It is the waste by-product of the nuclear weapons and civilian nuclear programme. It is left over after the process of enrichment which increases the U235 concentration from ~0.7% in the natural ores to ~3.4% in enriched uranium.

For every 8 tons of uranium - 1 ton of enriched uranium and 7 tons of DU is produced. Over 750,000 tons of DU are now stockpiled (LAKA, 1999).

The ratio of U235 to U238 is uniquely characteristic of DU and provides unequivocal evidence of its presence. DU is both a toxic heavy metal (like lead) and a radiological poison.

The properties and composition of natural uranium and DU are listed in Table 1. The radiological decay processes in DU are given in Table 2 together with those for natural uranium.

 
Furthermore, in the course of one year, 390 million alpha particles, 780 million beta particles and associated gamma rays are emitted. This is equivalent to over one billion high energy, ionising, radioactive particles and rays which can produce extensive biological damage.

The energy of each a-particle (alpha particle) exceeds that which is required to damage important macromolecules such as DNA, RNA, enzymes and proteins. By breaking bonds within them and water molecules, novel chemical reactions, which alter or destroy the shape, organisation and function of these molecules are initiated. There is no lower limit for these effects; they are stochastic. (Busby, Bertell, Zadjic).

DU WEAPONS

DU is selected for weapons for the following reasons:

1. It is cheap and was made available to arms manufacturers free of charge.
2. It is heavy, 1.7 times the density of lead. Tungsten has a higher density.
3. It is pyrophoric, i.e. it ignites and burns on hitting a hard target, and acts as a self-sharpening penetrator.

During the Persian Gulf War, it is estimated that between 359 to 800 tonnes (359 to 800 billion milligrams) of DU was delivered on targeted areas (LAKA 1999). Of this, 59 tonnes have been attributed to forces from the UK.

THE NUB OF THE PROBLEM

When DU weapons hit a target, a fine aerosol of uranium oxides is formed. The majority of particles (46 - 70%) are less than 10 micron. This allows them to be readily inhaled by humans. Particles under 2.5 micron are particularly dangerous as they can lodge deep into the lungs.

Once released, these fine particles can be spread by the wind and are readily re-suspended by modest breezes or vehicle and personnel movements. There is no existing study measuring the distance travelled by such particles. However, there is a documented instance were particles were physically captured 42 km away. (Deitz 1999). This only proves migration beyond the specific site but does not preclude the suspicion that particles can travel a great many times more kilometers.

Whilst some of the DU is soluble, the majority in the form of other oxides is insoluble and remains in the body for years. Once in the body, DU slowly spreads from the lungs, mainly into the lymph nodes and bone. Excretion from the body is very slow.

A US study of 10,000 Gulf War Veterans indicated that 4 out of 5 had been in situations where they could have been exposed to DU (Kornkven, 1998).

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