Environmental radioactivity and cancer: Radon as an example

The natural radiation exposure of man by radon and its daughter products represents the largest contribution to the average annual radiation exposure of the public (nearly one to a few Millisievert a year). The critical bronchial region of the lung, therefore, experiences an average natural exposure ten times higher than other tissues and organs outside the lung. The resulting mean lifetime exposure of the public is lower only by a factor of 4 than the value where among miners a statistically significant increase of the lung cancer rate was found. Under the present assumptions on the dose-effect relationships for radon and its decay products, up to 10 percent of the annually nearly 25,000 lethal lung cancer cases in the Federal Republic of Germany might be due to the inhalation of these radionuclides. A number of simple protection measures exist to reduce this radiation risk which is for the world population each single year larger by about two orders of magnitude than the 50 year cumulated radiation risk from the reactor accident in Chernobyl. (orig.)