Contamination from depleted uranium (DU) is an issue covering several sites worldwide. The properties of DU, such as its high density (19.05 gcm~3) and penetrating strength, have led to its use in a number of civil and military applications including munitions. Such munitions have been used in a number of conflicts over the past few decades with a summary provided in Table 4. Many of these rounds miss their target and can penetrate some distance into the ground.

The experimental test firing of depleted uranium munitions is also respon­sible for contamination at various firing ranges in both the UK and the USA. The UK Ministry of Defence (MOD) estimates that 15 tonnes of DU rounds were fired at an armour plate at the Eskmeals firing range in Cumbria between 1981 and 1995, with an additional 30 tonnes fired into the Solway Firth at Kirkcudbright, Scotland since 1982 (ref. 52). Experimental firing of DU rounds began in the USA at the Aberdeen and Yuma proving grounds in the early 1970s. More than 70 tonnes of DU have been deposited over 1500 acres at the Aberdeen Proving Ground, Maryland, into the sediments and the aquatic environment.53,54

Natural and depleted uranium share a similar chemotoxicity but the radio­toxicity is around 60% higher for the former. The low specific radioactivity combined with the dominance of alpha emissions means that no acute risk is associated with external exposure to DU but internal exposure presents serious health risks. Therefore, the main risk arises from DU dust generated from the impact of DU munitions on hard surfaces. Re-suspension of settled DU dust can occur if the particle size is sufficiently small. Traces of 236U and 239+240Pu have been found in DU penetrators collected in Kosovo55 and trace amounts of americium, neptunium and 99Tc are also thought to be present in DU.56

A review by the Royal Society57 estimates that in a worst case scenario for DU exposure in the battlefield, a soldier who experiences level I exposure to DU (exposure dominated by inhalation of aerosols generated by DU impact) has a increased risk of 1.2 per 1000 of death from lung cancer. However, they cite that poor data collection on battlefield exposure makes estimating such health risks very difficult. DU fragments left on the battlefield also pose a concern as a slightly increased risk of skin cancer is expected from long-term exposure to DU pene — trators. This is of particular concern for children who may be attracted to such objects. DU penetrators remaining in the ground also pose a longer term risk through potential migration to food sources or into water supplies. The mobility of the DU from the contaminated ‘‘hotspot’’ depends on a number of factors including corrosion rates, DU particle re-suspension, and proximity to surface soils and water sources. Although this form of radionuclide contamination has been the focus of much recent media interest, there is comparatively little work published on the scale of the problem, or strategies to decontaminate environ­ments contaminated by DU munitions. However, the reader is directed to a recent review on the environmental fate of DU for a more detailed critique.58