Agent Orange and Dioxin Hot Spots in Vietnam

Wayne Dwernychuk
Hatfield Consultants

During the American War, US military forces released over 72 million litres of herbicide into the environment of southern Viet Nam in a code-named mission called Operation Ranch Hand that extended from 1962 to 1971. The majority of the chemicals sprayed were Agent Orange in order to destroy forest cover and food crops. The Vietnamese have been exposed to these chemicals during the actual spraying, and it is suspected on a regular basis for the past 30+ years, primarily through contact with former US military infrastructure/bases. The "Hatfield Hot Spot Theory” was proven through field validation studies in A Luoi District, Thua Thien Hue Province in central Viet Nam. The ‘theory’ highlights those areas of Viet Nam where the most serious dioxin contamination is present. During the war, A Luoi District was known as the A Shau Valley, an important segment of the Ho Chi Minh Trail, immediately south of the former Demilitarized Zone (DMZ) which separated the former North and South Viet Nam.

In the fall of 1994, Hatfield scientists first visited Viet Nam and met with Professor Hoang Dinh Cau, Chairman of the 10-80 Committee in Ha Noi, the government body in charge of Agent Orange/dioxin research in Viet Nam. Hatfield representatives and Professor Cau developed a close working relationship and sincere friendship that fostered many successes in collaborative Agent Orange research, which continued until his death a few years ago. The early successes of Hatfield Consultants can be attributed to the hard work and dedicated efforts of other Vietnamese working closely with Professor Cau in the 10-80 Committee, including Dr. Le Cau Dai, Dr. Hoang Trong Quynh, Dr. Tran Manh Hung, and Dr. Phung Tri Dung.

Over the course of two years, subsequent to Hatfield’s first introduction to Viet Nam in 1994, numerous meetings were held to engage local scientists and government departments. After the two-year planning stage was completed, the Canadian/Vietnamese team decided to undertake Hatfield’s first study, in country, in A Luoi District, approximately 65 km west of Hue.

The objectives of the study were to determine dioxin levels in the environment and human population in A Luoi District, which included those areas that were sprayed by US aircraft (fields and forests), and areas that were used by the US military for their Special Forces bases. Three such bases existed in A Luoi District during the American War: A So, Ta Bat, and A Luoi. The A So base was in operation for the longest period of time, and was the site of extensive Agent Orange use.

Hatfield and Vietnamese scientists randomly selected sampling sites in A Luoi District including soils, sediments from fish ponds, a variety of foods (e.g., fish, ducks, chickens, rice, manioc, pork, and beef), human blood, and human breast milk. All samples were sent to Canada for laboratory analyses.

The dioxin data produced in the Canadian laboratory revealed a clear pattern of dioxin contamination in A Luoi District. Those areas sampled on the former US bases had the highest levels of dioxin, with the A So base (the one in operation the longest) recording the highest levels of the three bases. Areas that were sprayed by US aircraft (farmer’s fields and previously forested areas) had significantly lower levels of dioxin contamination.

At that point in time, these investigations were the most ‘systematic’ and ‘comprehensive’ studies ever undertaken in Viet Nam focusing on dioxin contamination. Hatfield/10-80 Committee studies were unique in that they not only addressed the issue of site-specific sampling data from a variety of environmental media, but they included the ‘integration of ecological consequences’ of Agent Orange use in A Luoi District by following dioxin in the food chain from contaminated soils, into contaminated fish pond sediments, into contaminated fish (and ducks that used these ponds), and ultimately into humans who consumed these fish/ducks. Clear evidence of this contaminant pathway was revealed, with the origin of dioxin in this pathway being Agent Orange, without any doubt. These studies centred on a single geographic region and integrated the elements of this ecosystem into a model for the movement of the dioxin molecule throughout the various structural compartments of this ecosystem.

From the many years of research in A Luoi District, Hatfield scientists theorized that other former US military bases in southern Viet Nam, where Agent Orange was present and used, also had a high probability of significant dioxin levels. Team members hypothesized that what was discovered in A Luoi District mirrored the situation that may exist in other areas of southern Viet Nam. Additional Hatfield studies were undertaken in the Ma Da Forest and Vung Tau area, as well as in the Mekong Delta and Central Highlands. These areas were sprayed by US aircraft. Dioxin levels in these soils were significantly lower than those levels recorded at the former US bases sampled by the Hatfield/10-80 Committee team. These data added further credence to the Hatfield Hot Spot Theory, and confirmed that areas aerially sprayed during the American War were now nearing background levels for dioxin in the environment

With the financial assistance of the Ford Foundation, studies were undertaken by Hatfield and the 10-80 Committee to assess former US bases in southern Viet Nam as to their potential to be contaminated with dioxin. The military history and present environmental conditions, related to dioxin contamination, were studied at Da Nang, Pleiku, Phu Cat, Nha Trang, Bien Hoa, Can Tho, Tan Son Nhut and other areas in southern Viet Nam. This series of studies concluded that the former US bases at Da Nang, Bien Hoa, and Phu Cat are the most contaminated of the bases studied and should be considered significant dioxin ‘hot spots’, with recommendations to initiate remediation of soils as soon as possible. Situated in close proximity to these bases are significant numbers of people who, in some way, may be in contact with contaminated soils and/or food that may have originated on these former US bases. Concern for the health of local people is of primary concern. As a result, it is critical that the pathways of dioxin transfer to people are understood and measures are taken to prevent human contamination.

Dioxin hot spots exist today in Viet Nam, and are potentially contaminating human populations living in close proximity to these locations. The most significant hot spots have been identified, but we recognize that others may also exist which have not yet been identified. However, Bien Hoa, Da Nang and Phu Cat require immediate remediation. These hot spots have very high dioxin levels due to higher levels of Agent Orange use during the American War, and the fact that these were key military bases for implementing Operation Ranch Hand. A significant point is that Hatfield hot spots are not the vast forested areas targeted by routine flights of Operation Ranch Hand C-123 aircraft. In the barren regions of A Luoi District, once consisting of triple-canopy jungle and heavily sprayed with Agent Orange, soils do not retain high levels of dioxin, given years of tropical rains, erosion, and chemical degradation. Forces of nature have reduced dioxin in soils in those areas where defoliants were originally dispensed from aircraft during planned spray missions.

Hot spots that exist today include those areas where Agent Orange was spilled, applied by truck-mounted and back-pack sprayers, including intensive perimeter spraying of bases, and washed out of aircraft spray tanks, thereby adding high levels of dioxin to soils; levels that were significantly higher than that resulting from aerial spray applications. For example, on the Bien Hoa base in the early 1970s, a 7500 gallon spill of Agent Orange occurred. This event contributed significantly to the establishment of Bien Hoa as a present-day dioxin hot spot. In addition, the ‘ditch’ shown in the above photo was the depository of drainage from the spray tanks of Ranch Hand C-123 aircraft.

The Vietnamese government is working with haste to contain the dioxin contaminated areas near/on former US bases labeled as hot spots. Dioxin contamination on the Da Nang airbase has received considerable international press following the discovery of significant contamination on the base and in local populations (especially in people fishing in Sen Lake, adjacent to the base). The Ford Foundation has contributed substantial finances to assess the extent of the dioxin contamination problem, and to continue research/remediation on the base.

Hot spots identified by Hatfield (i.e., former US military installations) must be the focal point of studies to determine appropriate remediation measures, in order to protect local populations. This strategy is particularly justified where former US bases have been abandoned and are now sites of concentrated human activity. Remediation efforts must also consider topographical features near former US bases facilitate downstream migration of contaminants (e.g., through runoff water) to areas presently used for food production by local inhabitants (e.g., fish ponds). These contaminated areas are logical sites for comprehensive epidemiological and human health investigations, including appropriate interventions.

Although approximately 12% of southern Viet Nam was sprayed during Operation Ranch Hand, only very limited areas are considered highly toxic due to dioxin contamination, specifically airbases formerly used by the US military. As dioxin in soil may remain toxic for many decades, and possibly over a century, it is crucial that contaminated sites are identified and remediation measures implemented, ultimately to protect the health of local Vietnamese. Viet Nam requires international assistance to address site specific Agent Orange/dioxin contamination throughout the country. It is hoped that as knowledge increases and the wounds of war continue to gradually heal, efforts will be adopted by the international community to address the dioxin issue in Viet Nam, and assist its people to live safely in those areas that were ravaged by the wartime herbicide, Agent Orange.

Operation Ranch Hand C-123 spray aircraft on the Bien Hoa airbase during the American War.
Source: Gary White
Canadian International Development Agency
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