Radium (Ra-226/228)

Radium-226 (half-life 1,600 years) and Radium-228 (half-life 5.75 years) are produced by radioactive decay of uranium-238 and thorium-232 respectively — natural geochemical processes that have occurred since the Earth formed [1]. Where uranium- or thorium-bearing rock formations underlie aquifers, groundwater dissolves radium salts and carries them into drinking water wells. The Midwest and South-Central United States — particularly Iowa, Illinois, Missouri, Texas, and Wisconsin — have extensive geological formations (black shales, sandstones) with elevated radium [2]. The 'Radium Girls' tragedy of the 1920s, when watch-dial painters who licked their radium-paint brushes developed bone sarcomas and jaw necrosis, revealed radium's specific affinity for bone and its extraordinarily long biological residence time [1]. EPA set MCLs for combined radium-226/228 at 5 pCi/L in drinking water [2].

Private wells in high-radium geological formations are the primary drinking water exposure route [1]. Municipal water supplies are monitored and treated; private well owners are responsible for their own testing. Radium in groundwater is odorless and tasteless — there is no sensory warning [2]. Dietary intake from food grown in high-radium areas (particularly root vegetables) is a secondary pathway [1]. Occupational exposure occurs in uranium mining, radium processing (historically), oil and gas production (NORM — naturally occurring radioactive material), and construction in radium-bearing rock [2].

Radium mimics calcium because both are alkaline earth metals — the body deposits radium into bone where it irradiates surrounding tissue with alpha and beta radiation for the rest of a person's life [1]. The resulting bone sarcomas, leukemia, and bone marrow failure defined the Radium Girls' fate. At the lower doses in drinking water, the primary long-term concern is increased leukemia and bone cancer risk from years of internal irradiation [2]. Radium-226 also decays to radon-222, meaning high-radium groundwater also contributes to radon in well water and, upon release indoors, to indoor radon levels [1].

Private well users in radium-rich geological regions who have never tested their water are the most at-risk group [1]. Children, with their rapidly dividing bone cells, are most sensitive to radiation-induced bone cancer [2]. Pregnant women ingesting radium expose the fetus, whose growing skeleton avidly incorporates the bone-seeking metal [1]. Oil and gas workers handling NORM-contaminated produced water and pipe scale have occupational radium exposure [2].

1. If you have a private well in a state with known radium geology (check your state's geological survey), test for radium-226 and radium-228 through a certified lab [1]. 2. Reverse osmosis filtration effectively removes radium from drinking water; ion exchange (cation exchange) systems are also effective for radium specifically [2]. 3. EPA's safe drinking water hotline (1-800-426-4791) can help identify state-certified testing labs [1]. 4. Contact your county health department — many offer subsidized well testing programs [2]. 5. For municipal water users, your utility's annual Consumer Confidence Report (CCR) must report radium results [1].