More research urged on DU

Leading UK scientists say they do not think exposure to depleted uranium (DU) puts soldiers or civilians in danger.

The scientists say troops exposed to DU may absorb far more radiation than the annual permitted dose, but they believe the increased death risk from radiation-induced cancer is very small.

However, they urge more research to clear up the considerable uncertainty over DU's effects.

In a report for the Royal Society, the British academy of sciences, scientists say: "A good deal is known scientifically about DU; it is also clear that a good deal remains to be learned."

The first part of the report deals with the amounts of DU to which soldiers could be exposed, DU's radiological effects, and the lessons of epidemiological studies.

The second, still unpublished, will cover DU's health effects linked to its properties as a toxic heavy metal, and its environmental impacts.

Three situations

DU was used by Allied forces in the 1991 Gulf War and later in Bosnia and Kosovo.

It is the by-product of enriching natural uranium for civil and military use. It is 1.7 times as dense as lead, and is used in munitions where its kinetic energy allows it to punch through tanks and other armoured vehicles.

The authors of the Royal Society report consider three situations they describe as "generic".

• Level One: concerns people in a vehicle struck by a DU round, or who enter a struck vehicle immediately: they will probably inhale DU dust or be hit by shrapnel.
• Level Two: typically involves people working on or in contaminated vehicles who inhale or ingest DU dust.
• Level Three: "includes all other exposures, for example during combat being downwind of impacts or fires".

They say: "The central estimate radiation doses are less than 0.1 mSv (millisieverts), except for the Level One inhalation exposure, which is about 20mSv, corresponding to the annual dose limit for workers in the UK."

But they add: "The worst-case doses for Level One and Two inhalation exposures are substantial at around 1 Sv (sievert)". On dust inhalation, they say it seems likely that worst-case intakes of more than one gram of DU are possible.

Turning to the link between radiation and cancer, they put the worst-case excess risk of fatal lung cancer from Level One dust inhalation at 6.5 per hundred (a 6.5% increased chance of dying of cancer in an individual's lifetime).

This, they say, would mean a soldier exposed to that much DU would have a risk of dying of cancer at the age of 75 roughly twice that of the general population.

Research needed

For Level Two, the risk is 2.4 per 100. The authors find backing for their low estimate of DU's risks in the epidemiological studies of uranium miners and others who work with the substance.

They say: "There is no evidence of a significant increase in deaths from any cause, or from all cancers, or individual types of cancer, in the large cohorts of uranium workers whose health has been monitored."

And they add: "The epidemiological studies thus provide some support for our views that exposure to DU is unlikely to increase greatly the risks of cancer."

But they say children need to be aware of the slightly increased skin cancer risk from long exposure to DU fragments. And they urge more research to "help in assessing the hazards that may arise from the use of DU".