Radon revisited; invisible gas continues to elude scientists.
The concern seems justified. Radon-222 is found virtually everywhere because its predecessors - radium-226 and uranium-238 - are in soil and rocks everywhere. Outdoors, the average radon gas concentration is under 0.5 picocuries per litre (pCi/L) - a negligible health risk. But the hazards of breathing radon-laden air in uranium mines and towns situated near uranium waste dumps are well documented: Uranium miners who for years worked in poorly ventilated mines suffered high rates of lung cancer.
While the potential dangers of uranium mines and dumping grounds are easy to spot, indoor radon is harder to pin down. "We don't have any population studies showing a significant cancer risk associated with radon in homes," says Ellen Silbergeld, a toxicologist with the Environmental Defense Fund in Washington, DC. "But we can extrapolate downward [from high radiation exposures, as in uranium mines] for radiation hazards. And we do have data from comparable types of low level radiation exposure. Radon is a public health concern [but]... the only reliable measurements are averages over nine to 12 months."
Despite the lack of solid evidence, the EPA continues to rank indoor radon as the nation's number one environmental hazard. EPA officials say our basements contain more radioactivity than the land around nuclear power plants, and that Americans living in high-radon homes receive as large a radiation dose annually as did residents of Chernobyl in 1986.
Such pronouncements have spawned considerable radon-phobia. According to the report of the 1992 International Conference on Radon, the public is more fearful of radiation than any other environmental risk. The very word "radon" suggests radioactivity. Since the gas is emitted from virtually every ounce of soil on the planet, if you're alive and on land at this moment, you're probably breathing radon.
The National Council on Radiation Protection (NCRP), a quasi-government agency aligned with the nuclear industry, recently estimated that indoor radon comprises about 55 percent of all radiation exposure. By contrast, they say radiation exposure from the entire nuclear fuel cycle (wastes, uranium tailings and reactor emissions) comprises only 0.1 percent, or 555 times less than radon. Says Alfred Craig, head of EPA's Radon Reduction Research and Development Program, "Radon is clearly among the most serious causes of death in the country, and I predict that as we study the problem further, death rates will only increase."
But Dr. Ernest Sternglass, professor of radiological physics at the University of Pennsylvania, disagrees: "The NCRP's estimates make indoor radon look horrendous and nuclear pollution look trivial by comparison. That's simply a gross fabrication," he says. Others argue that in most studies, the EPA overestimates radon by monitoring basements, where radon levels are highest, instead of on floor levels closer to where people actually live.
"We're the first to admit that the basement level is about three times higher than the upstairs," Craig says. "We've intentionally designed our surveys to measure the highest detectable radon levels. And because basements are closed up, we can get a clearer reading." But a basement reading may be a poor measure of one's actual radon exposure. Ironically, conservation-oriented energy audits favor airtight, well-insulated homes that tend to trap more radon.
Despite millions of dollars already spent on radon testing and remediation, research on its health risks remains inconclusive. Naomi Harley of New York University's Institute of Environmental Medicine feels that the concern has been overblown by the EPA, which currently regulates indoor radon at one-fifth the level of Canada's 20 pCi/L standard. Officials have "literally tried to hit the public over the head with a hammer to get them to pay attention to radon," says Harley. William A. Mills, a former EPA head of radiation standards, also believes that the agency has made "misleading" pronouncements that exaggerate both radon's danger and the potential for reducing it.
Amid this climate of scientific uncertainty, the Department of Energy (DOE) has portrayed radon as the deadliest of eco-threats. "We get more radiation in our living rooms than from nuclear power plants," proclaimed a late 1970s Nuclear Regulatory Commission Print Advertisement. And though today's campaign is toned down, excessive indoor radon continues to mesh nicely with public relations efforts by the nuclear industry.
"Blaming radon may also divert attention from tobacco smoke and industrial air pollution, which cause the vast majority of lung cancer deaths each year," says Sternglass. The EPA has drawn criticism for soft-pedaling restrictions on industries which befoul the environment. According to the American Lung Association, industries that pollute the air cost taxpayers $40 billion in health care annually. And although the National Academy of Sciences has found that the risk of leukemia, lung cancer and other cancers is higher for people living near nuclear facilities, DOE officials maintain that such low-level radiation poses no threat to public health.
The political nature of the issue is underscored by the DOE's history of financing research on radon. John Gofman, professor of medical physics at the University of California in Berkeley, and author of the book, Radiation-Induced Cancer from Low-Level Exposure, began studying the risks of radon exposure in the 1950. Says Gofman, "It's been a great boon to people in the nuclear business to say, 'Hey look, we've got nuclear power under control. What you really should be concerned about is what we don't have under control, namely radon.'"
Despite public belief in the dangers of radon, many people appear unconvinced that their own risk of radon-related cancer is significant. The American Journal of Public Health recently reported that the public takes health risks more seriously when blame for the problem and responsibility for remediation falls on industry or government. But since governments have little authority to control indoor radon, regulatory action is limited; all that federal agencies can do is sponsor radon detection and educational programs. Meanwhile, contamination of the food chain by the low-level fallout from nuclear power plants continues at "permissible" levels, says Gofman.
Finally, ascribing radon's health hazards solely to natural and unpreventable causes may also be misleading. After two decades of studying water samples from major U.S. rivers, Louis G. Williams, a University of Alabama professor of ecology, notes that the Clinch, Savannah and Tennessee Rivers - all of which run past major nuclear power plants - are highly contaminated with uranium and radium isotopes which decay into radon, posing an increased cancer risk to people living downstream. Greenpeace has made a similar discovery in the Columbia River, which runs past the Hanford nuclear plant in Washington.
Independent research and a well-informed environmental press can best help us maintain a proper perspective on indoor radon. For the time being, if you're worried about radon, be sure to keep your home well-ventilated - and don't spend all your spare time in the basement.
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|Date:||Feb 1, 1994|
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