Dose assessment for airborne radionuclides emitted from Sakurajima volcano and discussion for lung cancer risk (case-control study)

1.我们调查了鹿儿岛县11个城市的肺癌死亡率。在这些城市中，Tarimizu的女性肺癌死亡率最高。20世纪80年代，樽水市的樱岛火山降灰量非常高。2.我们在鹿儿岛市、雾岛町和樽水市的樱岛山和雾岛附近的室外测量了氡及其子体的浓度。鹿儿岛的平均浓度为3 Bq/m^3，雾岛为5 Bq/m^3;它们的水平与全国平均水平5 Bq/m^3相差不大。另一方面，樽水经常记录到高达50 Bq/m^3的浓度。通过获取气象资料，分析了气象参数对氡及其子体浓度的影响。分析表明，氡及其子体浓度与降灰量有关，而与SO2浓度和悬浮颗粒物水平无关。3.对健康对照组的室内氡及其子体浓度进行了测量。鹿儿岛的浓度为14.5 Bq/m^3，雾岛为14.5 Bq/m^3，樽水的平均浓度为11（范围为5-25）。这些水平与全国平均水平15.5 Bq/m^3没有显著差异。4.我们采访了肺癌或慢性呼吸道疾病患者，并测量了这些患者居住的房屋中的氡及其子体水平。平均浓度为10.8 Bq/m^3，与健康对照房屋中记录的水平没有显著差异。然而，有两间房子的氡浓度高达43 Bq/m^3和90 Bq/m^3。辐射水平约为10-20 mSv/年，远高于辐射防护委员会建议的一般公众1 mSv/年的剂量限值。

1.We examined lung cancer mortality in 11 cities in Kagoshima Prefecture. Among those cities, Tarimizu showed the highest lung cancer mortality among women. Tarumizu City had extremely high amount of ashfall from Sakurajima volcano in the 1980s.2.We measured outdoor concentrations of radon and its progeny in Kagoshima City, Kirishima Town, and Tarumizu City located in the vicinities of Mt Sakurajima and Kirishima. Their average concentration was 3 Bq/m^3 in Kagoshima, and 5 Bq/m^3 in Kirishima ; their levels were not much different from the national average level of 5 Bq/m^3. On the other hand, Tarumizu recorded the concentration as high as 50 Bq/m^3 frequently. By obtaining meteorological data, the effects of meteorological parameters on the concentration of radon and its progeny was analyzed. The analysis showed that the concentration of radon and its progeny was related to the amount of ashfall but was not associated with sulfur dioxide concentration or the levels of suspended particulate matters.3.We measured the indoor concentration of radon and its progeny in the houses inhabited by healthy controls. The concentration was 14.5 Bq/m^3 in Kagoshima, 14.5 Bq/m^3 in Kirishima, and 11 on average (ranging 5-25) in Tarumizu. Those leves were not significantly different from the national average levels of 15.5 Bq/m^3.4.We interviewed patients with lung cancer or chronic respiratory diseases and measured the levels of radon and its progeny in the houses inhabited by those patients. The average concentration was 10.8 Bq/m^3 and was not significantly different from the levels recorded in the houses of healthy controls. However, there were two houses where the radon concentration was as high as 43 Bq/m^3 and 90 Bq/m^3. The radiation levels correspond to about 10-20 mSv/year, which is much higher than the dose limit of 1 mSv/year for the general public recommended by the ICRP.