Approaches to the assessment of long term exposure to radon and its progeny

In recent years a number of case-control epidemiological studies have taken place and others are inprogress to evaluate the lung cancer risk to the general population from exposure to radon and itsshort-lived progeny in the indoor residential environment. While it is actually long term exposure overpast decades to radon progeny by inhalation that dominates lung doses, for a number of practicalreasons it is radon gas that is measured in these studies. Because the risk from radon and its progenyresults from cumulative exposure over past decades rather than from contemporary exposure, it isnecessary to reconstruct the historical exposures of subjects. A number of factors limit the accuracyof this approach of which the following are perhaps the most important: the mobility and residentialhistory of the subjects, radon exposures elsewhere and changes that may have occurred in the radonlevels in current and previous residences. Measurement techniques to assist in making more directretrospective assessments of radon exposure have appeared in the recent past and are the subject ofthis paper. These are based on the measurement of the long-lived radon progeny 210Po trapped inhousehold artefacts such as glass or porous and spongy materials. In vivo measurements of skeletal210Pb in exposed persons is also a method that is currently being investigated as a means to assesshistorical exposures to radon. The advantages and disadvantages of these methods are described hereas well as their potential in future radon epidemiological studies