Modan B
Department of Clinical Epidemiology, Chaim Sheba Medical Center, Tel Aviv University Medical School, Israel.
Med Oncol Tumor Pharmacother. 1987;4(3-4):151-61. doi: 10.1007/BF02934511.
Quantification of delayed low dose radiation (LDR) effects is still controversial. The current concept of the shape of the dose-response curve, particularly at the very low levels, is derived primarily by extrapolation from high doses and is affected by economic, social and political implications of cancer yield. Evidence based on epidemiological studies of populations exposed to fallout, occupational, intrauterine or background LDR is limited, due to methodological drawbacks and the need for extremely large sample sizes. Nevertheless, recent data indicate that LDR-induced childhood leukemia and thyroid cancer may exceed the rates predicted on the basis of the linear quadratic curve. The high yield in utero and in early childhood could be associated with low cumulative load of background radiation, and a consequently more effective radiation increment. A long term follow up of children exposed to 90 mSv after scalp X-irradiation revealed a relative risk of 3.8 and an excess risk of about 1.08 per 1000 man-sievert per year for thyroid cancer. Application of these findings to the post-Chernobyl state of events suggests that an increment of up to 20% in thyroid cancer might occur in a population exposed to 5 mSv as an aftermath of a similar accident. Prediction of future risk estimates should therefore be made with alertness and an open mind.
低剂量延迟辐射（LDR）效应的量化仍存在争议。当前关于剂量反应曲线形状的概念，尤其是在极低剂量水平下，主要是通过从高剂量进行外推得出的，并且受到癌症发生率的经济、社会和政治影响。由于方法学上的缺陷以及需要极大的样本量，基于对受沉降物、职业、宫内或背景低剂量辐射影响人群的流行病学研究的证据有限。然而，最近的数据表明，低剂量辐射诱发的儿童白血病和甲状腺癌可能超过基于线性二次曲线预测的发生率。子宫内和幼儿期的高发生率可能与背景辐射的低累积负荷有关，因此辐射增量更有效。对头皮X线照射后接受90毫希沃特辐射的儿童进行长期随访发现，甲状腺癌的相对风险为3.8，每年每1000人·希沃特的超额风险约为1.08。将这些发现应用于切尔诺贝利事故后的情况表明，在类似事故后暴露于5毫希沃特辐射的人群中，甲状腺癌可能会增加高达20%。因此，在预测未来风险估计时应保持警惕并持开放态度。
