Be careful not to fall into the WMD range, hehehe

Cerium is a rare earth metal, a group of metals that includes those of the lanthanide series, and may include yttrium, scandium, and thorium. Naturally occurring radioactivity from the uranium or thorium decay series is possible from rare-earth mineral operations. In this case, thorium contamination in the cerium oxide is the cause of the radiation readings found. While the radiation readings are higher than the background readings, for workers handling the material for only about 10 minutes a day the total radiation dose is a fraction of annual occupational radiation dose limits established by the Occupational Safety and Health Administration. The total radiation dose from this activity is also well below the average annual radiation dose received by all individuals from other naturally occurring sources of radiation, which is typically 300 millirem per year (National Council on Radiation Protection and Measurements [NCRP] Report No. 94 "Exposure of the Population in the United States and Canada from Natural Background Radiation").