Certain minerals are radioactive and may emit forms of radiation known as photons and beta radiation. Some people who drink water containing beta and photon emitters in excess of EPA's standard over many years may have an increased risk of getting cancer. Some people who drink water containing radium 226 or 228 in excess of EPA's standard over many years may have an increased risk of getting cancer. Radon gas can dissolve and accumulate in underground water sources, such as wells, and in the air in your home. Breathing radon can cause lung cancer.
Drinking water containing radon presents a risk of developing cancer.
Radon in air is more dangerous than radon in water. Inorganic Contaminants Antimony Asbestos Barium Beryllium Cadmium Chromium Copper Cyanide Mercury Nitrate Nitrite Selenium Thallium Technical fact sheets on Inorganic Contaminants Arsenic . Some people who drink water containing arsenic in excess of EPA's standard over many years could experience skin damage or problems with their circulatory system, and may have an increased risk of getting cancer. Many communities add fluoride to their drinking water to promote dental health. Each community makes its own decision about whether or not to add fluoride.