Radon Research Typifies Challenges Facing Risk Assessment

Sidebar: Gauging the Dangers of Radon Blame the radon fuss on Stanley Watras. In 1984, the young engineer was leaving work at the Limerick Nuclear Power Plant in Pottstown, Pa., when he set off the radiation alarm. Safety officials were perplexed. They could find no leak in the new facility. No other workers were contaminated. Yet when Watras walked past the radiation checkpoint on his way home, the siren began to sound. Safety officials solved the mystery by taking radiation readings at the

Feb 17, 1992
Tom Abate

Sidebar: Gauging the Dangers of Radon

Blame the radon fuss on Stanley Watras. In 1984, the young engineer was leaving work at the Limerick Nuclear Power Plant in Pottstown, Pa., when he set off the radiation alarm. Safety officials were perplexed. They could find no leak in the new facility. No other workers were contaminated. Yet when Watras walked past the radiation checkpoint on his way home, the siren began to sound.

Safety officials solved the mystery by taking radiation readings at the Watras home in Boyerstown, Pa. What they discovered sounded a national alarm.

Watras, his wife, and their two sons were living over a crack in the earth's crust that acted like a natural chimney, filling their home with radon, a gas that is a byproduct of the decay of uranium and radium underground (see accompanying story). Radon is not itself radioactive. But upon entering the atmosphere, the gas decays into particles that emit alpha radiation. These alpha particles stick to dust in the air, causing background radiation.

But the radiation in the Watras home measured more than 100,000 times the background level. In fact, their air contained as much radon as the atmosphere in a uranium mine. Epidemiological surveys in the 1970s had established a link between high radon exposure and increased lung cancer among uranium miners. Suddenly it seemed that people could get the same dangerous dosage of radiation in their homes.

Spurred on by widespread publicity about this new radon risk, the Environmental Protection Agency (EPA) began a crash program to estimate how many cancers might be caused by radon and how to lessen the risk. The Department of Energy (DOE) studied how to insulate homes against the gas and started basic studies on alpha radiation and lung cancer.

Radon research could serve as a case study illustrating the difficulties inherent in the science of risk assessment. Radon researchers--including epidemiologists, biophysicists, physicists, radiation health specialists, and engineers--are still in conflict over the fundamental issues facing the field. After seven years of investigations, epidemiologists and other scientists disagree on issues such as the number of people who are at risk from home radon, whether cigarette smokers are so disproportionately affected that a more effective policy might be to target tobacco use rather than radon, and the best ways to find and fix the radon danger that does exist.

Agencies' Roles EPA had a two-person radon staff with a $240,000 budget in 1984. Today the agency pays 40 people about $30 million a year to map radon "hot spots" across the country and encourage homeowners to test and radon-proof their homes.

EPA estimates that 10 percent of Americans breathe indoor radon at concentrations above 4 picocuries per liter of air (a safety threshold on which DOE agrees). Yet EPA says fewer than 6 percent of homes have been tested, and the agency estimates that its efforts have prevented perhaps 30 cancers a year--$1 million per life saved in EPA spending alone.

Even now, as EPA and DOE slowly reach consensus on how to deal with radon in the air, another branch of EPA is preparing rules for reducing radon in drinking water. These rules will be costly to implement, and scientists say they aim to reduce the radon to levels that are absurdly low. Bureaucrats say it's not their fault if radon policies seems foolish. They point to strong but erratic public pressure to reduce radiation risk to zero.

Engineer Margo Oge, director of the EPA's radiation office in Washington, D.C., says radon was unlike any other risk EPA faces. EPA usually regulates corporate pollution. Cleanup costs are invisible to the public. But EPA could not order the earth to reduce radon emissions. The agency could not even order Americans to do radon tests on their homes.

"There was no corporate villain," Oge says. "We were asking the homeowner to pay.

"It is interesting to me to see the different public attitudes. If you live close to a nuclear power plant, you get less than 10 millirems of radiation a year [1 percent of the `safe' radon dose of 4 picocuries per liter]. The same public that wants us to regulate those lower levels at any cost is apathetic about radon."

Radon Risk Assessment EPA tried to persuade homeowners to invest $20 in do-it-yourself radon test kits. EPA ran television commercials showing people whose bones glowed from absorbed radiation. Scientists were aghast. "We really don't have that good a handle on the risk," says Wayne Lowder, a physicist and director of DOE's radon testing laboratory in New York. "Some people are now asking if the EPA has gone too far in trying to dramatize the risk."

EPA bases its risk estimates on a series of epidemiological studies done in the late 1970s that found highly elevated lung cancer rates among uranium miners exposed to radon. Based on the cancer rates of miners and studies of survivors of the atom bomb dropped on Hiroshima, EPA thinks radon will cause, or contribute to, between 7,000 and 30,000 fatal lung cancers each year. That estimate is the crux of the debate between DOE and EPA over the extent of the risk.

Jonathan Samet, an epidemiologist at the University of New Mexico Medical School in Albuquerque, headed a committee of the National Research Council (NRC) that recently lowered by 30 percent the EPA's estimate of cancer risk from radon. "There is always uncertainty in a scientific risk estimate," Samet says. "Sometimes focusing on the uncertainty obscures the danger. Despite the reduction, indoor radon is still a major problem." In its 240-page report, the committee concluded that the same dose of radon did more damage in mines than at home. Exertion made miners breathe harder. The dustier air carried more radioactive particles past cancer-prone lung tissue. For these and other reasons, the report said, "direct extrapolation of risk estimates from the mining to the home environment . . . overestimates the number of radon-caused lung cancer cases."

Samet says studies are now being done to compare radon levels in the homes of cancer patients against levels in "healthy" homes. "Then we won't be so dependent on the miner studies," he says. But those results are not due for three years.

Naomi Harley, a professor in radiation studies at New York University, thinks the NRC committee was wrong to reduce the risk. "That report infuriates me," says Harley, who has begun a new radon study for the National Council on Radiation Protection in Bethesda, Md., an independent scientific committee set up by Congress.

Harley says radioactive particles passing through the lungs fire alpha rays indiscriminately. To trigger a cancer, the particle must strike a specific gene in the cell nucleus. That's a long shot. At home, where people breathe more slowly than workers do in a mine, particles linger in the bronchial tubes, giving them more time to score hits. For this and other reasons, Harley says, dose for dose, radon at home is as deadly as in the mine. Her conclusions support EPA's estimate.

Smoking Vs. Radon Risks Biophysicist William Mills thinks the radon risk is overblown because the uranium miners in the original studies were mostly smokers. High radon exposure probably contributed to their cancer risk, he says. But Mills questions how many cancers radon causes in nonsmokers.

"My main criticism of the EPA has been that they have not emphasized that almost all the cancers affected by radon in the home will be among smokers," says Mills, director of the Federal Interagency Committee on Radiation Research and Policy, made up of scientists from 18 federal agencies.

"The radon issue is so confounded by the smoking habit that you have to wonder whether all this hype is saving any lives." Steven Page of EPA estimates that radon will induce 800 fatal lung cancers a year in nonsmokers. But the agency cites larger estimates that include the deaths of smokers, in which radon is a secondary cause.

"Critics say, `Why not just go after smoking? " Page says. "We have identified many causes of heart disease. We don't just go after diet or exercise. The classic public health approach is [to] treat all the causes."

The cost of this approach concerns some EPA officials, like environmental engineer Kevin Teichman of the Washington, D.C.-based indoor pollution program. He is a coauthor of a scientific paper critical of the agency for urging that all homes be radon tested (Environmental Science & Technology, 24:774-782, 1990). The paper said it would cost $2.2 billion to test 80 million residences, and another $6.6 billion to reduce indoor radon levels by sealing basement floors with epoxy, or ripping out foundations to install fans.

"More than 90 percent of the lung cancer risk associated with radon could be controlled by eliminating smoking," the paper argues. "Reducing lung cancer incidence may be more easily achieved by changing the population's smoking habits than by aggressive measures to reduce indoor radon concentrations."

Minimizing The Radon Risk Critics also say EPA should focus on high radon areas rather than try to test every home. With the help of the U.S. Geological Survey (USGS), EPA has been mapping states with high radon levels.

Geologist Linda Gundersen of USGS's Denver office says the radon hazard map is based on prospecting surveys done in the search for uranium mines. "The western half is already done," Gunder-sen says. "A preliminary paper on the eastern half is being reviewed." EPA is also criticized for encouraging quick tests over longer readings. Lowder at DOE's radon test laboratory in New York says home test kits use charcoal canisters to attract radioactive particles. After two to 10 days indoors, the kits are sent to a lab for analysis.

Because radon levels fluctuate, DOE thinks accurate readings can be obtained only over time, from devices like track etch detectors--polymer strips that record radioactive collisions over a three-to-six-month period.

"The canisters give you a snapshot, but they don't give an accurate reading over time," Lowder says. "But certain people feel the test should be as easy as possible."

Last year EPA took this criticism to heart. In an unusual step, radiation chief Oge invited 40 agency critics to appear before top EPA officials. Don Barnes, the staff director of EPA's Scientific Advisory Board (SAB), took part in this review panel, which is expected to produce a report this spring recommending, among other things, that EPA focus its testing efforts in high-radon states.

"The SAB has been critical of the [EPA] radon program, but we have been arguing over the margins," Barnes says. "Even after NRC reduced the [radon] risk by 30 percent, you're still looking at the highest risk EPA deals with."

But even as EPA heeds scientific criticism of its efforts to control home radon, a new controversy is brewing over proposed new standards to control radon in drinking water.

Gregory Helms, director of EPA's radon in drinking water program, says the 1986 Safe Drinking Water Act required the agency to reduce radon in underground water supplies like aquifers and wells. Radon dissolved in water passes through the body. But in hot showers, where water is vaporized, a fraction of dissolved radon becomes a gas. It then decays, producing alpha radiation, which, if inhaled, could trigger lung cancer.

Using risk formulas in the 1986 law, Helms proposed regulations to limit radon in water to 300 picocuries per liter. That may sound high, but scientists say only one radon atom in 10,000 escapes into the atmosphere. That works out to .03 picocurie per liter of radon in the air. EPA's water division is thus saying the air in a shower may have less than 1 percent as much radon as the air in a living room. If the regulation becomes law, 80,000 public water systems will spend millions to reduce radon levels. EPA's SAB has criticized the radon-in-drinking-water standards. But Helms says he has no leeway. "The law says we must reach the lowest levels attainable with present technology," he says.

Meanwhile, Sen. Frank Lauten-berg (D-N.J.) has introduced a bill requiring that antiradon measures be built into all homes financed by federal loans. The National Association of Home Builders says that would add more than $250 to the cost of many homes with no radon risk at all. If passed, Lautenberg's bill would also require that radon testing and repair companies be licensed by EPA. Mandatory licensing would please Stanley Watras. The man who sounded the radon alarm seven years ago now runs his own radon testing firm. "My obsession is now my life's work," Watras says. He and his family moved back into their infamous home after installing underground fans to vent radon past the roof. He says he stays because no one would buy the home.

Watras says business is booming, thanks to real estate agents who are now making radon tests almost as common as termite inspection in states with high radon levels. What DOE science and EPA ads failed to do, the free market is apparently doing to forestall lawsuits--finding and fixing high-radon homes.

"There's got to be a reason why all this happened to us," Watras says. "All I know is that when I mitigate a house for radon, it's like a therapy to me."

Tom Abate is a freelance science writer based in Brooklyn, N.Y.