16. 尽管解决日本原子弹爆炸幸存者数据中剂量测定不一致的问题在估计受到低剂量辐射照射的人口罹患癌症的风险方面减少了一个不确定性来源，但还有大量其他的不确定性来源存在。其中一个重要来源与从日本原子弹爆炸幸存者受到的中等剂量高剂量率照射推及低剂量和低剂量率的有关。在解释与受到治疗照射的许多群体有关的数据时也是如此。另外，在根据癌症风险推算生命何时终结方面也存在不确定性。特别是日本原子弹爆炸幸存者中，约有一半人仍然活着。在根据有关这些幸存者的数据估计风险度时，关键是要确定在儿童时期受过辐射照射而现在到了可能会患上各种自发性癌症年龄的人群中与辐射有关的癌症风险的变化模式。另一个不确定性来源与辐射诱发的癌症风险估计在自发性癌症发病率不同的人群间的转移有关。
16. Although the resolution of dosimetric inconsistencies in the data on Japanese atomic bombing survivors has reduced one source of uncertainty in estimating cancer risks to a population from low doses of radiation, a considerable number of other sources of uncertainty remain. A major source relates to extrapolation from the moderate dose but high dose-rate exposures received by the Japanese atomic bombing survivors to low doses and dose rates. This is also true for interpreting data on many therapeutically exposed groups. There is also uncertainty relating to the extrapolation of cancer risk to the end of lifetime. In particular, about half of the cohort of Japanese atomic bombing survivors are still alive. In estimating risk factors from the data on this cohort it is vital to determine the pattern of variation of radiation-associated cancer risk for those exposed in childhood, who are now reaching the age at which larger numbers of cancers would be expected to arise spontaneously. Another source of uncertainty relates to the transfer of radiation-induced cancer risk estimates between populations with different spontaneous cancer rates.