Response to `Comments upon human exposure to depleteduranium during and after the Gulf and Balkans conflicts'

Abstract

Dear SirEric Hamilton takes the Royal Society and myself to taskfor investigating the health hazards of depleted uranium munitions. In his view the matter appears to be clear. Exposures to uranium have been studied extensively for decades in the nuclear industry and there is little evidence of adverse health consequences. Exposures to DU on the battlefield are therefore unlikely to have health consequences and setting up an independent working group to look at the scientific issues only suggests there are doubts about the science, and leads to mistrust and confusion in the minds of the public. This type of robust approach to addressing the risks of exposure to radioactive materials, and of attempting to assuage the concerns of veterans exposed to DU during the Gulf War, may have worked in the past but it doesn't work today.The Royal Society is accused of having failed to address the main issue, which Hamilton considers to be the failure to implement well established and validated monitoring procedures at the time DU weapons were deployed, so that intakes and risks could have been calculated. This is a curious perspective as, from the outset, the remit of the Royal Society working group was to provide an independent view of the science, rather than the deficiencies in procedures, in response to public concerns and to the very different pronouncements about the dangers to health and the environment arising from the deployment of over 300 tonnes of DU munitions in the Gulf War.Some of the comments in the Royal Society reports and the editorial are considered to be questionable or not acceptable. It is not clear which particular aspects cause offence. One aspect appears to be the claim that DU measurements are difficult, where Hamilton appears to misunderstand the nature of the problem of quantifying exposures to DU. Of course uranium concentrations and isotope ratios are routinely measured in the nuclear industry and in geochemical laboratories, but the problem is not one of analysing `DU debris' but of looking for, and quantifying, the minute amounts of DU that are being excreted in the urine of veterans who were exposed to DU aerosols during the Gulf War. Reliably measuring uranium isotopes (particularly the very small percentage of 235U) in urine that contains a few nanograms of total uranium per litre is a challenge.Hamilton doubts that epidemiological studies of veterans will be useful, and comments that radioactive exposures or releases by the nuclear industry have not impaired the health of the population or workforce, and that uranium has never been identified as an element of concern. Epidemiological studies do indeed provide little evidence that exposure to uranium in industrial settings is associated with excess overall mortality, or with increased mortality from cancers or kidney disease. However, the exposures to insoluble DU oxides on the battlefield may be significantly different (in solubility, particle size, amount) from typical exposures in industry, and the existing epidemiological studies of worker cohorts are not particularly sensitive, and I disagree that epidemiological studies are of no value in the context of exposures to DU on the battlefield. Certainly there were multiple exposures to toxic, or potentially toxic, agents in the Gulf War, but tests that measure the amounts of DU in the urine of soldiers have been promised to veterans and, if these identify a group of soldiers who received substantial intakes, case-control studies should allow a sensitive evaluation of any link between exposure to DU and ill health.Hamilton is also concerned that the issue of `hot particles' is not examined in sufficient depth but in the same sentence he says that data are lacking upon which a judgement can be made. In any case, it is very unclear why `hot particles' should have been discussed in depth. Hamilton himself (reference [6] of his letter) defines such particles as `highly radioactive and potentially hazardous unprocessed, spent-reactor uranium fuel debris', something quite different from the very much less radioactive particles released in DU penetrator impacts. However, the Royal Society reports do flag up the need to re-assess the robustness of current estimates of risks from the inhalation of radioactive particles and CERRIE is currently addressing this question.There is one point made by Hamilton with which I agree. Far more effort should have been made to understand intakes of DU during the Gulf War, and the Royal Society working group has consistently been critical of the lack of data on intakes of DU by soldiers in the Gulf War, and has been pressing the Ministry of Defence to ensure that there is adequate and timely monitoring in any future conflict where DU munitions are deployed. It is only when we have these intake data that we can really evaluate the risks associated with these exposures and the uncertainties associated with these estimates.Yours faithfully,