The TRW Project aims to assess, through scientific desk studies, the potential of common military toxic substances (for example explosives or heavy metals) to cause public health and environmental problems. The remediation of dioxin contamination from defoliant spraying during the Viet Nam War has only recently received funding for a few sites and health assistance to affected Vietnamese is still not universally agreed. Therefore, the problem of dioxin remains a relevant example of military-origin contamination. In this post, the origins of the dioxin problem are briefly examined, as is a recent environmental and exposure assessment that contributed to the landmark clean-up decision. Parallels with more recent military pollution are also briefly discussed.
Historical problem development
Dioxin contaminated many of the defoliants used in the US herbicide spraying programme in Viet Nam, known as Operation Ranch Hand. The US government did not publicly acknowledge the contamination of Agent Orange with dioxin till the late 1960s, even though it later became obvious that the level of contamination and harm was well known but disregarded, as Dr James Clary, a US Air Force scientist stated in a letter to the US Congress in 1988:
“When we [military scientists] initiated the herbicide program in the 1960s, we were aware of the potential for damage due to dioxin contamination in the herbicide. We were even aware that the military formulation had a higher dioxin concentration than the civilian version, due to the lower cost and speed of manufacture. However, because the material was to be used on the enemy, none of us were overly concerned.”
These concerns were ignored because protecting Vietnamese civilians wasn’t a priority. In the 1960s and 70s, mounting independent scientific concern of the potential health problems caused by dioxin and its environmental persistence eventually led to the programme being cancelled.
Declassified US military communications from the 1960s now show that herbicide spraying continued, even though its military effectiveness was in doubt:
“The effect of defoliation on the enemy, in itself, is of little military value. Its military potential is realized only when it is channeled into selected targets and combined with combat power… The herbicide program carries with it the potential for causing serious adverse impacts in the economic, social, psychological fields.”
Because of dioxin’s persistence in the environment, contamination remains in specific sites in Viet Nam, Laos and Cambodia. It is also easily incorporated into the human food chain.
As with any matter of environmental health, the presence of dioxin and its health effects are intertwined, particularly where there is potential for it to enter the food chain. Associations between dioxins and specific diseases remain a matter of debate and uncertainty, but this does not negate the necessity of remediation and the importance of addressing health problems in civilians as a matter of humanitarian urgency.
Dioxin environmental assessments
Dioxin contamination was measured in the environment and food chain in Viet Nam as early as 1970 in the work of Baughman and Meselson (1973). Dwernychuck et al. (2006) later found that areas of Viet Nam where herbicides were sprayed did not necessarily have high concentrations of dioxin. The major contamination was at the former US military bases used for Operation Ranch Hand, and areas that were very heavily sprayed. At bases, spillages of defoliant resulted in contamination hotspots requiring clean up. The work of Dwernychuck et al. (2006) and others measured the dioxin concentrations in samples of soil, fish, river sediment, and the breast milk of local residents; it found elevated concentrations of dioxin in all of them. The most significant conclusion from this finding was that the contamination is still causing human exposure and that the concentrations measured would breach US environmental limits, triggering environmental remediation.
In 2012, the US Agency for International Development began funding a clean-up of dioxin at Da Nang air base in Viet Nam, many other sites are also likely to require attention.
Dioxin and health: Vietnamese and veterans
While dioxin is known to be associated with spina bifida and anencephaly, in the offspring of Vietnamese residents and US military personnel, studies so far cannot unequivocally confirm the connection to other diseases and congenital malformations (Shechter and Constable, 2006).
The US Veterans Association uses a list of ‘presumptive diseases’ – those believed to be connected to dioxin exposure during military service – in assessing whether to grant compensation to veterans. The same applies to congenital birth defects in the children of US Viet Nam war veterans.
Vietnamese civilians exposed to dioxin do not qualify for similar US support. The US government takes the position that there is no scientific evidence to link dioxin contamination to health problems encountered in Viet Nam. It is noteworthy that health problems of US Viet Nam veterans were similarly unacknowledged until the US Congress enacted the bill in 1991 relating to presumptive diseases. The political influence of the manufacturers of contaminated herbicides was important in delaying Veterans’ health problems. Nevertheless the Vietnamese government provides a monthly stipend of about US$17 to more than 200,000 Vietnamese believed to be affected by the toxic herbicides. This totals about US$40 million each year according to the Aspen Institute.
While there is certainty about the extreme toxicity of dioxin, and its association with some health problems, there remains uncertainty regarding other diseases. The wider question of epidemiological confirmation of the link between dioxin exposure and disease is also difficult to resolve. Nonetheless, the fact remains that due to its proven environmental persistence, high toxicity, teratogenic and carcinogenic nature, dioxin is a tightly regulated substance.
Lessons to learn
The case of dioxin is unique in the extent and severity of its effects but there are parallels with other cases where use of munitions or the bombing of infrastructure and industry has resulted in contamination (e.g. toxic heavy metals, industrial chemicals or contaminants from munitions).
Environmental hotspots in Iraq and the Balkans were found to have a variety of persistent contaminants, including polychlorinated biphenyls, other forms of dioxin contamination in addition to the ongoing legacy of depleted uranium munitions in Iraq. The management of this contamination has varied widely.
The Vietnamese dioxin case shows that allowing contamination to persist is detrimental, most importantly to public health but also to bilateral relations between the polluting and affected states. Establishing formalised mechanisms to ensure the release of the funds and expertise required for clean-up could help ensure that the humanitarian impact of conflicts ends with the hostilities. It is also clear, particularly in the case of Viet Nam, that the problem could have been prevented through environmental due diligence.
It is hard to say whether a problem of the scale, severity and persistence of AO/dioxin could arise again from military related contamination. There is increased environmental awareness and due diligence in some aspects of military activity (e.g. the screening of emerging contaminants and other substances of concern). However issues such as the use of depleted uranium munitions, the use of burn pits and the worrying environmental burden of intense bombardment are cause for concern.