背景:白俄罗斯和乌克兰是1986年受切尔诺贝利核电站后果影响最大的国家。对白俄罗斯围产期死亡率的研究发现,在1990年代,受污染最严重的州戈梅利的死亡率在统计上有了很高的显着增长,但在此期间,白俄罗斯其他地区没有增长。作为一种可能的机制,将这种增加解释为晚期的托诺贝效应,有人认为,切尔诺贝利尘埃中含有锶-90,在初潮期间合并,会损害孕妇的免疫系统,进而增加围产期死亡率。在本研究中,这一假设是使用乌克兰的数据进行检验的。
方法:围产期死亡率的年度数据,在1981-2006年期间,由乌克兰公共卫生部提供。将乌克兰污染最严重的地区(基辅和Zhytomyr州以及基辅市;研究地区)的围产期死亡率趋势与乌克兰其他地区(控制区)的死亡率进行了比较。为了确定研究区域和对照区域之间围产期死亡率趋势的任何差异,使用计算的锶浓度作为预测因子,分析了研究区域围产期死亡率与对照区域的比率.
结果:对乌克兰围产期死亡率的趋势分析显示,与1990年代初和末期的长期指数趋势有两个钟形偏差,具有最大值。在研究区和控制区的数据中发现了相同的模式,但是研究区域的偏差几乎是对照区域的三倍。对研究区域围产期死亡率与控制区死亡率之比(优势比)的分析表明,在1990年代,这种增加和减少近似为对数正态分布。计算的锶浓度,当用作预测器时,也很好地拟合了数据。因此,乌克兰的数据证实了白俄罗斯的结果。对优势比的分析显示,在1990-2004年期间,研究地区约有1000例围产期死亡。整个乌克兰的相应数字估计为3500例围产期死亡。
结论:假设1990年代观察到的围产期死亡率增加可能是掺入锶90对孕妇免疫系统的后期影响。分析基于理论模型,由于没有锶浓度的数据,因此应谨慎解释结果。白俄罗斯的最新研究将有助于证实结果。
BACKGROUND: Belarus and Ukraine were the countries most affected by the consequences of the Chornobyl nuclear power plant in 1986. A study of perinatal mortality in Belarus found a highly statistically significant increase in the 1990s in the most contaminated oblast Gomel but no increase during this period in the rest of Belarus. As a possible mechanism to interpret this increase as a late Chornobyl effect, it has been suggested that strontium-90 contained in Chornobyl fallout, incorporated during menarche, impairs the immune system of pregnant women which in turn increases perinatal mortality. In the present study, this hypothesis is tested using data from Ukraine.
METHODS: Annual data on perinatal mortality, in the period 1981-2006 were provided by the Ministry of Public Health of Ukraine. Trends in perinatal mortality rates in the most contaminated regions of Ukraine (Kyiv and Zhytomyr oblasts and the city of Kyiv; study region) were compared with rates in the rest of Ukraine (control region). To identify any differences in perinatal mortality trends between the study and control regions, the ratios of perinatal mortality rates in the study region to the rates in the control region were analyzed using the calculated strontium concentration as a predictor.
RESULTS: A trend analysis of perinatal mortality rates in Ukraine revealed two bell-shaped deviations from a long-term exponential trend with maxima at the beginning and end of the 1990s. The same pattern was found in the data from the study and control regions, but the deviations were almost three times higher in the study region than in the control region. An analysis of the ratios of perinatal mortality rates in the study region to the rates in the control region (odds ratios) showed an increase and decrease during the 1990s which was approximated by a lognormal density distribution. The calculated strontium concentration, when used as a predictor, also fitted the data well. Thus, the data from Ukraine confirms the results from Belarus. The analysis of the odds ratios revealed about 1000 excess perinatal deaths in the study region in the period 1990-2004. The corresponding figure for Ukraine as a whole was estimated at 3500 perinatal deaths.
CONCLUSIONS: It is hypothesized that the observed increase in perinatal mortality in the 1990s may be a late effect of incorporated strontium-90 on the immune system of pregnant women. The analysis is based on a theoretical model, as no data on strontium concentrations were available; the results should therefore be interpreted with caution. An updated study for Belarus would be desirable to corroborate the results.