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A radionuclide is an atom with an unstable nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created radiation particle within the nucleus, or else to an atomic electron. The radionuclide, in this process, undergoes radioactive decay, and emits a gamma ray(s) and/or subatomic particles. These particles constitute ionizing radiation. Radionuclides may occur naturally, but can also be artificially produced.[1]

Radionuclides are often referred to by chemists and physicists as radioactive isotopes or radioisotopes. Uranium, radium, and radon are naturally occurring radionuclides found in the environment.[1]

Coal contains minor amounts of the radioactive elements, uranium and thorium. When coal is burnt, such as in power stations, the fly ash contains uranium and thorium "at up to 10 times their original levels."[2]

Radionuclides and coal

In 2007, Scientific American noted that, over the past few decades, a series of studies had found coal waste produced by coal plants is actually more radioactive than that generated by nuclear plants. The fly ash emitted by a power plant carries into the surrounding environment 100 times more radiation than a nuclear power plant producing the same amount of energy, due to coal's content of uranium and thorium, both radioactive elements. They occur in such trace amounts in natural, or "whole," coal that they aren't a problem. But when coal is burned into fly ash, uranium and thorium are concentrated at up to 10 times their original levels.[3]

Fly ash uranium sometimes leaches into the soil and water surrounding a coal plant, affecting cropland and, in turn, food. People living within a "stack shadow"—the area within a half- to one-mile (0.8- to 1.6-kilometer) radius of a coal plant's smokestacks—might then ingest small amounts of radiation. Fly ash is also disposed of in landfills and abandoned mines and quarries, posing a potential risk to people living around those areas.[3]

Robert Finkelman, a former U.S. Geological Survey (USGS) coordinator of coal quality who oversaw research on uranium in fly ash in the 1990s, says that for the average person the by-product accounts for a miniscule amount of background radiation, probably less than 0.1 percent of total background radiation exposure. According to USGS calculations, buying a house in a stack shadow—in this case within 0.6 mile [one kilometer] of a coal plant—increases the annual amount of radiation you're exposed to by a maximum of 5 percent. But that's still less than the radiation encountered in normal yearly exposure to X-rays.[3]

Health effects

Animal studies have reported inflammatory reactions in the nasal passages and kidney damage from acute inhalation exposure to uranium. Chronic (long-term) inhalation exposure to uranium and radon in humans has been linked to respiratory effects, such as chronic lung disease, while radium exposure has resulted in acute leukopenia, anemia, necrosis of the jaw, and other effects. Cancer is the major effect of concern from the radionuclides. Radium, via oral exposure, is known to cause bone, head, and nasal passage tumors in humans, and radon, via inhalation exposure, causes lung cancer in humans. Uranium may cause lung cancer and tumors of the lymphatic and hematopoietic tissues. EPA has not classified uranium, radon or radium for carcinogenicity.[1]



  1. 1.0 1.1 1.2 "Radionuclides (including Radon, Radium and Uranium)" EPA, accessed October 2010.
  2. Mara Hvistendahl, "Coal Ash is More Radioactive than Nuclear Waste", Scientific American, December 13, 2007.
  3. 3.0 3.1 3.2 Mara Hvistendahl, "Coal Ash Is More Radioactive than Nuclear Waste" Scientific American, December 13, 2007.

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