A comparative analysis of the stillbirth rate in radioactively contaminated areas of Bryansk region after the Chernobyl accident (1986–2016)

The purpose of the study: Based on the official statistics for 1986–2016, this paper presents the findings of a comparative analysis of the rate of stillbirth in boys and girls in radioactively contaminated areas of the Bryansk region with different radioactive contamination densities by the long-lived radionuclides Cesium-137 and Strontium-90 after the Chernobyl accident. Methods: radioecological, mathematical statistics (Student t-test, Shapiro-Wilk test, White test, Spearman correlation analysis, regression analysis, cluster analysis). Results: No significant differences were found in the stillbirth rate for both the boys and girls between the radioactively contaminated and non-contaminated areas of the Bryansk region over the 31 years following the Chernobyl accident (1986-2016). The rate of stillborn boys over girls was significantly higher in radioactively contaminated areas (17%) compared with the corresponding data across the oblast (10%) and in the control areas (8%), with the most significant differences observed in the third period after the accident (52%). No considerable dependences have been identified between the density of Cesium-137 and Strontium-90 radioactive contamination and stillbirth rates among boys and girls estimated both for the Bryansk region (mean value) overall and for the radioactively contaminated South West Territories (SWT) separately over the period of 1986–2016. In contrast to the findings averaged for the entire Bryansk region and for the SWT, the linear regression revealed a statistically significant relationship between the stillbirth rates and densities of contamination by Cesium-137 and, to a lesser extent, with Strontium-90 in the most heavily radioactively contaminated areas (from 373 to 567 kBq/m² by ¹³⁷Cs and from 6 to 20 kBq/m² by ⁹⁰Sr). Conclusions: The results obtained may indicate a higher sensitivity of male fetuses to low-dose radiation exposure. Key words: stillbirth, teratogenic effect, Chernobyl accident, Bryansk region, radioactive contamination, Cesium-137, Strontium-90. This work was procured by the state (no. 19.9992.2017/5.2) and supported as a part of the Mikhail Lomonosov Program in the context of the international scientific and educational cooperation between the Ministry of Education and Science and DAAD.