Hendry Jolyon H, Simon Steven L, Wojcik Andrzej, Sohrabi Mehdi, Burkart Werner, Cardis Elisabeth, Laurier Dominique, Tirmarche Margot, Hayata Isamu
Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria.
J Radiol Prot. 2009 Jun;29(2A):A29-42. doi: 10.1088/0952-4746/29/2A/S03. Epub 2009 May 19.
Natural radiation is the major source of human exposure to ionising radiation, and its largest contributing component to effective dose arises from inhalation of (222)Rn and its radioactive progeny. However, despite extensive knowledge of radiation risks gained through epidemiologic investigations and mechanistic considerations, the health effects of chronic low-level radiation exposure are still poorly understood. The present paper reviews the possible contribution of studies of populations living in high natural background radiation (HNBR) areas (Guarapari, Brazil; Kerala, India; Ramsar, Iran; Yangjiang, China), including radon-prone areas, to low dose risk estimation. Much of the direct information about risk related to HNBR comes from case-control studies of radon and lung cancer, which provide convincing evidence of an association between long-term protracted radiation exposures in the general population and disease incidence. The success of these studies is mainly due to the careful organ dose reconstruction (with relatively high doses to the lung), and to the fact that large-scale collaborative studies have been conducted to maximise the statistical power and to ensure the systematic collection of information on potential confounding factors. In contrast, studies in other (non-radon) HNBR areas have provided little information, relying mainly on ecological designs and very rough effective dose categorisations. Recent steps taken in China and India to establish cohorts for follow-up and to conduct nested case-control studies may provide useful information about risks in the future, provided that careful organ dose reconstruction is possible and information is collected on potential confounding factors.
天然辐射是人类接触电离辐射的主要来源，而对有效剂量贡献最大的成分是吸入（222）Rn及其放射性子体。然而，尽管通过流行病学调查和机理研究已对辐射风险有了广泛了解，但慢性低水平辐射暴露对健康的影响仍知之甚少。本文综述了居住在高天然本底辐射（HNBR）地区（巴西瓜拉帕里、印度喀拉拉邦、伊朗拉姆萨尔、中国阳江）（包括氡易发地区）的人群研究对低剂量风险估计的可能贡献。关于HNBR相关风险的许多直接信息来自氡与肺癌的病例对照研究，这些研究提供了令人信服的证据，证明一般人群中长期持续的辐射暴露与疾病发病率之间存在关联。这些研究的成功主要归功于仔细的器官剂量重建（肺部剂量相对较高），以及开展了大规模合作研究以最大化统计效力，并确保系统收集潜在混杂因素的信息。相比之下，其他（非氡）HNBR地区的研究提供的信息很少，主要依赖生态设计和非常粗略的有效剂量分类。中国和印度最近采取的建立队列进行随访以及开展巢式病例对照研究的举措，若能进行仔细的器官剂量重建并收集潜在混杂因素的信息，可能会在未来提供有关风险的有用信息。
