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Health Indicator Report of Community Water: Radium Concentration

Radium (chemical symbol Ra) is a naturally-occurring silvery-white radioactive metal or radionuclide formed by the radioactive decay of uranium and thorium. Radium-226 (Ra-226) and radium-228 (Ra-228) are the most common isotopes or forms of radium; Ra-226 originates from the decay of uranium-238 (a long-lived uranium isotope, which has a half-life of almost 5 billion years), which is the most common isotope of natural uranium and Ra-228 originates from thorium-232, which is the most common isotope of natural thorium. Therefore, the combined radium-226 and -228 are products of natural uranium and thorium minerals or deposits. In the natural environment, all rocks, soil, surface and ground water, air, plants, and animals contain very low amounts of radium. Therefore, everyone has some minor exposure to radium. However, when rocks contain high levels of uranium (such as in the Southwestern US) or thorium, radium is also found in high levels. Some geographic areas regions of the United States, particularly the areas of southwestern states such as New Mexico, have concentrated natural deposits of uranium. Because radium and its compounds are soluble in water, groundwater in areas where concentrations of radium are high in surrounding rocks and soils typically also has relatively high content of radium. Higher levels of radium tend to be found in groundwater than in surface water of drinking water. Therefore, some private well drinking water sources in New Mexico may contain higher than average radium-226 concentrations; in such areas private well water can become source of exposure to radium. Ionizing radiation is energy that can knock electrons out of molecules with which they interact, thus creating ions (e.g., from molecules such as water, protein, and DNA, with which they react). This process is known as ionization, and therefore, this type of radiation is named "ionizing radiation". The three main types of ionizing radiation are alpha particles, beta particles (electron & positron), and gamma rays and X-rays (electromagnetic radiation or photon: gamma or X). The type(s) of ionizing radiation emitted depends on the isotope or radionuclide. Radium-226, which is the most common radium isotope in the natural environment, is primarily an alpha emitter and partial gamma emitter and has a very long of half-time of about 1600 years. Radium-228 is mainly a beta emitter with a half-life of about 5.76 years. Radon gas is produced from the radioactive decay of radium. Alpha particles are mainly only harmful if emitted inside the body. However, both internal and external exposure gamma radiation is harmful, because gamma rays can penetrate the body such that gamma emitters such as radium can produce exposure even when the radium source is a distance away. Exposure to radium can cause adverse health effects such as anemia, cataracts, fractures teeth, and cancer. There is sufficient evidence in humans that ingestion of high levels of radium causes bone cancer (bone sarcomas) and cancer of the paranasal sinuses. Exposure to high levels of radium can also result in an increased risk of developing liver and breast cancer. The Environmental Protection Agency (EPA), the National Academy of Sciences Committee on Biological Effects of Ionizing Radiation, and the International Agency for Research on Cancer concluded that radium is a known human carcinogen. However, the greatest health concern for radium exposure is exposure to its radioactive decay product radon, which tends to accumulate in indoor air. Bathing and showering with water that contains dissolved radon gas may be a health concern (more information on indoor radon can be found at https: Lung cancer development is the health concern for radon gas.


Data Source: New Mexico Environment Department's Drinking Water Bureau, New Mexico Safe Drinking Water Information System (SDWIS). Measured radium concentrations in finished drinking can be used to understand the distribution of potential radium exposure level for populations served by community water supplies. Due to potential errors in estimating service population, the measures may overestimate or underestimate the number of potentially affected people. These measures allow for comparison of potential uranium exposure between the populations served by different water systems over time.

Data Source

New Mexico Environment Department, Drinking Water Bureau

Data Interpretation Issues

Measures do not account for the variability in sampling, number or sampling repeats, etc. Furthermore, concentrations in drinking water cannot be directly converted to exposure because water consumption varies by climate, level of physical activity, and between people. Due to potential errors in estimating service population, the measures may overestimate or underestimate the number of potentially affected people.


Radium (combined radium-226 and radium-228) concentrations in picocuries per liter of water or pCi/L in community drinking water systems (CWS) are used in conjunction with information about each CWS (such as service population) to generate the following measures shown in this report: 1) statewide radium concentration distribution in CWSs by mean and maximum over time, 2) annual distribution of mean and maximum radium concentration for persons served by CWS and 3) annual distribution of mean and maximum radium concentration by CWS. EPHT data queries -- -- provide detailed results by year for 1) mean radium concentration by CWS for a select year, 2) maximum radium concentration by CWS for a select year, 3) mean radium concentration and the number of CWS by year, 4) maximum radium concentration and the number of CWS by year, 5) mean radium concentration and the number of persons served by year or 6) maximum radium concentration and the number of persons served by year. Additionally, users may query the number of persons served and the number of CWS in the state for a select year. A CWS is a public water system (PWS) that serves year-round residents of a community, subdivision, or mobile home park that has at least 15 service connections or an average of at least 25 residents. These CWSs are a subset of all New Mexico PWSs. To measure radium concentration in CWS, drinking water samples are usually taken at entry points to the distribution system or representative sampling points after water treatment has occurred.


Concentration of Radium.


Not applicable.

How Are We Doing?

Nearly 60 years ago, radium was used as a component of the luminous paints used for watch and clock dials instrument panels in airplanes, military instruments, compasses, and other devices; however, most of these early uses of radium have been stopped. Radium was also an early radiation source for cancer treatment; however, it has been replaced by safer and more effective radiation sources (e.g., cobalt-60). People can also be exposed to radium if it is released into the air from the burning of coal or other fuels. Some occupations can also result in high exposure to radium, such as working in uranium mine or a uranium ores processing plant. For the general public, ingestion of drinking water and food, especially root vegetables grown in uranium-containing soil are the primary sources of radium exposure. In New Mexico, people may also be exposed through inhalation of radon gas, which is a breakdown product of natural radium in their homes, if they live in an area where the amount of uranium (and radium) is high in rocks. Most of the ingested radium in drinking water or food (about 80%) leaves the human body in feces and some (about 20%) is absorbed into the bloodstreams and accumulates preferentially in the bones. Some of this absorbed radium is excreted in the feces and urine over long periods of time. However, a portion of it will remain in the bones over the person's lifetime.

What Is Being Done?

Radium (i.e., combined radium-226 and -228) levels in drinking water from most community water systems (CWS) are low; however, there is wide variation in the levels of radium found in CWS supplies across New Mexico. A CWS is a system that serves at least 15 locations or 25 people year-round, including most cities and towns, apartment buildings, and mobile home parks with their own water supplies. As of December 8, 2003, the EPA established a drinking water standard or Maximum Contaminant Level (MCL) for combined radium 226 and radium-228 of 5 picocuries per liter (5 pCi/L) to protect public health. This MCL is the highest level of combined radium-226 and -228 which is allowed in drinking water and it is the enforceable standard. The EPA-estimated lifetime exposure excess cancer risk for radium at the MCL is approximately 1-2 cases per 10,000 people. Community systems' drinking water is routinely monitored and tested for radium to comply with the 5 pCi/L EPA standard for combined radium 226 and -228. In NM in 2004, monitoring was initially required for combined radium 226 and radium-228. Every year, CWS send their customers a consumer confidence report (also called a water quality report) that lists any levels of uranium measured. EPA also requires all CWS to give their customers public notice when their water supply violates the uranium standard. This would include information about what is being done to correct the situation. However, people who use their private wells water for drinking are solely responsible for testing the water for uranium (for information about laboratories certified to test drinking water and certified home treatment units visit

Page Content Updated On 04/17/2019, Published on 04/17/2019
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Content updated: Wed, 17 Apr 2019 15:43:23 MDT