic compound in waging war? In this article, we'll look at why Agent Orange was used, its effects on the environment and human health, and its complicated legacy. We'll also examine dioxin, the deadly compound that continues to pollute the Vietnamese countryside.


Uses of Agent Orange and Effects on Foliage

A U.S. Air Force plane spraying a delta area 20 miles from Saigon with Agent Orange during the Vietnam War
Time & Life Pictures/Getty Images

The U.S. military used aircraft to spray Agent Orange in order to deprive enemy Viet Cong soldiers of thick jungle that they used for cover, whether for snipers along riverbanks or for supply roads secretly carved through the undergrowth. Other uses of Agent Orange included destroying crops that the Viet Cong relied on for food.

The Vietnam War wasn't the first use of herbicides in war -- for example, the British deployed herbicides against Malaysian rebels in the 1950s -- but it was by far the most ambitious. Over the course of more than 6,000 missions, 10 percent of Vietnam was sprayed with Agent Orange [source: BBC News]. Agent Orange was sprayed secretly in Cambodia and in Laos to undermine the Ho Chi Minh Trail, a key supply route for the Viet Cong.


When deployed, Agent Orange kills vegetation of all types, destroying roots as well. Leaves die and fall off, transforming a thick forest into a mass of barren trees. Once green areas turn black. A sharp, unpleasant odor fills the air [source: Glaberson].

­I­n ­hi­s pion­eering research,­ Galston worked with the growth regulator triiodobenzoic acid, which in smaller doses spurs plants to flower more quickly but in larger doses causes leaves to fall off. The same principle is applied to Agent Orange. Plants subjected to Agent Orange die because the substance contains an excess of growth regulators that cause plant tissue to grow too rapidly and for plants to dry out [source: Buckingham].

­Besides the effects previously described, Agent Orange had some other consequences for Vietnam's ecology. The topsoil, so vital to supporting thick jungle growth, disappeared after the monsoon rains without plant life to anchor it [source: Aschwanden]. Invasive species of grasses appeared, hindering the regrowth of the environment's native plant life. The agricultural industry, a major part of Vietnam's economy and its people's livelihood, was ravaged. And into the soil seeped large quantities of dioxin, a deadly substance that we'll look at on the next page.


Dioxin and Agent Orange

Ex-Mayor Marilyn Leistner of Times Beach, Mo., which became a ghost town after dioxin contamination in 1983
Time & Life Pictures/Getty Images

Dio­xin is the name given to a class of highly toxic substances found in Agent Orange and some of the other Agent herbicides. The U.S. Department of Veterans Affairs claimed that Agent Orange had only "mi­nute traces" of dioxin (in this case, the potent dioxin known as TCDD), but areas where Agent Orange was sprayed or stored show high concentrations of the compound. In some areas of Vietnam, people have bl­ood levels of dioxin tens of times above normal [source: BBC News]. Small doses of dioxin may actually decrease the incidence of certain cancers, but in anything above small doses, dioxin has been linked to numerous, potentially deadly health problems.

The World Health Organization has classified dioxin as a "known human carcinogen" that can damage essential bodily systems, such as the endocrine, immune and nervous systems [source: WHO]. It also has been linked with miscarriages in women [source: Bertazzi et al]. Studies of people exposed to dioxins through workplace accidents have been found to have an increased risk of cancer (about 40 percent) [source: GreenFacts]. Studies of dioxin on animals have yielded similar adverse health effects.


­There are different types of dioxins, some of which appear naturally in the environment, though in small quantities. Dioxin develops as a byproduct of some industrial processes, usually those that involve something being burned, like copper smelting or incinerating waste. It can also be manufactured synthetically, as it was during the Vietnam War [source: Schechner].

When dioxin isn't contained, it seeps into the ground and the groundwater sources, polluting the local ecology and becoming part of the food chain. Dioxin pollution has, in general, decreased in recent years as government regulations have caused companies to make various industrial processes cleaner, but it remains a pressing issue in Vietnam [source: Dioxin Facts].

When people eat animals and plants contaminated with dioxin, it begins accumulating in their fat tissue, since the poison is fat-soluble. Everyone has at least a small amount of dioxin in his or her ­body. It's unknown how long it takes dioxin to dissipate. Some forms of dioxin have half-lives lasting seven years or more, but more recent research shows that when found in large concentrations, dioxin takes far longer to decay [source: Dioxin Facts]. And when dioxin seeps into soil, its half-life increases significantly [source: Dioxin Facts].

­The effects of dioxin can be clearly seen in the case of Ukrainian politician Viktor Yushchenko, who was poisoned with dioxin but survived. After being poisoned, Yushchenko's appearance changed dramatically. His once youthful face became pockmarked, scarred and shaded an eerie green-grey. He had terrible pain in his torso, in part because of lesions that contributed to his facial scarring. It's amazing that he even survived. His blood-dioxin levels were 6,000 times above normal, the second highest number recorded in a human being [source: CBC News]. He has recovered, and some of the scarring on his face has receded, but some dioxin will likely continue to be in his body for several years.


Agent Orange and Health Problems

These children from Ho Chi Minh City, Vietnam, were born without arms, birth defects likely caused by Agent Orange.
AFP/Getty Images

There is a lot of controversy and debate about the actual health effects of Agent Orange. The Institute of Medicine of the National Academy of Sciences claimed that an "association" exists between Agent Orange and some types of cancer. Some, such as the chemical companies facing lawsuits, argue that there's no way to judge definitively whether a health problem has been caused by Agent Orange or the dioxins it contains [source: Glaberson]. But areas in Vietnam where Agent Orange was used showed and continue to show a high rate of certain diseases, birth defects and cancers.

Some Vietnamese who came into direct contact with Agent Orange quickly developed skin irritations that turned into lesions and tumors. Others attribute their cancers and multiple miscarriages to living in areas sprayed with the herbicide [source: Glaberson].The massive number of sick Vietnam veterans, especially those who handled Agent Orange, and Vietnamese civilians has all but eliminated any other possible cause. In addition, many Vietnamese have very high quantities of dioxin in their blood, up to 200 times above normal levels [source: Hitchens]. That substance's toxicity is not disputed.


Among the many complications associated with Agent Orange and dioxin are:

  • Skin irritation and skin diseases, such as chloracne
  • Neurological disorders
  • Nerve disorders, including peripheral neuropathy
  • Miscarriages in women
  • Type 2 diabetes
  • Birth defects, physical deformities, spina bifida
  • Cancers: multiple myeloma, respiratory system cancers, Hodgkin's disease, prostate cancer, leukemia

In 1978, the Veterans Administration set up a program to deal with veterans exposed to Agent Orange. The VA claims to have conducted health exams on 315,000 veterans [source: Veterans Administration]. Because of the difficulties involved in testing for Agent Orange-caused illnesses, the "VA makes a presumption of Agent Orange exposure for Vietnam veterans" [source: Veterans Administration]. Some veterans who served in Korea in 1968 and 1969 also were exposed to Agent Orange, though reportedly Korean soldiers did the spraying [source: Veterans Administration]. These and other veterans who may have been exposed to toxic herbicides are eligible for health care from the VA.

The VA recognizes many of the aforementioned medical conditions as linked with Agent Orange exposure. Vets can receive health care and disability compensation for injuries or health problems related to serving in the military, including Agent Orange exposure. The VA also provides medical care for children of Vietnam veterans whose health problems appear to be caused by Agent Orange (numerous Vietnam War veterans have had children with birth defects apparently attributable to the father or mother's exposure to Agent Orange).

­On the­ next page, we'll take a look at some of the lawsuits and attempts at reparations resulting from the use of Agent Orange.


Agent Orange Lawsuits and Reparations

Vietnamese civilians exposed to Agent Orange and others head to U.S. court in June 2007 in New York.
Stan Honda/AFP/­Getty Images

­American and Vietnamese plaintiffs have filed numerous lawsuits in U.S. courts seeking compensation for exposure to Agent Orange. To protect itself from claims of wrongdoing, the U.S. government has used the doctrine of sovereign immunity, which dictates that a government can't be sued, even in cases of alleged negligence. In lawsuits against the United States dealing with atomic testing and Agent Orange, the Supreme Court has upheld the legality of sovereign immunity.

The 1946 Tort Claims Act placed restrictions on sovereign immunity, but some loopholes have been carved out based on the wording of the law and subsequent Supreme Court decisions. The law protects against "discretionary" acts by the government, and the Supreme Court has ruled against plaintiffs in cases affecting military veterans [source: Taylor].


Some lawsuits have accused chemical companies of war crimes for selling Agent Orange to the military. These lawsuits generally claim that companies such as Dow, Monsanto, Hercules and Diamond Shamrock knew more than they revealed at the time about the dangers of the herbicide. In 1984, a massive class-action lawsuit was settled in U.S. court. Seven U.S. compa­nies agreed to pay a total of $180 million to 291,000 people, mostly Vietnam War veterans [source: Glaberson]. The final settlement, including interest, was around $240 million [source: AP].

Other lawsuits have appeared after that major settlement. Some of these plaintiffs say that they missed out on the first class-action suit. Others say that they have a right to sue because more information is now available about the dangers of Agent Orange and dioxin. In their defense, chemical companies usually offer some of the following claims [source: Glaberson]:

  • The government ordered them to produce Agent Orange.
  • Too much time has passed since its use for people to claim reparations.
  • The connection is uncertain between Agent Orange and health problems.
  • Vietnamese claims should be settled by the U.S. government.

­In recent Agent Orange lawsuits, courts have ruled that chemical companies aren't liable because they were government contractors [source: Graybow]. One attorney, representing Vietnamese plaintiffs, said that these decisions may herald the end of Agent Orange-related lawsuits. But human rights and victims groups continue to lobby the U.S. to pay for dioxin cleanup in Vietnam, citing the precedent of the U.S. government paying for mine removal in Vietnam.


The Legacy of Agent Orange

A path lined with bare palm trees in Ben Tre, South Vietnam, after the area was sprayed with Agent Orange during the Vietnam War.
Ralph Blumenthal/New York Times Co./Getty Images

No longer in use, Agent Orange remains a powerful symbol. Although the United States and Vietnam have normalized relations, Agent Orange and its cleanup are still contentious issues. Dioxin has dissipated in many areas, but concentrations of the poison are still high in some regions, particularly where South Vietnamese and U.S. soldiers stored Agent Orange.

Much of the Vietnamese countryside has regrown, in part because of reforestation efforts by local and international groups. Because dioxin cleanup is potentially very expensive, one activist has tried to implement cheaper, low-tech solutions in highly contaminated areas by planting "fences" of trees. These makeshift fences do more than protect villagers from dioxin. They also provide a potential source of income from products derived from the trees.


The health effects of Agent Orange truly form the core of its legacy. Numerous people in Vietnam still say that Agent Orange has irreparably damaged their health, killed friends and relatives, and caused birth defects and health problems in their children. One man told BBC News that Agent Orange essentially destroyed his legs and gave him chronic headaches [source: BBC News]. One of his sons also suffers from headaches, while another of his children died from complications related to birth defects.

Areas sprayed with Agent Orange show a much higher incidence of the serious health problems previously discussed. For example, the town of Ben Tre has 140,000 residents; the Red Cross estimates that 58,000 of them have suffered adverse health effects because of Agent Orange [source: Hitchens]. Overall, an estimated 1 million out of 84 million Vietnamese have been poisoned by Agent Orange, and children continue to be born with birth defects likely caused by the herbicide [source: Hitchens]. There is no consensus as to how lo­ng dioxin will remain in the soil in Vietnam, but without a large-scale cleanup, the next generation of Vietnamese children likely will be subject to some of the same health problems that their parents and grandparents have faced.

Many American veterans of the Vietnam War continue to suffer from health problems, some of which are passed onto their children. Perhaps no Agent Orange story is complete without discussing Elmo R. Zumwalt Jr., a Navy admiral who commanded naval forces in Vietnam and was credited with helping to end race and gender discrimination in the Navy [source: Goldstein].

During the Vietnam War, Zumwalt was concerned about snipers in the Mekong Delta. He ordered that Agent Orange be sprayed to deprive snipers of cover. Coincidentally, Admiral Zumwalt's son, Lt. Elmo Zumwalt III, commanded a boat that operated in the Mekong Delta. At age 42, Elmo Zumwalt III died of cancer, likely caused by dioxin exposure. His son, Elmo IV, had a severe learning disability.

When both were still alive, Zumwalts II and III wrote a book together in which they acknowledged the likely connection between Agent Orange exposure and health problems in the family. Admiral Zumwalt said he didn't regret ordering the use of Agent Orange -- at the time, he had been told the herbicide didn't pose a health risk -- but that his son and grandson's problems haunted him daily [source: Goldstein]. Both Zumwalts pointed out that using Agent Orange to clear away the thick jungle along the Mekong Delta helped in fighting snipers and significantly decreased the casualty rate of American soldiers. Later in life, Admiral Zumwalt advocated for compensation for Agent Orange victims.

For more information about Agent Orange and related topics, please scroll through the links on the next page.



Agent Orange: Lots More Information

Related H­owStuffWorks Articles

More Great Links


  • "Agent Orange Home." United States Department of Veterans Affairs.
  • "Dioxin Potency." Dioxin Facts. March 31, 2005.
  • "Dioxin Sources." Dioxin Facts.
  • "Frequently Asked Questions About Agent Orange." Lewis Publishing.
  • "In Memoriam: Arthur Galston, Plant Biologist, Fought Use of Agent Orange." Yale University Office of Public Affairs. July 18, 2008.
  • "Information for Veterans Who Served in Vietnam." United States Department of Veterans Affairs. July 2003.
  • "Le Cao Di, 74, Expert on Agent Orange." The New York Times. April 22, 2002.
  • "Questions and Answers." Dioxin Facts.
  • "Technical Factsheet on: DIOXIN (2,3,7,8-TCDD)." U.S. Environmental Protection Agency. Nov. 28, 2006.
  • "The legacy of Agent Orange." BBC News. April 29, 2005.
  • "What are the effects of dioxins on human health?" GreenFacts.
  • "Yushchenko's dioxin level 2nd highest in history." CBC News. Dec. 16, 2004. dioxin041215.html
  • Aschwanden, Christie. "Through the Forest, a Clearer View of the Needs of a People." The New York Times. Sept. 18, 2007.
  • Associated Press. "Elmo R. Zumwalt 3d, 42 Is Dead; Father Ordered Agent Orange Use." The New York Times. Aug. 14, 1988.
  • Bertazzi, Pier Alberto, et al. "Health Effects of Dioxin Exposure: A 20-Year Mortality Study." American Journal of Epidemiology.
  • Buckingham Jr., Major William A. "Operation Ranch Hand: Herbicides In Southeast Asia." Air University Review. July-August 1983. 1983/Jul-Aug/buckingham.html
  • Glaberson, William. "Agent Orange, the Next Generation; In Vietnam and America, Some See a Wrong Still Not Righted." The New York Times. Aug. 8, 2004. 8103CF93BA3575BC0A9629C8B63&scp=1&sq=agent %20orange&st=cse
  • Goldstein, Richard. "Elmo Zumwalt, Jr., Admiral Who Modernized the Navy, is Dead at 79." The New York Times. University of North Texas Library. Jan. 3, 2000.
  • Graybow, Martha. "US court upholds dismissal of 'agent orange' suit." Reuters. Feb. 22, 2008.
  • Hitchens, Christopher. "The Vietnam Syndrome." Vanity Fair. August 2006.
  • Pearce, Jeremy. "Arthur Galston, Agent Orange Researcher, Is Dead at 88." The New York Times. June 23, 2008.
  • Schechner, Sam. "What Is Dioxin, Anyway?" Slate. Dec. 13, 2004.
  • Smith, J.Y. "Navy Reformer Elmo Zumwalt Dies." The Washington Post. University of North Texas Library. Jan. 3, 2000.
  • Taylor Jr., Stuart. "Supreme Court Roundup; Nevada A-Test Plaintiffs Lose Appeal." The New York Times. Jan. 12, 1988. 940DE2D81731F931A25752C0A96E948260&sec=health& spon=&pagewanted=all
  • World Health Organization (WHO). "Dioxins and their effects on human health." (Oct. 30, 2008)
  • ­Wrig­ht, Laura. "New Study Finds Agent Orange Use Was Underestimated." Scientific American. April 17, 2003.