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EPA survey elevates concern over radon.

EPA survey elevates concern over radon

Last year, the Environmental Protection Agency named radon -- estimated to cause up to 20,000 U.S. lung cancer deaths annually -- the biggest air- and water-pollution problem (SN: 8/15/87, p.105). But results of a new indoor-radon survey, announced this week, suggest the natural radioactive pollutant is an even more widespread and serious health hazard than previously suspected.

"I think it's clear that we have a national problem," says EPA Administrator Lee M. Thomas, who now recommends that "virtually everyone" test their dwelling for radon -- especially those living in a detached house, an attached row house, a trailer or the basement or first two floors of apartment buildings.

In the new study, radon levels exceeded the EPA's action level of 4 picocuries per liter (pCi/l) in 1 out of 3 of the 11,000 homes the agency monitored last winter in Arizona, Indiana, Massachusetts, Minnesota, Missouri, North Dakota, Pennsylvania and several midwestern Indian lands. Last year's survey in 10 other states found that 1 in 5 homes exceeded a reading of 4 pCi/l. According to Richard Guimond, director of EPA's radiation programs, this concentration poses about the same lung-cancer risk to dwellers as smoking half a pack of cigarettes daily or receiving 200 to 300 chest X-rays annually.

Emitted by rocks in the soil, radon enters homes largely through cracks in a building's foundation. The new study identified a large, previously unrecognized geological "hotspot" contributing to excessively high radon levels in North Dakota and Minnesota. Unlike Pennsylvania's notorious "Reading Prong," where radon-emitting granite bedrock lies close to the surface, the newly identified hotspot results primarily from glaciation, Guimond says. Not only did the last glacial advance dump uranium-bearing rocks there, but it also scraped away covering materials in some areas--bringing bedrock closer to the surface -- and increased soil porosity. As a result, the three highest indoor-radon readings in EPA's 17-state sampling -- from 127 to 184 pCi/l -- have been recorded in North Dakota.
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Author:Raloff, Janet
Publication:Science News
Date:Sep 17, 1988
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