Several European nations have demanded that NATO investigate cancers and deaths in troops suffering from "Balkan Syndrome".
A number of countries are now claiming that troops may have developed leukaemia and other illnesses directly from depleted uranium (DU). As with other radiation scares, the assumed risks tend to rush well ahead of the actual dangers posed by the material.
The assumed radiation exposures during the Balkan conflict relate to the use of DU in armour-piercing shells, 30mm projectiles fired at high speed and heavy enough to punch through metal plating. Ordinary bullets are made of lead but DU is much denser and so a given volume is heavier than lead, explained Capt Paul Connors of the Irish Defence Forces.
"Historically, rounds have been made of lead but if you take DU, it is 1.7 times more dense. If you use DU, it has more punch," he said. The 30mm by 173mm rounds weigh 69 grammes (about 1.8 oz) and their weight gives them extra energy for breaking into metal shielding.
They do not contain high explosives, he explained, but the sudden deceleration when they strike metal releases tremendous energy. This smashes through the metal, vaporising part of the round in the process. Injuries caused to those inside a tank or armoured personnel carrier come both from metal fragments but also the heat caused by the impact.
The unfired shells are not dangerous to handle because of the nature of the DU inside them, Capt Connors said. About 95 per cent of the radiation they give off is called alpha radiation, a type which is easily stopped by a sheet of paper.
The DU is encased in tough metals such as tungsten carbide or titanium so very little radiation can escape. NATO describes the rounds as having "no risk" for troops handling them.
After firing, however, DU does escape and can represent a potential radiation hazard to those exposed to it. NATO reported that about 31,000 DU rounds were fired in Kosovo and another 10,000 to 18,000 in Bosnia, Capt Connors said.
Most were fired by A-10 Thunderbolt "Warthog" aircraft at armoured columns, although the American troops also used them against certain buildings such as communications centres, Capt Connors added. This meant they were used both in rural areas to attack vehicles on the road and also in some built-up areas.
The two main pathways for exposure are by breathing in the radiation or by ingesting contaminated food or drinking water. Between five and 35 per cent of the round vaporises on impact, Capt Connors said and this re-forms into a glassy, dust-like material. This is the focus of the risk associated with the remains of DU, both for soldiers on the scene afterwards but also for civilians who have remained in contaminated areas.
The claims about illness currently being made are not realistic, however, according to Prof Peter Mitchell, head of the department of experimental physics at University College Dublin. "The thing doesn't make common sense, the assertions that are being made."
Uranium when taken in with food tends to build up on bone surfaces and in the kidney and liver, he said. Yet it is not easily absorbed by the stomach and most passes harmlessly through the system. There are exposure levels at which disease is possible both through eating or breathing in the dust but these are "very difficult to achieve unless you have a very heavy concentration", he said. There would have to be "sustained exposure at very high concentrations or ingestion levels."
Breathed-in dust would represent the greatest hazard as lodged particles would deliver a radiation dose to a single area over long periods. If the assumptions about DU were correct, then lung cancers should be a common out-turn but it could take years before they emerge.
Leukaemias in troops are being claimed as possibly caused by the DU residues but this is a disease that develops six to 12 years after radiation exposure, "certainly not one or two years", Prof Mitchell said.