Friday, December 22, 2006

Radon: The Silent Intruder

Many of us here in Western Massachusetts worry about Vermont Yankee (our local, and famously old nuclear power plant). We ask the dentist, “Do the kids really need another x-ray?” and we balance the benefits of mammograms with the risks of radiation. Yet we ignore the radiation than in many homes seeps through basements, through the floorboards and the heating ducts, and into the rooms where our children sleep. We ignore the silent intruder: radon.

We ignore it – yet radon is estimated to provide many of us with over one half of our annual average radiation dose. It is an undisputed human carcinogen. It is an undisputed cause of lung cancer, considered by many health agencies second only to cigarettes. It is also one of the easier contaminants (unlike lead in old paint, formaldehyde in building materials or even mold) to rid from our homes.

At the urging of our lawyer, my husband Ben and I tested our future home just before signing the purchase and sale agreement. Friends and family were skeptical. “Oh radon,” said a family member, “it’s just another one of those scams, someone must be making money off it.” A friend suggested radon is one of those “don’t know, can’t tell,” issues when homes exchange hands. “Why bother to find out? Then you’ll be responsible,” they said.

Sure enough, when we tested our soon-to-be home, it was just a bit above the Environmental Protection Agency action level. This, when the current owners had “inadvertently” opened the window near our radon test can. We requested they allow us to run another – though I can just imagine those doors and windows accidentally flapping open now and again during that test period. In the end, the radon was high enough to ask the sellers to chip in for remediation -- yet low enough for me to rationalize my inattention to it several years later.

As a toxicologist, I know that there is a lot of science - toxicology studies, epidemiological studies, and risk analysis - that go into each and every EPA guideline, standard and action level. Very often politics and economics are mixed in as well.

I know when information on human exposure is unavailable for a chemical, as it often is, that animal models are used to help scientists develop standards, and when this happens, the EPA employs what are called “safety factors,” basically reducing the estimated “safe” dose often by up to as much as 100 times or more. Sometimes that is enough, and sometimes not.

But this is not the case with radon. There are unfortunately plenty of data on human exposure. Five hundred years ago early toxicologists and physicians described a disease of the lungs in mine workers who wasted away and died young. That disease is now known as lung cancer, and the primary suspect is radon. A recent study by the National Cancer Institute found that the rate of lung cancer deaths in underground miners is five times that of the general population.

Radon occurs naturally. It is produced when uranium present in most rocks (but more prevalent in some like granites and shales) breaks down. As a radioactive compound, uranium disintegrates or decays releasing progeny (or daughter) products such as radium, along with energy in the form of radiation. Very often the progeny are also radioactive. In this case, radium decays into radon gas. And so it goes, with radon decaying into polonium and other radioactive products, each releasing radiation as they decay or disintegrate.

Upon disintegration, in the case of radon and its progeny, the radiation released is primarily in the form of an alpha particle - or two protons and two neutrons - that has the potential to cause lung cancer. If a speck of dust containing a speck of disintegrating polonium landed on your hand, it is unlikely it would do you much harm. Unlike x-rays or gamma rays, alpha particles cannot penetrate your skin. However, should you inhale that speck of polonium-containing dust, or air containing radon gas, or any of the radon decay products, and they further decay in your lungs, then that alpha particle can penetrate the delicate membranes surrounding your lung cells and damage genetic material.

Radon for indoor air is measured in pico-Curies (pCi). In the ambient or outdoor air of the United States, the EPA estimates that concentrations of radon generally range from 0.2 to 0.7 pCi/Liter of air, with some locations in places like Iowa reaching 1.4 pCi/Liter year round. However, it is virtually impossible to predict concentrations in the home based on ambient concentrations, or the type of rocks and soil beneath a home. Some homes have very low levels of radon, near ambient concentrations, while others have whoppingly high concentrations, reflecting a combination of the subsurface geology, and specific characteristics of a home, including foundation type, and number of floors.

In the United States there was little public awareness of radon until the day in 1984 when Stanley Watras set off radiation alarms at the Pennsylvania nuclear plant where he worked. Turns out, his exposure was not from the plant but from his home, which measured upwards of 2,700 pCi/Liters in the basement.

In response, the EPA quickly initiated a public awareness program and set 4 pCi/L as a “non-enforceable” or voluntary action level, at which EPA advises mitigation. The level was based in part on guidelines developed a decade earlier to protect Colorado citizens’ homes that had been built on uranium mine tailings. But, according to Dr. R. William Field, an associate professor of Occupational and Environmental Health and Epidemiology at the University of Iowa, College of Public Health, who led one of the largest studies on residential exposure to radon gas and lung cancer in the United States, the “Iowa Radon Lung Cancer Study,” the EPA level of 4 pCi/L is “...not a health based guideline. The Iowa Study and both the North American and European Pooled Radon Studies noted an increased lung cancer risk for prolonged exposures at and below the US EPA’s action level.”

In other words, though the EPA would prefer we reduce concentrations in our home to ambient levels, at the time the action levels were set, 4 pCi/L was considered an achievable goal. But, according to William Bell, coordinator of the Massachusetts State Radon Control Program, “EPA believes that most homes in the US can be fixed to below 4 pCi/L cost effectively. The action guide, the point where you take action and the mitigation goal, the point at which you deem the repairs successful, are in our view, not the same.”

In our case the fix was relatively simple and standard. A thick layer of plastic sealed over our dirt-floor crawl space, a few PVC pipes tucked into the concrete basement floor and an outside fan. Though the most likely time for radon exposure was winter --when the warm air rises up and out of our homes, causing more air and any co-occurring radon to be literally sucked out of the ground and into our home -- much to the dismay of my husband Ben, we were instructed to run the fan year round. “It sucks up electricity,” he grumbled. “I hate hearing the hum of that fan.” I’ve since been informed by Dr. Field that a fan should draw no more than a 60-watt bulb and that only poorly installed fans make much noise.

Still, after five years of sucking our radon away, one construction project which required dismantling of the external pipe and removal of the fan, and a peace-making decision to turn the thing off each spring when we opened our doors and windows for good, the fan rebelled, refusing to budge when we flipped it on for the fall season. From the surly technicians, to put it kindly, who represented the company that installed it, I learned that replacing the fan would cost a few hundred dollars. Not wanting to spend the money and not wanting to deal with that particular company – at the time one of the few choices locally - the rationalizations began. I rationalized the radon away, blissfully unaware that the action level was technology, rather than health based. I practiced my own kind of “don’t know can’t hurt” toxicology, instead of reading the bountiful literature on the contaminant in my home, I concentrated on industrial contaminants in other people’s homes. Though I did occasionally crack open the windows in winter, whenever my thoughts returned to radon.

Until now. This past summer after using a roll of duct tape and my vacuum cleaner to unsuccessfully battle an army of sex-starved winged creatures who had invaded my son’s room, we were informed that the large beam upon which our living room rested for over a hundred years also served as a feeding ground for generations of termites. While replacing the beam, we discovered the “fresh air return” was not so fresh, coming primarily from the dreaded basement, rather than the first floor vents. Thoughts of basement air blowing throughout the house awakened my concern about the air quality in my own home.

This article is the result of that new respect for that invisible intruder. Radon is one of the few chemicals where there is little disagreement among scientists as to its danger. It is one of the few chemicals to which we are exposed that is not in some way associated with industry. And it is a chemical we can, if not rid from our homes, at least reduce without too much expense and effort.

After five years our radon fan is up and running and I have just received two radon test kits to retest the concentrations. This winter the windows in my office will remain closed, and I won’t worry so much about what’s blowing through that heat duct in my children’s room.

Radon Information in Massachusetts:

According to William Bell, in Massachusetts, a radon test kit costs about $20, and makes a great gift. K its can be purchased through the EPA website at or or at local hardware stores. There is only one certified site in the state of MA, which is AccuStarLabs, Should your home need remediation, according to Bell, quality remediation should run between $1500-2000. For further information about testing and mitigation contact the MA DPH Radon Hot Line; 1-800-723-6695.

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