Depleted uranium and human health: Ron Smith debunks sensationalist claims about the adverse effects of depleted uranium.

• Author: Smith, Ron

A recent officially sponsored visit to New Zealand and the broadcasting of a somewhat sensational video-documentary have renewed concern about the supposed dangers to human health from depleted uranium and, especially, those arising from its military use. This has been the subject of extensive investigation over the last fifteen years by a variety of independent agencies, including the UN Environment Programme, World Health Organisation and Britain's Royal Society, as well as specialised organisations such as the Australasian Radiation Protection Society and Sweden's Radiation Protection Institute. The following discussion draws upon the findings of these investigations to offer a considered response to two questions:

* Is there a particular health problem associated with the military use of depleted uranium?

* Are New Zealand persons who have been deployed to recent battle zones at any significant risk from any exposure they may have had to the remains from depleted uranium munitions?

The content of a June 2005 local publication from the National Consultative Committee on Disarmament (Is Depleted Uranium an issue for the New Zealand Government?) will also be considered. In the light of present knowledge, it would seem that the answer to all three questions (including that raised by the title of the NCCD pamphlet) is 'no'.

Natural uranium is a mixture of two isotopes, both of which are radioactive. These isotopes are: uranium-238 (99.3 per cent) and uranium-235 (0.7 per cent). Both these isotopes have extremely long half-lives (4.5 billion and 700 million years, respectively); that is to say, they are only very feeble sources of radiation. Not only that, the radiation they do emit (alpha radiation) does not penetrate the skin (unlike beta or gamma radiation). Thus, the only danger that could arise from either isotope would be from ingestion.

Uranium-235 is fissile. It is the form of uranium that is required for nuclear explosive weapons and, more particularly these days, for civilian power reactors. For the latter purpose an isotopic mixture that contains 3-4 per cent of uranium-235 is commonly required. This means that the original uranium must be enriched (in respect of U-235) and it also means that a very large quantity of depleted uranium (uranium from which the uranium-235 has been taken) is left behind. This depleted uranium is now almost pure uranium-238 and, as such, it has about half the (already low) radioactivity of natural uranium. The production of fuel rods for nuclear reactors (of which there are now some 450 world-wide) gives rise to large quantities of depleted uranium, as does the reprocessing of spent-fuel.

It is the fact that depleted uranium has a density approximately twice that of lead that makes it such an attractive material for a variety of military and civilian uses. Amongst the latter is its use as a counter-weight or ballast in aircraft or sailing boats, or for shielding X or gamma radiation. Military uses include armour plate and, particularly, high velocity armour-piercing shells.

Potential danger

A depleted uranium projectile, striking tank armour, produces a number of effects. Amongst these are blast, heat and metal fragments (shrapnel) inside the tank. Because of the particular properties of uranium, fine material produced by the impact will also burst into flame and this will produce an aerosol of uranium oxide. For a tank crew, this consequence...