The United Nations Environment Programme says depleted uranium (DU) weapons used in Kosovo should cause no alarm.

Publishing its findings on the environmental impact of the use of DU, Unep says the radiological risks in target areas are insignificant.

But it says there are still many uncertainties, especially about the safety of groundwater.

And it wants an examination of Bosnia-Herzegovina, where DU was used more than five years ago.

DU, a waste product left after uranium is enriched for civil or military use, is a very heavy substance, 1.7 times denser than lead, and it is highly valued by armies for its ability to punch through armoured vehicles.

Tested samples

When a weapon with a DU tip or core strikes a solid object, like the side of a tank, it goes straight through and then erupts in a burning cloud of vapour.

Kosovo veterans may have been exposed to DU

This settles as dust, which is chemically poisonous and also radioactive.

The report presents the findings of a multinational Unep team of 14 scientists which last November visited 11 of the 112 sites identified by Nato as having been targeted by DU weapons in the 1999 conflict.

The team collected soil, water and vegetation samples, and carried out smear tests on buildings, destroyed army vehicles and DU penetrators (a component of the weapons).

It found DU remnants at eight of the 11 sites, and 355 samples were analysed by laboratories in Sweden, the UK, Austria and Italy. Switzerland paid for the assessment.

Nuclear reactors

The scientists found seven and a half penetrators, with low levels of radiation close to the point of impact. They measured mild contamination from DU dust near the targets.

They also found evidence showing that the penetrators had contained traces of enriched (not depleted) uranium, and of plutonium.

Unep says these showed "that at least some of the material has been in nuclear reactors".

But it says the amount of these transuranic isotopes "is very low and does not have any significant impact on their overall radioactivity".

The team found no widespread ground contamination in the areas it investigated, and concludes that "the corresponding radiological and chemical risks are insignificant".

Recommended precautions

Unep's executive director, Dr Klaus Toepfer, said: "These findings should alleviate any immediate anxiety that people living or working in Kosovo may have been experiencing."

But he said DU could still pose risks in certain circumstances, and therefore Unep recommended some precautions.

Troops search for DU remains

These include the removal of all radioactive shrapnel on the surface at all DU sites in Kosovo, decontaminating areas where possible, and telling local people what to do if they find DU.

The head of the Unep Kosovo team, Mr Pekka Haavisto, said: "There are still considerable scientific uncertainties, especially related to the safety of groundwater.

"Additional work has to be done to reduce these uncertainties and to monitor the quality of water."

Unep says remaining fragments of DU rounds which may be buried several metres beneath the surface risk future contamination of groundwater and drinking water.

Other missions

And heavy firing of DU in one area could increase the potential source of uranium contamination of groundwater by from 10 to a 100 times.

Unep concludes that the team's findings should not cause alarm, but acknowledges the scientific uncertainties over the longer-term behaviour of DU in the environment.

It wants a similar assessment of Bosnia-Herzegovina, "where DU ordnance has persisted in the environment for over five years".

And with the International Atomic Energy Agency and the World Health Organisation, Unep will consider whether there is a need for missions to other areas where DU has been used in wars.