BSE was such a huge political debacle that no government could fail to learn from it. Right? Well, it seems not. There is a familiar sound echoing round Europe and the US this week: governments telling us that something is safe, on the basis of little discernible science. This time it's weapons made of depleted uranium (DU). Maybe they are safe. Maybe not.

There is every reason to suspect that DU may be unhealthy. It is a heavy metal, like lead. It also emits alpha particles, which are definitely not good for you (see p 4). DU shells form a fine dust on impact, and armed forces that use them know enough about uranium toxicity to make their people wear full protective gear when handling the resulting debris.

And yet governments that use DU weapons tell us only that they don't emit enough radiation to be harmful on a whole-body basis. In a move reminiscent of then-minister John Gummer feeding his daughter a beefburger at the height of the BSE epidemic, NATO officials in Brussels last week carried around lumps of DU to show journalists during briefings.

Get serious. A lump of DU in your pocket is a different proposition from specks of DU zapping alpha and beta particles directly into a lymph node or bone. If officials really want to convince us, let them inhale a pinch of DU dust, as they are asking the people of Kosovo and Iraq to do.

As the DU crisis deepens, the parallels with BSE get even starker. In the 1980s and 90s, British government politicians insisted for as long as they could that they didn't have any evidence that beef was unsafe. Of course they didn't. They hadn't done the research that would have found it.

Now "scientists have no evidence that DU weapons are harmful" is the mantra in London, Washington and Brussels. The weapons may or may not be safe. There is no evidence of a hazard because nobody has looked in the right place.

The US and now Germany have measured total uranium levels in the urine of service personnel. They found no elevations that correlated with service or medical history. Look! It's not harmful, they say.

Uranium pharmacology isn't that simple (see p 5). Those urine measurements are meaningless. There are other tests that will show whether someone has been exposed to DU, but apart from a few activists in Canada and the US, no one has commissioned them.

So why all the bland reassurances? Could it be something to do with the cost of cleaning up battlefields contaminated with DU? Or perhaps the fact that the only potential replacement for DU is tungsten, which is a lot more expensive?

If generals really want to use DU, they must first do a proper examination of veterans. And, yes, the same tests should be done on the people now living amid DU debris, to see who was exposed and by how much. The tests should be followed up for long enough--and that means many years--to see what illnesses emerge. Then we'll know.