Hahn F F, McClellan R O, Boecker B B, Muggenburg B A
Inhalation Toxicology Research Institute, Albuquerque, NM 87185.
Health Phys. 1988 Aug;55(2):303-13. doi: 10.1097/00004032-198808000-00024.
Radiation-protection standards are based on minimizing or preventing biological effects in exposed populations. Radiation-induced biological effects can be classified as stochastic--malignant and hereditary diseases for which the probability of an effect occurring is a function of dose without threshold--and nonstochastic--inflammatory and degenerative diseases for which the severity and frequency of the effect varies with the dose and for which a threshold is present. The current International Commission on Radiation Protection (ICRP) approach for setting limits for intakes of radionuclides by workers, which accounts for doses to significantly exposed organs of the body, is based on limitation of stochastic effects in most situations. When setting exposure limits, nonstochastic effects are generally considered to be unlikely at the limits for stochastic effects. In some situations, limits based on prevention of nonstochastic effects are lower than for stochastic effects. This review considers the threshold radiation doses for thyroid, bone, liver and lung and their relationship to the limits recommended by the ICRP and the cancer risks at the limits. This review indicates that the threshold dose for nonstochastic effects in thyroid and lung is much above the dose limit as advocated by ICRP. The threshold dose for nonstochastic effects in bone and liver is much closer to the dose limit, but protection from nonstochastic effects should still be afforded by the dose limits.
辐射防护标准的依据是尽量减少或预防受照人群中的生物效应。辐射诱发的生物效应可分为随机性效应——恶性疾病和遗传性疾病，其发生效应的概率是剂量的函数且无阈值——以及非随机性效应——炎症性和退行性疾病，其效应的严重程度和发生频率随剂量而变化且存在阈值。国际辐射防护委员会（ICRP）目前制定工作人员放射性核素摄入量限值的方法考虑了身体中受照显著的器官所接受的剂量，在大多数情况下是基于对随机性效应的限制。在设定照射限值时，通常认为在随机性效应的限值下非随机性效应不太可能发生。在某些情况下，基于预防非随机性效应的限值低于随机性效应的限值。本综述考虑了甲状腺、骨骼、肝脏和肺部的阈值辐射剂量及其与ICRP推荐限值的关系以及限值下的癌症风险。本综述表明，甲状腺和肺部非随机性效应的阈值剂量远高于ICRP所倡导的剂量限值。骨骼和肝脏非随机性效应的阈值剂量更接近剂量限值，但剂量限值仍应提供对非随机性效应的防护。
