Objective The purpose of this study is to investigate the possible effects of long-term exposure to dust containing thorium and thoron progeny dust-exposed miners. Methods A negative, high voltage, exhaled thoron progeny measurement system was used to estimate the miners thorium lung burden. Results The highest thorium lung burden of 638 miners was 11.11 Bq. The incidence of stage 0+ pneumoconiosis was higher among dust-exposed miners. Lung cancer mortality of the dust-exposed miners was significantly higher than that of controls (P