Recent trend of research on the adaptive response induced by low dose radiation and its significance

本総説は,低線量放射線に対する生体の適応応答(以下,適応応答)に関してその効果を含む最近の研究動向,さらに放射線防護との関係についてまとめたものである｡特にこの分野で最も検討が進んでいる｢低線量放射線照射の生物学的影響｣に関する国際研究組織(BELLE)での動向を中心に報告するものである｡即ち,ヒトと自然放射線との共存などヒトの生活環境と適応応答について,適応応答の短期的･長期的効果など適応応答の効果とその生物学的意義について言及した｡次に,適応応答の医療などへの応用の可能性について,また,適応応答と放射線防護との関係についても言及した｡ここで,低線量放射線にはヒトへの有益な効果があるとの多くの報告例がある半面,放射線防護の面では微量放射線でも危険とする考え方がその根拠にあることがわかった｡このため,今後は更なる低線量放射線の生体影響研究を進めるとともに,両者の間の隙間をなくす現実的･合理的な対応が求められている｡We reviewed the recent trend of research on the adaptive response induced by low dose radiation and its significance. The following view were obtained. Risk assessment is fundamental to the protection of public health from radiation exposure, but any estimate of risk is subject to numerous major uncertainties. In view of the uncertainties surrounding the shape of dose-response curves at low doses of ionizing radiation. the linear nonthreshold dose-response model is now widely accepted as a paradigm in radiation protection practice and risk analysis. However, interest among scientists in obtaining a more conclusive understanding of the effects of low dose radiation has been evident in recent initiatives, such as adaptive response of low dose radiation, in part to help verify or disprove the linear model. A vigorous worldwide effort is now apparently underway to understand the basic mechanisms underlying the biological effects of low dose radiation. This review presents a series of papers representing the progress going on, which will undoubtably make an important contribution to this field of research