Chen J, Dessau J C, Frenette E, Moir D, Cornett R J
Radiation Protection Bureau, Health Canada, Ottawa, Canada.
Radiat Prot Dosimetry. 2010 Oct;141(4):322-7. doi: 10.1093/rpd/ncq226.
Radon has been identified as the second leading cause of lung cancer after tobacco smoking. (222)Rn (radon gas) and (220)Rn (thoron gas) are the most common isotopes of radon. In this study, thoron exposure in Canada was assessed based on three community radon/thoron surveys conducted recently. It was confirmed that thoron was detectable in most homes and thoron progeny were present in every home surveyed. Results demonstrated that thoron concentrations varied more widely than radon. No clear correlation between (222)Rn and (220)Rn concentrations was observed in simultaneous measurements. It is estimated that thoron contributes to about 7 % of the radiation dose due to indoor radon exposure based on measurements in about 260 individual homes. Because indoor measurements and geological gamma-ray surveys did not support a reasonable association between (222)Rn and (220)Rn, thoron concentrations could not be predicted from widely available indoor radon information. In order to better assess thoron exposure in Canada and thoron risk to the Canadian population in various geographic locations, more thoron progeny measurements are required.
氡已被确定为仅次于吸烟的第二大肺癌致病因素。（222）Rn（氡气）和（220）Rn（钍射气）是氡最常见的同位素。在本研究中，基于近期开展的三项社区氡/钍射气调查对加拿大的钍射气暴露情况进行了评估。结果证实，多数家庭中均可检测到钍射气，且在每个被调查家庭中均有钍射气子体存在。结果表明，钍射气浓度的变化范围比氡更大。在同步测量中未观察到（222）Rn与（220）Rn浓度之间存在明显相关性。根据约260个家庭的测量结果估计，钍射气导致的辐射剂量约占室内氡暴露所致辐射剂量的7%。由于室内测量和地质伽马射线调查并不支持（222）Rn与（220）Rn之间存在合理关联，因此无法根据广泛可得的室内氡信息预测钍射气浓度。为了更好地评估加拿大的钍射气暴露情况以及不同地理位置的加拿大人群面临的钍射气风险，需要开展更多钍射气子体测量工作。
