This website was created for Biology 361: Genetically Modified Organisms at Davidson College.by Mike Chase and Monica Siegenthaler
A Critical Report on The Effects of Agent Orange and Dioxin Following the Vietnam War.
The Twentieth Century has seen the boom of chemical agriculture. Pesticides, herbicides, and defoliants have improved immensely over the past decade giving rise to new and improved means of food distribution. Mankind can ill afford to turn its back on these advances, but we must watch ourselves as we find other outlets for our creative abilities. Although beneficial to many when used correctly, indiscriminate applications of them will cause gruesome damage to humans and irreversible damage to the environment. The use of Agent Orange during the Vietnam War proved to solidify the most negative outcome of our technological advancements (Ministry of Health, 1993).
Agent Orange received its name through the military coding system for herbicides used in Vietnam. The fifty-five gallon drums that the chemicals were transported and stored in were labeled with different colored bands to distinguish each one. Agent Orange was labeled with an orange band and was one of fifteen other types of herbicides sent to Vietnam. Agent White, Agent Blue, and Agent Pink were among other chemicals used in Vietnam, but none of them to the extent of Agent Orange (CDC, 1987).
Agent orange was an herbicide developed for US military use in the early 1960’s. A chemical mixture of 2,4-D (2,4, dichlorophenoxyacetic acid) and 2,4,5-T (trichlorophenoxyacetic acid), the resulting compound proved to be extremely toxic (Hatfield Consultants, 1999). Both herbicides used to create Agent Orange were developed as weed killers in the 1940’s and showed positive results on broad leaf plants and numerous crops. However, during the creation of 2,4,5-T, Dioxin, a compound with known toxicity to some experimental animals was generated (CDC).
Dioxin, also known as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is a human carcinogen and developmental toxin that has target sites on the skin, liver, immune system, and neuroendocrine system. TCDD was never made deliberately, but is highly persistent and has bioaccumulated throughout the biosphere. Today, there are measurable amounts of dioxins in all types of biota (Silbergeld, 1992).
From 1962 to 1971, the U.S. military sprayed over 20 million gallons of herbicides in Vietnam, 11 million of which were Agent Orange (~55%) (Ministry of Health, 1993). The U.S. Air Force project, Operation Ranch Hand, was responsible for the majority of the fly-by spraying. 1.6 million gallons were additionally sprayed by helicopter and surface spraying was also done by troops around camp perimeters. (Hunnicutt, 1999).
Agent Orange was used primarily for defoliating the jungle over-growth covering much of South Vietnam. All herbicides used in Vietnam were developed to deny concealment to the enemy and in extremely dense terrain they were used to protect American and Allied troops from ambush or other movements of the enemy. The leaves of trees became a yellowed color, shriveled, and fell off within a couple days of an Agent Orange application (Rose, 1972). According to official US reports, Operation Ranch Hand destroyed 14% of South Vietnam’s forests, including 50% of the mangrove forests (Hatfield Consultants). Perimeter spraying by hand or helicopter at base camps was used to control the growth of tall grasses and brush. To keep the brush at a desirable height, recurrent applications took place every 2-3 months (Hunnicutt).
During the war, fighting, bombing, defoliation, and forced population movements uprooted a normally static agricultural people and converted them into nomads. Main crops including cassava, maize, rice, sweet potato, bananas, and coconut withered in herbicidal exposure. In Vietnam’s ecosystem today, there remains a certain level of residual dioxin in areas where spraying and storage of Agent Orange occurred. Each of the two herbicides used to create Agent Orange break down easily in the environment, but dioxin is a highly persistent compound that remains in the environment for decades (Hatfield Consultants). Numerous environmental effects have continued to plague the residents of South Vietnam thirty years after the chemical spraying. Agent Orange devastated the hillsides of Vietnam; every tree and every plant was killed, leaving no root systems left to protect the soil from erosion. Without the sturdy root system of the massive jungle, the highlands have succumbed to horrible landslides, commonly blocking transportation routes. Landslides could not occur without an abundance of rain. Also attributed to the rootless earth are powerful floods—the worst in 100 years. Had the hillsides still been covered by the lush jungle growth, the floods would not have been that bad (Zwerdling, 2000).
The most noticeable environmental effect from Agent Orange is the new plant growth occurring on the bare soil. Where lumbering trees and overgrown vegetation once thrived, today there exists only a thick green grass. The Vietnamese call this grass “American Grass.” The grass grew in after the herbicidal spraying and has since choked out any chance of trees growing back (Zwerdling).
Environmental effects of Agent Orange have also begun to effect humans as well. There have been high levels of dioxin found in the blood of Vietnamese people born after the war, suggesting that contaminants are being transferred through the food chain. To substantiate this claim, dioxin was also found in lower trophic levels of the food chain including fish and other animals (Hatfield Consultants). Dioxin passed to humans through the food chain could also come from incinerators, chemicals, and pulp mill waste discharges. All sources of dioxin in the ecosystem are accumulated and biomagnified in the food chain when passed to top consumers, including marine mammals and humans (Silbergeld).
Arguably the most significant issue involved with Agent Orange and the chemical dioxin are human related effects. Dioxin has already made its mark as one of the most toxic chemicals ever studied and research in laboratory animals and humans suggest that dioxin can cause birth defects, cancer, and diabetes (Zwerdling). Countless studies have tried to associate multiple diseases and health problems with dioxin/Agent Orange exposure in Vietnam veterans. It is known that a chloracne, acne of the face similar to that of teenagers and young adults, is directly related to exposure of dioxin. This acne is used as a clinical sign of exposure to dioxin, but is extremely hard to identify. There have been some cases of veterans with persistent chloracne for over 25 years since first being exposed to Agent Orange (Rose).
The Department of Veterans Affairs has established regulations implementing provisions necessary to veterans exposed to dioxin or other herbicides. They also recognized soft tissue sarcomas and peripheral neuropathy as a basis for compensation. Soft tissue sarcomas develop from body tissues such as muscle, fat, blood, lymph vessels, and connective tissues. Tumors associated with soft tissues are relatively rare. Veterans, who have been exposed to herbicides containing dioxin and have peripheral neuropathy connected to their service in the armed forces, can claim some compensation from the government. Peripheral neuropathy is a nervous system condition that causes numbness, tingling, and weakness in the limbs (Department of Veterans Affairs, 1991).
Many studies performed by independent labs, the Vietnamese government, and the United States Government, have tried to associate a plethora of health problems to Agent Orange such study, performed in Canada by the University of Minnesota and the EPA, looks to link birth defects to Agent Orange and dioxin exposures. Spina Bifida, a neural tube disorder, was shown in the children of veterans, to have a strong association with exposure to dioxin. This study supports the actions of the United States Department of Veteran Affairs, which grant compensation for the children of veterans who suffer from spina bifida (Claxton, 1997).
In 1989, the science world attributed two cancers, softer tissue sarcomas and non-Hodgkin’s lymphomas, to Agent Orange. In an article written in 1997, the National Academy of Sciences (NAS) recognized ten cancers significantly associated with exposure to Agent Orange/dioxin in Vietnam veterans. Other Operation Ranch Hand studies have seen higher rates of diabetes in U.S. Air Force personnel who were exposed to Agent Orange/dioxin. Reinforced by animal studies conclusively showing that dioxin causes glucose imbalance and diabetes, a dose response relationship between dioxin exposure and diabetes in Vietnam veterans was established (Claxton). One criticism of this study was that the veterans’ tendency to be overweight and not exposure to herbicides caused the diabetes.
Every study involved with Agent Orange has brought about the same criticisms: there are numerous other factors that can blur the data collected and the results obtained. For instance, the ability of the government to correctly identify the exact location of spraying that occurred 30 years ago couldn’t be that accurate. Government documents allow for general locations to be assumed, but within those locations the movement of troops in and out of those areas during the war is almost impossible to document. Thousands of troops stationed at numerous bases could have been exposed in some manner to Agent Orange. In 2000, it was estimated that over 7,000 veteran have been compensated by the US government for exposure to Agent Orange (Zwerdling). Unfortunately, this number is nowhere near reality. How many soldiers have died in the past 30 years that fought in Vietnam? There is no conceivable way to calculate what effects dioxin had on them. The lack of knowledge and technology two decades ago didn’t allow scientists to uncover the facts about dioxin, overlooking what were thought to be natural deaths, but possibly could have been exposure deaths.
Most human effects of Agent Orange have concentrated on US soldiers and their families; however, we must remember who the chemicals were dropped on. Vietnamese soldiers, men, woman, and children were all affected by dioxin exposure in the late 1960’s. It is estimated some 70,000 people in Vietnam have medical or physical problems caused directly, or indirectly through their parents’ exposure, by dioxin. At the center for disabled children in Hanoi, a children’s home founded specifically for victims of Agent Orange, most children are mentally handicapped. Vietnamese government and foreign aid groups have joined forces to erect almost a dozen children’s homes called Peace Villages (Zwerdling). Vietnamese citizens recall the horrific tragedies of Agent Orange spraying on their physical being. Vomiting and nausea affected most of the exposed people. Diarrhea, skin burning, and reddening and inflammation of the eyes were some of the first side effects of spraying the chemicals. The next stages of exposure included long-term persistent effects including pustules, scabs, eczema, and the chloracne that allied soldiers experienced (Rose). Because children of the Vietnamese were not exposed to the chemical directly, it has been proposed that the effects of Agent Orange are genetically manipulating the human body.
Studies throughout the past 30 years have brought about many allegations about Agent Orange. Unfortunately, because time is passing quickly and studies depend on the data directly from those exposed to the chemicals, the sample size (those who fought in the war) is shrinking. To accurately assess what damages dioxin has done to the body, researchers must eliminate as many errors in data as possible. This becomes extremely difficult because of environmental exposure to other toxins. Some experts have questioned whether or not DDT is to blame for some of the problems attributed to Agent Orange. DDT has similar environmental and health effects as dioxin and there were significant amounts of DDT used to boost the agricultural reform in Vietnam in the early 1980’s (Tran, 2002). Exposure to smoke, chemicals, pollutants, and other toxins complicate the data that must be interpreted by scientists.
A quick and reliable outcome defining the effects of Agent Orange would be the optimum result of these studies. However, other factors will continue to delay accurate results. A newspaper in San Diego, California investigated the US Air Force’s $200 million study, which began in 1979 and will conclude in 2006. It was found to have so many flaws it could be considered useless. Two reports revealing serious birth defects among children of veterans was withheld for years and other facts about cancer and birth defects included in their report were altered, making the risks appear less serious. Others complain that the study is skewed because it was performed by scientists within the military, instead of objective scientists from the NAS. It is clearly shown that even the US government wants to downplay the health problems of Vietnam Veterans and the effects of Agent Orange (Hatfield).
Errors found in the US programs are only the tip of the iceberg in incompetent studies. Multiple issues arise when attempting to solve the dioxin exposure problem. Politics assume a great role in the solution to the problem, yet government agencies seem to be avoiding a direct answer. Discussions of the health effects associated with Agent Orange and dioxin have been fueled by contradictory results in studies (Gough, 1989). Since there is no definitive human data, the Environmental Protection Agency has assumed the worst possible results for dioxin exposure, implementing a linear risk assessment model that states there is no safe limit of dioxin and that toxic effects rise with dosage (Roberts, 1991).
In order to create effective remedies or preventive measures against dioxin, the mechanism by which the chemical works must first be determined. Some think Agent Orange and dioxin directly effected genes in the chromosomes, resulting in multiple aberrations that could be passed from generation to generation (Ministry of Health). Other more recent research has focused on the early cellular responses following binding of dioxin to its receptor. Dioxin binds to its receptor and is translocated to the nucleus, where an alteration of gene transcription occurs. This sequence of events seems to follow a linear relationship with concentrations of dioxin in the cell (Silbergeld). In a testimony to the United States Government, Dr. Silbergeld states,
“Most, if not all, of the significant toxicological effects of dioxin involve an endogenous, naturally occurring macromolecule found in many cells, including skin, liver, placenta, lymphocyte and glial cells from humans. This macromolecule serves to translocate dioxin within the cell, into the nucleus, and to mediate its effects on the transcription of specific portions of the genome. The type of cell, the presence of other regulatory proteins, and the developmental stage of the organism all influence the specific outcome at the cell and organ level, but across all cells and organisms the initial molecular steps of cellular response to dioxin appear similar (Silbergeld).”
If receptor binding is the first step in the acquisition of dioxin by a cell, then that implies there is a “safe” dose or practical “threshold” below which no toxic effects occur. Unlike many carcinogens, dioxin must first bind to and activate a receptor before it can cause cancer or any of its other effects. A threshold idea came into play because a minimum number of receptors must be occupied by dioxin before the receptor complex is “activated” (Roberts). EPA scientist Linda Brinbaum, director of the environmental toxicology division of EPA’s Health Effects Research Laboratory states, “It’s a new way to do risk assessment. We can set a limit below which there cannot be an effect, on a mechanistic basis (Roberts).” However, Silbergeld specifically states in his testimony that it is erroneous to suggest the existence of a receptor somehow implies that low level effects of dioxin at the cellular level must have a threshold (Silbergeld). These arguments presented by two different, respectable researchers prove the problem of inconsistent support behind the effects of dioxin exposure.
Political powers have tried to joint fix the national Agent Orange issue. In May of 2002, the United States-Vietnam Scientific Conference on Human Health and Environmental Effects of Agent Orange/Dioxin was held in Hanoi. Vietnamese and American scientists, and international experts came together to discuss the repercussions of Agent Orange. The broad assessment of Agent Orange that was expected to occur at the meeting was overridden by an independently launched campaign by the Vietnamese government to achieve its own goals, and not those of the conference. The issue of compensation for diseases associated with dioxin exposure awarded to US soldiers and not to Vietnamese loomed heavily over the conference. But, in defense of the US, President Clinton made a political decision to compensate veterans and US government scientists have not recognized a causal effect (Tran).
As the Vietnam War drifts further into the past, the expectation of solving issues of Agent Orange and dioxin exposure look forward into the distant future. Undiagnosable symptoms and refuting scientific reports questioning the origin of dioxin effects on the molecular level, have etched this issue into the woodwork of scientific history. As political powers butt heads and scientific researchers dawn their lab coats, we await the long overdue answers to Agent Orange’s devastating questions.
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