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Letter From The Editor
We don’t build each issue of HMI WORLD around a common theme, but sometimes those themes emerge on their own. The theme that jumps out in the November-December 2007 issue is outputs.
Around Harvard
This article originally appeared in the October 2007 Harvard Health Letter and is provided courtesy of Harvard Health Publications.
Radon revisited
The early warnings may have been overblown, but research since has shown that lung cancer risk from the gas is real.
Americans held their collective breath when news of radon, a radioactive gas, seeped into the headlines during the 1980s. Scientists had seemingly found lung cancer–causing monsters in basements across the nation.
But radon turned out to be more of a midsize gremlin than a giant ogre. Only a few years after making a big splash, the Environmental Protection Agency (EPA) scaled back its 1986 estimate of radon-related deaths. Estimates of the number of contaminated homes were similarly reduced. Press coverage fizzled, and there seemed to be collective muttering about a false alarm.
But that, too, is an overreaction. Radon may not be tobacco, but health officials still rank it as the second-leading cause of lung cancer in the United States. Slipping through the cracks of public consciousness, radon claims more lives each year than it should. Experts say a third of the roughly 20,000 American deaths caused by residential radon exposure could be prevented if homes were properly remediated so levels of the gas were below the EPA’s safety threshold.
There’s some awareness still of the danger of radon. In many parts of the country, home buyers will ask for a radon test before making a purchase. But initial dire warnings, and subsequent revisions, have left many people jaded. The ho-hum attitude also has something to do with the nature of the threat, say risk experts. “People are more fearful of synthetic than natural stuff,” says James Hammitt, director of the Harvard Center for Risk Analysis at the Harvard School of Public Health. “With radon, it’s not some evil industry dumping waste on us, so there was much less moral outrage.”
Moves up from the basement
Radon is an invisible and odorless radioactive gas that comes from uranium in the soil or water.
The gas travels through cracks in basement floors and walls before being sucked up through the rest of a dwelling because of differences in air pressure. While indoor exposures are initially worse closer to the basement, an entire building can become uniformly contaminated over time. The gas binds to dust particles which, once inhaled, may stick to lung tissue.
It’s been difficult to link lung cancer to radon exposure in homes. Lung cancer has other causes. Exposure is difficult to calculate: researchers can ask smokers about how long and how much they’ve smoked, but no one is going to know the level of their exposure to odorless, invisible radon unless their home has been specially monitored.
Scientists have identified some mutations in lung cancer tissues that might be specific to radon, but the findings are far from conclusive.
Further complicating matters is the fact that radon and tobacco seem to work hand in hand to cause lung cancer. By some estimates, smokers are 10 times more susceptible to radon’s cancer-causing effects than nonsmokers.
“Up to 90% of the estimated number of lung cancer cases possibly due to indoor radon could be reduced with smoking cessation,” notes Dr. John Boice, a radiation expert at Vanderbilt University in Nashville. “The best thing to do to reduce your radon risk of lung cancer is to stop smoking.”
Miner exposure
Underground mining of any kind may involve exposure to high levels of the gas, depending on the geology surrounding the mine. Observations that a disproportionate number of miners suffered and died from lung cancer go back to the 19th century. But it wasn’t till the 1920s when the gas could be accurately measured that a connection was made to radon exposure.
Researchers eventually documented that uranium miners, in particular, developed lung cancer at a predictable rate depending on how little or much radon they’d been breathing in the mine shafts.
Faced with all the uncertainties about home exposure and its consequences, radon experts used data from uranium miners to construct elaborate statistical models to generate estimates of the residential threat. These models have been criticized, partly because they assume that even small amounts of radon pose a lung cancer risk.
The experts concede that early versions of their models were flawed and led to some overestimations. But they also say that further investigation of miners’ health has justified the assumptions about the dangers of small amounts and that large studies of residential radon involving the EPA, the National Cancer Institute, and the World Health Organization have shown that estimates from an updated model are on target. Statistical models like these produce pretty wide ranges, not exact figures, so there’s some discrepancy in the numbers reported. The EPA pegs the annual number of radon-related lung cancer deaths at 21,000.
Radon risk by county
Hot homes
The EPA estimates that about eight million American homes have radon levels above 4 picocuries per liter, the level at which the agency recommends (it’s voluntary) remediation of some kind. That works out to be roughly one in every 15 American homes.
Residential radon pollution is worst from soil containing granite, shale, phosphate, and pitchblende. High radon levels in homes were first discovered in this country in houses built on the Reading Prong, a giant slab of uranium-filled granite in parts of Pennsylvania, New Jersey, and New York (see sidebar).
The northeastern states have various radon hot spots, and homes in Iowa have, on average, the highest radon concentrations in the country. Radon concentrations are lower in Alaska, Texas, and much of the South. But you can’t depend on these broad geographic generalizations: A “hot” home may be right next to one with normal radon levels.
Often radon tests are done when a house is being sold. The buyer can ask for a test, but generally speaking, there is no requirement that the sellers do or pay for it. Sometimes the buyer and seller agree to share the cost.
Testing for radon is fairly straightforward. A short-term testing device needs to stay in the house for several days. You need to keep the windows and doors closed as much as possible. Radon levels fluctuate, so testing for several months or more gives a more complete picture of exposure.
You can buy radon test kits from the National Safety Council at 1-800-557-2366. A short-term test kit (2–6 days) costs $9.95; the long-term one (over 90 days) is $20. Prices include the cost of postage and analysis of the results.
Radon as a cure-all?
People in certain regions of Europe and Japan have soaked in springs believed to contain mysterious healing powers, long before radioactivity and radon were understood. Some of these springs, including those at the Italian spas of Merano and Lurisia, turned out to contain high levels of radon. When Marie Curie isolated radium from pitchblende in 1904, radioactivity as a medical treatment was in vogue. Radon spas soon became popular as “natural” places of healing and many sought out radon drinks and inhalants as cure-alls.
Radon spas are still quite popular in some parts of Europe and Japan. Researchers there have reported that people who frequent them have reduced pain and other arthritic symptoms.
Several “radon health mines” operate in Montana. One we spotted on the Internet charges $35 a day and recommends about 30 visits to maximize the health benefit. Radon levels in this mine are 400 times higher than levels the EPA considers safe in your home, although the EPA’s safety threshold assumes exposure over a year’s time. Needless to say, these kinds of radon treatment are highly dubious and probably dangerous.
Fixing the problem
There are two basic approaches to bringing the radon level in a house down: Don’t let the gas in, and if it gets in, create enough airflow so it passes out. Sealing cracks and installing a radon-proof membrane are helpful steps that are particularly recommended when building a new home. But installing a vent pipe beneath the house with a fan that constantly sucks out the radon is the most popular method, according to the EPA Web site.
Several other options exist, and depending on the situation, the cost can range from $800 to $2,500. Just be sure that remediation is done by a certified member of the EPA-approved National Environmental Health Association or the National Radon Safety Board. The radon remediation industry has seen its share of scams and fly-by-night operators.
Radon can get into drinking water, but the risk is small relative to radon in indoor air. Filters on faucets will remove radon from water but some may escape into the air as the water comes out.
