Long-term exposure has been shown to result in damage to kidney function. The ingestion of insoluble particles of DU poses a much lower chemical health risk, as the fraction absorbed is lower still and nearly all the material is eliminated through the GI tract. Absorption by inhalation depends on the size and solubility of the particles. For smaller particles, a larger fraction will deposit in the lungs, where they main remain for months or years, unless they dissolve. Very small amounts may be retained in the lymphatic system for longer.
Insoluble particles pose a higher radiation risk owing to the longer stay in the lungs.
In the military environment, wounds represent an additional route of exposure if caused by the impact of DU projectiles or armour. Military personnel are exposed to shrapnel as well as dusts that can be inhaled, ingested or deposited on wounds. There is a theoretical possibility that exposure to alpha and beta radiation from inhaled insoluble DU particles might lead to lung tissue damage and increase the probability of lung cancer. Similarly absorption into blood and retention in other organs, notably the skeleton, is assumed to carry an additional risk of cancer, depending on the level of radiation dose. Some 15 years after the Chernobyl nuclear reactor accident, the main cancer resulting was a very steep increase in childhood thyroid cancer.