在目前的辐射防护系统中,电离辐射职业暴露的预防措施和职业暴露限值是基于线性无阈值外推模型。然而,目前,越来越多的证据表明,这种范式预测低剂量暴露区域的生物学反应非常差。此外,几项体外和体内研究表明,剂量反应曲线的存在与电离辐射低暴露相关。在这方面,值得注意的是,不同流行病学研究的结果,在不同类别的职业暴露工人中进行(例如,healthcare,核工业和机组人员),观察到暴露工人的癌症和/或其他疾病的死亡率和/或发病率低于未暴露工人或普通人群,然后暗示可能会发生刺耳语。然而,这些结果应谨慎考虑,因为在流行病学研究中,由于一些主要的局限性,确定患者的反应是相当具有挑战性的.在这方面,在暴露于电离辐射的工人中进行的流行病学研究中发现的一些最显著的缺点是缺乏或不充分的暴露剂量定义,使用暴露的替代品,窄剂量范围,缺乏适当的对照组和对混杂因素的评价差。因此,考虑到流行病学研究可能对复杂的风险评估和管理过程的重要作用和贡献,显然迫切需要克服上述限制,以实现适当的,有用的和更真实的风险评估,还应包括hormesis的关键概念。因此,在本概念性文章中,我们还讨论并提供了可能的方法,以提高流行病学研究的能力,以识别/定义睡眠反应,从而改善低暴露剂量下电离辐射风险评估的复杂过程。
In the current radiation protection system, preventive measures and occupational exposure limits for controlling occupational exposure to ionizing radiation are based on the linear no-threshold extrapolation model. However, currently an increasing body of evidence indicates that this paradigm predicts very poorly biological responses in the low-dose exposure region. In addition, several in vitro and in vivo studies demonstrated the presence of hormetic dose response curves correlated to ionizing radiation low exposure. In this regard, it is noteworthy that also the findings of different epidemiological studies, conducted in different categories of occupationally exposed workers (e.g., healthcare, nuclear industrial and aircrew workers), observed lower rates of mortality and/or morbidity from cancer and/or other diseases in exposed workers than in unexposed ones or in the general population, then suggesting the possible occurrence of
hormesis. Nevertheless, these results should be considered with caution since the identification of hormetic response in epidemiological studies is rather challenging because of a number of major limitations. In this regard, some of the most remarkable shortcomings found in epidemiological studies performed in workers exposed to ionizing radiation are represented by lack or inadequate definition of exposure doses, use of surrogates of exposure, narrow dose ranges, lack of proper control groups and poor evaluation of confounding factors. Therefore, considering the valuable role and contribution that epidemiological studies might provide to the complex risk assessment and management process, there is a clear and urgent need to overcome the aforementioned limits in order to achieve an adequate, useful and more real-life risk assessment that should also include the key concept of
hormesis. Thus, in the present conceptual article we also discuss and provide possible approaches to improve the capacity of epidemiological studies to identify/define the hormetic response and consequently improve the complex process of risk assessment of ionizing radiation at low exposure doses.