By Alex Kirby
BBC News Online environment correspondent
People in Iraq need urgent advice on avoiding exposure to depleted uranium (DU), the United Nations has said.
Japanese protestors reject depleted uranium
It wants the US and UK to provide precise details of sites targeted with DU weapons.
The Royal Society, the UK's national science academy, is also demanding targeting data to enable a clean-up to begin.
It says it is "highly unsatisfactory" to continue using DU without knowing people's exposure levels.
The UN Environment Programme (Unep) expressed its concern about DU in a report on Iraq.
It says humanitarian issues like restoring water and power, and cleaning up waste sites to reduce health risks, are priorities.
Another priority activity is "a scientific assessment of sites struck with weapons containing DU".
It wants guidelines distributed immediately to military and civilian personnel, and to the Iraqi people, on how to minimise the risk of accidental exposure to DU.
The report, the Unep Desk Study on Environment in Iraq, was prepared by Unep's Post-Conflict Assessment Unit.
Unep said: "The intensive use of DU weapons has likely caused environmental contamination of as yet unknown levels or consequences.
"Conducting a DU study would require receiving precise coordinates of the targeted sites from the military."
The Royal Society says details of the DU used in Iraq are essential to allow "an effective clean-up and monitoring programme of both soldiers and civilians".
While Unep had extensive experience, it said, it was vital for Iraq to acquire the capability to undertake long-term monitoring itself.
Concern for civilians
Professor Brian Spratt chaired a Royal Society working group which published two reports on DU's health hazards.
He said: "The coalition needs to acknowledge that DU is a potential hazard and make inroads into tackling it by being open about where and how much has been deployed.
"Fragments of DU penetrators are potentially hazardous, and the Royal Society study recommended they should be removed, and areas of contamination around impact sites identified and where necessary made safe.
"Impact sites in residential areas should be a particular priority. Long-term monitoring of water and milk to detect any increase in uranium levels should also be introduced in Iraq."
The society's study concluded that few soldiers or civilians were likely to be exposed to dangerous DU levels. But it is now calling for tests for soldiers exposed to "substantial" levels.
No time to waste
Professor Spratt said: "It is only by measuring the levels of DU in the urine of soldiers that we can understand the intakes of DU that occur on the battlefield, which is a requirement for a better assessment of any hazards to health.
"It is vital that this monitoring takes place, and that it takes place within a matter of months."
DU is an effective tank-killer
Professor Spratt called as well for monitoring of DU levels in a wide sample of soldiers, including "foot soldiers and field hospital staff across Iraq", and Iraqi civilians.
He said: "It is highly unsatisfactory to deploy a large amount of a material that is weakly radioactive and chemically toxic without knowing how much soldiers and civilians have been exposed to it."
The UK has said it will make available records of its use of DU rounds. It offers veterans voluntary DU tests.
The US says it has no plans for any DU clean-up in Iraq. It does not test all exposed veterans.
DU, left over after natural uranium has been enriched, is 1.7 times denser than lead, and effective for destroying armoured vehicles.
When a weapon with a DU tip or core strikes a solid object, like the side of a tank, it goes straight through before erupting in burning vapour which settles as dust.
Unep found DU traces in air and water in Bosnia-Herzegovina up to seven years after the weapons had been fired there.