Comparison of the Spatial Distribution of Thyroid Cancer Morbidity and Geochemical Factors in Areas of the Bryansk Region (Russia)
Authors: Baranchukov Vladimir , Korobova Elena , Romanov Sergey , Kurnosova Irina 
Published: March 2022

&lt;p&gt;Bryansk region is only Russian, where total radionuclide contamination exceeding 1480 kBq/m&lt;sup&gt;2&lt;/sup&gt; was detected after the Chernobyl accident. At the same time, a definite increase in the incidence of thyroid cancer (ICD-10 code C73) was recorded in this area. From 1990 to 2020, thyroid cancer morbidity in the region increased up to 18.7 cases per 100 000 population compared to the mean value of this parameter for Russia is 6.2 (Kaprin et al., 2020) and 6.0 global (Deng et al., 2020).&lt;/p&gt;&lt;p&gt;To study the geochemical factors responsible for the distribution of thyroid gland diseases, we applied some specialized geographic information system methods. Our approach is based on the idea of a two-layers spatial structure of the modern noosphere (Korobova, 2017). According to the developed approach, the natural geochemical background presented by the soil cover structure is overlain by technogenic contamination fields. In this case, we hypothesize that revealing the causes of the diseases is possible by evaluating the correlation between the two structures: the geochemical and the diseases'.&lt;/p&gt;&lt;p&gt;To analyze the spatial distribution of morbidity, we used the method of kernel density (Silverman, 1986) and the analysis of the obtained maps of thyroid cancer allowed us to identify five territories (with an area of 100-200 km&lt;sup&gt;2&lt;/sup&gt;) characterized by high morbidity (18.0-55.7 cases) and four territories with low morbidity (2.7-10.6 cases). Spatial evaluation of the difference between the original experimental data on iodine content in soils, drinking water, and &lt;sup&gt;137&lt;/sup&gt;Cs deposition in settlements located in areas with high and low thyroid mobidity was performed to estimate natural and anthropogenic geochemical factors contributing to the spread of thyroid diseases. Non-parametric Mann-Whitney U test showed significantly higher iodine content in centralized water supply (Z=1.46, p=0.06), pasture soils (Z=2.10, p=0.03), local milk (Z=1.71, p=0.08), and lower &lt;sup&gt;137&lt;/sup&gt;Cs deposition, which is used to the restoration of &lt;sup&gt;131&lt;/sup&gt;I contamination of the territory (Z=-4.43, p&lt;0.001) in areas with low thyroid morbidity). In our opinion, this witnesses a definite contribution of geochemical factors (iodine deficiency and radioiodine contamination) to the specific spatial distribution of thyroid gland diseases.&lt;/p&gt;&lt;p&gt;The study was partly funded by RFBR (project #20-55-00012) and BRFBR (project #X20P-386).&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Kaprin, A., Starinsky, V., Prteova, G. (Eds.) (2021).&amp;#160;Malignant neoplasms in Russia in 2020 (morbidity and mortality).&amp;#160;National Medical Research Radiological Centre of the Ministry of Health of the Russian Federation, Moscow (in Russian)&lt;/p&gt;&lt;p&gt;Deng, Y. et al. (2020). Global Burden of Thyroid Cancer From 1990 to 2017.&amp;#160;JAMA Network Open,&amp;#160;3(6), e208759.&amp;#160;https://doi.org/10.1001/jamanetworkopen.2020.8759&lt;/p&gt;&lt;p&gt;Korobova, E.M. (2017). Principles of spatial organization and evolution of the biosphere and the noosphere. Geochem. Int. 55, 1205&amp;#8211;1282 (2017) doi:10.1134/S001670291713002X&lt;/p&gt;&lt;p&gt;Silverman, B.W. (1986). Density estimation for statistics and data analysis: Monographs on statistics and applied probability. London; New York: Chapman and Hall&lt;/p&gt;