• radioactivity
  • Tellurium often has unpleasant effects (although some organisms can use it), and polonium is always extremely harmful, both in its chemical toxicity and its radioactivity. (wikipedia.org)
  • They predominantly emit α-particles, and the heat released in this process can serve as a heat source in radioisotope thermoelectric generators, but this application is hindered by the scarcity, high cost, and radioactivity of curium isotopes. (wikipedia.org)
  • Polonium was discovered in 1898 by Marie and Pierre Curie, when it was extracted from uranium ore and identified solely by its strong radioactivity: it was the first element to be so discovered. (wikipedia.org)
  • Polonium has few applications, and those are related to its radioactivity: heaters in space probes, antistatic devices, and sources of neutrons and alpha particles. (wikipedia.org)
  • ores
  • Due to the short half-life of all its isotopes, its natural occurrence is limited to tiny traces of the fleeting polonium-210 (with a half-life of 138 days) in uranium ores, as it is the penultimate daughter of natural uranium-238. (wikipedia.org)
  • calcium
  • There is no widely recognized deficiency syndrome for selenium, unlike the syndromes associated with calcium or magnesium (hypocalcemia and hypomagnesemia, respectively). (encyclopedia.com)
  • water
  • Selenium is also present in drinking water in some parts of the world and can be added to drinking water as a health measure. (encyclopedia.com)