As a radioactive element, radium is present in varying amounts in rocks and soil within the Earth's crust. While surface water is usually low in radium, groundwater can contain high levels of radium, potentially leading to radium in drinking water. Radium is typically found in drinking water in regions where it is present in the granite bedrock surrounding aquifers from which water supplies are drawn.
Radium isotopes in groundwater can sometimes exceed health-based regulatory standards and may pose a health hazard. While it is assumed that any radiation exposure carries a certain degree of risk, the U.S. Environmental Protection Agency (EPA) has established a maximum contaminant level (MCL) of radium in public water supplies of 5 picoCuries per liter (pCi/L).
In areas such as northern Illinois, high radium levels have been detected in water from deep aquifers (more than 500 feet) used for public supply. Radium has also been found in some private and public wells. As radium can not be seen, tasted or smelled in drinking water, it is critical for public water suppliers to test for radium to avert potential health risks.
How does radium in drinking water affect human health? Though only a small amount of radium is absorbed in the body, it can still be harmful. Radium behaves similarly to calcium and is deposited in tissues, especially bones. Radium in water used for washing or showering does not pose health risks, as alpha particles emitted by radium isotopes do not travel through skin.
Once internally deposited, emitted alpha particles may damage surrounding tissues over time. Exposure to high levels of radium is associated with: