The Hazards of Depleted Uranium
The obvious danger from uranium is radiation. U238 itself is primarily a low-level alpha emitter, but its decay products such as Thorium (Th-234) and Proactinium (Pa-234) are energetic Beta emitters, and within a year of creating a new batch of DU, these progeny exist in considerable quantities. Further down the decay chain, come the radon daughters, emitting significant alpha and beta radiation.
See WISE, for U238's decay chain (ie. the series of elements produced by its characteristic sequence of radioactive eruptions).
US forces have measured DU fragments in the Gulf emitting up to 250 millirads of radiation per hour (exceeds recommended US annual radiation dose in under 30 minutes), and the US military are on record as confirming activity levels of 2.5mGy/hr at the surface of a DU shell.
Each A-10 (American warplane) 30mm cannon anti-tank shell contains 300g of DU (10.1 Bq of activity).
Aerosol and Dust Clouds
When a DU projectile hits a target, up to 70% of the DU combusts, bursting into dense black clouds of highly toxic, radioactive, microscopic uranium-oxide particles - effectively creating a ceramic DU aerosol. Most of the particles are of respirable size (less than 10 microns), ie. they're small enough to be ingested via inhalation (as well as via open wounds of course, and they're even small enough to penetrate some gas masks), and can be carried long distances (25 miles or more) by the wind, before settling. They can then be resuspended again by wind or movement, and dispersed yet further again. They can also migrate long distances via the ground water table.
This ceramic formulation is significant, because it is highly insoluble in lung fluids, unlike the traditional uranium dust encountered by miners, which is rapidly excreted from the body. Once deposited in the lungs, kidneys or bone, DU particles generally remain in the body for many years. Indeed, veterans of the 1991 Gulf War are still passing DU in their urine to this day.
The unoxidised DU fragments left in the open eventually rust away into a very fine black dust, and spread through the air and water. The DU fragments, oxides and dust obviously all have the same chemical (ie. toxic) and radiological properties, but differ in their concentration, and in their patterns of absorption into the environment and living beings.
And of course, the environment remains radioactive forever (4.5 billion years).
Localised Internal Radiation
DU's alpha and beta particle radiation has limited ranges of penetration and hence is not expected to cause serious damage to living tissue via external exposure, ie. it does not penetrate human skin. However, it is internal tissue exposure that makes ingested DU particles such a hazardous radioactive source, and its alpha particles in particular cause significant internal ionisation, resulting in cell death and genetic mutations.
The significance of the term "localised" radiation refers to the fact that the nuclear industry's standard model (as propounded by the ICRP) for estimating radioactive exposure, is based on the averaged whole-body exposure produced by an instantaneous external source of radioactive emissions, and does not take into account the concentrated localised effects of continuous irradiation by an immobilised internal source of radiation (eg. a DU particle lodged in the lungs or bone marrow, which subjects the immediately adjacent tissues to non-stop radiation for years on end).
The LLRC therefore believe that applying the ICRP's radiology model to DU is fatally flawed, because over a prolonged period of time, although such a DU particle will emit a radiation dose which may appear mild if averaged over the whole body, since this dose is actually concentrated in the surrounding organic tissue, it has a severe effect on that tissue. In fact, the LLRC states:
A single particle of DU smaller than 5 microns can expose the surrounding tissue to radiation 800 times the annual dosage permitted by the Nuclear Regulatory Commission (NRC) for the entire body. (see Dietz below, for a more concise statement of the same point)
Earlier work by Dr Chris Busby had shown that the number of British leukemia deaths due to Chernobyl (which dispersed radioactive particles similiar to DU) was 100 times greater than predicted by the NRPB/ICRP models. As mentioned above, the latter base their predictive models on an acute one-time exposure to Gamma radiation (as occurred in the case of the Hiroshima and Nagasaki atomic bombs, their primary benchmark), and don't factor in the dangers of weaker, but persistent, radioactive particles (or the resulting Second-Event effect - see below).
When a DU particle is trapped in the lungs, the dead and severely damaged cells resulting from its constant radioactive bombardment may eventually be replaced by scar tissue, which could account for the severe lung fibrosis seen in the lungs of Gulf war veterans. Other damaged cells may eventually give rise to cancer.
See Dr Bertell, (IICPH, August 1999) for a discussion of the ceramic particles, and their longevity in the body. In fact, Dr Bertell describes DU as a "very powerful alpha emitter".
In the IAC's 1997 book Metal of Dishonor: Depleted Uranium, co-author John Catalinotto estimates that the radioactive dosage from a single ingested particle of DU, is equivalent to one chest X-ray per hour, for life (or what remains of it).
Retired nuclear scientist, Leonard Dietz (currently working for the UMRC), has estimated the radiation dose from a 5-micrometer (ie. small enough to inhale) DU oxide particle in the lung, as being 1360 rem per year.
This is 272 times the maximum permissible dose for radiation workers and 800 times the permitted dose for the general population.
This July 1996 paper by Dietz provides a concise overview of DU.
Second Event Theory
See section 3 of October 1999 article by Prof Margaret Ryle, which explains how due to its complex decay chain, combined with the localised nature of the radiation from the immobilised internal particles, U238 may in fact be much more radiologically dangerous, than its relatively low radioactivity would suggest.
This phenomenon resulting from U238's particular decay chain (ie. its characteristic sequence of radioactive emissions), is known as Busby's Second Event theory, and is further documented on the LLRC website, and in Dr Chris Busby's 1995 book, Wings of Death.
His theory basically states that the probability of cellular DNA damage (ie. mutation) is magnified many times for isotopes like U238, because they emit successive Beta radiation particles within a few hours of each other, the first of which damages each cell it passes through, while the second one strikes the cells during the vulnerable window of time during which they are still replicating themselves (in response to the earlier damage), and copying their genetic code.
At natural background levels of radiation (NBR), cells receive an average of one radioactive "hit" per year. Simple probability theory tells us that the chances of normal background radiation intercepting this critical window of time in a replicating cell are extremely low, but that dose for dose, internal radiation from incorporated sequential emitters (such as DU) is many thousands of times more likely to trigger the second-event hazard.
As we all know, the hazards of radiation include cancers and genetic mutations down the generations, and U238's radioactivity lasts for 4.5 billion years (could this be what Bush meant, when he spoke of waging war without end ?).
Additionally, the evidence of contamination with enriched uranium and plutonium (see Cover-Up page) means that DU may be vastly more radioactive than we would expect due to U238 alone.
These disturbing photos on The Fire This Time, show some resulting extreme birth deformities in Iraq (and amongst US vets).
Not surprisingly, many commentators have compared the use of DU weapons to low-level nuclear warfare.