There is substantial variation in the annual mean concentration of radon in the same North American homes measured several years apart. These findings call into question the assumption that year-long indoor air radon measurements offer a valid estimate of cumulative radon exposures in homes over a period of 15-20 years, the most biologically meaningful exposure period. All previous studies used detectors that measure current radon in air. In a new case-control study, DCEG investigators carried out both standard year-long air measurements and CR-39 alpha detector measurements (call surface monitors) which directly measure long-term (20- year and more) cumulative exposure using glass objects in the home. The surface monitors take advantage of the fact that the first long-lived radon progeny, 210-lead (half-life 22 yrs), becomes embedded in glass surfaces in homes. The alpha activity of 210-polonium, a decay product of 210-lead, is measured in glass objects in the home and serves as a long-term retrospective exposure-meter for residential radon. This population-based case-control study of lung cancer was specifically designed to complement an earlier DCEG study by evaluating the effect of cumulative residential radon exposure among Missouri women who were predominantly smokers and former smokers using a control selection technique that minimized the inherent imbalance in smoking frequency between cases and controls.
For more information, contact Michael Alavanja.