2018 年 53 巻 2 号 p. 47-64
For over four decades, a linear nonthreshold (LNT) model has been used for radiation protection purposes. In the United States of America, the National Council on Radiation Protection and Measurements (NCRP) established Scientific Committee 1-25 in 2015 to prepare a commentary to review recent epidemiologic data from studies with low doses or low dose rates and from the Life Span Study of atomic-bomb survivors to determine whether these epidemiologic studies broadly support the LNT model. In May 2018, NCRP published Commentary No. 27 “Implications of recent epidemiologic studies for the linear nonthreshold model and radiation protection”, noting that the ongoing development of science requires a constant reassessment of prior and emerging evidence to assure that the approach to radiation protection is optimal, even if not necessarily perfect. Based on the current epidemiological data, NCRP concluded that the LNT model (perhaps with excess risk estimates reduced by a dose and dose rate effectiveness factor) should continue to be utilized for radiation protection purposes. The Commentary will be used to support the work of NCRP Council Committee 1 who are charged to develop current radiation protection guidance for the United States, ultimately updating and expanding the basic radiation protection recommendations of NCRP Report No. 116 published in 1993. This review provides an outline and summary of the key points of NCRP Commentary No. 27.