Agent Orange in Vietnam: burden and consequence

Although I am not an expert in Agent Orange (AO), I have been interested in AO research for many years, because I have seen people affected by the chemical in my country (Vietnam). I have published some research on the issue in peer-reviewed literature. About 10 years ago, I was invited to contribute a book chapter on the effect of AO in Vietnam. However, the book was not published, because the book's editors could not raise enough money! So, I am posting the review article here for your perusal. Please keep in mind that this article was written 10 years ago, and since then data have not been updated.



Agent Orange in Vietnam


Among the most significant legacies of the war that Americans refer to as the “Vietnam War” are the lasting consequences of chemical defoliants used by the U.S. military. The primary defoliant used was Agent Orange, which contained the toxic chemical dioxin.1 Although the war ended more than four decades ago, millions of victims, including Vietnamese civilians and ex-servicemen in the American and Vietnamese militaries, are still suffering from exposure to these chemicals.


During the past forty years or so, a large number of scientific studies on the effects of Agent Orange or dioxin have been carried out around the world. These studies, which included basic and epidemiological research, have formed the basis upon which the U.S. government makes decisions regarding compensation to members of the military who suffered exposure to these agents. This paper will examine the scientific evidence of the relationship between Agent Orange or dioxin and human diseases.


Dioxin and Agent Orange


The term “dioxin” technically refers to a structurally similar group of 75 poly-chlorinated dibenzo-p-dioxins and 135 poly-chlorinated dibenzo-p-furans. The most toxic chemical in this group is 2,3,7,8-tetrachloro-dibenzo-p-dioxin (abbreviated as 2,3,7,8-TCDD). The numbers 2, 3, 7, and 8 indicate the positions at which chlorine atoms are located on the dioxin molecule. The compound 2,3,7,8-TCDD is often referred to simply as “dioxin” in the mainstream press, and will be identified as such in this chapter.


Dioxin was identified and synthesized by 1957,2 and has since become one of the most widely studied chemical compounds due to concerns about its effects on humans and other living creatures. Dioxin has very low solubility in water, requiring a temperature of 295oC to begin dissolving; it breaks down into its component parts at 500oC. As a result, dioxin in the environment does not readily dilute or degrade—it tends to accumulate in soil and sediment. Dioxin is also a lipophilic compound (i.e., it adheres readily to fat). Higher levels of dioxin thus tend to be found in fatty tissue, and the levels bioaccumulate as one goes up the food chain.


A toxic by-product of combustion and manufacturing processes, dioxin can be found in trace amounts throughout the world in air, water, soil, and industrial waste; it consequently enters the food chain and occurs in meat, vegetables, and especially in seafood. Common industrial sources include the incineration of factory waste and medical equipment and the bleaching of paper and textiles. Dioxin is also produced through wood combustion, including forest fires and wood burning—a large forest fire may generate anywhere from a few grams to a few kilograms of the compound.


During the Vietnam War, the U.S. Army used various defoliating chemicals, including mixtures of the phenoxy herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). The mixtures were shipped to Vietnam in fifty-five-gallon chemical drums marked with colored identifying stripes. By far the greatest quantity was a one-to-one mixture of 2,4-D and 2,4,5-T, which was stored in drums with orange stripes. Hence, this substance was called “Agent Orange.” Other mixtures, identified by their stripes as Agent Pink, Agent Green, Agent Purple, Agent White, and Agent Blue, were also used during the war. Agents Orange, Pink, Green, and Purple all were made with 2,4,5-T, and thus contained, in varying quantities, dioxin—a by-product of 2,4,5-T synthesis.3 (Agent White consisted of 2,4-D and picloram; Agent Blue contained cacodylic acid, an arsenic compound.) Since Agent Orange was the chief defoliant used, for the purposes of this chapter, “Agent Orange” will refer to all dioxin-containing mixtures.


A Brief History


At the end of the nineteenth century, when sodium chloride (table salt) and potash were the main substances used to kill weeds along roadsides, an inorganic selective herbicide was discovered by chance in France. Bordeaux vintners attempting to control downy mildew disease among their grape crops sprayed the grape leaves with a solution of copper sulfate and lime, and found that stray drops killed broadleaf weeds on the ground below. Subsequently, the copper sulfate component was identified as the weed-killing element of the “Bordeaux mixture.” Research experiments in France, Germany, and the United States determined that CuSO4 (copper[II] sulfate) could be used as an inorganic selective herbicide for controlling weeds in wheat, barley, and oat crops. Experimentation with other copper and sulfur compounds led to sulfuric acid, iron sulfate, and copper nitrate being used as popular herbicides over the next decade.


As the agricultural revolution brought Western farming into the modern age, developing chemicals to control plant growth—not only to kill weeds, but also to improve crop yields—became a priority for agricultural scientists in the United States and Europe. During the 1930s and 40s, both inorganic and organic selective herbicides were used for weed control, including boron compounds, ammonium sulfate, sodium chlorate, carbon bisulfide, sodium arsenite, and dinitrophenols. In 1935, U.S. scientists reported that phenylacetic acid (PAA) and naphthaleneacetic acid (NAA) could prevent premature fruit drop, induce rooting, accelerate fruit ripening, and produce seedless tomatoes.4 In 1941 British scientists, while conducting potted experiments on the effects of NAA as a plant growth regulator on wheat, found by chance that NAA killed a few wild mustard plants (Brassica kaber) growing as weeds in the wheat pots.


Also in 1941, U.S. scientists for the first time synthesized 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). The intention was to study the effects of 2,4-D and 2,4,5-T on fungal diseases in hopes of identifying new fungicides. In 1942, studies suggested that 2,4-D was an effective plant growth regulator, such that it induced the production of seedless tomatoes.5 A real breakthrough in selective chemical weed control was achieved in 1945 with the commercial introduction of both 2,4-D and MCPA (4-chloro, 2-methylphenoxyacetic acid) in the United States and England.

Military scientists, however, had ideas for using herbicides that went far beyond weed control. During World War II, the U.S. Army conducted biochemical warfare research through the Chemical Warfare Service, which was headquartered at Camp Detrick, Maryland. Extensive plans were drawn up for the use of defoliants against Japan.6 The main objectives of this project were to develop a chemical that could destroy rice and other food crops in order to deplete the food reserves in Japan, and to use herbicides as defoliants for destroying broadleaf trees that concealed and protected Japanese soldiers from U.S. forces. In 1944, substantial amounts of 2,4-D and 2,4,5-T were synthesized and experimentally sprayed from airplanes. However, after extensive discussion with U.S. President Roosevelt and General William D. Leahy, the U.S. military decided not to use the chemicals in the war against Japan.


At the end of 1950s, following the English military’s successful use of 2,4,5-T to destroy crops in their campaign against Malaysia,7 the U.S. Department of Defense (DOD) assigned the Advanced Research Project Agency (ARPA) to research and develop herbicides for military use. Large-scale testing on a mixture of 2,4-D and 2,4,5-T was successfully carried out at Drum Station, New York in 1959; the spray system used in the tests would be the model implemented a few years later in Vietnam.


As U.S. involvement in Vietnam intensified, American political and military leaders argued in favor of using herbicides to destroy forest vegetation, thereby exposing the hiding places of North Vietnamese forces. American soldiers could then cut off the supply route from the North through Truong Son Trail by heavy aerial bombardment. On November 20, 1961, U.S. President John F. Kennedy approved a plan for the U.S. Army to carry out defoliant activities on Vietnamese forests.8 This decision was enthusiastically supported by then-president of South Vietnam, Ngo Dinh Diem. Agent Orange was transported to South Vietnam from August to December 1961.

Operation Trail Dust was the name applied to the overarching program of spraying defoliants in Vietnam; within this program there were several separate campaigns. Operation Ranch Hand, the largest and longest campaign, comprised 95 percent of chemical spraying under Operation Trail Dust. In 1962, the U.S. Air Force began spraying herbicides on a large scale in the southern and central regions of Vietnam. The majority (approximately 90 percent) of Agent Orange was sprayed from C-123 airplanes and the remainder from helicopters, trucks, and other vehicles. Details of the specific areas to be sprayed and the chemicals to be used required the approval of the Oval Office. However, beginning in late 1962, President Kennedy assigned part of this responsibility to the U.S. ambassador to South Vietnam, Henry Cabot Lodge, and to General William Westmoreland, commander of U.S. forces in Vietnam.


Operation Trail Dust was harshly criticized and condemned worldwide. Virtually all major newspapers in the United States, Europe, and Asia considered that the operation was immoral and inhumane, and demanded that it be stopped immediately. The prominent British mathematician and philosopher Bertrand Russell accused the United States of conducting chemical warfare in Vietnam. U.S Senator Robert W. Kastenmeier also felt uneasy about the operation, and wrote a letter to President Kennedy questioning whether the use of chemicals in Vietnam was justified in light of the regime of Ngo Dinh Diem.9


In January 1966 Professor John Edsall of Harvard University and a group of twenty-nine prominent scientists in Boston published a letter in the magazine Science calling the use of chemicals in Vietnam inhuman and barbarous.10 One year later, the White House received a letter with signatures of five thousand scientists from all over the world, including seventeen Nobel laureates and 129 members of the U.S. National Academy of Sciences, asking that President Lyndon B. Johnson put an immediate stop to the ecocidal campaign in Vietnam.11 In 1967, the American Association for the Advancement of Science, with the help of Professor E. W. Pfeiffer from the University of Montana, advised the U.S. Department of Defense about unforeseen consequences to the Vietnamese people and the environment of Vietnam. In response, the DOD commissioned scientists from the Midwest Research Institute to study the effects of Agent Orange in Vietnam. Based on data at the time, the Institute concluded that the effects of Agent Orange were likely to be minor and short-lived; however, they also suggested further study of the effects of Agent Orange on human health.12


In 1969, Richard M. Nixon became U.S. president and, in an effort to reduce U.S. involvement in Vietnam, he ordered the intensity of Operation Ranch Hand to be reduced by 30 percent. In the meantime, the U.S Senate was about to ratify a UN resolution prohibiting the use of chemical and biological weapons. Although President Nixon wanted to ratify the resolution, he argued that the use of Agent Orange in Vietnam did not contravene the resolution. Nevertheless, the UN General Assembly did not accept Nixon’s argument and maintained that Operation Ranch Hand was illegal. In July 1971, President Nixon ordered the complete halt of Operation Ranch Hand.13


Magnitude of the Problem


By the time Operation Ranch Hand was halted, the U.S. military had conducted 19,905 aerial spraying missions, with an average of eleven missions each day. The exact volume of herbicide used by the U.S military in Vietnam remains unknown. A 2003 study by Columbia University scientists estimated that, between 1962 and 1971, the U.S military sprayed 76.9 million liters of herbicide in central and southern Vietnam.14 This figure was 9.4 million liters greater than a previous estimate. Of the total amount of herbicide sprayed, approximately 64 percent (or 49.3 million liters) was Agent Orange.


It is important to realize that these are minimal estimates, because large amounts of chemicals that were shipped to Vietnam have never been accounted for. For instance, procurement records showed that the military purchased 464,164 liters of Agent Pink and 31,026 liters of Agent Green, but only 65,000 liters of that total were reported to have been sprayed.15


By far most of the herbicide—approximately 90 percent—was sprayed between 1966 and 1969. It is interesting to note that those mixtures with the highest levels of dioxin concentration, such as Agent Pink, were sprayed during the first few years of the operation. However, crop-destroying chemicals, such as Agent Blue, continued to be sprayed until 1971.


By using Hamlet Evaluation Survey (HES) records—monthly data on security and population information for each hamlet in Vietnam, collected from 1967 until the end of the war—Columbia University scientists have estimated that, in total, 2.6 million hectares (ha) of land were affected by various herbicides during the war. This number was 1.1 million ha higher than a previous estimate. Of the affected areas, the scientists estimated that approximately 1.68 million ha were directly affected by dioxin. Furthermore, of the affected areas, 86 percent were sprayed at least twice. About 11 percent of the areas were sprayed more than ten times! (See Table 1.)



The number of villages or hamlets affected was estimated at 20,585. The number of individuals affected by herbicide was estimated at minimum of 2.1 million. This number is likely an underestimate, because there were thousands of villages where the population statistics were not recorded or estimated. Therefore, the scientists suggested that the number of civilians affected could be up to 4.8 million.16


Residual Concentration of Dioxin in Vietnam


Agent Orange and other herbicides were known to be highly toxic prior to and during the herbicide campaign in Vietnam. Indeed, as early as 1952, Monsanto Chemical Company—a major manufacturer of Agent Orange—already knew that 2,4,5-T was a toxic agent. In 1963, research conducted by the U.S. Army revealed that 2,4,5-T was associated with an increased risk of chloracne, a severe skin disease characterized by painful and disfiguring eruptions, and respiratory complications.17


Research conducted in 1966 indicated that 2,4,5-T caused many birth defects in mice and rats whose mothers had been exposed to 30 parts per million (ppm) of the chemical.18 This finding was consistent with the toxicity of dioxin in animals. Dr. Arthur Galston, a noted herbicide expert whose early research led to the development of Agent Orange, stated that a dioxin concentration as low as 5 ppt (parts per trillion—an amount roughly equivalent to one drop in 4 million gallons of water) can,


when supplied on a daily basis, induce a cancerous condition in rats. Concentrations about 1 ppb (part per billion) result in premature death from more acute causes, and concentration above 50 ppb produce rapid signs of acute toxicity and early death …. [Researchers] have found that lower concentrations of TCDD produce the same effects as higher concentrations, but merely take longer to do so .…Even the purest 2,4,5-T currently available commercially contains about 0.05 ppm (mg/kg) of TCDD.19


Although the exact amount of TCDD sprayed during the Vietnam War is unknown, scientists estimated that the total amount was least 366 kg.20


During the past forty years or so, most of the research on dioxin and Agent Orange has been conducted in the United States. Only a few studies have been done in Vietnam. Therefore, data on the herbicide contamination in Vietnam are rather limited. In one important study, a group of American and Vietnamese scientists analyzed the dioxin concentration in 3,242 residents from northern, central, and southern Vietnam.21 According to the results, residents living in the northern provinces had the lowest levels of concentration (an average of 2.7 ppt). However, residents of the central and southern regions had, on the average, levels of dioxin concentration six times higher (13.2 ppt and 12.9 ppt for central and southern residents, respectively), which is consistent with the geographical spraying of Agent Orange during the war. In some areas heavily sprayed during the war, the concentration was elevated to 32 ppt (Song Be), 28 ppt (Dong Nai–Bien Hoa), and 33 ppt (Tra Noc, Hau Giang). (See Table 2.)


Table 2. Average dioxin concentration in Vietnam 1995



In 2003, University of Texas scientist Arnold Schecter and colleagues analyzed the dioxin concentration in a small sample of foodstuffs in Bien Hoa province, and found that two ducks had the highest levels of concentration (276 ppt and 331 ppt, respectively). However, the concentrations in fish, pork, and beef were lower (between 0.2 ppt and 15 ppt).22


It is known that the half-life of dioxin is between seven and ten years.23 The above data clearly suggest that those areas where heavy aerial spraying was conducted during the war are still affected by dioxin. The data also indicate that dioxin has penetrated into the environment—soil, sediment, and foodstuff—in affected areas. The findings from Schecter, et al , are consistent with the contamination in Seveso, Italy, where high levels of dioxin concentration were still present thirty years after an industrial accident that released about 30 kg of dioxin into the environment.24


Effects of Dioxin and Agent Orange on Human Health


As was mentioned previously, there have been numerous studies on the associations between Agent Orange and human health, with the majority of studies conducted in United States and Europe. The studies have been highly controversial due to conflicting findings and differences in the interpretation of results, leaving the issue of the effects of Agent Orange without definite conclusion. In response to this uncertainty, under the Agent Orange Act of 1991 the U.S. Congress asked the Institute of Medicine (part of the National Academy of Sciences) to review all scientific and medical data regarding the health effects of exposure to Agent Orange. In 1992, the Institute of Medicine established the Committee to Review the Health Effects in Vietnam Veterans of Exposure to Herbicides, which was comprised of experts in epidemiology, occupational health, environmental health, toxicology, and biology, and chaired by Professor Irva Hertz-Picciotto. Results of the review were published in 1996 in the form of a report titled Veterans and Agent Orange: Update 1996. Because science is a progressive enterprise, in the sense that data are continuously accumulated over time, and the reliability of a scientific conclusion is strengthened with more data at hand, the committee regularly updates its findings approximately every two years. The latest findings were documented in the fourth publication, Veterans and Agent Orange: Update 2006.25

In this report, the associations between Agent Orange and/or dioxin exposure and human health are graded into four groups of evidence: “Sufficient Evidence of an Association,” “Limited or Suggestive Evidence of an Association,” “Inadequate or Insufficient Evidence to Determine Whether an Association Exists,” and “Limited or Suggestive Evidence of No Association.” The findings are summarized in Table 3.


According to this grading, the committee considers that after ruling out potential bias and confounding factors, there is sufficient evidence to conclude that a positive association exists between Agent Orange and/or dioxin and the following diseases: chronic lymphocytic leukemia, soft-tissue sarcoma, non-Hodgkin’s lymphoma, Hodgkin’s disease, and chloracne. During the past two decades, these diseases have consistently been shown to be linked to exposure to Agent Orange and/or dioxin.


However, the committee does not feel confident to conclude a definitive association between Agent Orange exposure and the following diseases: respiratory cancer (of lung and bronchus, larynx, and trachea), prostate cancer, multiple myeloma, acute and subacute transient peripheral neuropathy, porphyria cutanea tarda, type 2 diabetes, and spina bifida in the children of veterans, because an association could be compromised by chance, bias, and confounding factors.


Nevertheless, recent studies have confirmed that Agent Orange exposure is associated with an increased risk of prostate cancer. In a study known as “the Ranch Hand study,” investigators examined the incidence of prostate cancer in two groups of individuals: group 1 consisted of approximately 1,200 ex-servicemen who participated in Operation Ranch Hand during the war, and group 2 comprised 1,785 ex-servicemen who were not in any way involved in the handling of the Agent Orange. After twenty years of follow-up, investigators found that the risk of prostate cancer in ex-servicemen involved with Operation Ranch Hand (1966–1970) was between two and four times higher than in the general population. Among those who had served at least two years in Vietnam, the risk of developing prostate cancer was six to seven times higher than in the general population. Furthermore, the risk of melanoma among individuals in group 1 was two-fold higher than in group 2.26


On July 15, 2005, the DOD released a press statement in which it recognized that exposure to Agent Orange is associated with an increased risk of developing type 2 diabetes. The latest scientific finding27 suggests that the risk of type 2 diabetes in ex-servicemen who had been exposed to Agent Orange at the highest level is 2.6 times higher compared to unexposed individuals.





All these studies, however, suffered from a major drawback known as the “survival bias.” Exposure to Agent Orange is associated with an excess mortality risk. In an Italian study on residents of the aforementioned Seveso area, researchers found that individuals living in areas exposed to high levels of dioxin contamination had a 30 percent increased risk of mortality. Moreover, the risk of death from colon cancer among men with high levels of dioxin concentration increased by 2.4-fold compared to the general population.28 Most of the studies on the effects of Agent Orange were done long after the Agent Orange campaign was over, and it is possible that numerous individuals had died earlier due to exposure to the chemical. This makes the delineation of the effects of Agent Orange exposure on human health very difficult, because the “ideal” candidates for study are no longer available for analysis, and those available for study are only the relatively healthy ones. Therefore, it could be argued that the strength of association from these studies actually underestimates the true effects of dioxin and Agent Orange on human health.


Agent Orange and Birth Defects


The association between Agent Orange and birth defects remains one of the most contentious issues in science. While basic research using animal models has consistently indicated that exposure to 2,4,5-T may result in congenital malformation, studies in humans have produced conflicting results. As early as 1964, the U.S.-based Bionetics Laboratory was commissioned by the National Cancer Institute of the Department of Health, Education, and Welfare to investigate the carcinogenic and teratogenic (causing birth defects) effects of various pesticides and industrial compounds on animals. The results indicated that 2,4,5-T in small doses caused birth defects in mice and rats. In 1969, the National Cancer Institute released the Bionetics report—but without mentioning the teratogenic effects. Nevertheless, the causative role of 2,4,5-T in birth defects was leaked to some scientists at Harvard University, who subsequently confirmed that 2,4,5-T, 2,4-D, and the mixture of n-butyl esters that constituted Agent Orange were all teratogenic in tiny doses. The leaking of these data sparked a furor in the American public, which contributed to the halt of Operation Ranch Hand in Vietnam.29


In a 1990 report to the U.S Congress, former Naval Commander Admiral E. R. Zumwalt, Jr., also mentioned the findings that dioxin could cause birth defects:


Beginning as early as 1968, scientists, health officials, politicians, and the military itself began to express concerns about the potential toxicity of Agent Orange and its contaminant dioxin to humans. For instance, in February 1969 the Bionetics Research Council Committee ("BRC”) in a report commissioned by the United States Department of Agriculture found that 2,4,5-T showed a “significant potential to increase birth defects.”


By October 1969, the National Institute of Health confirmed that 2,4,5-T could cause malformations and stillbirths in mice, thereby prompting the Department of Defense to announce a partial curtailment of its Agent Orange spraying.


On the same day, the Secretaries of Agriculture, Health, Education, and Welfare, and the Interior, stirred by the publication of studies that indicated 2,4,5-T was a teratogen (i.e., caused birth defects), jointly announced the suspension of its use around lakes, ponds, ditch banks, recreation areas, and homes and crops intended for human consumption.30


Subsequent and recent studies have clearly suggested that dioxin can cause congenital malformation.31–32 In animal studies, maternal exposure to dioxin resulted in cleft palate and hydronephrosis in mice and hamsters, intestinal hemorrhage and renal abnormalities in rats, extra ribs in rabbits, and spontaneous abortions in lab animals. Moreover, dioxin was found to cause chromosomal anomalies in the bone marrow cells of some specific strains of rats and mice, and to stimulate RNA synthesis in rat liver.


When the Operation Ranch Hand was at its peak in 1969, Tin Sang, a Saigon newspaper, reported a surge in the incidence of birth defects. In its issue of June 26, 1969, the paper ran a story entitled “Defoliants are causing catastrophe of molar pregnancies at Tan Hoi hamlet.” (A molar pregnancy results when damage to the egg prevents the placenta and fetus from developing normally.) The Tin Sang article reported that women of Tan Hoi hamlet were flocking to a Saigon hospital to “[have] their abnormal fetuses from molar pregnancies, or monsters [sic], taken out….They unanimously say that after just about two months of being pregnant, their fetuses become unbearable to them; then blood starts coming out through their vulvas until the fetus is taken out or the unfortunate pregnant woman must die.”33 However, at the time, no systematic studies were carried out to assess the problem. It has been estimated that up to fifty thousand deformed children were born to parents exposed either by location or through access to sprayed foodstuffs. But this number is still a conjecture.


Concerned about the detrimental effects of Agent Orange, the American Association for the Advancement of Science set up a group called the Herbicide Assessment Commission to examine the association between Agent Orange exposure and birth defects in Vietnam. In December 1970 the Commission examined records of about four thousand abnormal births in Saigon Children’s Hospital from 1959 to 1968, and found a sudden rise in two types of defect (cleft palate and spina bifida) after the start of heavy spraying in 1966. Furthermore, the Commission found that the rate of stillbirths in Tay Ninh provincial hospital was 64 per 1,000, approximately two-fold higher than the average rate of 31.2 per 1,000 in South Vietnam at the time. The Commission’s report noted,


Although, as in other areas where Agent Orange has been used mainly for forest destruction (as opposed to crop destruction) the total number of directly exposed Vietnamese is probably low, the northern portion of Tay Ninh has been heavily defoliated and the rivers draining the areas of defoliants run through the remainder of the province and are a source of fish for some of the population.34


Thomas Whiteside, in his book Defoliation, estimated that, based on the standard dose of Agent Orange applied to wells and cisterns in South Vietnam, “If a Vietnamese woman who was exposed to Agent Orange was pregnant, she might very well be absorbing into her system a percentage of 2,4,5-T only slightly less than the percentage that deformed one out of every three fetuses of the pregnant experimental rats.”35


However, data from observational studies in the United States and elsewhere are inconsistent. Therefore, Agent Orange toxicity remains a controversial topic in medical science.36, 37 As mentioned above, the Institute of Medicine has reviewed the published data and concluded that there was “inadequate/insufficient evidence” to determine whether an association exists between Agent Orange exposure and birth defects, with the exception of spina bifida.38 However, the Institute’s review relied primarily on published studies in its deliberation, without considering unpublished data from studies in Vietnam and the United States.


We have conducted a meta-analysis of results from twenty-one studies, including thirteen Vietnamese studies and nine non-Vietnamese studies (seven American and two Australian studies), involving 205,398 individuals. We found that the risk of birth defects in individuals exposed to Agent Orange as compared to the non-exposed group increased 2.2-fold, and this increase was statistically significant. Furthermore, we found that there was a higher risk of birth defects associated with Agent Orange exposure in the Vietnamese studies than in the non-Vietnamese studies (Table 4). These data, collectively, suggest that the observed association between Agent Orange/dioxin in humans seems biologically plausible.



In a subgroup analysis, we found that the strength of association between exposure to Agent Orange/dioxin and birth defects in the Vietnamese population was substantially more pronounced than that in the non-Vietnamese populations. This observation is consistent with previous findings that higher dioxin concentrations were found in the Vietnamese population in affected areas than in U.S. Vietnam veterans. In addition, our findings were also consistent with the fact that in the Vietnamese civilian studies, women and men were both exposed so that effects could be both teratogenic and mutagenic, whereas in the studies of North Vietnam and Ranch Hand veterans only mutagenesis was possible, since the exposed were men.


Most of the above studies found various birth defects in Vietnamese children; the major groups were malformations of the nervous system, such as hydrocephalus, and of the heart, genitals, and urinary tract. Other major defects included cleft palate, clubfoot, and hand and limb deformities. Some studies also reported an increased risk of spina bifida in children of parents exposed to Agent Orange.


Chemical Warfare?


The Vietnam War spanned fourteen years, from 1961 to 1975. During that period, Agent Orange and related chemicals were used as weapons for almost ten years (from 1961 to 1970). Of course, the same chemicals had previously been used during World War II and the Malayan War in the 1950s; however, in terms of scale and quantity, the chemical campaign in Vietnam was the largest ever in military history.


One of the questions the world has pondered since the beginning of Operation Ranch Hand is whether the spraying of Agent Orange and other herbicides during the Vietnam War was a violation of international law, or whether it was chemical warfare. The 1907 Hague Convention prohibits the use of poison or poisoned weapons or more generally, the use of arms or materials calculated to cause unnecessary suffering.40 The Geneva Protocol of 1925 reinforced the Hague Convention and further banned the use of asphyxiating, poisonous, or other gases usually referred to as chemical weapons.41


In 1966, resolutions were introduced at the UN charging the United States with violations of the 1925 Geneva Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous, or Other Gases, and of Bacteriological Methods of Warfare. In 1969 the UN General Assembly resolved that the Geneva Protocol of 1925 outlawing the use of chemical or biological weapons applied to herbicide and riot control agents.42 However, the United States did not accept this interpretation and voted against the resolution. Nevertheless, the resolution was adopted on December 16, 1969, by a vote of 80 to 3 with 36 abstentions.

Therefore, the chemical campaign in Vietnam was considered by the international community to be a violation of international law. In 1964, the Federation of American Scientists had expressed opposition to herbicides in Vietnam on the grounds that the United States was capitalizing on the war as an opportunity to experiment in biological and chemical warfare. If the use of Agent Orange during the Vietnam War was chemical warfare, then it must stand as the largest waging of chemical warfare in human history. Indeed, after examining the evidence of the effects of Agent Orange in a 2002 conference at Yale University, the world’s leading environmental scientists concluded that the United States had conducted the “largest chemical warfare campaign in history.”43

Issues of Reparation


Human rights organizations, such as the European Convention for the Protection of Human Rights and Fundamental Freedoms of 1953 and the American Convention on Human Rights of 1978, have contended the right to compensation for victims of war.44 The issue of reparation to victims of Agent Orange has been raised, as there is evidence suggesting that the U.S. military knew of the toxicity of Agent Orange. Indeed, in a letter to Senator Tom Daschle dated September 9, 1988, Dr. James R. Clary, who worked at the Chemical Weapons Branch of the Air Force Armament Development Laboratory in Florida, wrote:


When we [military scientists] initiated the herbicide program in the 1960s, we were aware of the potential for damage due to dioxin contamination in the herbicides. We were even aware that the military formulation had a higher dioxin concentration than the civilian version due to the lower cost and speed of manufacture. However, because the material was to be used on the enemy, none of us were overly concerned. We never considered a scenario in which our own personnel would become contaminated with the herbicide. And, if we had, we would have expected our own government to give assistance to veterans so contaminated.45


In 1984, American and Australian veterans brought a class action lawsuit against the chemical companies that produced Agent Orange for military use during the war. (It should be noted that the U.S. government cannot be sued without its consent; therefore, all civil action has instead proceeded against U.S. companies). The suit resulted in an out-of-court settlement, in which an amount of $180 million was paid to veterans with death or total disability claims. Since 1991, the U.S. government has been required by law and the Agent Orange Act to provide health care and disability compensation to American veterans exposed to Agent Orange and suffering from any of the Agent Orange-associated diseases listed by the Institute of Medicine in Table 3.46


However, the United States has yet to compensate victims in Vietnam. In 2004, the Vietnamese Association for the Victims of Agent Orange/Dioxin (VAVA) filed a class action suit against the companies that manufactured Agent Orange for military use during the war. These companies include some of the biggest names in the industry: Monsanto Chemical Co., Dow Chemical Co., Hercules Inc., Occidental Chemical Corp., Pharmacia Corp., Uniroyal Inc., Diamond Shamrock Agricultural Chemicals, American Home Products Corp., and others. In the suit, VAVA alleged that the companies violated international law, committed war crimes, crimes against humanity, torture, intentional infliction of emotional distress, and unjust enrichment.


In early 2005, Judge Jack B. Weinstein of the U.S. District Court of New York dismissed all the charges against Agent Orange manufacturers. In his decision, the judge appears to have sided with the companies’ position and states that Agent Orange was an herbicide, not a poison, and that the agent was not used to intentionally inflict harm and suffering to people.47 However, this position can be challenged. Agent Orange contains a significant amount of dioxin, considered one of the most (if not the most) toxic compounds known to humankind. In 1997, the International Agency for Research on Cancer classified dioxin as a carcinogenic substance. As documented earlier in this chapter, four decades of scientific data, accumulated from numerous epidemiological, clinical, and basic studies, have clearly indicated that exposure to dioxin or Agent Orange is causally related to a number of cancers, diabetes, spinal bifida, and possibly birth defects. Therefore, from a scientific point of view, it seems illogical and erroneous to state that Agent Orange is not a poison.


Concerning the intent of use of Agent Orange, the judge seems to have confused the chemical companies with the soldiers who actually used the chemicals. The soldiers may not have known the extent to which Agent Orange was dangerous, and may not have used it intentionally to cause harm to people. However, the manufacturers did know about the product’s carcinogenic and teratogenic properties, and intentionally continued to manufacture the chemicals in high concentration. It should be noted here that cigarettes and asbestos (and, for that matter, many other products) were not initially designed to cause harm to people. However, since it is now known that they do, the companies that produce them have been found liable for the resulting harm, since they knew about the damaging effects and did nothing to prevent them.


The use of Agent Orange in the Vietnam War, as mentioned above, fits the description of a war crime according to the Nuremberg rulings. Due to a lack of political resolve from the Vietnamese government and lack of accessible judicial forums, the Vietnamese victims of Agent Orange still have not been recognized and/or compensated. In 2000, the Vietnamese government took a positive step toward compensation by introducing the Agent Orange Central Payments Programme. Under this program, adults and children who have partially or totally lost the ability to work due to exposure to Agent Orange are eligible for financial assistance. However, the assistance is very modest, ranging from only $3.40 to $7.14 per month per person.48


Wars have long and lasting echoes. In Vietnam, the echoes of the war are children born to parents affected by Agent Orange, people who have survived the trauma of their births, brain-damaged infants who cannot express themselves, luckless children so enraged and depressed at their miserable fate that they are tied to their beds just to keep them safe from harm. Some of them are the victims of Agent Orange in Vietnam. They, just like their counterparts in the United States, also share an innate belief in justice. Now that U.S.–Vietnamese relations are increasingly cordial, it is time for the U.S. government and the chemical companies involved in the Vietnam War to take responsibility for the damage caused by their actions and products, and to contribute toward the rehabilitation of the true victims of Agent Orange. These actions would help heal the wounds of the war, which have been prolonged for more than forty years. Let us hope that never again will Agent Orange or any such chemical be used in any war in the world.


PS: The reference section has been corrupted. I will post the reference list once I have figured out how to restore it.


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© 2018 Tuan V Nguyen

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