Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland; Graduate School for Health Sciences, University of Bern, Bern, Switzerland.
Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland.
J Environ Radioact. 2021 Nov;238-239:106734. doi: 10.1016/j.jenvrad.2021.106734. Epub 2021 Sep 11.
Exposure to high doses of ionizing radiation is known to cause cancer. Exposure during childhood is associated with a greater excess relative risk for leukemia and tumors of the central nervous system (CNS) than exposure in later life. Cancer risks associated with low-dose exposure (<100 mSv) are uncertain. We previously investigated the association between the incidence of childhood cancer and levels of exposure to external background radiation from terrestrial gamma and cosmic rays in Switzerland using data from a nationwide census-based cohort study. Here, we provide an update of that study using an extended follow-up period and an improved exposure model.
We included all children 0-15 years of age registered in the Swiss national censuses 1990, 2000, and 2010-2015. We identified incident cancer cases during 1990-2016 using probabilistic record linkage with the Swiss Childhood Cancer Registry. Exposure to terrestrial and cosmic radiation at children's place of residence was estimated using geographic exposure models based on aerial spectrometric gamma-ray measurements. We estimated and included the contribution from Cs deposition after the Chernobyl accident. We created a nested case-control sample and fitted conditional logistic regression models adjusting for sex, year of birth, neighborhood socioeconomic position, and modelled outdoor NO concentration. We also estimated the population attributable fraction for childhood cancer due to external background radiation.
We included 3,401,113 children and identified 3,137 incident cases of cancer, including 951 leukemia, 495 lymphoma, and 701 CNS tumor cases. Median follow-up in the cohort was 6.0 years (interquartile range: 4.3-10.1) and median cumulative exposure since birth was 8.2 mSv (range: 0-31.2). Hazard ratios per 1 mSv increase in cumulative dose of external background radiation were 1.04 (95% CI: 1.01-1.06) for all cancers combined, 1.06 (1.01-1.10) for leukemia, 1.03 (0.98-1.08) for lymphoma, and 1.06 (1.01-1.11) for CNS tumors. Adjustment for potential confounders had little effect on the results. Based on these results, the estimated population attributable fraction for leukemia and CNS tumors due to external background radiation was 32% (7-49%) and 34% (5-51%), respectively.
Our results suggest that background ionizing radiation contributes to the risk of leukemia and CNS tumors in children.
已知高剂量的电离辐射会导致癌症。与生命后期暴露相比，儿童时期的暴露与白血病和中枢神经系统（CNS）肿瘤的超额相对风险更高。与低剂量暴露（<100mSv）相关的癌症风险尚不确定。我们之前使用全国基于人口普查的队列研究的数据，研究了瑞士儿童癌症发病率与陆地伽马和宇宙射线外部背景辐射暴露水平之间的关系。在这里，我们使用扩展的随访期和改进的暴露模型提供了该研究的更新。
我们纳入了 1990 年、2000 年和 2010-2015 年瑞士全国人口普查中所有 0-15 岁的儿童。我们使用与瑞士儿童癌症登记处的概率记录链接，确定了 1990 年至 2016 年期间的癌症发病情况。使用基于航空光谱伽马射线测量的地理暴露模型估算儿童居住地的陆地和宇宙辐射暴露。我们估计并包括了切尔诺贝利事故后 Cs 沉积的贡献。我们创建了一个嵌套病例对照样本，并拟合了条件逻辑回归模型，调整了性别、出生年份、邻里社会经济地位和模型化的室外 NO 浓度。我们还估计了由于外部背景辐射引起的儿童癌症的人群归因分数。
我们纳入了 3401113 名儿童，确定了 3137 例癌症发病情况，包括 951 例白血病、495 例淋巴瘤和 701 例中枢神经系统肿瘤病例。队列的中位随访时间为 6.0 年（四分位间距：4.3-10.1），自出生以来的累积暴露中位数为 8.2mSv（范围：0-31.2）。每增加 1mSv 累积剂量的外部背景辐射的危险比为 1.04（95%CI：1.01-1.06），所有癌症合并，1.06（1.01-1.10）为白血病，1.03（0.98-1.08）为淋巴瘤，1.06（1.01-1.11）为中枢神经系统肿瘤。对潜在混杂因素的调整对结果影响不大。基于这些结果，由于外部背景辐射引起的白血病和中枢神经系统肿瘤的估计人群归因分数分别为 32%（7-49%）和 34%（5-51%）。
我们的结果表明，背景电离辐射会增加儿童患白血病和中枢神经系统肿瘤的风险。
