Answer to Question #3383 Submitted to "Ask the Experts"

How many states or localities have radium in their drinking-water supply above 5 pCi/L? We have groundwater wells here in Northeast Florida with radium levels around 6 pCi/L. (The Environmental Protection Agency [EPA] standard is 5 pCi/L.) The ²²⁶Ra source has been reported as from normally occurring, in addition to from former, contaminated chemical sites many years ago. The general public in this area is quite concerned and many schools have now provided bottled water versus the city water supply. The ²²⁶Ra has been identified in several wells that have now been closed. This is a major issue being reported here in the newspapers and on TV frequently. The State Health Department has conducted the testing of the well water sources. Everybody has an opinion!

Questions: (1)What is the probability of contamination in the existing water supply piping and in the storage tanks, (2) What is a radium removal or treatment method, and (3) Are there other locations with a similar problem? There are many experts on these issues, but I just thought information from the Health Physics Society might offer some additional resources to help combat the major concern voiced here in this area.

Radium in the drinking water has been a controversial topic for many years, especially during the time that the Environmental Protection Agency (EPA) was considering raising the Maximum Contaminant Level (MCL) from 5 pCi/L to 20 pCi/L. This change did not occur and the current MCL assumes drinking 2 liters per day for 70 years of combined ²²⁶Ra and ²²⁸Ra at 5 pC/L. The Maximum Contaminant Level Goal (MCLG) for all radionuclides in drinking water is zero.

Of the 59,000+ community water systems in the United States, at any time, approximately one to three percent exceed the drinking-water standard for radium. Remember that testing for radium is only required by the EPA at entry to the point of distribution (POD) in the system, not at the point of use (POU).

I would refer you to a US EPA document, "Radionuclides in Drinking Water", for a discussion of radium and other radionuclides in community water systems. In addition, the Wisconsin Department of Natural Resources Web site has an FAQ on radium in the drinking water and community water supply treatment methods. Also The Health Physics Society Ask the Experts questions #3399, 2377, 729, 689, 1946, 1852, 2304, 599, 639, 2816, and 258 may provide you with further information.

Researchers over the years have looked at POU sources of radium in community drinking-water systems. University of Iowa studies have pointed to radium deposits in scale on pipes in the distribution system and the POU. Radium, which chemically behaves similarly to calcium, is known to adsorb to sediment and could be deposited in scale depending on the pH of the water and other factors, including the composition of the pipe and the residence time of the water in the pipe. Thus, although the POD radium levels may be below 5 pCi/L, it is possible, in certain locations due to the above factors, that POU radium levels could be elevated. Potential remedies for these situations include flushing of water lines on a regular basis, installation of whole facility ion-exchange water-treatment systems (water softeners), placement of a POU reverse osmosis system, or, possibly, water-distillation devices.

Hot-water tanks and storage tanks would naturally collect solids at their bottoms. This is why manufacturers of hot water heaters suggest regularly flushing them to ensure the long life of these units. Any sediments and scale at a tank’s bottom could contain radium as well as other radionuclides and minerals. The EPA does not regulate water from hot water heaters. The general consensus is that hot water should not be used for drinking or cooking purposes.

John J. Lanza, MD, PhD, MPH, FAAP