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High-radon homes may be widespread.

High-radon homes may be widespread

Dwellers in an estimated 1 million U.S. homes with high indoor radon levels may be receiving radiation exposures that meet or exceed those received by the average uranium miner, according to a study by researchers at Lawrence Berkeley Laboratory (LBL) in Berkeley, Calif. At present, there are no federal regulations limiting nonoccupational exposure to the gas. There is also little money available to fund radon research, notes Anthony Nero, a physicist and one of the study's authors. Nero and his co-workers report in the Nov. 21 SCIENCE that the cancer risks posed by inhalation of radon and its decay products are 100 to 1,000 times greater than many of the chemical hazards for which the Environmental Protection Agency (EPA) has already issued regulations.

Over the past decade, there has been growing concern about the hazards posed by indoor radon. The gas, generated by the natural radioactive decay of radium in the soil, enters home privarily through cracks in the foundation. Though radon is a naturally occurring source of low-level background radiation, various factors can cause buildings to accumulate dangerous concentrations of the radioactive gas and its "daughters," or decay products. Actually it is the daughters that pose the real health concern (SN: 1/18/86, p.43): Unlike their parent gas, the daughters adhere to respirable dust particles in the air. Once inhaled, they tend to adhere to the lungs, where they can eventually emit cell-damaging energy.

In the new study, Nero and his colleagues in LBL's Indoor Environment Program looked at 38 different collections or surveys of radon measurements in U.S. single-family homes. Eventually they focused on those 22 collections which, because there had been no presampling reason to suspect test sites contained high radon concentrations, appeared to offer the most random sampling. The 22 data sets include homes from 17 states and every major geographic region, including many major metropolitan areas such as New York City, San Francisco and Houston. Because indoor radon can vary seasonally -- with peak levels typically in winter -- less-than-year-long measurements were "normalized," or adjusted to approximate an average annual reading. Nero says his group derived its normalization formula from the four data sets available with radon readings for multiple seasons.

The study found an average home-radon concentration of 1.5 picocuries per liter (pCi/l) in air, a level the researchers say would pose a 0.3 percent increased risk of lung cancer mortality, or 10,000 excess lung cancer cases per year in the United States. An estimated 7 percent of U.S. homes -- about 4 million -- may have more than 4 pCi/l radon, the level at which EPA recommends taking remedial action. LBL data also suggest that approximately 1 million single-family homes have indoor radon concentrations of 8 pCi/l or greater. The latter concentrations could lead to annual radiation doses of 1.5 to 2 "working level months" (the standard measure of occupational radiation dose), Nero notes, or a level that he says is 50 to 100 percent higher than the average annual dose received by U.S. uranium miners.

"That, in itself, is provocative," says Nero. But more to the point, he believes, is the fact that the federal government "spends a lot of time regulating risks that are much lower." For example, he notes, more than $1 billion is being spent to control radiation risks from uranium mill tailings -- voluminous uranium-processing wastes. However, Nero says, "those people exposed to an average of 8 pCi/l of radon from uranium mill tailings are only numbered in the tens or hundreds."

Rep. Gus Yatron (D-Pa.), who authored legislation in July aimed at boosting federal support for the study and control of radon, believes the LBL data could serve as a catalyst for reshaping the current radon policy debate. Congressional action on the pollutant bogged down earlier this year over discussion of whether to focus on this gas individually, or as just one part of a broader indoor-air-quality improvement program. "I think radon is the indoor-air pollutant that poses the greatest threat to human health," Yatron told SCIENCE NEWS. "It would be very unproductive to allow this policy debate to slow our efforts [to control radon]."

Yatron Says he would like to see the federal government, especially EPA, given more support - over and above the $5 million in the new Superfund reauthorizations (SN:10/25/86,p.264)-for developing low-cost indoor-radon mitigation technologies applicable to a wide range of homes. States, he says, should focus on disseminating radon information, testing homes for the gas and providing low-interest loans for radon-mitigation renovations. Finally, he would like to see local governments work with builders and realtors in amending building codes and standards to limit radon's infiltration into homes. Developing such government programs "will be made much easier," Yatron says, "if Nero's findings have the impact that they ought to have."
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Author:Raloff, Janet
Publication:Science News
Date:Nov 22, 1986
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