Thus, radon studies have to carefully include the effects of the smoking behavior of the different groups that they study. The best study style for a disease that has multiple causes is called a case-control study. The best analysis of the miner data is summarized in a National Academy Report, BEIR VI . The most comprehensive case-control study of residential radon exposure in North America took place in Iowa. The study results have been published.
More work needs to be done to refine and extend the risk factor to lower concentrations.
Additional groups need to be included to better understand the effects of tobacco smoke and radon interaction. Unfortunately, no new epidemiologic studies are in progress in North America. Since a comprehensive study requires many years to complete, we will only have the new results from Europe, where housing and population characteristics are frequently quite different, to improve the dose-response relationship. Studies of the molecular and cellular effects of low doses of alpha particles are underway. These studies may improve our sensitivity to detect radon-specific lung cancers.