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New radon reports have no effect on policy.

Indoor radon poses a difficult policy problem, because even average exposures in U.S. homes entail estimated risks that substantially exceed the pollutant risks that the Environmental Protection Agency (EPA) usually deals with and because there are many homes with radon concentrations that are very much greater than average. In 1998, the National Research Council (NRC) released two studies that redid earlier analyses of the risks of radon in homes. As expected, both found that there had been no basic change in the scientific understanding that has existed since the 1980s. More important, neither study addressed much-needed policy changes to deal with these risks. As I argued in "A National Strategy for Indoor Radon" (Issues, Fall 1992), a much more effective strategy is needed. It should focus first and foremost on finding and fixing the 100,000 U.S. homes with radon concentrations 10 or more times the national average.

One NRC committee study [Health Effects of Exposure to Radon (BEIR VI, February 1998] revisited the data on lung cancer associated with exposure to radon and its decay products. It is based primarily on a linear extrapolation of data from mines, because lower indoor concentrations make studies in homes inconclusive. The panel estimated that radon exposures are involved in 3,000 to 33,000 lung cancer deaths per year, with a central value around 18,000, which is consistent with earlier estimates. Of these deaths, perhaps 2,000 would occur among people who have not smoked cigarettes, because the synergy between radon and smoking accounts for most of the total radon-related estimate.

The estimated mortality rate even among nonsmokers greatly exceeds that from most pollutants in outdoor air and water supplies; however, it is in the same range as some risks occurring indoors, such as deaths from carbon monoxide poisoning, and is smaller than other outdoor risks, such as those from falls or fires. On the other hand, the radon risks for smokers are significantly greater, though they are still far smaller than the baseline risks from smoking itself, which causes about 400,000 deaths per year in the United States.

No one expects to lower the total risk from radon by a large factor, except perhaps Congress, which has required that indoor concentrations be reduced to outdoor levels. But the NRC committee implicitly supported the current EPA strategy of monitoring all homes and remedying those with levels a factor of three or more times the average, by emphasizing that this would lower the total risk by 30 percent. This contrasts with the desire of many scientists to rapidly find homes where occupants suffer individual risks that are 10 or even a 100 times the average, then lowering their exposures by a substantial factor.

A second report, Risk Assessment of Radon in Drinking Water, released in September 1998, creates a real policy conundrum. Here too, the picture changes very little from earlier evaluations, except that the estimated 20 stomach cancer deaths due to direct ingestion of radon (of the total of 13,000 such deaths annually in the United States) is smaller than earlier EPA estimates. The main risk from radon in water is from release into indoor air, but the associated 160 deaths are only 1 percent of the total (18,000) from airborne radon and are less than the 700 resulting solely from outdoor exposures to radon.

The difficulty is that the legal structure for regulating water appears to compel EPA to set the standard for a carcinogen to zero, or in this case at the limit of monitoring capability. This would result in spending large sums of money for a change in risk that is essentially irrelevant to the total radon risk. At EPA's request, the NRC committee examined how an alternative standard might be permitted for water districts that reduced radon risks in other ways. But Congress would have to act to permit EPA to avoid this messy and ineffective approach and to simply set an exposure limit at what people receive from outdoor air.

All of this avoids the principal need, which is to rapidly reduce the number of homes where occupants are exposed to extraordinary radon concentrations. Related needs are to emphasize the reliability of long-term monitoring (as opposed to the tests lasting several days that currently prevail) and to develop information and programs that focus on, and aid in solving, the problem of high-radon homes. These were compelling needs in 1992 and they remain compelling today.
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Author:Nero, Anthony V., Jr.
Publication:Issues in Science and Technology
Date:Dec 22, 1998
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