29. 通过对日本原子弹爆炸幸存者和其他人群进行详细的流行病学研究，已较为清楚地了解高剂量和中等剂量辐射所致的癌症风险。但是，对于在环境和职业中较常遇到的低剂量辐射所产生的风险，往往是从高剂量数据推算出来的，具体方法是加入各种因素来说明低剂量和低剂量率所致的风险。对于与辐射照射有关的人类健康风险的估计是机械地建立在一种认识之上的，这就是辐射产生的有害影响源自于被辐射的细胞，或者在遗传效应情况下，源自于被辐射的细胞所直接产生的下一代细胞。但是，据认为，辐射照射产生的许多所谓的非目标效应和延迟效应可能会对这种观点提出质疑。2006 年报告附件 C“电离辐射照射的非目标效应和延迟效应”审查了有关这类效应的证据，并考虑了它们可能会对低剂量和低剂量率辐射风险的估计所需作出的机械判断而产生的影响。
29. The risks of cancer after high and moderate doses of radiation are relatively well understood from detailed epidemiological studies of the Japanese atomic bombing survivors and others. However, risks at the lower doses more typical of environmental and occupational exposures are generally extrapolated from the high dose data by incorporating factors to account for low dose and low dose rates. The estimation of the human health risks associated with radiation exposures are based mechanistically on the view that the detrimental effects of irradiation have their origin in irradiated cells or, in the case of heritable effects, in cells directly descended from them. However, a number of so-called non-targeted and delayed effects of radiation exposure have been described that may challenge this view. Annex C to the Committee’s 2006 report, entitled “Non-targeted and delayed effects of exposure to ionizing radiation”, reviews the evidence for such effects and reflects on how they may influence the mechanistic judgements required for the estimation of risk at low doses and dose rates.