Kellerer Albrecht M, Walsh Linda, Nekolla Elke A
Radiobiological Institute, University of Munich, Schillerstrasse 42, 80336 Munich, Germany.
Radiat Environ Biophys. 2002 Jun;41(2):113-23. doi: 10.1007/s00411-002-0154-7.
A previous investigation has uncoupled the solid cancer risk coefficient for neutrons from the low dose estimates of the relative biological effectiveness (RBE) of neutrons and the photon risk coefficient, and has related it to two more tangible quantities, the excess relative risk (ERR1) due to an intermediate reference dose D1 = 1 Gy of gamma-rays and the RBE of neutrons, R1, against this reference dose. With tentatively assumed RBE values between 20 and 50 and in terms of organ-averaged doses--rather than the usually invoked colon doses--the neutron risk factor was seen to be in general agreement with the current risk estimate of the International Commission on Radiation Protection (ICRP). The present assessment of the risk coefficient for gamma-rays incorporates--in terms of the unchanged A-bomb dosimetry system, DS86--this treatment of the neutrons, but is otherwise largely analogous to the evaluation of the A-bomb data for the ICRP report and for the recent report of the United Nations Scientific Committee on the effects of ionizing radiation, UNSCEAR. The resulting central estimate of the lifetime attributable risk (LAR) for solid cancer mortality is 0.043/Gy for a working population (ages 25-65), and is nearly the same whether the age at exposure or the attained age model is used for risk projection. For a population of all ages 0.042/Gy is obtained with the attained age model and 0.068/Gy with the age at exposure model. The values do not include a dose and dose rate effectiveness factor (DDREF), and they are only half as large as the new UNSCEAR estimates of 0.082/Gy (attained age model and all ages) and 0.13/Gy (age at exposure model and all ages). The difference is only partly due to the more explicit treatment of the neutrons. It reflects also the fact that UNSCEAR has converted ERR into LAR in a way that differs from the ICRP procedure, and that it has summed the overall risk coefficient for solid tumor mortality and incidence from separate estimates for eight solid tumor categories, whereas the present study employs a combined computation for all solid tumors and uses the ICRP procedure for the conversion of ERR into LAR. The appendix gives results for the solid cancer incidence data.
先前的一项调查已将中子的实体癌风险系数与中子相对生物有效性（RBE）的低剂量估计值以及光子风险系数分离开来，并将其与另外两个更具体的量相关联，即由于中间参考剂量D1 = 1 Gy的γ射线导致的超额相对风险（ERR1）以及中子相对于该参考剂量的RBE，R1。在初步假设RBE值在20至50之间且以器官平均剂量（而非通常引用的结肠剂量）表示的情况下，中子风险因子被认为与国际辐射防护委员会（ICRP）当前的风险估计总体一致。本次对γ射线风险系数的评估纳入了——就不变的原子弹剂量测定系统DS86而言——对中子的这种处理方式，但在其他方面与ICRP报告以及联合国原子辐射影响科学委员会（UNSCEAR）近期报告中对原子弹数据的评估大致类似。对于工作人群（25至65岁），实体癌死亡率的终生归因风险（LAR）的最终中心估计值为0.043/Gy，并且无论使用暴露年龄模型还是达到年龄模型进行风险预测，该值几乎相同。对于所有年龄段的人群，使用达到年龄模型得到的值为0.042/Gy，使用暴露年龄模型得到的值为0.068/Gy。这些值未包括剂量和剂量率有效性因子（DDREF），并且它们仅为UNSCEAR新估计值的一半，UNSCEAR的新估计值为0.082/Gy（达到年龄模型和所有年龄段）以及0.13/Gy（暴露年龄模型和所有年龄段）。差异仅部分归因于对中子更明确的处理。这也反映了这样一个事实，即UNSCEAR将ERR转换为LAR的方式与ICRP的程序不同，并且它将实体瘤死亡率和发病率的总体风险系数从八个实体瘤类别的单独估计值中相加，而本研究对所有实体瘤采用综合计算，并使用ICRP程序将ERR转换为LAR。附录给出了实体癌发病率数据的结果。
