Pesticide and Environmental Update

In Memory of Richard Schneider from Fort Collins, Co
who served As a Marine in Vietnam
(1950-2003)

More Were Exposed to Agent Orange

Researchers at Colombia University have dramatically increased estimates of both the levels of exposure and the number of people sprayed with Agent Orange during the Vietnam War. The study, published in the British journal Nature on April 17, 2003, reports the dioxin contaminants to be as much as four times higher than previous estimates, and mapped villages in which 2.1 million to 4.8 million people were directly sprayed with the herbicides.

From 1961 to 1971, the U.S. and South Vietnamese armies sprayed millions of liters of toxic herbicides, mainly Agent Orange, over approximately 10% of South Vietnam to destroy the dense tropical forests and crops that provided cover and food for combatants. According to official U.S. reports, "Operation Ranch Hand," as the spraying programs were called, destroyed 14% of South Vietnam's forests, including 50% of the mangrove forests.

The spraying program identified various herbicide mixtures with colored stripes on the containers, as Agents purple, white, pink, blue and green. Agent Orange was the most common herbicide formulation used.

About 65% of the herbicides were 2,4,5-trichloropheneoxyacetic acid (2,4,5-T), which contains TCDD, the most dangerous form of dioxin. Dioxin is highly toxic and a known human carcinogen. In the U.S., Vietnam veterans are now compensated for ten diseases as well as the birth defect spina bifida that have been linked to exposures from spraying in Vietnam.

The Colombia University report's new estimates of dioxin contamination in Vietnam and neighboring Laos are derived from an extensive search of flight logs in the U.S. National Archives. Researchers were able to determine that more chemicals were sprayed in the earlier years of the war when the herbicides had higher levels of dioxin and were, therefore, more dangerous than those used later. By connecting census data collected during the war with the more accurate flight mapping, the researchers found that a far greater number of people had been exposed. The author of the report, Dr. Jeanne Mager Stellman of the Mailman School of Public Health said, "The number of people in hamlets that flights were directly over number in the millions. I was quite astounded by this."

The report points out that no large-scale epidemiological study of herbicides and the health of affected populations in Vietnam or of war veterans has been done. In the late 1990s, the Vietnamese government estimated that over 70,000 people in that country were experiencing medical problems caused by their exposure or their parents' exposure to Agent Orange; the Vietnamese Red Cross has tallied more than a million people affected.

Two years ago, the U.S. and Vietnam agreed to study dioxin contamination in Vietnam, partly in response to evidence that dioxin residues were still exposing residents through the food supply. A 2001 study by U.S. and Vietnamese government scientists found alarming levels of dioxin in the blood of residents of a southern Vietnamese city, Bien Hoa--even among those who didn't live there during the Vietnam War or were born after the war ended. Based on these results, researchers called for immediate widespread testing of blood and food samples. Because consumption of animal fat is the source of 95% of dioxins found in humans, researchers emphasized the urgency of determining which foods were contaminated.

The Colombia University researchers also raised the urgent need for additional study. The new information that pinpoints spraying locations should be the basis for a comprehensive study of the effects of the herbicides, "The major point is there is a new inventory and we now have an experimental methodology," said Dr. Stellman. "It's time to go ahead and do some studies before we are all dead."

Sources: The extent and patterns of usage of Agent Orange and other herbicides in Vietnam, Jeanne Mager Stellman, Steven D. Stellman, Richard Christians, Tracy Weber & Carie Tomasallo, Nature, April 17, 2003, http://www.nature.com; Researchers Raise Estimate on Defoliant Use in Vietnam War, New York Times,