Emerging Picture of Uranium’s Health Risks
Brice Smith and Arjun Makhijani
Uranium, including depleted uranium (DU), is usually most dangerous to people when it gets inside the body, whether through ingestion, inhalation, or through breaks in the skin (though prolonged contact can also result in significant external radiation dose). Inside the body, uranium creates risks both as a toxic heavy metal and as a radioactive material. Additionally, there are some indications that synergisms might exist between these two types of health effects.
Current federal safe drinking water regulations limit the concentration of uranium in drinking water to 30 micrograms per liter (mg/L) based primarily on its chemical toxicity. For natural uranium, this limit translates into 20 picocuries per liter (pCi/L) of radioactivity from uranium. For depleted uranium, the drinking water limit translates into about 12 pCi/L of uranium activity. Federal regulations limit uranium inhalation based on cancer risk and limit drinking water intake based mainly on kidney toxicity.
Exposure to uranium in water is regulated for chemical toxicity largely because uranium is known to be nephrotoxic (toxic to the kidneys). The kidneys are responsible for controlling the composition of blood and eliminating wastes. Important uncertainties remain as to the level of sensitivity of human kidneys to depleted uranium. Animal studies have shown toxic thresholds that differ by more than an order of magnitude between experiments on rabbits (more sensitive) and rats (less sensitive).
The science surrounding uranium’s effects on the body is rapidly expanding due in large part to the concerns that have arisen in the wake of the 1991 Gulf War, the 1999 NATO bombing campaign in the former Yugoslavia, and the gradual recognition of the many health problems that have come to be known as Gulf War Syndrome. We discuss below the emerging picture from this research.
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Published by Alla Yaroshinskaya
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