Answer to Question #11833 Submitted to "Ask the Experts"

Category: Environmental and Background Radiation — Radon

The following question was answered by an expert in the appropriate field:


When we bought our house in Connecticut in 2012, the air radon test came in at 255 Bq m-3 (the well water came in at 127,200 Bq m-3), so we put in an air mitigation system which reduced the air radon to 22 Bq m-3. But we never knew to test the water for uranium.

Recently we did multiple tests of our well water and found out that we have a uranium level of 2,630–4,652 micrograms per liter (µg L-1), and radium-226 (226Ra) came in at 1,602 becquerels per cubic meter (Bq m-3). The radon in our water fluctuated from 255,400 to 505,700 Bq m-3.

We are considering drilling a new well instead of installing a whole-house water-treatment system. Until then we are drinking bottled water, but we are showering, washing dishes, and doing laundry in the raw well water. Are we safe? Is it safe to use our bedroom and living room humidifiers using this untreated well water?

Also, my husband was diagnosed with an aggressive form of metastatic prostate cancer in March 2015. Could there be any correlation?


In my opinion, there is a very low likelihood that your husband's cancer is attributable to the natural radioactivity in your water for the following reasons:

  1. Uranium, like other heavy metals, is known to accumulate in the kidneys. This will result in kidney ailments.
  2. Radium is known to accumulate in the bones, which results in bone cancer and other bone-related ailments.
  3. Radon in water has a weak correlation with stomach cancer. But the primary issue with radon in water is that radon does not "like" to be in water, so it off-gasses into the air. Once the radon is in the air the concern is inhalation of the radon, which can lead to lung cancer.
  4. The minimum latency period (time between exposure and effects) for cancer caused by exposure to ionizing radiation is about five years. Leukemia has the shortest latency period, and other cancers take longer. It seems that your husband was exposed for about three years before the cancer was discovered, which is too short a time for a radiogenic cancer to appear.

I am sure that you want to try to find the root cause for the cancer, but in my opinion radiation exposure is not the cause of your husband's prostate cancer for the four reasons stated above.

I am glad to hear that you are not drinking the water and that you have installed an air mitigation system. Your raw well water is not safe for human consumption! I am also glad to see that the air mitigation system has reduced the concentration of radon in your indoor air to an acceptable level. As indicated above, the radon that off-gasses to the air and is subsequently inhaled is the real concern. When you shower and bathe, be sure to run the bathroom ventilation fan to keep your radon exposure as low as possible.

Washing dishes and doing laundry in the raw well water is okay. In all of these cases the real issue is that radon will come out of the water and you will be breathing it. Since you have measured the radon in your indoor air at 22 Bq m-3—which is a really low concentration—all is relatively safe. Uranium and radium are not a problem for washing dishes and laundry.

Without knowing more about your humidifier, I cannot comment with certainty on whether uranium and radium are potential issues. If your humidifier heats the water, then the uranium and radium will not be in the air, but instead they will concentrate as a mineral deposit on the heating element. If your humidifier uses ultrasonic energy to mist the water into the air, you have a potential inhalation exposure. With an evaporative humidifier, the uranium and radium will be part of the mineral deposit that builds up on the filter.

I don't know the geology of your area, but there is no guarantee that if you drill another well, the new well will be free of radionuclides. I am fairly certain that you are going to find radon in any well water in your area. Ask your neighbors what the radionuclide concentrations are in their water, if you have not already done so. I am guessing that if they have measured it, radon is in their raw well water too. My recommendation would be to install a water-treatment system. With commercially available technology, your raw water can be treated so that it is safe for human consumption. These systems come as "whole-house" or "point-of-use" systems. The whole-house system is more expensive. I don't know the actual costs of a whole-house water-treatment system, but it can be less expensive than drilling a well (depending on how deep you have to drill to find water). The annual cost of maintaining the system will be offset by not having to purchase bottled water.

Timothy A. DeVol, PhD, CHP

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