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New Publication from the US National Academy of Sciences on Health Effects of Depleted Uranium Weapons

US scientific body issues a new report on DU weapons - but is it saying anything new, is it even asking the right questions? ICBUW's Science Team investigates...
22 July 2008 - Gretel Munroe

The National Defense Authorization Act of 2007, signed into law by President Bush in October 2006, contained a clause requiring a comprehensive study of health effects due to the use of depleted uranium weapons, to be completed within a year. The result was The Review of Toxicologic and Radiologic Risks to Military Personnel from Exposure to Depleted Uranium During and After Combat, published by the National Academy of Sciences early this year, and herein referred to as the NAS Report.

NAS logo

The U.S. Department of Defense (DoD) asked the National Research Council to put together a committee which came to be the Committee on Toxicologic and Radiologic Effects from Exposure to Depleted Uranium During and After Combat. The Committee with a staff of seven wrote the report. The DoD also asked the National Research Council to do an independent review of the U.S. Army’s Capstone Report, a $1 million study of DU aerosols created from the firing of 120mm DU shells at Abrams Tanks and Bradley Fighting Vehicles. A half dozen members of the U.S. Army assisted in the preparation of the NAS Report.

The NAS Report starts with a six-page summary and ends with a 20-page evaluation of the Capstone Report. Chapters in between deal with such topics as toxicological effects of uranium on the kidney, the lungs and other organ systems, radiologic effects of DU, and uranium carcinogenicity and genotoxicity. Little that is new has come out of this report.

There are two appendices and 11 pages of references. One appendix consists of biogs of the 14 men and women on the committee. They include a former Chief of Research at the Radiation Effects Research Foundation in Hiroshima who had also served on several committees of the International Commission on Radiological Protection (ICRP), and another committee member who had been a Staff Scientist for Battelle which had been involved in the Capstone Report. In all, six members of the committee had worked in the radiation field in one capacity or another. The Committee also included toxicologists, pharmacologists and statisticians. The second appendix deals with epidemiological studies of uranium workers in the US and the UK.

Although there are 11 pages of references, the NAS Report omitted to include at least two dozen recent peer-reviewed scientific articles, mostly indicating potentially harmful effects of DU. Specifically the 2007 book, Depleted Uranium: Properties, Uses and Consequences edited by Alexandra C. Miller of the Armed Forces Radiobiology Research Institute and her paper: “Leukemic transformation of hematopoietic cells in mice internally exposed to depleted uranium,” Mol. Cell. Biochem. 279, 97-104, 2005, are not listed among the references. Miller’s research on mice that developed leukemia is also discussed in her book. Other research articles by Miller and co-workers are listed in the references.

The NAS Report also obscures the results of various experiments a small number of research papers where the findings indicate that DU may be harmful and may lead to disease. That is not to say that there is not good research in the NAS Report.

The NAS Report is not user-friendly and the average Congressional aide could be overwhelmed or put to sleep reading it. No Congressman or Congresswoman would consider banning DU weapons based on this report. However the NAS Report is also not written for scientists. Nor is it a user-friendly guide for learning about the health effects of DU, although it makes positive statements on DU as well as negative ones. Here are a few of both types of statements.

For one, DU exposure may lead to an inflammatory response as well as damage to the kidney. However damage to the kidney is not permanent. Also NAS states that exposure to uranium will not result in lung cancer. But later NAS notes that there may be “a small but significant risk of cancer and possibly lymphoma due to irradiation of pulmonary-associated lymph nodes” (p. 60) due to inhalation of insoluble DU.

NAS states that many animal studies on uranium use very high doses in experiments making extrapolations to humans difficult if not invalid. It is true that a number of studies have used high doses of uranium or DU, sometimes along with lower doses.

The NAS Report mentions the bystander effect but does not define it. The bystander effect refers to the ability of cells nearby targeted cells to be irradiated in the same degree as the cells hit by radiation. Taking the bystander effect into consideration could increase safe radiation standards.

Among the recommendations at the end of a chapter on toxic uranium effects on organ systems, is the following: “The Committee does not recommend additional studies of the hematologic or hepatotoxic effects of DU”. (p. 46). Research on blood-forming tissues and organs could show whether or not DU causes leukemia or lymphoma

The liver is a vital organ and an important function is detoxification. Y. Guegen and co-workers in a study dealing with the liver and xenobiotics (defined as drugs, carcinogens and insecticides),1 found that DU could disrupt xenobiotic metabolism. This could possibly lead to dysfunction in the liver’s ability to detoxify xenobiotics and the authors hypothesized that over time this could lead to lipid diseases. (Lipids are fats). Research on the liver is urgently needed.

The Committee’s reasoning for their recommendations against further research as per above was that the studies discussed in the text on these topics, for hematologic and “possibly hepatic (liver) effects of DU” was that “the exposure durations or concentrations do not appear to be appropriate for extrapolation to human exposure conditions.” (p. 45)

In a section on immunological effects, research by Wan et al. (2006) was summarized by NAS. The summary ended with a mention of the up-regulation of IL-10 (Interleukin-10) and IL-5, which was a finding of the study – in fact they were highly up-regulated. The rest of the story however, which NAS did not mention, is that this up-regulation permitted a micro-environment favouring a Th2 shift in a Th1-TH2 profile. Wan explained that this shift has been correlated with the development of allergic responses, cancer and autoimmune disease. In addition, Wan stated that elevated levels of IL-1- have been found in ill Gulf War veterans.

Research by Harsock et al. is briefly discussed in the chapter on carcinogenicity and genotoxicity. NAS’ description of the paper was succinct. It said only: “Hartsock et al (2007) reported evidence of a chemical mechanism by which uranium might alter DNA transcription and repair. In in vitro assays, uranyl acetate, but not sodium arsenite, inhibited the DNA-binding activity of both zinc-finger (Aart- and Sp1) and non-zinc finger (AP1 and NFk3) DNA-binding proteins”. (p. 66) Did DU inhibit DNA-repair proteins? It is not apparent from this summary. Who is to say?

Hartsock et al. (2007) did demonstrate that DU inhibited the ability of DNA-repair proteins to repair DNA in their paper.2 They also stated that: “The inability to repair DNA damage could lead to the accumulation of mutations or other types of genomic instability (the passing of mutations to future generations). Most human cancers exhibit genomic instability and an increased mutation rate due to underlying defects in DNA repair.”3

The NAS Report also discussed research on Gulf War veterans with embedded shrapnel who are in the Follow-Up Program of the Baltimore Veterans Administration Hospital, all of whom are thought to be healthy – or at least not suffering illnesses due to DU.4 They continue to excrete uranium in their urine. A number of studies of these veterans over seven years have revealed that the members of the high urine uranium group had approximately twice the number of hprt mutations in their peripheral blood lymphocytes as the veterans in the low urine uranium group. In a 2007 paper, McDiarmid et al. also reported finding that the total number of chromosomal abnormalities assessed by the procedure known as fluorescent-in site hybridization (FISH) were higher in the first group of veterans than in the second.5 NAS remarked that the sample sizes in these studies were small and that they contained no “normal,” meaning non-exposed, control group as a way of comparison. (p. 67)

In their summary on the chapter on uranium carcinogenicity and genotoxicity, NAS states: ”Experimental evidence indicates that insoluble forms of uranium are weakly carcinogenic in animals,” (p. 66).

The Capstone Report

The aim of the Capstone Report was the collection of data on DU aerosols created by the firing of DU shells at Abrams tanks or Bradley fighting vehicles, and the generation of mortality statistics for crews of the tanks and Bradley fighting vehicles depending on the situation and length of time that members of the crew or first responders (also included) were exposed to the DU aerosol.

The NAS Committee did an independent analysis of the data, or used data from other sources for their analysis and was usually in agreement with the Capstone analysis.

It is somewhat difficult to determine from the NAS Report how many 120mm DU shells were fired on tanks and Bradley fighting vehicles but on careful reading and having also read part of the Capstone Report, it is certain that one 120mm DU shell was fired at one vehicle at a time in most instances. The vehicles taking part in the project were Abrams tanks with and without DU armor, and a Bradley fighting vehicle with DU armor. All of these vehicles were stripped down and could not burst into flames, or explode non-existent ammunition. The Army also fired a shot into an operational Abrams tank that had an operating ventilation system which was very efficient.6

Capstone had three different exposure situations that attempted to mimic combat and post-combat settings. Level I exposure dealt with crew who were inside an Abrams tank or Bradley at the time of impact of a DU shell, and who would have left the tank within one or five minutes, or one hour or two hours after impact. A first responder who went into the tank or Bradley within five minutes of impact for rescue purposes was also classified as having a Level I exposure.

Level II exposures concerned soldiers or workers who spent time in a DU-perforated tank or Bradley or just outside the vehicle, for purposes of decontamination or repair of the vehicle. Level III exposures included soldiers who went into a destroyed tank or vehicle looking for souvenirs.

Capstone estimated that a maximum of 7 percent of a DU shell inside a tank and one percent of a DU shell inside a Bradley fighting vehicle would aerosolize after impact (p. 70). Particle size ranged from 0.6 nanometers to 100 micrometers (p. 70). Exposure data was reported using the median (the point half way between the largest value and the smallest) with the 10th and 90th percentiles.7

The Committee in their estimations of aerosolized DU inside the tank, assumed that 50 percent of the aerosol was made up of particles larger than respiratory size and 50 percent that were respirable. Of this 50 percent, 25 percent were of “small” respirable particles, with a mean size of one micron – indicating that some of these particles would have been nano-sized. They added that: “The material is assumed to be in a moderately soluble form (corresponding to ICRP solubility classification M (for moderate).” However, Dr Rosalie Bertell states that the National Radiological Control Board in the UK found that ceramic particles (such as the particles formed at very high temperatures when a DU shell hits a tank) are more insoluble than uranium oxide “which is rated Very Insoluble.” (personal communication). So these particles would be mostly insoluble and could stay in the body irradiating for a long time.

There is a health section in the Capstone Report which deals with renal effects and risk of cancer death.

Renal Effects

Capstone developed a system of REGs to calculate kidney effects. The REGS went from REG 0: “no detectable renal effects,” to REG 3:”likely to become ill.” Whereas NAS agreed with Capstone on REGs 2 and 3, the Committee found fault with REGs 0 and 1. They redefined REGs 0 and 1 as follows: REG 0 “no low-level transient renal effects and no clinical symptoms.” REG 1: “may exhibit low-level transient renal effects.” REG 0 had renal uranium concentrations of less than or equal to 2.2 ug/g renal tissue whereas REG 1 was over 2.2 ug/g to equal to or less than (p. 79). However as transient proteinuria and albuminuria (both symptoms of kidney disease) had been found at renal concentrations as low as 1 ug/gram kidney tissue (p. 80), the Committee felt that Capstone should redo the guidelines for REGs 0 and 1.

The Committee also asserted that there was really not enough data to back up the REGS and that some of the supporting research was not necessarily applicable to battlefield or post-combat situations. (p. 78). The Committee concluded however that: “overall, detectable renal effects are not like to occur” in soldiers in Levels I, II and III (p. 82).

Cancer Risk

The cancer risk assessments made by Capstone were based solely on alpha radiation risk. NAS states that “the radiation dose estimates are within US radiation standards for occupational exposure” (p. 83).

Dr. Rosalie Bertell noted that if occupational radiation standards are to be used for soldiers, they should be trained in the handling of DU weapons and how to deal with their hazards on the battlefield - which would require advance notification prior to deployment as to whether DU would be used in the conflict. (personal communication).

Dr. Ian Fairlie in a DU Workshop at the UN in Geneva, stated that beta radiation inside the body is as important a source of radiation as alpha particles.8

Another unexpected source of radiation would come from nano-sized particles. Dr. Rosalie Bertell stated that: “ultra fine particles (nano-diameter) deliver about a 36 times higher dose than the same mass in one particle…because the material makes contact with about 3.6 times as much tissue.” (personal communication)

To return to the Committee, they were concerned that several DU shells hitting a tank or Bradley, given a worst case scenario, would double the estimated median increased risk of death from lung cancer to 9 percent, or one death in 111 persons, (p. 85) which they felt was a definite risk. (p. 85)

The UN Environmental Programme, (UNEP) stated that Iraqi tanks that had been destroyed had normally sustained 2-7 hits by DU shells.9 These were 30mm DU shells shot from jets, not 120mm DU shells. However, it is likely that more than one 120mm DU shell would strike a tank in a friendly fire incident. The NAS Report itself mentions that “multiple perforations can occur on the battlefield” (p. 85).

The Committee noted that Capstone had not taken DU’s chemical toxicity into account as potentially carcinogenic, which could increase mortality risks.

The Committee faulted Capstone for not making estimates of lifetime fatal cancer risks for wounded soldiers and Gulf War veterans with embedded DU fragments. They said that this lack: “leads to an underestimation of risk due to increased, prolonged systemic exposure to DU in this cohort of soldiers and of the risk of developing sarcomas in the vicinity of the embedded fragments.” (p. 88) NAS felt that Capstone should have made estimates of cancer mortality for soldiers with Levels II and III exposures. (p. 88)

The Committee also emphasized the importance of decontamination of vehicles where needed for the protection of other military personnel. They further stated that Level II workers should work for limited amounts of time and be required to wear protective equipment, such as respirators. (p. 88).

With regard to the NAS Report overall, Dr. Rosalie Bertell stated that the report should have dealt with the nano-particles that are present in DU aerosols, that they should have considered their ceramic nature (produced by the intense temperatures when a DU shell impacts a tank), the possibility that they can travel from the nose into the brain, their ability overall to enter cells and the kidney’s inability to filter out or excrete nanoparticles. (personal communication)

The NAS Report does not indicate that DU weapons do real harm but it does indicate in a number of places, that there should be further investigation into the extent to which DU weapons may be harmful. It is not an educational report and is not really a useful tool for Congressmen and women. It is too bad that such time and effort went into producing a report that is flawed.


The NAS Report is available on the website of the National Academy of Sciences, at

1. Y. Gueguen et al., “Short-term hepatic effects of depleted uranium on xenobiotic and bile acid metabolizing cytochrome P450 enzymes in the rat”, Arch. Toxicol. 80, 187-195, 2006.

2. Wendy J. Hartsock et a., “Uranyl Acetate as a Direct Inhibitor of DNA-Binding Proteins”, Chem. Res. Toxicol. 20, 784-789, 2007

3. Ibid p. 787.

4. Dr. Melissa McDiarmid and co-workers have been careful, as here, not to mention lymphoma or tumors in their statement about the health of their veterans. One veteran in the program developed Hodgkins Lymphoma and another veteran had a bone tumor removed from his arm – these two cases are never mentioned. See Dan Fahey, “Unresolved Issues Regarding Depleted Uranium And the Health of US Veterans of Operation Iraqi Freedom and Operation Enduring Freedom”, 24 March 2004, p. 9.

5. M.A. McDiarmid et al., “Health Surveillance of Gulf War I Veterans Exposed to Depleted Uranium: Updating the Cohort”, Health Physics 93(1), 60-73, 2007.

6. The Committee in several tables added a Bradley fighting vehicle with an operational ventilation system (it had not been used in Operation Desert Storm).

7. The median is usually used with small samples. It does not indicate wide variability in data.

8. Dr. Ian Fairlie, “Some Aspects of DU Risks:, ICBUW Workshop, United Nations, Geneva, April 2, 2008. Available at

9. The United Nations Environmental Programme (UNEP), Assessment of Environmental “Hot Spots” in Iraq, Geneva: UNEP, 2005, p. 115.