Estimating past exposure to indoor radon from household glass.

CR-39 plastic was attached to household glass objects to learn whether residual radioactivity from radon decay products could be measured and correlated with cumulative radon exposures over defined time periods. Such an approach could be used to increase the completeness of exposure data collected in epidemiologic studies of residential radon. Inability to estimate radon concentrations for all residences adversely effects statistical power and thus the ability to detect an effect of radon exposure on lung cancer risk. A feasibility study was performed to determine if affixing CR-39 surface monitors to selected glass, ceramic, or enameled objects provided comparable estimates of past residential radon exposure to those obtained from year-long ambient alpha track-etch measurements. The CR-39 measurements of alpha activity in the surface of selected objects correlated with ambient radon measurements (R2 = 0.48) provided that reliable information was obtained on the history and age of the objects. This technique has now been incorporated into an epidemiologic study of radon and lung cancer to more fully estimate past exposure to indoor radon.