Acknowledgements: the authors would like to express their appreciation to Yulia V. Tzareva, PhD, research fellow at the Department of Epidemiology, Southern Urals Biophysics Institute, for discussing the study results.

Author contribution: Osipov MV — concept, design, research coordination, statistical analysis and data interpretation, drawing conclusions, manuscript writing, and translation; Sokolova VA — analysis, study planning, data interpretation, discussion; Kushnir AS — literature analysis, data interpretation, manuscript writing.