PRELIMINARY ASSESSMENT OF ENVIRONMENTAL
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National Committee for the Investigation of the Consequences of the Chemicals Used during the Viet Nam War (10-80 Committee)
Tôn Thãt Tùng Street
Hatfield Consultants Ltd. (West Vancouver, Canada) and the government of Viet Nam 10-80 Committee (Ha Noi, Viet Nam) cooperated in a preliminary assessment of environmental impacts related to spraying of Agent Orange herbicide during the Viet Nam war. Approximately 76 million litres of herbicides were sprayed over 10-14% of Southern Viet Nam. The HCL/10-80 Committee work included determining dioxin levels in the environment of Viet Nam and assessing impacts on forests. The investigation covered the period 1994-1998.
Dioxin was a manufacturing contaminant present in Agent Orange, a 50/50 mixture of 2,4,5-T and 2,4-D herbicide. Dioxins are a family of chemicals which have been implicated to cause serious health effects in humans.
The sophisticated analysis and subsequent high cost required for dioxin sample analyses and the post-war isolation of Viet Nam has hampered in-country dioxin sampling and analyses. Although Viet Nam has qualified scientists, procurement of adequate funding for dioxin-related research has been a problem, given other pressing health and economic concerns.
The Aluoi Valley, 65 km west of Hue, near the Laos border, was selected as the main dioxin study area in order to minimize the anthropogenic influences of the more urbanized or intensive agricultural areas farther south. A greater degree of industrialization may be accompanied by environmental input of dioxin and other contaminants (e.g., waste-water discharges, air emissions) which have the potential to confound data interpretation.
The Aluoi Valley was an integral part of the Ho Chi Minh trail during the war and was heavily sprayed from approximately 1965 to 1970 principally with Agent Orange and to a lesser extent, Agent Blue and Agent White. Inhabitants of Aluoi are primarily hill tribes living "off the land" at a more or less subsistence level.
A 1996 sampling expedition consisted of a wide-spectrum sampling approach throughout the valley. Data from the 1996 program showed that the commune of A So, situated in the southern sector of Aluoi, contained soils and fish tissues contaminated with dioxin (specifically 2,3,7,8 – Tetrachlorodibenzo-p-dioxin or 2,3,7,8-T4CDD, known to be the Agent Orange congener).
Data from 1996 formed the basis for a more focussed expedition in 1997 in A So and a small former US Special Forces airbase in the area. The study was designed to follow the pattern of dioxin movement through the food chain in this relatively restricted area.
Farmer’s soil, former airbase soil, fishpond sediment, cultured fish and duck tissues and human blood were collected from A So in 1997. A parallel sampling program, undertaken as a component of a concurrent RADARSAT satellite remote sensing study by Hatfield, enabled the collection of soils and aquatic sediments from the heavily sprayed Ma Da forest area of southern Viet Nam (northeast of Ho Chi Minh City). The satellite assessment also enabled analysis of extensive land use changes and vegetation impacts caused by the herbicides.
As in the 1996 expedition, former US airbase soils contained the highest levels of dioxin. Fish and pond sediment also contained high levels of dioxin in this area.
Soil dioxin contamination levels in A So commune if they occurred in a western jurisdiction would probably result in the area being declared a "contaminated site". Fish dioxin levels would trigger a consumption advisory process (i.e., recommendations on maximum human consumption levels) and possibly prohibitions against consumption if they were from a location in Canada.
Human blood samples were contaminated with Agent Orange dioxin. High levels were recorded in pooled blood from males and females >25 years of age, and males and females 12 to 25 years of age. The detection of dioxin in the younger generation provides evidence that the valley environment remains contaminated and dioxin is presently moving through the food chain into humans.
Data indicate that soils in the vicinity of former airbases and other military installations (i.e., firebases, naval bases, field camps, etc.) in Viet Nam may also be contaminated with dioxin since many of these facilities experienced activities related to the Agent Orange spraying program. The existence of other contaminated "hotspots" in Viet Nam is likely, given that Agent Orange spraying was particularly heavy around bases, along roads and in areas of high strategic military importance.
The ultimate receptacle for dioxin moving through the local environment near A So in the Aluoi Valley is human beings. In this isolated valley both the older and younger generation have significant levels of dioxin in their blood relative to data from northern Viet Nam where Agent Orange was not applied. Deformities, early cancers, and other medical conditions have been noted in the valley. Vietnamese health studies have indicated that birth defects are an order of magnitude higher in the A So area than similar areas of unsprayed northern Viet Nam. A thorough multinational epidemiological investigation is required before defensible conclusions regarding the relationship between dioxin exposure and human health problems can be made.
The HCL/10-80 Committee report contains ten major conclusions and thirteen recommendations from the study. Scientists involved in the work believe that there is a strong urgency to draw up health risk mitigation plans in the Aluoi Valley and to further examine the extent of the Agent Orange contamination problem in the country. An expansion of present reforestation activities to rehabilitate defoliated areas is also necessary to prevent further erosion of soils, increase wildlife diversity and create enhanced economic activities for local people. The Agent Orange contamination problem in Viet Nam represents a good opportunity for international scientists to study environmental and health effects of dioxin. Study results would have worldwide applications.
Further information on this
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