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Precaution in Practice - challenging the acceptability of depleted uranium weapons

A report for policy-makers and campaigners which judges the acceptability of DU weapons by utilising the structure of common interpretations of the precautionary principle. In doing so it asks whether a precautionary approach should be applied to DU and whether its use could ever be compatible with precautionary values.
1 October 2012 - ICBUW

Precaution in Practice cover image A PDF version of Precaution in Practice is available to download at the end of this article.

Executive summary


Depleted uranium (DU) weapons have proved a controversial addition to the conventional arsenals of militaries since their first development in the Cold War. Opposition to their use has varied in pitch over the years but has tended to correlate closely with their deployment in conflict. Yet throughout this period, it has been clear from the column inches printed, the parliamentary debates and, more recently the bills, motions and resolutions passed, that the use of DU munitions appears to be intrinsically unacceptable to most people.

The stigmatisation of inhumane and unacceptable weapons has been crucial to extending the impact of the international treaties banning anti-personnel landmines and cluster bombs. But while DU has shown itself, to a degree, to be self-stigmatising – evidence for which is clearly demonstrated by the energetic public relations strategies of its proponents, the difficulty of establishing a causal link between its use and humanitarian impact requires a different approach to judging its acceptability to those that have historically been applied to explosive weapons.   

Throughout the last three years, ICBUW has been applying a precautionary prism to different aspects of what remains a complex issue, from what is known about DU as a material and how it is regulated in peacetime, to how and where it is used in conflict, how it is managed after conflict and, crucially, to the cost/benefit calculations relating to its use. 

The purpose of this report is to discuss the findings of ICBUW’s research on precaution and, we hope, to provide policymakers with an accessible means of judging the acceptability of DU’s use in conventional weapons. 

A role for precaution?

When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. European Commission.

From the outset, ICBUW believed that any precautionary approach would require that a thorough assessment of DU’s properties, the nature of its use in conflict and the constraints on the post-conflict management of contamination be made. We also felt that further guidance should come from a critical appraisal of DU’s costs to civilians and affected governments and the benefits that militaries claim from its use.

Examples from environmental law, International Humanitarian Law and the Convention on Cluster Munitions demonstrate that, while no single interpretation of the Precautionary Principle has gained worldwide legal acceptance, precautionary thinking and approaches are widespread in relevant and related fields of law and regulation.

Precautionary approaches are now the peace time norm for reducing human exposures to hazardous substances. As the legacy of DU use lasts beyond the end of conflicts, it is reasonable to suggest that a similar approach is justified to protect human health. Doubtless lessons could also be drawn from how governments would manage widescale releases of DU under their own national regulatory frameworks.  

ICBUW believes that sufficient evidence is now available to pass the threshold of plausibility, i.e. even though uncertainties may remain, enough is known about the nature of the potential risks to civilians and the costs of inaction, to support the adoption of a precautionary approach.

ICBUW is not alone in advocating for an approach based on precaution. The UK Royal Society suggested a range of precautionary measures in response to scientific uncertainties following its detailed review of the potential health effects of DU use. Similarly, the UN Environment Programme specifically called for a precautionary approach, with hazard awareness programmes and decontamination, following its fieldwork on DU strike sites in the Balkans, renewing this call in 2010 in a report to the UN Secretary General. The WHO has also issued a range of precautionary guidelines for reducing the risks to civilians in areas where DU has been used.

Is DU a hazard?

On the basis of reports by the Royal Society and others, the MoD does not consider DU is ‘safe’. It is hazardous (making the accepted health and safety distinction between a hazard and a risk). Dr Liam Fox, UK Defence Minister, 2011.

DU’s chemical toxicity and radioactivity, when combined with its propensity to combust and form particles of a respirable size, result in it being a recognised hazard. DU has been intensively studied and a wealth of new research, much of it carried out by the US military, indicates that DU may have an impact on health through a variety of different chemical and radiation-induced mechanisms. Much of this research post-dates the widely cited WHO Monograph on DU’s risks and the UK Royal Society’s study.

As Intermediate Level Radioactive Waste, its storage, use, disposal and transportation is tightly regulated in peacetime. Civil radiation protection norms seek to avoid unnecessary exposures wherever possible, and any exposure must be justified on the basis of its wider benefits. 

Militaries have adopted a precautionary approach to DU, avoiding unnecessary exposures through hazard awareness training and providing health monitoring as required. When forced to operate within peacetime health and environmental regulations, DU users face considerable challenges.  

It appears, therefore, that DU’s intrinsically hazardous nature is well accepted and that its uncontrolled or accidental dispersal into the environment is broadly viewed as undesirable.

Uncontrolled and unpredictable: factors influencing the risks to civilians from DU use.

Circumstances vary so enormously in war, and are so indefinable, that a vast array of factors has to be appreciated—mostly in the light of probabilities alone. Carl von Clausewitz.

Significant uncertainties develop when DU munitions are used. Some of these are avoidable although unlikely to be resolved – the timely release of targeting data for example, or avoiding the use of DU in civilian areas – but most relate to the nature of the weapons themselves and their mode of use. This results in a significant variability in the likely risks from different DU strike sites. This poses a challenge to the generalised statements often used to dismiss concerns over DU contamination and underscores the importance of detailed data collection and risk analysis for individual sites. 

Recent use of DU demonstrates that it has been used in populated areas, leaving civilians facing contamination from weapons designed for very different military scenarios. That international mechanisms are not in place to fund and undertake DU clearance work ensures that civilians face a greater risk of exposure. Fear of radiation, particularly where information gaps or mistrust exists, increases the likelihood of the politicisation of DU, which in turn reduces the likelihood that effective hazard awareness work will be completed. Even on the rare occasions where DU contamination is adequately managed, DU’s psychological legacy will live on in affected communities. 

The uncontrolled release of DU in conflict not only breaches radiation protection norms but also presents a challenge to risk modellers. The risk of civilian exposure to DU residues is increased markedly by factors that are, to a certain extent, constants in post-conflict environments. Institutional capacity, technical expertise, access to analytical equipment, limited finances and a range of competing health and environmental problems will all pose challenges for efforts to safely remediate DU contamination – and to the acceptability of DU use.

Quantifying risk and responding to uncertainty

The absence of scientific proof of the existence of a cause-effect relationship, a quantifiable dose/response relationship or a quantitative evaluation of the probability of the emergence of adverse effects following exposure should not be used to justify inaction. European Commission.

The ongoing requirement to maintain the acceptability of DU munitions has resulted in the projection of an overly simplistic view of the health hazards that DU poses.

The data on uranium’s chemical toxicity is a case in point, with many studies predating the development of modern analytical methods. The science of toxicology itself is currently in a state of renewal as it seeks to provide more sophisticated and detailed data on substances. Similarly, recent developments in our understanding of the means through which radiation interacts with cellular processes and repair mechanisms have highlighted that modelling the estimated dose and safe exposure limits to internal radiation is fraught with uncertainties. This is largely unsurprising as exposure limits have been on a downward trajectory ever since the discovery of radiation. While it has proved politically useful to communicate a clear safety message on DU, this is not supported by the science. 

Uncertainties and gaps in the data needed to undertake detailed civilian risk assessments for DU appear to have rendered accurate risk characterisation impossible. As a result there are compelling reasons to suggest that a precautionary threshold has been passed. 

Just as the uncertainty over accurate risk characterisation should not be used to justify inaction, the lack of detailed epidemiological data from Iraq and elsewhere should not be interpreted by the users as supporting the ongoing use of the weapons. The complexities of such studies are rarely mentioned by user states but are all too familiar to those physicians and researchers who have sought the truth about the potential civilian harm from DU munitions.  

Costs and benefits

Examination of the pros and cons cannot be reduced to an economic cost-benefit analysis. It is wider in scope and includes non-economic considerations. ...the protection of public health should undoubtedly be given greater weight than economic considerations. European Commission.

An analysis of the costs and benefits of the use of DU sees the strategically overstated utility of the weapons pitched against the health, psychological and management burden they place on affected states, the lifecycle costs associated with manufacturing, development and testing and ultimately the public acceptability of using radioactive materials in conventional weapons.

State practice, and recent procurement decisions, appears to support the claim that their utility has been overstated, thus weakening the primary justification promoted by states to support DU’s use. Contrary to DU users’ hopes, the public’s acceptability of DU has not increased with time, a trend that is unlikely to change as more work is undertaken to document its legacy in affected states and further research is undertaken on its interactions with the human body.

Although some lessons seem to have been learned by the US and UK militaries in the wake of concerns over DU’s potential health impact on troops and civilians, it would be naive to expect these lessons to be adopted in future decision making without some external pressure requiring them to do so, be this through political pressure or a legal obligation.

Precaution in Practice?

...if a proposal is made in the 1979 Weaponry Conference for a ban on the use of DU there might be scope for considering whether we should propose, as an alternative, restrictions on the uses to which such ammunition might be put... The difficulties of any such proposal in terms of verification are, of course, considerable. UK Foreign and Commonwealth Office.

The problems outlined throughout this report are intrinsic to the nature of DU and its mode of use in weapons, thus there are no quick technological fixes that might resolve them. Models for precautionary approaches that have been suggested in the past place too great a reliance on legal reviews and voluntary controls on behaviour, which past state practice suggests would do little to limit the worst problems associated with DU use. Stricter regulation might be one possible avenue to explore but this would require a level of transparency that has hitherto been lacking. 

Therefore, it is reasonable to conclude that a voluntary moratorium, while potentially useful as part of a process of further stigmatising DU weapons, would not be the ultimate in precautionary measures – however a global ban on the use of uranium in all conventional weapons, would. 

As they have most to lose from a ban on DU weapons, it is understandable that the military has historically sought the greatest influence in the debate over their acceptability. But this is a morally unsustainable situation as the users of DU are unlikely to voluntarily surrender a means of warfare that they perceive as valuable. Yet when those weapons overwhelmingly affect those not party to a conflict, and well beyond the cessation of hostilities, it raises questions of moral and political acceptability; questions that those with a vested interest in maintaining DU weapons are poorly placed to answer.

DU is a complex and emotive issue. Yet for all the scientific and technical arguments there is a simple principle at play: is it politically acceptable to disperse large quantities of a chemically toxic and radioactive heavy metal, which is widely recognised as hazardous, in conventional warfare?

Throughout our DU research, ICBUW has been conscious of the emergence of a broader thematic area relating to the humanitarian and environmental impact of the toxic legacy of military activities. This has included the means through which weapons components are assessed for toxicity and environmental behaviour prior to use; the role of precautionary approaches to civilian health because of the constraints on post-conflict monitoring and assistance; the need for analytical capacity and remediation expertise for managing toxic remnants of war and finally, a recognition of state responsibility for the environmental and health legacy of toxic substances released or abandoned during conflict. An acceptance by states of the need to resolve these issues could yet prove to be a positive outcome of the development and use of DU munitions.


1. Adopt a precautionary approach

On the basis of their potential civilian harm, the historical use of DU munitions in civilian areas and against civilian objects and the costs and technical difficulties inherent in their remediation, states should support calls for a precautionary approach to DU weapons and give serious consideration to a voluntary moratorium on their use.

2. Broader understanding of civilian harm

While they are far better documented, states must recognise that the risks to civilians resulting from munitions are not restricted to explosive hazards. Monitoring the health and environmental legacy of toxic and radioactive substances is challenging, therefore guidance should be sought in the precautionary health and environmental protection norms in place in domestic standards.

3. Provide technical and humanitarian assistance

DU users and affected states should recognise their obligations to protect civilians from the post-conflict legacy of DU. Far greater transparency over where the weapons have been used, and in what quantities, is urgently required as a first step towards implementing comprehensive risk reduction measures and decontamination. The international community should provide technical and financial assistance to affected states, both for health programmes and to assist in the assessment and effective management of contaminated materials. 

4. Assessment of other materials and practices

As part of the developing normative framework for the protection of civilians during, and after, times of conflict, states should consider a broader range of military materials and practices that may result in environmental contamination and whose legacy lasts beyond the cessation of hostilities. Consideration should also be given to mechanisms to fund and undertake environmental impact assessments, health monitoring and post-conflict remediation of toxic remnants of war.

5. Accelerate removal of DU and consider mechanisms for a ban

If, as seems apparent, the use of DU munitions runs counter to both public acceptability and health and radiation protection norms, states should accelerate its removal from their arsenals and consider mechanisms through which to formally ban its use in conventional weapons.  


    Throughout the last three years, ICBUW has been applying a precautionary prism to different aspects of what remains a complex issue, from what is known about DU as a material and how it is regulated in peacetime, to how and where it is used in conflict, how it is managed after conflict and, crucially, to the cost/benefit calculations relating to its use. The purpose of this report is to discuss the findings of ICBUW’s research on precaution and, we hope, to provide policymakers with an accessible means of judging the acceptability of DU’s use in conventional weapons.
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