Home Inspections: Radium
What is radium?
Radium is a naturally radioactive, silvery-white metal when freshly cut. It blackens on exposure to air. Purified radium and some radium compounds glow in the dark (luminesce). The radiation emitted by radium can also cause certain materials, called "phosphors" to emit light. Mixtures of radium salts and appropriate phosphors were widely used for clock dials and gauges before the risks of radium exposure were understood. Metallic radium is highly chemically reactive. It forms compounds that are very similar to barium compounds, making separation of the two elements difficult.
The various isotopes of radium originate from the radioactive decay of uranium or thorium. Radium-226 is found in the uranium-238 decay series, and radium-228 and -224 are found in the thorium-232 decay series.
Radium-226, the most common isotope, is an alpha emitter, with accompanying gamma radiation, and has a half-life of about 1600 years. Radium-228 is principally a beta emitter and has a half-life of 5.76 years. Radium-224, an alpha emitter, has a half-life of 3.66 days. Radium decays to form isotopes of the radioactive gas radon, which is not chemically reactive. Stable lead is the final product of this lengthy radioactive decay series.
Where is radium found?
The highest radium levels in water are found in water drawn from two rock formations; the deep sandstone of Wisconsin's eastern quarter and the crystalline granite rock of north-central Wisconsin.
Immediate health risks from drinking water containing low radioactivity levels are small, but consuming this water for a lifetime increases the health risks. Another natural radioactive element, uranium, has been detected in a few Wisconsin wells. Currently, there is no drinking water standard for uranium.
Currently, approximately 50 of Wisconsin's 1,300 community water systems exceed the drinking water standard for radium. The Wisconsin Department of Natural Resources (DNR) is providing guidance to help water system officials take corrective action to safeguard the environment as well as human health. Efforts are underway to identify the best methods of reducing radium in drinking water and disposing the wastes from treatment processes.
Where is radium a problem?
All rock contains some radium, usually in small amounts. Groundwater, which moves slowly through the pores or cracks in underground layers of rock, dissolves minerals as it travels. Where the rock contains significant amounts of radium, and the groundwater moves at a slow enough rate, the water can pick up higher amounts of radium.
In Wisconsin, most of the community water supplies which exceed the radium standard draw water from a deep sandstone aquifer and are located in a narrow band that stretches from Green Bay to the Illinois state line. In addition, a few high radium levels have been found in groundwater from sandstone formations in west-central Wisconsin and in granite formations in north-central Wisconsin. In all cases, the radium was there long before the first well was drilled.
How is radium in drinking water monitored?
By law, all community water systems must be monitored for radioactivity. The testing process for water samples begins with a screening for "gross alpha particle activity" which measures the total amount of one type of radioactivity given off by the water. If gross alpha activity is found, further testing for radium is conducted. Radioactivity levels are measured in "picocuries" per liter of water (abbreviated "pCi/l"). The state drinking water standard is five pCi/l for the combined total of two forms of radium, Radium-226 and Radium- 228. The standard applies to levels in the water distribution system, as determined quarterly and averaged over a one-year period.
What are the health risks of radium?
Radium emits several different kinds of radiation, in particular, alpha particles and gamma rays. Alpha particles are generally only harmful if emitted inside the body. However, both internal and external exposure to gamma radiation is harmful. Gamma rays can penetrate the body, so gamma emitters like radium can result in exposures even when the source is a distance away.
Long-term exposure to radium increases the risk of developing several diseases. Inhaled or ingested radium increases the risk of developing such diseases as lymphoma, bone cancer, and diseases that affect the formation of blood, such as leukemia and aplastic anemia. These effects usually take years to develop. The National Academy of Sciences has concluded that long-term exposure to elevated levels of radium in drinking water does indeed pose a "higher risk of bone cancer for the people exposed." The U.S. Environmental Protection Agency estimates that long-term consumption of water containing five pCi/l radium will cause 44 added cancer deaths for every million people exposed. The risk doubles to 88 per million at 10 pCi/l, triples to 132 at 15 pCi/l, etc.
External exposure to radium's gamma radiation increases the risk of cancer to varying degrees in all tissues and organs. However, the greatest health risk from radium is from exposure to its radioactive decay product radon. It is common in many soils and can collect in homes and other buildings.
What about private wells?
Generally, private wells are not drilled into the deeper geologic formations containing higher concentrations of radium. Nevertheless, radium has been found in a small number of private and non-community public wells.
A geological and geographical cross-section of Wisconsin's private wells has now been tested for radium. Concerned owners whose wells have not been tested can contact their regional DNR office, which may be able to estimate groundwater radioactivity levels from previous well samplings. DNR staff will need well construction and location details to make this determination. Water samples can be analyzed for signs of radioactivity by private laboratories or the State Laboratory of Hygiene.
Private well owners wishing to reduce radium levels by reconstructing or replacing wells (the preferred methods) should seek DNR guidance on construction details. A good alternate groundwater supply is the most important factor with these options. In some cases, forming a community system or connecting to an existing system may be feasible.
How is radium treated in private wells?
Of the treatment methods described earlier, ion exchange using zeolite softening is effective for home use. Radium, however, could get past a softener that is improperly maintained. Owners need to check softeners regularly to assure that they are operating properly. These home units also build-up wastes that need to be properly disposed of and will increase sodium levels in the water.
Small "reverse osmosis" units and distillation units may be effective in radium removal in-home systems, but the units have limited capacity and severely restrict water flow. The devices can only be used to treat water from a single faucet rather than the entire water supply. Additionally, other water quality problems such as high iron or manganese may interfere with these treatment methods.
For more information visit these websites:
EPA's main radium page.
Includes information about radium and its health effects.
Wisconsin DNR radium page.
Includes information about radium in drinking water.