Lung cancer and indoor radon exposure in the north of Portugal--an ecological study

Abstract

Background: Indoor radon exposure is a well documented environmental factor as a leading cause of lung cancer.

Objectives: The aim of this study was to assess the risk of lung cancer and estimate the number of deaths due to indoor radon exposure in the north of Portugal, between 1995 and 2004.

Methods: The sixth Biological Effects of Ionizing Radiation Committee (BEIR VI) preferred models were applied to estimate the risk of developing lung cancer induced by indoor radon exposure, by age and level of exposure, and calculated the number of lung cancer deaths attributable to this exposure. Lung cancer mortality data were granted by the North Regional Health Administration and indoor radon concentrations resulted from a national survey conducted by the Portuguese Environmental Agency. The smoking habit was accounted with two methods. A submultiplicative interaction between smoking and indoor radon exposure was considered.

Results: Depending on the model applied and the method used to account for the smoking habit, the estimated number of lung cancer deaths attributed to indoor radon exposure, in northern Portugal, ranges from 1565 to 2406, for the period between 1995 and 2004. This indicates that of the 8514 lung cancer deaths observed, from 18 to 28% could be associated with indoor radon exposure.

Conclusions: This was the first study realized in Portugal on the impact of indoor radon exposure in lung cancer mortality. The application of the BEIR VI models led to a high number of lung cancer deaths due to indoor radon exposure.