摘要
数十年来 ,为了辐射防护目的 ,通常假定辐射诱发癌的总危险是随着剂量呈线性无阈函数增加。现有的资料并不排除有阈存在 ,然而 ,剂量响应关系的变化是依赖于所论及的癌症类型 ,剂量 ,剂量率 ,以及辐射的 L ET,受照个体的年龄、性别和生理状态 ,以及其他因素 ,其中包括在低剂量条件下的适应性响应和旁观者效应的潜在影响。所以 ,根据不断发展的科学知识 ,下列机构定期对低水平辐射的剂量响应关系进行再评估 ,这些机构是 :美国国家辐射防护与测量委员会 ( NCRP) ,国际放射防护委员会 ( ICRP) ,联合国原子辐射效应科学委员会 ( UN SCEAR) ,美国国家科学院 ( USN AS)以及其他机构。近来这些评论普遍发现的重要证据认为 ,作为癌症前体的损伤 (例如突变和染色体畸变 ) ,以及某些类型癌症 ,其发生率在低剂量范围内将随着剂量线性增加。在此基础上 ,可以得出以下结论 :对于低水平辐射的致癌效应 ,尽管不排除有其他剂量响应关系 。
In recent decades,it has been customary,for radiation protection purposes,to assume that the overall risk of radiation induced cancer increases as a linear nonthreshold function of the dose.The existing data do not exclude the existence of a threshold,however,and the dose response relationship is known to vary,depending on the type of cancer in queation,the dose,dose rate,and LET of the radiation,the age,sex,and physiological state of the exposed individuals,and other variables,including the potential influence of adaptive responses and bystander effects at low doses.In light of advancing knowledge,therefore,the dose response relationship for carcinogenic effects of low level radiation has been reevaluated periodically by the National Council on Radiation Protection and Measurements,the International Commission of Radiological Protection,the United Nations Scientific Committee on the Effects of Atomic Radiation,the U.S. National Academy of Sciences,and other organizations.The most recent such reviews have generally found the weight of evidence to suggest that lesions which are precursors to cancer(i.e., mutations and chromosome aberrations),and certain types of cancer as well,may increase in frequency linearly with the dose in the low dose domain.On this basis,it is concluded that no alternative dose response model for the carcinogenic effects of low level radiation is more plausible than the linear nonthreshold model,although other dose response relationships cannot be excluded.
出处
《辐射防护通讯》
2003年第2期1-5,共5页
Radiation Protection Bulletin
