Radon: have its risks been overplayed?

In recent years, federal health officials have estimated that as many as 15,000 lung cancer deaths in the United States each year result from radon, a naturally occurring radioactive gas. But the authors of a major new study say they have been unable to demonstrate convincingly any association between exposure to indoor radon and this disease.

Michael C.R. Alavanja of the National Cancer Institute in Bethesda, Md., and his coworkers measured radon for a year in the homes of 1,721 Missouri women, 538 of whom had lung cancer and 1,183 of whom did not. All of the women, who were matched by age, were nonsmokers or former smokers who had given up the habit at least 15 years earlier.

In the Dec. 21, 1994 Journal of the National Cancer Institute, the researchers report that average residential radon concentrations were "exactly the same" (1.82 picocuries per liter of air) in both groups of women. However, Alavanja's team did note that among the lung cancer patients whose type of malignancy had been identified, half of those diagnosed with adenocarcinomas showed a slightly increased risk of disease with increased exposure to radon. A study of Swedish women, published earlier last year, reported a similar trend.

While a lifetime of exposure contributes to risk, such contemporary studies measure only exposures at an individual's current address, notes Jonathan M. Samet of Johns Hopkins University in Baltimore. For the statistical significance needed to assess accurately whether low residential exposures constitute no risk -- or a risk very different from that posed to underground miners by high radon concentrations -- the study would have required many more participants than the number used in this or any other residential-radon study to date, Samet argues in an accompanying editorial. But those numbers may soon become available, he adds, as researchers complete a spate of new studies whose data can be pooled for reanalysis.