Uranium tailings are a waste byproduct (tailings) of uranium mining. In mining, the raw uranium ore is brought to the surface and crushed into a fine sand. The valuable uranium-bearing minerals are then mechanically removed, and the remaining radioactive sand, called "uranium tailings", is stored in huge impoundments.
If these uranium tailings are left on the surface and allowed to dry out, the radioactive sand can be carried great distances by the wind, entering the food chain and bodies of water. The danger posed by such sand dispersal is uncertain at best given the dilution effect of dispersal. The majority of tailing mass will be inert rock, just as it was in the raw ore before the extraction of the uranium, but physically altered, ground up, mixed with large amounts of water and exposed to atmospheric oxygen, which can substantailly alter chemical behaviour.
Uranium tailings contain over a dozen radioactive nuclides, which are the primary hazard posed by the tailings. The most important of these are thorium-230, radium-226, radon-222 (radon gas) and the daughter isotopes of radon decay, including polonium-210.
An EPA estimate of risk based on uranium tailings deposits existing in the United States in 1983 gave the figure of 500 lung cancer deaths per century, if no countermeasures are taken.[1] This unit of reporting the risk greatly underestimates risk to local populations.