University of Michigan, Department of Nuclear Engineering and Radiological Sciences, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109-2104, USA.
Health Phys. 2011 Dec;101(6):693-702. doi: 10.1097/HP.0b013e318222249f.
The cancer risk due to chronic transuranic intakes is properly calculated using an integration over multiple years of intake of the annual effective dose rates arising each year following an intake multiplied by age-dependent risk functions for the year during which the dose is actually received. Approximate computations of risk involving sums of the products of committed effective dose and the age-dependent risk functions for each year of intake indicate the appropriateness of the committed effective dose as a surrogate quantity for risk when applied to different circumstances. The assumptions that all dose is received at the time of intake with committed effective dose and that risk is uniform over a range of ages both lead to a misuse of the available age-dependent risk functions and thus contribute to a divergence from the true risk associated with an intake over multiple years. Comparison of the correctly integrated risk functions with the approximations gives insights into how the current committed effective dose models used for regulatory purposes are not necessarily indicative of the risk for chronic intakes of radionuclides with long biological and radiological half-lives. A summary and comparison of such computations for transuranic intakes was prepared for the ingestion of water and the inhalation of different particle sizes by both males and females. Risk results for committed effective dose consistently overestimated risks by approximately 100% for all transuranics for ingestion models and approximately 75% for all transuranics for Type M inhalation models considering age-dependent risk models. For constant risk as a function of age, the committed effective dose integration underestimated the actual risk situation by nearly 60% for ingestion and 50% for Type M inhalation during the first 20 y.
因慢性超铀元素摄入而产生的癌症风险是通过对每年摄入的年度有效剂量率进行多年积分计算得出的，该剂量率是每年摄入后产生的，并乘以与实际接受剂量的年份相关的年龄依赖性风险函数。涉及摄入各年的累积有效剂量与年龄依赖性风险函数的乘积的风险近似计算表明，当应用于不同情况时，累积有效剂量作为风险的替代量是合适的。所有剂量都在摄入时被摄入，并且风险在年龄范围内是均匀的，这两个假设都导致了对可用年龄依赖性风险函数的误用，从而导致与多年摄入相关的真实风险产生偏差。将正确积分的风险函数与近似值进行比较，可以深入了解当前用于监管目的的累积有效剂量模型如何不一定能反映与长生物和辐射半衰期的放射性核素慢性摄入相关的风险。为了水的摄入和不同粒径的吸入，分别为男性和女性准备了超铀元素摄入的此类计算的摘要和比较。对于摄入模型，对于所有超铀元素，累积有效剂量的风险结果始终高估了风险，约为 100%；对于所有超铀元素，对于考虑年龄依赖性风险模型的 M 型吸入模型，风险结果也约为 75%。对于作为年龄函数的恒定风险，对于摄入，累积有效剂量积分在最初 20 年中低估了实际风险情况，约为 60%；对于 M 型吸入，该积分低估了实际风险情况，约为 50%。
