A few examples include radon, radium 226, radium 228 and uranium.
Radioactive minerals exist in all areas of New Hampshire.
They dissolve easily in water. In some areas this causes the groundwater to exceed current or proposed public drinking water standards for radioactivity. Wells that derive water from sand and gravel deposits generally have substantially lower concentrations of both radon gas and dissolved mineral radioactivity and much greater uniformity of quality in a given area. Exposure to radioactivity increases one's cancer risk. At lower exposures, the risk of cancer is reduced.