Introduction: Along with the mortality rate, the indicator of Potential Years of Life Lost (PYLL) is used to assess health losses in the population.
   Objective: To assess the structure and rates of mortality from diseases of the circulatory system and to estimate the number of potential years of life lost due to this category of disorders in the population of the Orenburg Region.
   Methods: We conducted a retrospective analysis of deaths registered among the population of the Orenburg Region in 2010–2020 using a depersonalized database of medical death certificates within the mortality monitoring system of the Medical Information and Analytical Center of the Orenburg Region. The results were evaluated using parametric and nonparametric methods. Potential years of life lost due to the diseases of the circulatory system were estimated by 5-year age groups for the population aged 18–75 in the years 2019 and 2020.
   Results: We established that the greatest demographic and socio-economic damage was caused by the diseases of the circulatory system, external causes of death, and neoplasms. We also estimated that in 2019, the mortality rate from diseases of the circulatory system was 633.7 per 100,000 population, i.e. 0.7 % lower than that in 2018 (638.2 per 100,000). In 2010–2020, the circulatory disease mortality rate was the highest in 2010 (842.0 per 100,000 population) and the lowest in 2016 (608.2 per 100,000). The average age of the deceased was 72.9 ± 13.8 years, and we observed its increase from 72.0 ± 10.9 years in 2019 to 73.6 ± 9.4 years in the year 2020 (p = 0.014). In 2019, the indicator of premature mortality was 30,895 and 10,515 years for men and women, including 24,323 and 5,404 potential years of life lost in working-age men and women (< 59 and < 54 years of age), respectively. In 2020, the number of PYLL rose to 39,425 and 16,868 years in men and women, respectively. We found significant age and sex differences in the level of losses from premature mortality.
   Conclusion: Our findings show that the regional mortality rates from diseases of the circulatory system in 2010–2020 exceeded the national averages. The structure of causes of death from diseases of the circulatory system did not change. In 2020, the number of potential years of life lost increased compared to 2019 and was more than twice as high for men than for women.

   Introduction: Trace elements found in natural drinking water can play a key role in making up the chemical composition of the human body in the area of residence.
   Objective: To study the relationship between indicators characterizing the elemental status and oxidative metabolism of residents of the Khanty-Mansi Autonomous Okrug and poor-quality tap water treatment.
   Materials and methods: Hair concentrations of iron, manganese, calcium, magnesium, zinc, and selenium were established in 155 regional residents using atomic emission and inductively coupled plasma mass spectrometry. Contents of the products of lipid peroxidation (lipid hydroperoxide and thiobarbituric acid reactive substances) and antioxidant defense of the body (total antioxidant capacity and thiol status) were determined in blood serum using test kits. The oxidative stress index was calculated as lipid hydroperoxide × thiobarbituric acid reactive substances / total antioxidant capacity × thiol status.
   Results: The residents of the northern Russian cities notorious for poor-quality water treatment have elevated hair levels of Fe and Mn (p < 0.001) and a decreased Se concentration (p = 0.012) combined with a statistically higher level of lipid hydroperoxides, thiobarbituric acid reactive substances, oxidative stress index (p < 0.001), and a low level of antioxidant defense of the body (p < 0.001–0.002). We established a direct correlation between selenium levels in hair and indicators of antioxidant defense status (r = +0,784 ... r = +0,531) and an inverse correlation with lipid peroxidation parameters (r = –0,679 ... r = –0,465). Accumulation of iron and manganese in the human body is closely related to activation of lipid peroxidation (r = +0,472 ... r = +0,413) and suppression of the antioxidant defense status (r = –0,521 ... r = –0,379).
   Conclusion: The observed relationships between the parameters of oxidative metabolism give evidence of a weakening of antioxidant protection and activation of lipid peroxidation in the population of the cities of the Khanty-Mansi Autonomous Okrug supplied with poor-quality tap water.

   Introduction: Intensive introduction of digital technologies and educational tools poses risks of visual impairment in children and adolescents as the most active users of the digital space.
   Objective: To assess risks of visual impairment in children and adolescents in the context of active dissemination of digital technologies in education and everyday life based on a literature review in order to choose directions for pediatric prevention of eye diseases.
   Materials and methods: We did a review of Russian and English language scientific literature published in 2007–2021, found on eLIBRARY.ru, PubMed, Web of Science, and Scopus information portals and platforms. We selected 48 articles containing an evidence-based assessment of risks of eye diseases related to e-learning and long screen time in children and adolescents, especially during the COVID-19 pandemic and associated lockdown.
   Results: We observed combined risks of visual impairment and musculoskeletal disorders due to violation of hygienic requirements for illumination, working posture, distance to the screen, and screen time when using various gadgets. Concomitant risk factors for eye diseases related to vitamin D deficiency were evaluated.
   Conclusions: We identified groups at risk of visual impairment based on health indicators and the intensity of using the digital environment. We also specified basic methodological and regulatory documents, the compliance with which could reduce the risks of visual impairment in children, adolescents, and students, and proposed up-to-date directions of research on the topic of the review for maintenance of eye health.

   Introduction: Extracurricular activities are an important tool of preparing children for a successful life, setting essential core values, and identifying professional preferences. Student participation in after-school educational programs determines the density of elements contributing to acquiring new skills, knowledge, and physical capabilities in their daily routine.
   Objective: To assess the coverage of schoolchildren with supplementary education and to give a hygienic assessment of their extracurricular activities.
   Materials and methods: We analyzed data of the Internet-based survey of over 46,000 schoolchildren from 64 regions of the Russian Federation conducted in January – March 2021 using a standard Excel package and Statistica 10.
   Results: We estimated a smaller coverage of schoolchildren of all age groups with after-school sports (33.1–43.0 %) than with other types of activities, including circles/sections and studios (39.4–62.6 %). We established that 35 % of the respondents did not participate in extracurricular activities at all, with the largest and smallest proportions of such students in grades 9–11 (45.5–47.3 %) and grades 3–5 (27.7%–28.4 %), respectively. On average, 17.6 % of the respondents reported having regular classes with a tutor; the proportion of children attending tutorials was higher among school graduates and tended to increase with school age from 7.5 to 46.2 %. The proportion of eleventh graders studying with tutors was 35.9 % higher than that attending sports clubs. It should be noted that 20.7 % of the respondents reported having no walk on school days, except walking to school and back home, and the share of such children increased with age.
   Conclusion: Our study revealed age-specific characteristics of extracurricular activities and leisure of schoolchildren, availability and demand for supplementary educational services, and demonstrated the lack of skills of effective after-school time planning in modern students.

   Introduction: High standards are set for university students in the learning process while young people are not always psychologically and emotionally ready to comply with such requirements. New living conditions, difficulties of higher education, and/or the forthcoming examination period can suppress adaptive capabilities and cause stress and anxiety in students.
   Objective: To compare the levels of situational and personal anxiety in medical university students having different intensity  of physical activity.
   Materials and methods: The study involved 684 medical students (30.7 % of boys and 69.3 % of girls) aged 18 to 25 years. Based on the International Physical Activity Questionnaire (IPAQ) and in accordance with the metabolic equivalent of task (MET) indicators, all students were divided into three groups by their physical activity intensity (low (1), moderate (2), and high (3)). The level of situational and personal anxiety was assessed using the State-Trait Anxiety Inventory, a 40-item self-completed questionnaire, developed by Charles D. Spielberger and adapted by Yuri L. Hanin.
   Results: We established a higher level of situational anxiety in students with low physical activity compared to those with high intensity (42.18 ± 3.67 against 31.29 ± 3.45 points, respectively, p < 0.05). Similar results were obtained in groups 1 and 3 for personal anxiety (47.69 ± 3.71 against 33.30 ± 3.50 points, p < 0.01). The sex-specific analysis of average levels of situa-
tional and personal anxiety in group 2 showed higher personal anxiety in young women than in men (48.14 ± 3.81 against 36.06 ± 3.49 points, respectively, p < 0.05).
   Conclusions: Our findings demonstrated a statistically significant inverse correlation between the levels of both situational and personal anxiety and the intensity of physical activity among the medical university students.

   Introduction: Data on the chemical composition of food products are important for solving many problems in medical and social spheres. The development of mechanisms for updating existing databases of the chemical composition of foodstuffs, including the need to change approaches to obtaining primary data and develop algorithms of their processing, is in de-
mand.
   Objective: To develop an algorithm of obtaining statistically correct values of average concentrations and variability of the main micro– and macronutrients in bakery products.
   Materials and methods: To develop and test the algorithm, we used the results of testing bakery products obtained in 2020 within the Federal Project on Public Health Strengthening by the laboratories of the Russian Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing (Rospotrebnadzor).

   Results: A good separating power was demonstrated by k­means clustering into two groups by the fat content. An algorithm for generalization of data obtained from different laboratories is proposed due to impossibility to assess the whole aggregate of potential errors related to testing, laboratory personnel, data entry, etc. To assess the effectiveness of each stage and the algorithm as a whole, we used the value of the deviation of the resulting variability from the initial one. As a result of processing, this indicator ranged from 5 % for the carbohydrate content to 72 % for the fat content. For the contents of car - bohydrates, ash, dietary fiber, vitamin B1, sodium and moisture in both clusters, statistically significant differences were obtained between the processed and original data. This result and the comparability of the obtained values of the mean and variability with the reference ones may indicate the correctness of the algorithm. There were no statistically significant differences between the obtained values of fat and protein content, but the consistency of the order of values with the reference
ones was also recorded.
   Conclusion: The developed algorithm made it possible to obtain up-to-date information about the chemical composition of bakery products. Further research should be aimed at testing and, if necessary, adjusting the algorithm for all major food groups.

   Background: Nutritional supplements, herbal assemblages, and herbal teas are of particular interest in the global market of specialized food products, with the issues of a safe use becoming particularly relevant in the light of the reports on their potential contamination with tropane alkaloids, which content ranges from 0.01 % to 3 % depending on the type of raw materials.
   Objective: Analysis of the safety of dietary supplements, herbs and herbal teas contaminated with tropane alkaloids, based on data currently presented in domestic and international scientific publications.
   Materials and methods: We did a review of Russian and English language scientific literature published in 2001–2021, found on Scopus, PubMed and RSCI databases for tropane alkaloids. The initial sample included 49 articles, of which 19 articles were excluded following a primary analysis. The selection criteria included the presence of classification of tropane alkaloids, their contents in herbs and foods, methods of detection, and potential human health effects. We selected 30 full-text publications meeting the above criteria. The study results were systematized by the type of intervention.
   Results: The analysis showed that the content of tropane alkaloids in some herbal teas by the sum of atropine and scopol-amine can exceed the established level of a single safe intake (0.016 µg/kg body weight). Since scopolamine is a derivative of hyoscyamine (atropine), safety of foods and raw materials should be assessed by their content of atropine that will allow effective monitoring of contamination with tropane alkaloids of all types of the specified food products for the purpose of their safe use.
   Conclusion: For the safe use of herbal preparations and plant-based dietary supplements, it is recommended to monitor these types of food products for the presence of tropane alkaloids in them. It is advisable to develop a method for their analysis using high-performance liquid chromatography coupled with mass spectrometry.

   Background: Workplace air pollution with fine particulate matter in industrial premises contributes to imbalance of nonspecific and specific immunity factors, increasing the risk of developing premorbid conditions in workers.

   Objective: To study the features of phagocytic activity and subpopulation T-lymphocytes composition in workers engaged in the potassium chloride production.
   Material and methods: The study was conducted in 2019–2022 within the Research Program of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing on hygiene problems, Clause 2.2.18 “Development of approaches to early diagnosis of production-related diseases using genomic and postgenomic analysis technologies in workers
associated with harmful factors of working conditions”, R&D No. 121081900044-4. The observation group consisted of 54 workers of the main occupations exposed, inter alia, to fine respirable particulate matter in potassium chloride production. The comparison group included 67 individuals having no occupational exposure to industrial hazards. We evaluated the
phagocytic activity of peripheral blood leuko¬cytes and determined the level of CD25 + and CD95 + differentiation cluster expression on T-lymphocytes by flow cytometry.
   Results: We measured high airborne concentrations of fine particles at workplaces of mill, centrifuge and filter operators, granulation and drying workers that were 6.6 and 7 times higher than those of PM 2.5 and PM 10 in the working environment of the administrative staff, respectively. We also observed that the ability of neutrophils to absorb and digest foreign particles
was 20 % lower in the workers of the observation group (p = 0.047), while the proportions of CD25 + and CD95 + lymphocytes in them were 30 % and 60 % lower than those in the comparison group, respectively (p = 0.001–0.046).
   Conclusion: We established the effect of fine particulate matter as a priority workplace air pollutant on innate and adaptive immunity in workers of the main occupations in the potassium chloride production facility. Parameters of innate (phagocytic number) and adaptive (CD25 + and CD95 + lymphocytes) immunity are recommended for use in early diagnosis of immune dysfunction and the development of occupational diseases in workers with inhalation exposure to fine particles.

   Introduction: West Nile fever is a zoonotic, vector-borne viral infection caused by West Nile virus. The possibility of persistence of West Nile virus in overwintering mosquitoes in regions with a temperate climate is of great importance for understanding the mechanisms of pathogen circulation.
   Objective: To detect West Nile virus in mosquitoes during the inter-epizootic period in the Volgograd Region.
   Materials and methods: In 2013–2021, we collected overwintering mosquitoes in different locations of the Volgograd Region using a battery-powered aspirator with a Krishtal’s trap to detect West Nile virus RNA in them using a real-time reverse transcription polymerase chain reaction. An isolate (WNV Volgograd_o16/19) was obtained from sample o16/19 (Cx. pip-
iens, collected on April 2, 2019) with detected West Nile virus RNA using a VERO cell culture. After that, total RNA was isolated from the filtered cell supernatant of that isolate. Metagenomic sequencing of the sample was performed using a high-throughput Illumina MiSeq sequencer, Illumina Inc.
   Results: In total, we collected 4,070 mosquitoes in wintering shelters and tested 157 pools of the insects for West Nile virus RNA. The latter was detected in two pools of Culex pipiens and in one pool of Anopheles maculipennis complex. The phylogenetic analysis showed that the WNV Volgograd_о16/19 strain isolated from the pool of wintering mosquitoes belonged to lineage 2 of West Nile virus. We also established its belonging to the monophyletic clade of West Nile virus strains isolated in the Volgograd, Astrakhan, and Rostov regions in the years 2007 and 2018–2020.
   Conclusions: We were first to detect West Nile virus in overwintering mosquitoes in the Volgograd Region. Our findings confirm the hypothesis that lineage 2 strains of encephalitic West Nile virus persist in mosquitoes during the inter-epizootic period and can be transmitted from mosquito to bird in springtime as one of the mechanisms of forming autochthonous foci in WNV endemic areas of the Russian Federation in the absence of the annual import of this infection.