I have, during a career of some 30 years, developed expertise in evaluating risks regarding the environmental and occupational exposure to ionising radiation and radioactive materials in many different situations. I have done this in the context of employment by the UK Medical Research Council (1971 to 1991) and the European Regional Office of the World Health Organisation (1991 to 2003), both ostensibly "independent" organisations.

Between 2000 and 2002 I examined the evidence relating to risks from the mildly radioactive depleted uranium. My concern was especially raised by the specific exposure context of inhalation of the dust particles produced when a depleted uranium munition impacts a hardened target and burns, producing fine particles of DU oxide (DUO). This material has no natural analogue and does not arise in the normal refining and processing of uranium for nuclear fuel. There is, therefore, no prior experience of exposure to this material than its use in Iraq in 1991.

According to the International Commission for Radiological Protection (ICRP), inhaled DUO would pose a hazard to the lung from radiation if it were insoluble and a chemical toxicity risk to the kidney (physiological toxicity of kidney malfunction) if it were soluble.

DUO is in fact part insoluble and part sparingly soluble. Since 1998 evidence has accrued that human cells exposed in the laboratory to low concentrations of DU exhibit changes characteristic of malignant cells and indeed, when implanted into host animals, will lead to malignancy. In these experiments it seems unlikely, given the low concentrations and the experimental conditions, that this effect is mediated by radiation, but is rather a chemically mediated genotoxicity. (See for example [1-6] the non-radioactive element, nickel, produces similar effects and is an established carcinogen)

In 2001 this evidence led me to believe that inhaled DUO particles, which are capable of penetrating the deep lung (where they would be retained for long periods) posed, for a period of weeks to months, not only a radiotoxicity risk but also a chemical genotoxicity risk and potentially a synergy between the two. Thus any risk evaluated on the basis of the ICRP recommendations would be likely to underestimate the true risk.

In addition, that DU is only mildly radioactive through alpha emission, raises the possibility of a further risk route mediated by the so called "bystander effect". (See for example [7, 8]) Here a single cell "hit" by an alpha particle sends signals to surrounding cells causing them to behave as if they had been irradiated. In circumstances where bystanders predominate (low dose exposure to alpha particles for example) the bystander effect acts to amplify the "radiation effect".

Thus, detailed examination of DUO reveals three potential risk routes in addition to the conventional radiotoxicity caused by direct irradiation, namely, chemical genotoxicity, synergy between radiation and chemical toxicities and a bystander route.

Since 2002 the evidence for these three routes has not diminished, indeed the reverse is the case. More recent studies have confirmed the earlier studies [9, 10] and concern about the bystander effect in radiotherapy patients continues to rise.

Furthermore, US veterans with DU embedded in their bodies as a result of friendly fire incidents and with high concentrations of DU in their urine, show further evidence of DU's mutagenic potential in their peripheral blood cells [11].

In my view it is highly irresponsible to continue to ignore this evidence. There is an overwhelming case for the application of the precautionary principle and that, at the very minimum, would require that DUO is cleaned up at battle sites. The problem is particularly severe in Iraq where arid climatic conditions allow DUO particles to retain the sparingly soluble component that primarily gives rise to the extra risk routes, over long periods and promotes conditions in which re-suspension and inhalation are optimised.

The organ primarily at risk is the lung, but DU dissolved in the lung will locate initially in the bone, entering via the bone marrow cavities where it can give rise to leukaemia through its chemical genotoxic potential. The kidney, through which all systemic DU is excreted is another potential target tissue, again from the genotoxic potential. Thus, exposure through inhalation to DUO has the potential to cause malignancy in a number of tissues.

A number of organisations, including the World Health Organisation [12], the International Atomic Energy Agency [13], the UK Royal Society [14], the International Commission on Radiological Protection [15] and the European Commission Article 31 Group [16] have, since 2001, published advice relating to the health consequences of exposure to DU. You may wonder, as I do, how such authoritative and independent Organisations, making ostensibly "independent" assessments of the situation can all ignore the evidence that exists in the scientific literature.

It is worth noting that these assessments may not in fact be truly independent. For example, staff of the UK National Radiological Protection Board (NRPB) are acknowledged as contributing to the WHO and RS reports, the Chairman of the ICRP was recently the Director of the NRPB. Staff members of the NRPB collaborate with the IAEA and have been members of the Article 31 Group. It is, therefore, possible that a few individuals have influenced the outcome of these so called independent assessments.

For me, as a scientist, it is the fact that this evidence is IGNORED, as opposed to being ADDRESSED and if appropriate discredited, through rational scientific debate that is worrying. Science is about a reality that over-rides political expediency. Ignoring the evidence does not mitigate the health consequences of exposure to DU and not looking for the consequences does not mean they do not exist. Mark Danner [17], writing in the New York Review of Books recently, detects a currently resurgent belief that "Power, [political power] ..... can shape truth: power in the end can determine reality, or at least the reality that most people will accept." He further notes that that this was stated rather directly by the "last century's most innovative authority on power", Joseph Goebbels.

I am on record [18] as saying that "politics has poisoned the well from which democracy must drink." By this I mean that political expediency has all but eliminated truly independent research and along with that went PUBLIC TRUST. Without public TRUST democracy cannot work. In the context of risk assessment SCIENCE should provide the evidence, openly and transparently, and unalloyed with any interest in the outcome except that it be the truth. On the basis of this evidence POLITICS should decide the risk that is acceptable within the social and legal context of the time.

Selected References

1. Miller, A.C., et al., Urinary and serum mutagenicity studies with rats implanted with depleted uranium or tantalum pellets. Mutagenesis, 1998. 13(6): p. 643-8.
2. Miller, A.C., et al., Transformation of human osteoblast cells to the tumorigenic phenotype by depleted uranium-uranyl chloride. Environ Health Perspect, 1998. 106(8): p. 465-71.
3. Miller, A.C., et al., Urinary and serum mutagenicity studies with rats implanted with depleted uranium or tantalum pellets. Mutagenesis, 1998. 13(6): p. 643-8.
4. Miller, A.C., et al., Observation of radiation-specific damage in human cells exposed to depleted uranium: dicentric frequency and neoplastic transformation as endpoints. Radiat Prot Dosimetry, 2002. 99(1-4): p. 275-8.
5. Miller, A.C., et al., Depleted uranium-catalyzed oxidative DNA damage: absence of significant alpha particle decay. J Inorg Biochem, 2002. 91(1): p. 246-52.
6. Miller, A.C., et al., Potential late health effects of depleted uranium and tungsten used in armor-piercing munitions: comparison of neoplastic transformation and genotoxicity with the known carcinogen nickel. Mil Med, 2002. 167(2 Suppl): p. 120-2.
7. Mothersill, C. and C. Seymour, Radiation-induced bystander effects: past history and future directions. Radiat Res, 2001. 155(6): p. 759-67.
8. Belyakov, O.V., et al., Direct evidence for a bystander effect of ionizing radiation in primary human fibroblasts. Br J Cancer, 2001. 84(5): p. 674-9.
9. Miller, A.C., et al., Effect of the militarily-relevant heavy metals, depleted uranium and heavy metal tungsten-alloy on gene expression in human liver carcinoma cells (HepG2). Mol Cell Biochem, 2004. 255(1-2): p. 247-56.
10. Miller, A.C., et al., Genomic instability in human osteoblast cells after exposure to depleted uranium: delayed lethality and micronuclei formation. J Environ Radioact, 2003. 64(2-3): p. 247-59.
11. McDiarmid, M.A., et al., Health effects of depleted uranium on exposed Gulf War veterans: a 10-year follow-up. J Toxicol Environ Health A, 2004. 67(4): p. 277-96.
12. WHO, Depleted Unanium: Sources, Exposure and Health Effects. 2001, World Health Organisation: Geneva.
13. Bleise, A., P.R. Danesi, and W. Burkart, Properties, use and health effects of depleted uranium (DU): a general overview. J Environ Radioact, 2003. 64(2-3): p. 93-112.
14. RS, The health hazards of depleted uranium munitions Part II, in Policy Document. 2002, The Royal Society: London.
15. Valentin, J. and F.A. Fry, What ICRP advice applies to DU? International Commission on Radiological Protection. J Environ Radioact, 2003. 64(2-3): p. 89-92.
16. EC, Depleted Uranium, in Opinion of the Group of Experts Established According to Article 31 of the Euratom Treaty. 2001, European Commission: Luxembourg.
17. Danner, M., The secret way to war, in The New York Review of Books. 2005. p. 70 - 74.
18. Baverstock, K., Science, politics and ethics in the low dose debate. Medicine, Conflict and Survival, 2005. 21: p. 88 - 100.