For years, the defense ministries of states like the US, Canada and the UK have denied that exposure to depleted uranium (DU) produce negative health effects. At the same time, the conduct research looking for ways to render DU less toxic. Their latest hope comes in the form of the humble mushroom.
Depleted uranium is a byproduct of uranium 238 (U238) enrichment and contains a higher percentage of U235, a more fissile isotope that makes DU useful in the production of nuclear weapons and energy. This depleted byproduct is 1.7 times the density of lead, and because of its durability, has been used extensively by militaries for things like armor piercing projectiles and anti-tank weapons. During the Iraq and Balkans wars, when vehicles and weapons clashed together, dust from depleted uranium was released. Bullets made with the depleted uranium were scattered in battle, and shrapnel was strewn about and embedded in soldiers' wounds. Depleted uranium ordnance now lies scattered throughout previous war zones where children play and civilians attempt to carry on their lives.
Humans and other species are exposed to depleted uranium not only during war, but via dust in the air around weapons factories and in groundwater near firing test ranges. At a test range in Solway, Scotland scientists find worms carrying uranium isotopes. All of this exposure could prove toxic to animals and humans.
Depleted uranium is not as radioactive as U235 but it is suspected of causing various illnesses, from cancer, immune disorders like Gulf War Syndrome, and even birth defects in offspring born of soldiers who inhale or ingest it. In lab animals, depleted uranium is a teratogen and carcinogen which can affect various mammalian systems. Although some point to the deteriorating health of returning soldiers as proof of the dangers, the dangers of DU, governments and militaries, generally don't medical, and recognize the danger. Even as evidence accumulates, militaries still claim DU safety. The US Department of Defense says:
- "The health effects of uranium have been studied extensively for over 50 years."
- "The Department of Defense has comprehensively studied the environmental fate of depleted uranium both before and after the Gulf War."
- "Fortunately, DU is only mildly radioactive emitting alpha and beta particles, and gamma rays.....The risk of chemical toxicity is also minimal because there is little likelihood that sufficient quantities of DU could be inhaled or ingested to cause a heavy metal concern."
- "Since the Gulf War, the DoD has dramatically stepped up its emphasis on increasing soldier and leader awareness of the hazards associated with the battlefield use of depleted uranium..." through training, handbooks and "support materials".
- "...there is no reason to believe that other exposed Service members have any elevated risk to their health due to their DU exposures."
Similarly, the Ministry of Defense (MOD) for the UK has repeatedly asserted minimal health effects from exposure to depleted uranium. But confusingly, the MOD gave warning cards to all UK servicemen deployed to Iraq, which stated possible health effects of DU. The Ministry of Defense suggests that it's reducing use of DU, and offered some DU inventory details: "In 2003, during the recent Iraq conflict, UK tanks expended 1.9 tonnes of DU ammunition and none has been fired since the official ending of the conflict." The MOD urged soldiers to get monitored for depleted uranium, but after testing the urine of returning servicemen the Ministry of Defense told papers in 2006 that "no evidence of DU was found in their urine". Critics question the sensitivity of their tests.
Clearly, the effects of depleted uranium are still disputed and perhaps not a problem but new research suggests a potential solution. Scientists have discovered a fungus that will break down depleted uranium to a less toxic mineral, research sponsored in part by the Ministry of Defense, produced by scientists at the University of Dundee in Scotland and published in the recent issue of Current Biology. They describe how a plant symbiotic fungus can be grown on the surface of depleted uranium, where it will transform the depleted uranium into uranyl phosphate minerals, a more stable form of the metal that is less likely to be absorbed into plants, animals and water. The mycorrhizal fungi live in the roots of plants, where it transforms carbon into nutrients that plants use. Moisture in the air helps the fungi cover the surface of the metal, which accelerates the corrosion process of the uranium. The resulting products can be take up by the fungi or broken down to less toxic uranium holding minerals. The fungi could be used for various bioremediation projects in uranium polluted soils. In business they warn never to point out a problem unless you have a solution. Maybe the military follows a business protocol.
