Radionuclides are trace elements that occur naturally in rocks and soil from the decay of radioactive decay of uranium-238 and thorium-232. There is limited data in North Carolina on the occurrence of radionuclides. Long-term exposure to radionuclides may increase a person’s risk of developing cancer. Well water testing can identify radionuclides. If elevated, a treatment system can be installed by a certified installer to remove radionuclides from the water.