Caldwell Glyn G, Zack Matthew M, Mumma Michael T, Falk Henry, Heath Clark W, Till John E, Chen Heidi, Boice John D
Department of Epidemiology, College of Public Health, University of Kentucky, Lexington, Kentucky, USA.
J Radiol Prot. 2016 Sep;36(3):474-489. doi: 10.1088/0952-4746/36/3/474. Epub 2016 Jun 29.
Health effects following low doses of ionizing radiation are uncertain. Military veterans at the Nevada test site (NTS) during the SMOKY atmospheric nuclear weapons test in 1957 were reported to be at increased risk for leukemia in 1979, but this increase was not evaluated with respect to radiation dose. The SMOKY test was one of 30 tests in 1957 within the PLUMBBOB test series. These early studies led to public laws where atomic veterans could qualify for compensation for presumptive radiogenic diseases. A retrospective cohort study was conducted of 12219 veterans at the PLUMBBOB test series, including 3020 at the SMOKY nuclear test. Mortality follow-up was through 2010 and observed causes of death were compared with expected causes based on general population rates. Radiation dose to red bone marrow was based on individual dose reconstructions, and Cox proportional hazards models were used to evaluate dose response for all leukemias other than chronic lymphocytic leukemia (non-CLL leukemia). Vital status was determined for 95.3% of the 12 219 veterans. The dose to red bone marrow was low (mean 3.2 mGy, maximum 500 mGy). Military participants at the PLUMBBOB nuclear test series remained relatively healthy after 53 years and died at a lower rate than the general population. In contrast, and in comparison with national rates, the SMOKY participants showed significant increases in all causes of death, respiratory cancer, leukemia, nephritis and nephrosis, and accidents, possibly related in part to lifestyle factors common to enlisted men who made up 81% of the SMOKY cohort. Compared with national rates, a statistically significant excess of non-CLL leukemia was observed among SMOKY participants (Standardized Mortality Ratio = 1.89, 95% 1.24-2.75, n = 27) but not among PLUMBBOB participants after excluding SMOKY (SMR = 0.87, 95% 0.64-1.51, n = 47). Leukemia risk, initially reported to be significantly increased among SMOKY participants, remained elevated, but this risk diminished over time. Despite an intense dose reconstruction, the risk for leukemia was not found to increase with increasing levels of radiation dose to the red bone marrow. Based on a linear model, the estimated excess relative risk per mGy is -0.05 (95% CI -0.14, 0.04). An explanation for the observed excess of leukemia remains unresolved but conceivably could be related to chance due to small numbers, subtle biases in the study design and/or high tobacco use among enlisted men. Larger studies should elucidate further the possible relationship between fallout radiation, leukemia and cancer among atomic veterans.
低剂量电离辐射对健康的影响尚不确定。据报道，1957年在内华达试验场（NTS）参加“烟雾”大气层核武器试验的退伍军人在1979年患白血病的风险增加，但这种增加未根据辐射剂量进行评估。“烟雾”试验是1957年“铅球”试验系列中的30次试验之一。这些早期研究促成了一些公共法律，规定原子退伍军人可因推定的放射性疾病获得赔偿。对“铅球”试验系列中的12219名退伍军人进行了一项回顾性队列研究，其中包括3020名参加“烟雾”核试验的退伍军人。死亡率随访至2010年，并将观察到的死亡原因与基于一般人群发病率的预期原因进行比较。红骨髓的辐射剂量基于个体剂量重建，并且使用Cox比例风险模型评估除慢性淋巴细胞白血病（非CLL白血病）之外的所有白血病的剂量反应。确定了12219名退伍军人中95.3%的生命状态。红骨髓的剂量较低（平均3.2毫戈瑞，最大500毫戈瑞）。“铅球”核试验系列中的军事参与者在53年后仍相对健康，死亡率低于一般人群。相比之下，与全国发病率相比，参加“烟雾”试验的人员在所有死因、呼吸道癌、白血病、肾炎和肾病以及事故方面均有显著增加，这可能部分与占“烟雾”队列81%的应征入伍者共有的生活方式因素有关。与全国发病率相比，在参加“烟雾”试验的人员中观察到非CLL白血病有统计学上的显著超额（标准化死亡比=1.89，95%可信区间1.24 - 2.75，n = 27），但在排除“烟雾”试验的“铅球”试验参与者中未观察到（标准化死亡比=0.87，95%可信区间0.64 - 1.51，n = 47）。最初报道参加“烟雾”试验的人员中白血病风险显著增加，该风险仍然较高，但随着时间推移有所降低。尽管进行了深入的剂量重建，但未发现白血病风险随红骨髓辐射剂量水平的增加而增加。基于线性模型，每毫戈瑞的估计超额相对风险为-0.05（95%可信区间-0.14，0.04）。观察到的白血病超额的原因仍未得到解决，但可以想象可能与样本量小导致的偶然性、研究设计中的细微偏差和/或应征入伍者中高烟草使用率有关。更大规模的研究应进一步阐明原子退伍军人中沉降辐射、白血病和癌症之间的可能关系。
