Wild claims were made about the health risks posed by the use of depleted uranium rounds used by NATO during the conflict in Kosovo. These were easily dismissed but questions remain about more subtle threats left after the use of these weapons.
A research team from University College Dublin has begun looking into these threats, with scientific colleagues in Belgrade. In particular, they are looking at any possible effect on groundwater and whether people living near where the rounds were used are absorbing depleted uranium (DU).
A major scare was raised earlier this year when claims were made that six Italian soldiers had contracted leukaemia after exposure to DU residues left behind on the battlefield. Portugal also reported cases allegedly linked to DU.
Medical experts dampened down these scares, pointing out that the disease usually only arises many years after exposure, not within 12 to 18 months. No high radiation levels were found in Kosovo that could have altered this picture.
Earlier this year Dr James McLaughlin, head of Natural Radiation Studies in the Physics Department at UCD, travelled to Kosovo and toured DU sites with Dr Zora Zunic of the Vinca Institute of Nuclear Sciences, Belgrade.
He had a long-standing scientific collaboration with Vinca through the study of natural radiation levels in the Balkans.
Dr McLaughlin managed to recover an intact DU round and brought it back to Dublin for analysis. The research team discovered that aside from the expected uranium-238, it discovered small amounts of plutonium, a particularly persistent and dangerous radioactive material linked both to nuclear weapons and nuclear power plants.
Analysis of the plutonium led Dr McLaughlin to speculate it was weapons grade. "The ratio between plutonium-238 and plutonium-239/240 is possibly an indication of weapons grade material in the production plant" where the DU was made.
DU plants tend to be involved in uranium fuel and weapons production, he said. There can be cross contamination of the DU from either of these sources.
The Irish analysis showed however that even in the worst case scenario the DU did not pose an immediate health risk to the people living in regions where DU rounds were fired. Despite containing plutonium, the expected dose was so low as to be negligible and lower than the dose received from natural uranium found in the Balkans.
This did not preclude long-term risks, particularly if the DU in rounds that missed their targets, now resting deep in the ground, begin to leech into groundwater. Dr McLaughlin is involved in studies of groundwater and urine samples to see if the DU begins migrating into the food chain.
Plutonium is likely to remain a trace ingredient in DU rounds given the way uranium is refined. DU is a by-product of the enrichment process that feeds both the weapons and nuclear power industries. Uranium ore after conversion into metal typically contains a mix of 99.28 per cent uranium-238 and 0.72 per cent uranium-235. The nuclear industries are only interested in the U-235 content.
The leftover U-238 is the depleted uranium found in armour piercing rounds and other specialised applications. It is used as shielding in some medical x-ray units and because of its density and toughness is sometimes used in aircraft-part manufacture.
It makes an ideal weapon for several reasons. It is 40 per cent denser than lead so even a small amount makes a projectile with a great deal of mass. This increases the energy delivered when it impacts a target.
Plutonium is also "phyrophoric", a word derived from the Greek for "fire-bearing". Much of its volume disintegrates to dust on impact and spontaneously ignites. The round effectively melts through the armour, punching a hole into the metal plate.
Initial health worries related to the DU dust left behind either outside or inside the vehicle hit by the round. The concern was that the dust could be inhaled, but Dr McLaughlin's analysis suggests that only a very small number of people may have inhaled or ingested DU during and in the immediate aftermath of hostilities.