Increased Mortality of Respiratory Diseases Including Lung Cancer in the Area with Large Amount of Ashfall from Mount Sakurajima Volcano

摘要

Objectives. Mount Sakurajima in Japan is one of the most active volcanoes in the world. This work was conducted to examine the effect of volcanic ash on the chronic respiratory disease mortality in the vicinity of Mt. Sakurajima. Methods. The present work examined the standardized mortality ratios (SMRs) of respiratory diseases during the period 1968–2002 in Sakurajima town and Tarumizu city, where ashfall from the volcano recorded more than 10.000 g/m²/yr on average in the 1980s. Results. The SMR of lung cancer in the Sakurajima-Tarumizu area was 1.61 (95% CI = 1.44–1.78) for men and 1.67 (95% CI = 1.39–1.95) for women while it was nearly equal to one in Kanoya city, which neighbors Tarumizu city but located at the further position from Mt. Sakurajima, and therefore has much smaller amounts of ashfall. Sakurajima-Tarumizu area had elevated SMRs for COPDs and acute respiratory diseases while Kanoya did not. Conclusions. Cristobalite is the most likely cause of the increased deaths from those chronic respiratory diseases since smoking is unlikely to explain the increased mortality of respiratory diseases among women since the proportion of smokers in Japanese women is less than 20%, and SPM levels in the Sakurajima-Tarumizu area were not high. Further studies seem warranted.