Editors’ Note: The following blog post originally appeared on Forbes.com.
I thought I knew everything there was to know about the effects of radon on health, having written a long chapter on radon in my book Hyping Health Risks (2008). But until I came across a lively graphic essay a few days ago, I had no idea that, for over half a century, people suffering from a wide array of ailments have been flocking to decommissioned gold and uranium mines in Montana to soak up the healing radiation deep in the earth.
The graphic journalist Wendy MacNaughton begins her essay with the words, “Most of us go to great lengths to avoid carcinogens, but some people travel thousands of miles to the tiny towns of Basin and Boulder in Montana to sit inside decommissioned gold, silver, and uranium mines and inhale radon gas and drink radon water.”
Apparently, this niche business started in the 1950s, when little was known about the health effects of radon. This suggests that, over time, a substantial number of people have been exposed to levels of radon that are several orders of magnitude higher than the Environmental Protection Agency’s recommended limit of 4 picoCuries/liter.
The existence of a radon tourism industry raises a number of questions and serves to highlight the many intricacies and paradoxes of this naturally-occurring form of radioactivity. It also helps explain the awkward efforts to regulate the population’s exposure to radon and the difficulty of communicating the true health risks associated with exposure.
Below I lay out some of the key considerations that we need to grasp in order to see the risk associated with radon in perspective. (Many of these points are taken from my book Hyping Health Risks where they are backed up by detailed discussion).
Radon is a radioactive gas resulting from the decay of radium, and ultimately from uranium, that occurs naturally in rock and soil. Radon itself decays to form “progeny,” which emit a type of radiation (alpha-radiation) capable of being inhaled and damaging cells in the lung, thereby possibly initiating cancer.
The possibility that radon in homes could pose a danger to health only became a subject of concern in the 1980s, when extraordinarily levels were detected by chance in a home in eastern Pennsylvania.
The degree of radon exposure depends on the geology of the area one lives in, as well as on the construction of the housing one lives in. Areas with high radon concentrations in the soil include the Reading Prong in Pennsylvania, the Appalachian Mountains, and the Black Hills. But the levels in nearby houses can vary greatly. Radon levels in homes tend to be highest in the basement, due to seepage through cracks and fissures in the foundation. High levels of radon in homes can be effectively remediated by sealing such entry points and by installing adequate ventilation.
It has been known since the early twentieth century that underground miners exposed to high levels of radon gas have an increased risk of lung cancer. Because studies of underground miners, such as those of miners in the Colorado Plateau, provided the main source of information on human exposure to radon, elaborate analyses were undertaken to extrapolate downward from the effects of exposure in miners to those in the general population due to residential exposure. However, this type of extrapolation entails a number of assumptions and limitations. Most importantly, miners had much higher radon exposures, and the majority of miners were smokers. Furthermore, the underground miners were exposed to dust and other substances.
A crucial, but under-appreciated, fact is that the effects of radon are much greater in smokers than in people who have never smoked. This is referred to as an “interaction” or “synergism” between smoking and radon exposure. The risks associated with a given radon exposure are roughly 7 times higher in smokers than in never smokers. Furthermore, roughly 90 percent of radon-induced lung cancers occur in smokers. These facts entail the paradoxical implication that the best way to prevent lung cancer caused by radon is for smokers to quit smoking.
The National Cancer Institute and the Environmental Protection Agency list radon as the second leading cause of lung cancer, after smoking. But, here again, it is important to emphasize that most lung cancers caused by radon occur in people who have smoked and that only 10 percent of lung cancer due to radon occur in people who have never smoked.
Thus, radon is a distant second cause of lung cancer.
In the 1980s, the EPA initiated a poorly-conceived campaign to encourage homeowners to measure radon in their homes to identify high levels, which could then be mitigated. However, by focusing narrowly on radon, the agency failed to give weight to the disproportionate effects of radon in smokers, and this resulted in an alarming emphasis on the dangers of radon, even at the relatively low levels found in most homes. The agency also set a relatively low cutoff for levels requiring remediation, thereby defining a larger number of homes in need of remediation. What was referred to as the EPA’s “terror campaign” was roundly criticized by prominent figures in environmental engineering and public health. Aside from over-estimating the effects of radon exposure, the EPA failed to take into account human psychology. Radon is 100 percent “natural,” and it is hard to convince people that something natural could be a serious threat. The above bare-bones points underscore how difficult it has been 1) to use the scientifically-available information to delineate the true impact of radon exposure on the general population; 2) to formulate a rational and practical radon mitigation program; and 3) to explain the risks accurately to regular people.
Finally, the contrast between Montana’s laissez-faire attitude toward health risks and California’s extreme precautionary stance could not be starker. Under Proposition 65, over-zealous California regulators have seen fit to post warnings regarding such notorious – though, scientifically, totally unsubstantiated – carcinogens as coffee, the weed-killer glyphosate (in Roundup), and cell phone emissions. If the decommissioned mines were in the Golden State, a prominent sign would be posted at the entrance informing visitors as follows, “WARNING: Visiting this site entails exposure to high levels of radon gas, known to the State of California to cause lung cancer.”
None of the above should be taken as implying that it is a good idea to spend long periods of time in old uranium mines or to drink radon-impregnated water.
Postscript: It is too bad that there is no follow-up mortality study of the people who have visited the mines for treatment over the past decades. However, this would be a difficult study to organize, given the challenge of maintaining contact with, and monitoring the mortality status of, the many individuals who came to different mines in Montana for treatment from all over the U.S. and from abroad, over many years.