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• <br />4.17 Human Health <br />The mine sites on each of the lease tracts currently are considered inactive: however, both <br />radiological and nonradiological physical hazards that could pose a threat to human health <br />exist on the lease tracts. <br />4.17.1 Radiological Hazards <br />Long-term exposure to ionizing radiation has been shown to cause a statistical increase in the <br />occurrence of cancer in humans (International Commission on Radiation Protection 1990). <br />Mine sites on the DOE lease tracts comprise rocks and soils that contain naturally occurring <br />radioactive material (NORM); the majority of NORM is derived from the uranium-238 and <br />uranium-235 decay chains. One of the products in these decay chains is radium-226, which <br />is the principal radionuclide of concern for characterizing the redistribution of radioactivity in <br />the environment. <br />Background levels of radium-226 are normally present in soil in trace concentrations of about <br />1 picocurie per gram (pCiJg); however, background concentrations within ore-bearing <br />formations may be as high as hundreds of thousands of picocuries per gram. Background <br />concentrations of radium-226 in mine-rock waste piles average 23.7 pCi/g (EPA 1991). The <br />primary radioactive sources on the DOE lease tracts are mine-rock waste piles, mine portals. <br />ore-bearing outcrops (Salt Wash Member of the Morrison Formation}, and airborne <br />particulates derived from these sources. In underground mines, the primary radium-226 <br />source is the ore-bearing Salt Wash Member. <br />The amount of radiation that is received by mine workers and members of the public is <br />directly related to the amount of time they spend on or near the radioactive sources and to <br />the level of radioactivity inherent to the sources. At the present time, mine workers typically <br />visit the lease tracts for approximately 3 hours each month of the year, or for a total of <br />36 hours per year. Because most of the lease tracts are readily accessible by public roads <br />and are not secured by fences or locked gates. members of the public may spend more or <br />less time on the lease tracts than the mine worker. Although members of the public are not <br />permitted to permanently or temporarily reside on the lease tracts, some visitors may camp <br />for 1 or more days. Other activities that bring public visitors to the lease tracts include <br />hunting, hiking, and mountain biking. In general, a public visitor would not spend more <br />than 2 weeks (336 hours) per year on the lease tracts. <br />An individual may be exposed to radiation on the lease tracts through three primary <br />pathways: (1) external exposure to gamma radiation, (2) inhalation and ingestion of <br />resuspended radioactive particulates. and (3) inhalation of radon and radon daughter <br />products. These exposure pathways are analyzed to determine health effects on mine <br />workers and members of the public. Presently, the leaseholders ensure that worker and <br />public exposures do not exceed MSHA, NRC, and EPA regulations (see discussion in <br />Section 3.2 for exposure thresholds). <br />DOE Gr:wd Juoctioa Projects OBce ULh1P EA <br />11fay 19, 1995 Pape 49 <br />