The results were statistically adjusted for factors known to be correlated with lung cancer risk, including smoking, occupational exposure to carcinogens, and level of education. The adjusted results show that the odds ratios of developing lung cancer fall below one (the no effect level) at radon exposure levels within the range measured in about 90 percent of homes across the United States (0-150 Becquerel per cubic meter of air, or about 0-4 picoCuries per liter). The Environmental Protection Agency (EPA) recommends that homeowners take remediation actions when household radon exposure levels rise above 4 picoCuries per liter, based on the belief that radon exposure presents a linearly increasing lung cancer risk (a view not supported by the new study in the low-dose region).
In a statistical analysis led by Richard E. Thompson, associate scientist in the department of biostatistics at the Johns Hopkins University Bloomberg School of Public Health, two mathematical techniques were used to compute the odds ratios of developing lung cancer. They each showed a statistically significant lowered lung cancer riska reduction of as much as 60 percent--over portions of the 0-150 Becquerel per cubic meter range.
The results of the current study do not fall within the linear, no threshold (LNT) model commonly used to analyze radons cancer risk (in fact, the current study calls into question the validity of that model). The model starts with cancer risks documented for exposure to high levels of radon (for example, by uranium miners) and extrapolates a considerable distance to risks at low levels (for example, for homeowne
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| Contact: Michael Dorsey mwdorsey@wpi.edu 508-831-5609 Worcester Polytechnic Institute Source:Eurekalert |