Study Blames Radon In Homes For Tenth Of Lung Cancer Deaths

Up to one-tenth of U.S. lung cancer deaths may be caused by radon gas in homes, according to an analysis of how the radioactive chemical affects miners.

A study in the Journal of the National Cancer Institute said radon, seeping into homes from the ground, may cause about 14,400 lung cancer deaths in the United States, and may be responsible for up to 30 percent of lung cancers among nonsmokers.

The conclusions are based on an analysis of 11 studies of lung cancer among hard-rock miners who were exposed to radon while at work. By relating the rate of exposure to radon among miners and their rate of lung cancer, the researchers were able to estimate the number of lung cancers that may be caused by residential radon exposure.

But the authors added that the estimates “should be interpreted with caution” because miners are also exposed to other chemicals, such as diesel exhaust, that could affect their lung cancer rates.

Radon is a naturally occurring radioactive gas that escapes from underground rocks and soils. Radioactive emissions from radon are known to affect the cells lining the lungs when the gas is breathed in.

All people are exposed, to some extent, to the gas, but experts believe it poses a lung cancer risk only when it reaches certain concentrations. The Environmental Protection Agency recommends that home owners vent areas where radon concentrations reach 4 picocuries per liter of air. A picocurie is a measure of radiation used for radon.

Jay H. Lubin, a National Cancer Institute researcher, said the new study confirms an earlier, smaller study that first suggested the hazard of radon in the home. He said the earlier study was based on 360 lung cancer deaths among miners.

The new study analyzes 2,700 lung cancer deaths among miners and examines the underground radon risks of about 65,000 workers.

To relate the miners’ radio exposure to that in residences, the researchers used a measure called “working-level months,” or WLM.

“In an average home, yearly exposure results in approximately .2 WLM or an approximate lifetime cumulative exposure of 10 to 20 WLM,” the study found. Between 5 percent and 10 percent of American homes have radon levels that would produce a lifetime exposure of 40 to 50 working-level months, the study found.

Based on the miners’ experience and the estimated radon levels in American homes, Lubin said, the radioactive gas in residences causes about 4,700 lung cancer deaths among nonsmokers and about 9,700 among smokers.

About 149,000 Americans died of lung cancer in 1993, and about 85 percent of those deaths were attributed to smoking.

Lubin said the study suggested strongly that residents in homes with more than 4 picocuries per liter of radon do have a sharply increased risk of lung cancer. The risk is particularly increased for nonsmokers, he said.