This is Bob Doughty. And this is Ray Freeman with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in Science. Today we tell about a chemical used by American forces during the Vietnam War in the Nineteen-Sixties and Nineteen-Seventies.
The Vietnam War ended more than twenty-five years ago. South Vietnamese forces officially surrendered to North Vietnam on April thirtieth, Nineteen-Seventy-Five. The Vietnam War affected the lives of millions of people. Today, it still affects many lives. Studies say chemicals used during the war continue to affect people many years after the fighting stopped.
During the war, American military forces attempted to destroy the natural hiding places of enemy forces. They sprayed about seventy-two-million liters of chemicals to kill plant growth over more than one-million hectares of what was then South Vietnam. They sprayed the chemicals between Nineteen-Sixty-Two and Nineteen-Seventy-One.
Most of the chemical mixtures contained dioxin. Dioxin is a substance known to cause cancer and birth defects in animals. The chemical mixture used most often was called Agent Orange.
Many Americans who fought in Vietnam experienced health problems after the war. Hundreds of the veterans blamed Agent Orange.
One critic of Agent Orange was Elmo Zumwalt, Junior. Admiral Zumwalt served as Commander of American Naval Forces in Vietnam from Nineteen-Sixty-Eight to Nineteen-Seventy. Later, he served as Chief of Naval Operations and a member of the Joint Chiefs of Staff. Admiral Zumwalt thought the United States should not have been involved in the Vietnam War. For him, the war represented a useless loss of life. It also represented a painful personal loss. His oldest son served with the American navy in Vietnam. Several years later, he died of cancer -- possibly caused by Agent Orange.
Admiral Zumwalt had ordered the spraying of Agent Orange along rivers guarded by his son's boat. At the time, military officials did not know about the harmful effects of the chemical.
After he retired, Admiral Zumwalt worked to correct the wrongs done by Agent Orange. He said government officials refused to admit the harm that had been done to Vietnam veterans. He said there were attempts to hide the link between Agent Orange and the diseases it may have caused.
Veterans groups repeatedly criticized studies that showed little or no health problems caused by Agent Orange. One study in Nineteen-Ninety, for example, found no evidence of a link between Agent Orange and disease in humans. Another report said the chemical dioxin appeared to be less dangerous than some scientists believed. That study showed very high levels of dioxin can cause cancer in humans. But it also found dioxin might not be a cancer threat at lower levels.
In Nineteen-Ninety-One, Congress ordered an independent scientific study of the Agent Orange issue. The National Academy of Sciences organized the study. Congress also told the government to begin paying former soldiers who developed any of three diseases after serving in Vietnam. Two of the diseases are cancers – non-Hodgkin's lymphoma and soft tissue sarcoma. The other is a severe skin disease – chloracne.
In Nineteen-Ninety-Three, a committee of the Institute of Medicine released its report. Committee members studied almost six-thousand-five-hundred scientific reports about the effects on humans of the chemicals used to kill plants.
The committee found a link between two other health conditions and Agent Orange. One is another kind of cancer – Hodgkin's disease. The second is a serious skin disease – porphyria cutanea tarda. The government added them to the list of diseases for which American veterans can receive payment and free medical treatment.
Later, other cancers were added to the list. Government assistance also is offered to the children of some veterans. Studies found that veterans who worked with Agent Orange face an increased risk of having a child born with spina bifida. Spina bifida is a serious birth defect in which the baby's spinal cord is not completely covered.
Last year, the Defense Department released evidence linking Agent Orange to the disease diabetes. The information came from a study of one-thousand former members of the Air Force. They all had worked on airplanes that sprayed Agent Orange or other chemicals. The study found that the Air Force veterans were more likely than other war veterans to get diabetes. It also showed that the disease seemed to affect them sooner and more severely.
A few months later, the National Academy of Sciences released another report on the effects of the chemicals used in Vietnam. The Academy reported limited evidence of a link between the chemicals and Type Two diabetes. The Department of Veterans Affairs estimates that about nine percent of Vietnam veterans have Type-Two diabetes.
Three months ago, a study by the National Academy of Sciences also linked Agent Orange to a form of leukemia found in some children. It said the children of veterans exposed to the chemicals used in Vietnam might have an increased risk of developing the disease.
Acute myelogenous leukemia is a cancer of the bone marrow cells that form two kinds of white blood cells. The disease spreads quickly, often killing its young victims.
Agent Orange also has affected many people in other countries. The government of Vietnam estimates that as many as two-million Vietnamese adults and their children have health problems caused by chemicals used during the war.
In Nineteen-Ninety-Four, a Vietnamese committee joined with a Canadian group, Hatfield Consultants, to begin studying the effects of Agent Orange. Research scientists selected the Aluoi Valley -- a place near the border with Laos -- as the main study area. The Aluoi Valley was heavily sprayed with Agent Orange and other chemicals from Nineteen-Sixty-Five to Nineteen-Seventy.
The study was designed to follow the movement of dioxin through the environment. The researchers tested soil from a farm and a former American military base. They also tested tissue from fish and ducks, and blood from people living in the area.
Tests showed soil from the former military base had the highest levels of dioxin. Fish and material from waterways also had high dioxin levels. Agent Orange dioxin also was found in human blood. High levels were found in people older than twenty-five, and in those between the ages of twelve and twenty-five. The researchers said the presence of dioxin in the young people provides evidence that the environment remains harmful. They say it shows dioxin is moving from the food grown in the area into humans.
Two years ago, the researchers carried out more studies in the Aluoi Valley. The tests confirmed higher than normal levels of dioxin in soil taken from the valley and in food. High levels of the chemical also were found in fish and bird tissues. And high levels were found in human blood and human breast milk collected from a village near the former American military base.
The researchers said adults and children born after the war continue to eat foods with higher than normal levels of dioxin. They said chemicals at the military base may be continuing to pollute the area.
Earlier this month, scientists representing Vietnam and the United States met in the Vietnamese capital, Hanoi. The scientists agreed to work together to study the effects of Agent Orange on human health and the environment. They also agreed to examine the soil in Vietnam for dioxin.
The American side included representatives from the Environmental Protection Agency and the Centers for Disease Control and Prevention. The Vietnamese delegation included scientists from the National Center for Natural Science and Technology.
The Vietnamese and American scientists also agreed to hold a joint scientific conference on the effects of Agent Orange. Plans call for the conference to open next April in Vietnam.
This SCIENCE IN THE NEWS program was written by George Grow. It was produced by Caty Weaver. This is Ray Freeman. And this is Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.