MEDICAL EFFECTS OF DEPLETED URANIUM IN KOSOVO

by Zbigniew Jaworowski

Central Laboratory for Radiological Protection, Warsaw, Poland

The total mass of depleted uranium dispersed over Kosovo ranged between 2.5 and 25 tons. The radioactivity of one round was about 10 megabecquerels (MBq). Assuming that 30 000 rounds were fired, one can easily calculate that a total activity of about 300 000 MBq of uranium-238 activity was dispersed over the environment of Kosovo. In a 1 cm thick layer of soil in Kosovo (area: 10 887 km²) the radioactivity of natural uranium-238 in equilibrium with its daughters amounts to about 100 000 000 MBq. Thus, a 1-cm thick layer of soil in Kosovo contains about 300 times more natural uranium than that dispersed there by American forces. However, at the target sites, the local concentrations of depleted uranium may be higher than the average concentration of natural uranium in the soil. From these patches of activity depleted uranium may be resuspended into the air, and also enter the food chain. This, however, should not lead to any observable medical consequences.

The weak beta and gamma radiation does not pose any serious radiation protection problems. For example, radiotoxicity of inhaled uranium-238 (in terms of Sv per Bq) is over 1000 times lower than radiotoxicity of cesium-137. Because of these features of depleted uranium, its radiation protection standards are based not on its radioactivity but on its chemical toxicity. Like other heavy metals (lead, cadmium, or mercury) uranium is a toxic agent. Experimental and epidemiological studies, carried out over half a century, suggest that the main adverse effect of uranium-238 is chemical impairment of the renal function. Secondary protection standards for uranium-238 (for example concentration limits in air and food) are based on a limit of 3 micrograms of uranium per gram of kidney.

In epidemiological studies of over 32 000 workers, exposed to uranium between 1943 and 1986 in nuclear installations in the USA and UK, except for renal problems, no other health impairment was observed, which could be related to this metal. Among this worker cohort mortality due to all diseases was lower than in the general population, and mortality due to all cancers and leukemia was also lower.

Among about 150 000 soldiers, who for various periods of time were stationed in Kosowo between March 1999 and the end of 2000, up to now 17 died due to leukemia. This corresponds to about 11 deaths per 100 000 soldiers. The annual leukemia death rate in the United Kingdom is 11 per 100 000. Thus, the rate of soldiers dying due to leukemia appears to agree with European norms.

Some years ago "clusters" of leukemia were found in several countries, in which the morbidity of leukemia was higher (up to ten times) than that in the general population. The first of such clusters was discovered in the village of Seascale, near Sellafield, which is the site of the main nuclear fuel reprocessing plant in the United Kingdom. The excess was reported in a television program in November 1983, and later similar clusters were found in other places in the UK and later in Germany, France, Canada and the USA. At first it was suspected that the cause of clusters are radioactive emissions from nuclear installations. However, it was soon realized that they also appear at other non-nuclear sites where migration of large number of people occurred. In an extensive review of these findings in its 1994 report UNSCEAR concluded that a possible explanation is that these excesses are due to a spread of infection resulting from the mixing of populations from urban and rural areas. One might expect that this phenomenon could also occur among large military formations. But this may not be the case in Kosovo, where the incidence of leukemia fits the European norm rather well. The shortest latency time for leukemia induced by ionizing radiation is two years. As this disease began to appear among the soldiers much earlier, and since no reports on a dramatic increase of renal problems were filed, the cause of leukemia in Kosovo, does not seem to be radiation from depleted uranium, but rather a natural one. This is supported also by the fact that no increase in diseases of kidneys, which are a critical organ for uranium, occurred among the soldiers in Kosovo.

Professor T. Domanski from Poland before few years served as a head of a study group of the Ministry of Health of Kuwait responsible for estimation of health effects depleted-uranium munition in this desert country. He recently reported that according to estimate of this group about 100 000 rounds with depleted uranium were fired over Kuwait during the Gulf War, what corresponds to about 300 tons of uranium dispersed in the environment. Unexploded munition, splinters and military equipment destroyed with uranium munition are stored at depots in the desert. Uranium contamination of the ground, up to a level 10 to 20 times higher than average natural level, was found only to a distance of up to 100 meters from the depots, and no contamination of local vegetation was observed. Profesor Domanski reported that until 1998 no increase of leukemia and other cancers was observed in Kuwait, that might be related to depleted uranium.

So, is this just much ado about nothing, or is it merely an expression of a negative feeling towards a new type of ammunition or towards Americans?