Two Harvard biochemists have found that a herbicide used by American forces in Indochina included a highly toxic contaminant which could seriously threaten human life.
Matthew S. Meselson, professor of Biology, said yesterday that he and Robert W. Baughman, a graduate student in Chemistry, have discovered traces of the poison, dioxin, in fish and crustaceans caught in South Vietnamese rivers and coastal waters.
Dioxin forms during the manufacture of 2, 4, 5-T, a chemical in the military herbicide arsenal known as "agent orange." "Dioxin is 100 times more poisonous than the most powerful nerve gas," Meselson said.
The most popular of three herbicides used by the United States to defoliate forests and kill crops in Indochina, "agent orange" was used until April 1970, according to Meselson, primarily in South Vietnam and Laos, and once in Cambodia and the Demilitarized Zone.
Although some American personnel recognized the danger of the herbicide's side-product, reports "never made it up the chain of command, as far as I know," Meselson commented. But members of the American Association for the Advancement of Science, recognizing the hazards, asked Meselson to study the effects of the chemical.
After collecting specimens and data in South Vietnam in the fall of 1970, a five-man team, including Meselson, Baughman and John D. Constable, assistant clinical professor of Surgery, began to study various effects of the herbicide.
They found that dioxin is especially dangerous because of its stability and cumulative toxicity, Meselson said. "As a result of these properties, the poison may pass down the food chain until eventually a human could eat an animal with a high accumulated level of dioxin," he noted.
Dioxin has caused birth defects and death in animals, and Meselson said that there have been scattered reports in South Vietnam of fatal herbicide poisoning. In addition, the five scientists found that in some areas in South Vietnam, after herbicide spraying, the rate of still births doubled.
"An evil genius could not devise a toxin with more evil properties," Meselson said.
The study should be completed in six weeks, after samples of South Vietnamese mothers' milk and the statistics on still births are reviewed, Meselson said. Afterwards, he added, he hopes to study the possible harmful effects of spraying 2, 4, 5-T on farmland in the United States.