Le Cao Dai, 74; Top Vietnamese Expert on Agent Orange’s Effects


Le Cao Dai, Vietnam’s leading expert on the damaging effects of the defoliant Agent Orange, which the U.S. used to clear jungle cover during the Vietnam War, died Monday in Hanoi. He was 74.

Dai had been hospitalized for acute pancreatitis for two weeks before his death.

Thirty years ago, Dai was a North Vietnamese army surgeon treating wounded soldiers in the South Vietnam jungle near Pleiku when a thick fog drifted down from a plane. Within days, the dense vegetation around the army hospital began to yellow and die.

The cause was Agent Orange, vast quantities of which the U.S. sprayed over swaths of what was then South Vietnam. Its chief ingredient was dioxin, one of the deadliest toxins created by man and known for its persistence as an environmental contaminant.


Of the 19 million gallons of herbicides the U.S. sprayed over South Vietnam between 1962 and 1971, about 55% was Agent Orange.

“I knew it was some kind of chemical, but I didn’t know what,” Dai told People Weekly magazine a few years ago, recalling the first time he witnessed the release of the defoliant. “What we didn’t know then was that Agent Orange would go on killing people and causing many kinds of illnesses and disorders in their children.”

Dai carried out some of the earliest studies in Vietnam showing Agent Orange’s toll. He went on to direct the Agent Orange Victims Fund of the Vietnam Red Cross, which raises money to care for roughly 1 million people believed to be suffering from dioxin poisoning.

He also was outspoken in his call for the U.S. to help clean up the problems associated with dioxin contamination.

“He was the Albert Einstein of Agent Orange and dioxin research,” said Dr. Arnold Schecter of the University of Texas School of Public Health in Dallas, who collaborated with Dai on several studies. “He had a wonderful gift for knowing where to look, where to sample people. And he had a historic knowledge of the actual spraying of Agent Orange. A major Vietnamese scientist is gone ... the most knowledgeable by far” on Agent Orange and its legacy.

In the mid-1980s, Dai and Schecter began to jointly investigate the consequences of Agent Orange use. They gathered soil and river-bottom samples, and examined former North Vietnamese soldiers and their children to determine the human price of exposure to dioxin.

Based on their findings, the Vietnamese government estimated that the use of Agent Orange killed or maimed 400,000 Vietnamese. The survey concluded that another 500,000 children suffered defects such as retardation and spina bifida.

The researchers found that of the offspring of North Vietnamese soldiers who fought in the south and were exposed to Agent Orange, 5% were born with defects, compared with only 1% of the children of those who fought in the north.


Vietnam cares for several hundred of the children believed damaged by their fathers’ Agent Orange exposure in eight “peace villages,” mainly in Hanoi and Ho Chi Minh City.

Dai often urged the U.S. government to help clean up the areas polluted by dioxin. He and other researchers have identified as many as 50 dioxin “hot spots” in southern Vietnam, mostly around former U.S. air bases.

Last month, he and Schecter announced the results of a study that showed extremely high levels of dioxin in the blood of people living near the former U.S. base at Bien Hoa, near Ho Chi Minh City.

“We’re not talking about guilt here,” Dai said a few years ago. “But I believe the U.S. has a moral responsibility to help us clean up contaminated areas.”


According to Schecter, Dai was frustrated by what he felt was an inadequate response to the problems of dioxin contamination not only from the U.S., but also from his own government, which worried that too much publicity about dioxin levels would hurt the country’s agricultural exports.

“You cannot forget the people who are suffering just to make profits in trade,” Dai said recently.

Dai served as an army surgeon from 1966 to 1974 in a North Vietnamese Army field hospital near Pleiku in the Central Highlands. He retired as a colonel in 1984 because of an eye condition that left him nearly blind.

Dai said he had experienced a mild exposure to Agent Orange during the war, but no dioxin was ever found in his blood. He attributed his luck in this regard to his distaste for fish, which he believed to be a major source of dioxin poisoning in Vietnam.


Although still suffering the ill effects of a serious stroke last year, Dai participated in March in an unusual joint conference on Agent Orange in Hanoi that brought together environmental officials and scientists from the U.S. and Vietnam.

The meeting produced an agreement to set priorities for research on cleanup efforts, as well as on possible links between dioxin poisoning and a host of health problems from miscarriage to cancer.

He is survived by a wife, a daughter and sisters.