The true size of the lung cancer risk from indoor radon:
Hidden behind a smoke screen?

Jürgen Conrady, Karl Martin, Jürgen Lembcke, Horst Martin

PreCura Institute for Preventive Medicine, Auguststra├če 2, D-16321 Schoenow, ICS 1225

Abstract

The estimation of the relative lung-cancer risk (Odds Ratio) by exposure to radon in dwellings with main emphasis on non-smoking women and control for misspecification of the smoking behaviour was the objective of the Schneeberg Study. This case-control study was performed in a highly exposed population to indoor radon from 50 Bq/m³ to more than 3.000 Bq/m³. The dose-response-analysis was conducted under consideration of differently accumulated exposures over 30 years. A validation of self-reported cigarette consumption and smoking status by lung cancer cases before and after diagnosis of lung cancer was performed. The misspecification of cigarette consumption and the smoking status was systematically shifted in one direction only: underreporting of cigarettes smoked and denial of the smoking habit. Therefore results of lung cancer risk estimation from indoor radon in studies with a high proportion of smokers among cases and controls and low exposure levels can easily be explained by misspecification of cigarettes smoked. The presented risk estimation for lung cancer risk from indoor radon with highly exposed non-smoking women resulted in Odds Ratios (OR) not elevated up to 1.000 Bq/m³ as a mean value. Only for higher radon values the OR rose steeply up to about 7 with more than 3.000 Bq/m³. The results from the study are firstly, that radon is a cause for lung cancer but probably not at the low level as found in most houses and secondly, the problem to control the confounder smoking results in the necessity to conduct epidemiologic radon studies with non-smokers only.