As a result of the presence of elevated concentrations of radium-226 and other radionuclides in phosphate ores and mining wastes, many individuals residing in Central Florida are exposed to undesirable levels of radiation. In the absence of adequate measures to protect public health, many more could be exposed in the future, depending upon developing mining and land use patterns. The major exposure problem is associated with structures, principally residences, that are constructed on, near, or using radium-bearing materials related to phosphate ores…. In the United States, the phosphate deposits of Florida contain concentrations of uranium and its decay products at levels about 30-60 times greater than those found in average soil and rock. The presence of this radioactive material in extensive land areas in Central and Northern Florida creates the potential for radiation exposure of the general population living on or near this land.
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EPA Radiation Protection Standards