Luckey T D
University of Missouri, Columbia 65211, USA.
Nutr Cancer. 1999;34(1):1-11. doi: 10.1207/S15327914NC340101.
Whole body exposure to low-dose ionizing radiation appears to decrease overall cancer incidence. The data come from at least eight large studies of populations exposed to various forms of radioactive material and from more limited studies of occupational and environmental exposures to plutonium, radium, and radon. Earlier experiments in animals strongly support the protective effect that is apparent in humans. Also, experimental reports from invertebrates kept in radiation-deficient conditions suggest that ionizing radiation is essential for optimal growth and development. The combined evidence points to the presence of no-adverse-effect thresholds and of hormesis or beneficial effects at doses below those thresholds. Furthermore, according to the geological record, the high background radiation under which life first evolved has progressively attenuated up to the present. Thus it is intriguing to postulate that modern humans may live under conditions of partial deficiency of ionizing radiation; low doses of ionizing radiation may likely function as inducers of repair and detoxification mechanisms, much as low-level antigenic challenges are responsible for enhanced immune competence. This hypothesis runs contrary to the prevailing consensus of regulatory default assumptions, which negate the possibility of no-effect thresholds for agents that are carcinogenic at certain levels of exposure. Still, those are dogmatic policy assumptions without scientific or even empirical justification, whereas the hypothesis advanced here has consistent observational and experimental support. The implication is that a partial deficiency of ionizing radiation could be remedied by a safe supplementation, possibly through dietary means. Dose-response data from studies of nuclear workers and populations subjected to unusual exposures suggest that safe supplementation with about 0.4 cGy/mo would be beneficial and conservative.
全身暴露于低剂量电离辐射似乎会降低总体癌症发病率。这些数据来自至少八项对接触各种放射性物质人群的大型研究，以及对职业和环境中接触钚、镭和氡的更有限研究。早期的动物实验有力地支持了在人类身上明显的保护作用。此外，在辐射不足条件下饲养的无脊椎动物的实验报告表明，电离辐射对于最佳生长和发育至关重要。综合证据表明存在无不良反应阈值，并且在低于这些阈值的剂量下存在兴奋效应或有益效应。此外，根据地质记录，生命最初进化时的高背景辐射一直衰减到现在。因此，推测现代人类可能生活在电离辐射部分缺乏的条件下很有趣；低剂量的电离辐射可能像低水平抗原刺激增强免疫能力一样，起到修复和解毒机制诱导剂的作用。这一假设与监管默认假设的普遍共识相反，后者否定了在某些暴露水平下具有致癌性的物质存在无效应阈值的可能性。然而，那些是没有科学甚至实证依据的教条政策假设，而这里提出的假设得到了一致的观察和实验支持。这意味着电离辐射的部分缺乏可以通过安全补充来弥补，可能通过饮食方式。对核工人和遭受异常暴露人群的研究中的剂量反应数据表明，每月安全补充约0.4厘戈瑞将是有益且保守的。
