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Agent Orange

Agent Orange

Agent Orange is one of several herbicidal (plant-killing) preparations that was used by the U.S. military to destroy forests and enemy crops in Vietnam in the 1960s. Agent Orange was created by mixing equal quantities of two agricultural herbicides commonly used to kill weeds: 2,4-D and 2,4,5-T. Present in the 2,4,5-T as an impurity was 2,3,7,8-tetrachlorodibenzo-p-dioxin (usually abbreviated to TCDD), a dioxin contaminant that is highly toxic to some animals. (Dioxin is a term used collectively for a group of chemical by-products of papermaking and other manufacturing processes.)

History

During the Vietnam War (196175; a civil war between the communist North and the democracy-seeking South), North Vietnamese guerrillas found cover in the lush jungles of South Vietnam. To deprive their opponents of hiding places and food crops, the U.S. military instituted a program called Operation Ranch Hand, which involved the aerial spraying of herbicides. Ground spraying from boats, trucks, and backpacks occurred as well. In all, U.S. troops sprayed approximately 19 million gallons (72 million liters) of Agent Orange and other herbicides over 4 million acres (1.6 million hectares). This military strategy is thought to have saved the lives of many U.S. combat soldiers who had been sent to fight on behalf of the South Vietnamese.

Words to Know

Chloracne: A rash of skin lesions on the face, neck, and back caused by exposure to TCDD.

Herbicide: A chemical substance used to destroy or inhibit plant growth.

Hodgkin's disease: A type of cancer characterized by enlargement of the lymph nodes, spleen, and liver and with accompanied weight loss, heavy sweating, and itching of the skin.

Mangrove: Tropical coastal trees or shrubs that produce many supporting roots and that provide dense vegetation.

Non-Hodgkin's lymphoma: Tumors that develop from cells in lymph nodes, bone marrow, spleen, liver, or other sites in the body.

Soft-tissue sarcoma: A rare but varied group of tumors that arise in the muscles, connective tissue, inner layer of skin, bone, and other tissues.

Toxicity: The degree to which a chemical, in sufficient quantities, can poison humans and other organisms.

Concerns arise over health effects

Concerns about the health effects of exposure to Agent Orange were initially voiced in 1970, following a study that reported the incidence of birth defects in laboratory mice given high doses of the herbicide 2,4,5-T. TCDD, a dioxin contaminant of 2,4,5-T, was isolated as the actual cause of the birth defects. A commission established in 1970 to study the effects of herbicides on the ecology and population of South Vietnam reported that herbicides had not only destroyed vegetation and food, but 2,4,5-T and its associated dioxin contaminant might possibly have caused birth defects among South Vietnamese people who were exposed to it.

On April 15, 1970, all use of 2,4,5-T in the United States was suspended, except for the killing of weeds and brush on non-crop land. On May 9, 1970, Operation Ranch Hand flew its last mission in Vietnam, and U.S. forces stopped ground spraying in 1971. The herbicide was banned completely in 1985 by the Environmental Protection Agency.

Toxicity of TCDD. TCDD is a by-product of the manufacture of trichlorophenol, a chemical used to produce 2,4,5-T. Workers involved in accidents or spills at factories where the herbicide 2,4,5-T is manufactured have developed a condition called chloracne, a rash of skin lesions on the face, neck, and back. After researchers developed a method to produce trichlorophenol with a reduced level of TCDD as a by-product, the number of chloracne cases among factory workers in the herbicide industry decreased substantially.

The toxicity of the dioxin contaminant TCDD is the subject of continuing controversy and study. While some animals are very sensitive to TCDD, others are more tolerant to it. A very small amount can kill 50 percent of guinea pigs exposed to it, but a dose thousands of times larger is needed to cause the same number of deaths in hamsters.

Investigation of health effects

Serious health symptoms reported in 1977 by veterans of the Vietnam War spurred both the White House and the Veterans Administration (VA) to institute studies to evaluate the possible long-term health effects of herbicides and contaminants.

Exposure to TCDD in humans is measured by the amount of the contaminant found in blood and fatty tissue, where it tends to accumulate. Studies determined that levels of TCDD in the blood of chemical plant workers were strongly related to length of time of exposure.

Inadequate records of herbicide spraying and troop movements have made it difficult to determine to what degree individuals were exposed to herbicides and TCDD in Vietnam. Ranch Hand personnel who were heavily exposed to Agent Orange had significantly higher TCDD levels than other veterans. The average TCDD concentrations of Vietnam veterans who might have been exposed to Agent Orange on the ground did not differ significantly from that of other veterans and civilians.

The Agent Orange Act of 1991, passed by the U.S. Congress, ordered the National Academy of Sciences (NAS) to review and evaluate information regarding the health effects of exposure to Agent Orange and its components. Lacking enough information about the levels of herbicide exposure among Vietnam veterans to make any conclusions

regarding health effects, the NAS instead reviewed existing studies of people known to have been exposed to herbicides. In 1993, the 16-member panel of experts classified possible health effects in four categories, depending on the degree to which they could be associated with TCDD exposure.

In a 1996 update, the Institute of Medicine (IOM) reported new evidence upholding the 1993 finding of sufficient evidence of an association between TCDD exposure and various disorders with symptoms including tumors and skin lesions, including soft-tissue sarcoma, non-Hodgkin's lymphoma, Hodgkin's disease, and chloracne. Porphyria cutanea tarda (a rare skin disease) was downgraded from sufficient to "limited/suggestive evidence of an association," a category that also includes prostate cancer, multiple myeloma (cancer of bone marrow cells), and respiratory cancers (cancers of the lung, larynx, or trachea).

The IOM also reported there was new "limited/suggestive evidence" to show an association between TCDD exposure and the congenital birth defect spina bifida (incomplete closure of the spinal column at birth) in Vietnam veterans' children. A neurological disorder suffered by veterans was also placed in this category. The remaining two categories include cancers or disorders that have insufficient or no evidence of an association with TCDD exposure.

Ecological effects

The damage to the plant life of South Vietnam caused by the spraying of Agent Orange is still visible today. The most severe damage occurred in the mangrove forests (tropical trees and shrubs) of coastal areas where spraying left barren, badly eroded coastlines. The number of coastal birds declined dramatically, and with the disappearance of the web of water channels beneath the mangrove trees, fish were deprived of important breeding grounds. It is estimated that full recovery of the man-grove forests to their former state will take at least 100 years.

The loss of commercially useful timber due to aerial spraying of Agent Orange over dense inland forests was significant. About 10 percent of the tall trees making up the forest canopy were killed. Smaller shrubs now comprise the majority of vegetation in affected areas. Tussock grasses and bamboo replaced woody plants destroyed by the spraying. The beginnings of natural recovery can be seen, but it will be many years before the forests will approach their former productivity.

As the rich, diverse tropical forests disappeared, so did animal habitats. As a result, the number of bird and mammal species living in the areas that were sprayed declined dramatically. Wild boar, wild goat, water buffalo, tiger, and various species of deer became less common once the cover and food resources of the forest were removed. Domestic animals such as water buffalo, zebus (an Asian ox), pigs, chickens, and ducks were also reported to become ill after the spraying of Agent Orange.

The contaminant TCDD is not easily or quickly broken down in soil, and there is concern that herbicide residues might inhibit the growth of crops and other plants. These by-products, which can be toxic, could then be passed to humans through the food chain.

[See also Agrochemical ]

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Agent Orange

Agent Orange

Agent Orange is a defoliant, that is, a chemical that kills plants and causes the leaves to fall off the dying plants. The name was a code devised by the United States military during the development of the chemical mixture. The name arose from the orange band that marked the containers storing the defoliant.

Agent Orange was an equal mixture of two chemicals; 2, 4D (2,4, dichlorophenoxyl acetic acid) and 2, 4, 5T (2, 4, 5-trichlorophenoxy acetic acid). Another compound designated TCDD (which stands for 2, 3, 7, 8-tetrachlorodibenzo-para-dioxin) is a by-product of the manufacturing process, and remains as a contaminant of the Agent Orange mixture. It is this dioxin contaminant that has proven to be damaging to human health.

Agent Orange was devised in the 1940s. It was widely used during the 1960s during the Vietnam War. The dispersal of a massive amount of Agent Orange throughout the tropical jungles of Vietnam (an estimated 19 million gallons were dispersed) was intended to deprive the Viet Cong of jungle cover in which to hide.

By 1971, the use of Agent Orange in Vietnam had ended. Even today, however, the damage caused to the vegetation of the region by the spraying of Agent Orange is still visible. Agent Orange applications affected foliage of a diversity of tropical ecosystems of Vietnam, but the most severe damage occurred in the forested coastal areas.

Agent Orange was sprayed over 14 million acres of inland tropical forest. A single spray treatment killed about 10% of the tall trees comprising the forest canopy.

Because Agent Orange herbicide remains in the soil for some time, the contaminant TCDD is quite persistent in soil, with a half-life of three years. (In that period of time, one half of the dioxin originally applied would still be present in the soil.)

Evidence also suggests that the defoliant, and in particular the TCCD dioxin component, is a health threat to soldiers who were exposed to Agent Orange during their tour of duty in Vietnam. Tests using animals have identified TCCD as the cause of a wide variety of maladies. In the mid 1990s, the "Pointman" project was begun in New Jersey, which scientifically assessed select veterans in order to ascertain if their exposure to Agent Orange had damaged them. The project is ongoing. In the meantime, veterans organizations continue to lobby for financial compensation for the suffering they assert has been inflicted on some soldiers by Agent Orange.

FURTHER READING:

BOOKS:

Gough, M. Agent Orange: The Facts. New York: Perseus Books, 1986.

National Academy of Sciences. Veterans and Agent Orange: Health Effects of Herbicides Used in Vietnam. Washington, DC: National Academy Press, 1994.

Schuck, P. H. H. Agent Orange on Trial: Mass Toxic Disasters in the Courts. Boston: Harvard University press, 1990.

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Agent Orange

AGENT ORANGE

AGENT ORANGE was an herbicide used by the United States during the Vietnam War (1955–1975; U.S. involvement 1964–1975) to deprive Viet Cong and North Vietnamese soldiers of forest cover and food crops. "Operation Ranch Hand" was the code name for the application of Agent Orange, as well as other defoliants such as Agent White and Agent Blue, by specially equipped Air Force cargo planes. More than forty-six percent of South Vietnam's territory was sprayed with herbicide under Operation Ranch Hand between 1962 and 1970. Agent Orange proved to be the most effective of the herbicides, as it contained dioxin, an extremely toxic chemical agent. Within a few weeks after its application, Agent Orange would turn lush, green forests brown and barren. It also had a detrimental effect on humans.

In 1966, the North Vietnamese charged that herbicides such as Agent Orange were responsible for causing congenital deformities in infants. Three years later, a report in a South Vietnamese newspaper made the same allegation. That same year, a study by the National Institutes of Health presented evidence that the dioxin found in Agent Orange caused deformities in babies. The United States suspended the use of Agent Orange in 1970, and ended Operation Ranch Hand in 1971.

After the war, studies continued to probe the impact that the dioxin found in Agent Orange could have on people. Americans who served in South Vietnam and were exposed to Agent Orange reported high incidences of skin rashes, breathing problems, various types of cancer, and birth defects in their children. A class action suit brought by affected veterans against the Veterans Administration was settled out of court in 1985. As part of the settlement, the chemical companies responsible for Agent Orange established a $180 million fund to assist veterans with legitimate claims, as well as the families of veterans who died from Agent Orange exposure.

BIBLIOGRAPHY

Moss, George Donelson. Vietnam: An American Ordeal. 3d ed. Upper Saddle River, N.J.: Prentice Hall, 1998.

Olson, James S., ed. Dictionary of the Vietnam War. New York: Greenwood Press, 1988.

John A.Morello

See alsoChemical and Biological Warfare ; Insecticides and Herbicides ; Vietnam War .

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Agent Orange

Agent Orange,herbicide used by U.S. forces during the Vietnam War to expose enemy guerrilla forces in forested areas. Agent Orange contains varying amounts of dioxin. Exposure to the defoliant has been linked with chemical acne, non-Hodgkin's lymphoma, Hodgkin's disease, soft-tissue sarcoma, and hairy-cell leukemia. Many soldiers were exposed to Agent Orange in the Vietnam War. Afflicted veterans brought a class-action suit against manufacturers of Agent Orange, which was settled out of court by the establishment of a fund to compensate them and their families for any disabilities. That settlement, however, covered only those who became ill by 1994 and, as a result of a 2003 Supreme Court decision, veterans who became ill after 1994 can sue the herbicide's manufacturers. The herbicide has also been blamed for a significantly higher than normal rate of birth defects in areas of Vietnam that were sprayed; tests have shown persistent high levels of dioxin in the local environment and in people living there. Since 2006 the United States and Vietnam have worked together on problems in Vietnam resulting from the herbicide's use.

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"Agent Orange." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 21 Jul. 2017 <http://www.encyclopedia.com>.

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Agent Orange

Agent Orange a defoliant chemical used by the US in the Vietnam War.

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"Agent Orange." The Oxford Dictionary of Phrase and Fable. . Encyclopedia.com. 21 Jul. 2017 <http://www.encyclopedia.com>.

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"Agent Orange." The Oxford Dictionary of Phrase and Fable. . Retrieved July 21, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/agent-orange