Kuni Takahashi, Chicago Tribune

The most dangerous of the lingering environmental impacts is not the destruction of the landscape. It’s the continued presence of dioxin within the landscape.


At least two-thirds of the herbicides used during the war contained the herbicide 2,4,5-T, which was contaminated during the manufacturing process with dioxin (TCDD). It is difficult to know exactly how much dioxin was in the herbicides, as each company that produced the 2,4,5-T practiced different levels of quality control. Barrels of Agent Orange tested in Gulfport, MS and on Johnson Island before they were destroyed contained between 6.2 to 14.3 ppm TCDD contaminant. By examining the spray data, Dr. Jeanne Stellman and her colleagues at Columbia University Mailman School of Public Health determined that up to 366 kilograms of dioxin were sprayed over southern Vietnam during the war. Dioxin is a chemical that is normally measured in parts per trillion (ppt). One ppt is the equivalent of a drop of water in an Olympic-sized swimming pool.


The Investigation

Since 1994, Hatfield Consultants, a Canadian environmental firm, has done extensive soil, animal and human testing to determine how much of this dioxin remains in the soil and sediment in Vietnam, and whether or not it has entered into the food chain and into humans. The company began by testing in the A Luoi Valley just south of the DMZ, in a section of the country where the Ho Chi Minh Trail entered in from Laos and that was doused between 1965 and 1970 by 224 spray missions. In addition, the US military operated three special forces bases in the valley, including the A So base, which was used for three years and where barrels of herbicides were stored for use in the surrounding areas. The area is extremely remote, with no industry or intensive advanced agriculture by which dioxin or other Persistent Organic Pollutants (POPs) may be introduced into the environment. Any TCDD found in the A Luoi valley could confidently be traced back to the herbicides sprayed during the war. Hatfield tested soil in areas north of the sprayed regions and found no TCDD in the soil and very low levels of other POPs. The average level of dioxin in industrialized nations is less than 10 ppt, so any levels of dioxin found higher than this would be out of the ordinary in the US, never mind in areas of Vietnam with no industry.

Hatfield found that for the most part, where the herbicides were sprayed by airplanes, the dioxin has dissipated. Thirty years after the spraying occurred, TCDD levels ranged from zero to slightly elevated levels, with the latter especially pertaining below the soil surface. Some of the dioxin that remained on the surface after spraying may have broken down in the hot tropical sun, whereas the years of heavy rain and soil erosion may have also washed the dioxin away to where it may have pooled in isolated spots.



The Bases

However, the bigger concern was the bases that were in operation for several years and where the herbicides were stored. At the A So (A Shau) base, Hatfield researchers found

levels of dioxin up to 897.85 ppt. They also found that fish and ducks feeding in contaminated areas had high levels of dioxin in their fatty tissues. Moreover, the population that lived in the area also had elevated levels of dioxin, in the blood and breast milk. This proved beyond a doubt that the dioxin from Agent Orange was still found in pockets of the land in southern Vietnam, particularly around former military bases, and that the dioxin was entering into the food chain, causing a health threat to a generation born long after the end of the war. Even the Ta Bat and A Luoi special forces bases that were only in operation for one year had elevated levels of dioxin, ranging from 4.3 ppt to 35 ppt. (A Luoi spray map from Hatfield Consultants shown above.)


Hatfield theorized that there were other such "hotspots" throughout southern Vietnam and that former military bases were of particular concern, especially bases where Operation Ranch Hand was located. Since the mid 1990s, Hatfield has surveyed former US military installations in southern Vietnam and has identified at least 28 that are potential “dioxin hotspots." Testing by Hatfield and others at Da Nang, Phu Cat and Bien Hoa base, which were Operation Ranch Hand hubs, has found that parts of the bases are highly contaminated with TCDD. At the Da Nang airbase Hatfield found up to 361,000 ppt on the site where the barrels were loaded onto planes. In this part of the base you can still detect a strong chlorine smell from the phenols (solvents) in the herbicides reminiscent of garden weed-killer and see the blackened soil caused by the oxidized chlorine molecules in the herbicides.

“My children used to be healthy. But after we moved here,
my children grew weak and
passed away.”

– Can Van, re-located by the government in 1991 to the former
A So base, Chicago Tribune, 2009.

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Global Environmental Facility Report on Da Nang, Phu Cat and Bien Hoa Hot Spots.

Environmental Assessment of the Da Nang Remediation Project

Click on the image to view a map of the known and potential dioxin hot spots in Vietnam. The map was created by War Legacies Project. It is based on research by Hatfield Consultants and the 10-80 Committee. Funding for their research was provided by the Ford Foundation in a grant to the Vietnam's Ministry of Health in 2002. You must have Google Earth installed to view the map. VNDioxinhotspots.kmz