Exposure to low levels of radon appears to reduce the risk of lung cancer, new s...( WORCESTER Mass. March 25 2008 -- Ex...)

WORCESTER, Mass. March 25, 2008 -- Exposure to levels of radon gas typically found in 90 percent of American homes appears to reduce the risk of developing lung cancer by as much as 60 percent, according to a study published in the March 2008 issue of the journal Health Physics. The finding differs significantly from the results of previous case-control studies of the effects of low-level radon exposure, which have detected a slightly elevated lung cancer risk (but without statistical significance) or no risk at all.

The study, undertaken jointly by researchers at Worcester Polytechnic Institute (WPI), Fallon Clinic, and Fallon Community Health Plan, is the first to observe a statistically significant hormetic effect of low-level radon exposure. Toxins and other environmental stressors (including radiation) that have a beneficial effect at very low doses are said to exhibit hormesis (scientists believe that the low doses of toxins may stimulate repair mechanisms in cells). Home exposure to radon, a naturally occurring radioactive decay product of radium, has been thought to be the second leading cause of lung cancer, after cigarette smoking. Chemically inert, it can percolate out of the ground into basements.

The study was initiated and managed by Donald F. Nelson, now professor emeritus of physics at WPI, during the 1990s, a time when concern over the link between residential radon exposure and lung cancer was growing. Nelson says the aim was to try to establish what level of radon exposure actually correlated with significant lung cancer risk and to establish a safety zone for home radon levels. We were certainly not looking for a hormetic effect, says co-author Joel H. Popkin of Fallon Clinic and St. Vincent Hospital in Worcester. Indeed, we were stunned when the data pointed to that conclusion in such a strong way.

In the study, the exposure of 200 individuals with confirmed cases of primary lung cancer to radon was compared to t
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