Introduction. In terms of the prevalence and severity of complications, diseases of the circulatory system rank high in the structure of general morbidity among the causes of disability and premature mortality of the working-age population. The main reasons for the increased incidence of cardiovascular diseases are considered to be such behavioral risk factors as smoking, alcohol consumption, poor nutrition, hypertriglyceridemia, overweight, and physical inactivity. By now, contribution of adverse work-related and occupational factors in the development of cardiovascular disorders has been proven as well. Our objective was to study the relationship between work-related and behavioral risk factors and diseases of the circulatory system in oil workers.

Methods. We conducted an assessment of working conditions and health status of oil industry workers that included a questionnaire-based survey to identify unmodified and modifiable cardiovascular risk factors, anthropometry, blood pressure measurements, the analysis of lipid metabolism indicators, and examination by a cardiologist. We established that the working conditions of oil production and refinery workers belong to hazard class 3 and may contribute to increased rates of chronic non-communicable diseases including diseases of the circulatory system. The main work-related risk factors for oilmen include vibration, noise, workplace air pollution with saturated hydrocarbons and hydrogen sulfide, as well as the severity of the labor process. Strong interrelationships of the main risk factors were revealed. The proportion of workers with a high risk of developing cardiovascular disor­ders was about 30 % of the total number of employees.

Conclusions. Our findings demonstrate the role of work-related and non-occupational risk factors in the development of diseases of the circulatory system in oil workers and indicate the need to develop appropriate preventive measures.

Background. The task of preserving and improving health of university students is a priority in modern Russia. The purpose of the study was to analyze the health status and to identify priority health risk factors of junior students of a medical university.

Materials and methods. Health assessment was carried out with account for disease incidence (based on the journal of registration of student health records), lifestyle (results of a questionnaire-based survey), and physical devel­opment (medical examination results). The study involved 789 to 1,165 first to third-year medical university students.

Re­sults. We established an increase in the incidence of diseases with temporary disability in the surveyed students by 17.8 % in 2014–2017. The increase was more pronounced among the most common health disorders such as diseases of the respiratory, digestive, and musculoskeletal systems, injury, poisoning and certain other consequences of external causes. The most preva­lent behavioral risk factors included bad habits, lack of sleep and exercise. According to the results of a physical development study, 11.65 % of the boys and 10.93 % of the girls were overweight, 4.89 % of the boys and 3.68 % of the girls had classes I-III obesity while 29.03 % of the students were underweight. Bioelectrical impedance analysis showed a fat mass deficiency in 42.48 % and 33.29 % and an increased fat mass in 34.21 % and 43.20 % of the boy and girl students, respectively.

Conclusion. Our findings will help determine directions for maintaining health of medical students.

Introduction. During lockdown, a student is influenced by a combination of external factors including family en­vironment, increased social and emotional stress, higher educational and computer load, and higher responsibility for doing homework, which inevitably changes his psychoemotional sphere and coping behavior. In order to study characteristics of psychoemotional and behavioral reactions of schoolchildren before and during 2020 COVID-19 lockdown, we conducted a questionnaire-based survey of 1,160 fifth to eleventh graders aged 11–18 in the city of Chelyabinsk.

Results. We established a high level of reactive anxiety in 7.9 % and 9.9 % and a low level in 63.4 % and 59.4 % of schoolchildren before and during lockdown, respectively. A high level of personal anxiety was observed in 33.6 % and 42.6 % of children and a low level – in 19.8 % and 16.8 % of schoolchildren before and during lockdown, respectively. Higher levels of reactive and personal anxiety were more prevalent in girls than in boys. We noted a high and increased levels of aggression in 78.6 % and 80.5 % and very high and high levels of neuroticism in 44.6 % and 44.4 % of the respondents before and during school closure, respectively. A high level of emotional excitability and neurotization was observed in one third of the surveyed schoolchildren. The number of respondents with a high level of neurotization and emotional excitability rose by 7.5 % and 4.0 % during lockdown, respec­tively. The proportion of successful distance learning schoolchildren increased by 16.8 %.

Conclusions. Lockdown contributed to the increase in the levels of anxiety, aggressiveness, and neuroticism in school-age adolescents. The number of respondents complaining of sleep disturbance, visual impairment and headaches became 2.7, 1.1, and 1.1 times higher during lockdown. We revealed significant differences in sleep disorders, headaches, dizziness, complaints of vision impairment, fatigue, and irritability between successful and unsuccessful schoolchildren (p < 0.05).

Introduction. To improve the efficiency of prevention and elimination of adverse health effects of airborne chem­icals in children and adults, the industrially developed regions of Russian Federation face an urgent task of establishing the relationship between exposure to industrial emissions and diseases observed in the local population. The objective of our study was to establish a cause-and-effect relationship between inhalation exposure to components of pulp and paper industry emissions and health disorders in children.

Materials and methods. We carried out ambient air quality testing in the residential area, established target organs and systems, assessed non-carcinogenic risk, conducted an in-depth child health examination, and modeled cause-effect relationships.

Results. We established that phenol, benzene, toluene, xylene, and ethylbenzene were constantly present in the air in the vicinity of the pulp and paper mill. Their concentrations were up to 4.83 and 9.55 times higher than the average daily and one-time maximum permissible concentrations, respectively. High concentrations of chem­icals posed unacceptable chronic non-carcinogenic risk of developing diseases of the respiratory, cardiovascular, immune, and nervous systems, liver, and kidney, as well as acute non-carcinogenic risk of diseases of the immune system. Elevated (up to 1.5 times) blood levels of phenol and xylenes were associated with a 2.3 times higher incidence rate of allergic respiratory diseases and an almost 1.5 times higher incidence of digestive diseases. We established the relationship between blood phenol and xylene levels and a higher incidence of allergic respiratory diseases and diseases of the biliary tract, an increased eosin­ophil count, nasal mucus eosinophilia, higher direct and total bilirubin in serum.

Conclusion. Laboratory test results proved the relationship between inhalation exposure to phenol and xylene as components of pulp and paper industry emissions and higher incidence of diseases of the respiratory and digestive systems observed in the local child population.

Background. Fluoride compounds are one of the main components of industrial emissions from aluminum production. Natural deposition of fluorides with precipitation leads to their accumulation in soil and surface waters. In winter, the snow cover enables an assessment of industrial pollution with fluoride compounds. The objective of our work was to study fluoride levels in the snow cover in the emission zone of the primary aluminum smelter in the town of Shelekhov, Irkutsk Region.

Materials and methods. Snow sampling was performed at nine points at different distances from the plant and fluoride concentrations were then measured in the aqueous fraction and solid precipitate by a potentiometric method with ion-selective electrode.

Results. The aqueous fraction was a solution of hydrofluo­ride and sodium fluoride. Insoluble fluorides were found as a mixture of aluminum fluoride, calcium fluoride, cryo­lite, and aluminum tetrafluoride. We established that the soluble fraction exceeded 90 % in all snow samples. Within the urban agglomeration, snow pollution was distributed differentially. The total fluoride level in residential areas of Shelekhov was 14 to 21 times higher than that at the reference point. At the same time, in the area of a suburban rural settlement located downwind of the smelter, it reached a 33-fold excess.

Conclusion. The main source of envi­ronmental pollution in the Shelekhovsky district of the Irkutsk Region is the processing of cryolite and fluoride salts in the primary aluminum production technological cycle generating fluorine-containing gaseous emissions and solid wastes. Concentrations of industrial pollutants in snow correlated with the distance from the source of emissions and the prevailing wind directions. Contribution of a heat power engineering enterprise to the industrial pollution of the local environment with fluorides was also revealed.

Background. A high prevalence of chromium and benzene compounds in the environment associated with motor vehicle and industrial operations arouses interest in the study of these xenobiotics in a long-term experiment. The objective of this work was to analyze effects of a chronic combined exposure to chromium and benzene on the hypothalamic-pitu­itary-adrenocortical (HPA) and immune systems of male Wistar rats.

Materials and methods. Eighty male Wistar rats were administered potassium dichromate and benzene with drinking water in doses equaling one maximum permissible concen­tration (MPC) during 135 days. The hypothalamus, pituitary gland, adrenal glands, thymus, and spleen were then studied using morphometric, histological, and electron microscopy methods. The streptavidin-biotin peroxidase method was used to determine the expression of pro-apoptotic protein p53 and anti-apoptotic protein bcl2. We also measured the body, thymus and spleen weights of animals, nucleated cell counts in the thymus, spleen, and bone marrow and evaluated the cellular composition of the spleen and bone marrow as well as spontaneous and concanavalin A-induced secretion of interferon gamma (IFN-γ), IL-4, IL-6, and IL-10 cytokines by splenocytes.

Results. We established an adverse effect of the exposure on the HPA function expressed in the activation of its secretory activity, blocking the release of hypothalamic neuropeptides at the level of the neurohypophysis and leading to ultrastructural damage to the neurosecretory cells of the hypothalamus, pituitary adenocytes and adrenal cortical cells, as well as in an increase in the programmed death of thymocytes. We also ob­served a decrease in the thymus weight and thymocyte counts and a complex of structural and functional changes indicating the status of its accidental involution in the exposed rats. The revealed decrease in the splenocyte count in the experimental group was accompanied by an increase in the size of the white spleen pulp. An increase in the induced production of the main immunoregulatory cytokines IFN-γ and IL-4 by splenocytes was found.

Conclusion. Our findings can be used to ana­lyze impairments of the HPA and immune systems in workers with a chronic combined exposure to benzene and chromium compounds in the occupational setting.

Introduction. Coronavirus (SARS-CoV-2) infection is a global healthcare and social problem due to a rapid ubiquitous spread of the virus, a high rate of complications and deaths. The disease is often asymptomatic, which can contribute to its spread, while the most common complication is the development of pneumonia with or without acute respiratory failure and respiratory distress syndrome, which are often fatal. These characteristics of the disease, along with the almost complete lack of immunity in the population around the world (before the mass spread), allowed SARS-CoV-2 to spread freely among the population of all countries. Our objective was to assess the epidemiological features of the incidence of the novel coronavirus disease (COVID-19) in the population of the city of Moscow.

Materials and methods. We conducted a retrospective analysis of all confirmed COVID-19 cases, the total number of diagnostic tests for COVID-19, and the incidence of upper respiratory tract infections registered in Moscow from March 1 to August 31, 2020. The correlation analysis was performed by calculating the Spearman’s correlation coefficient and sub­sequent statistical significance of differences in the compared relative values (p) from the Student’s t-test. Confidence intervals were determined with the calculation of average errors of the compared variables – m(σ).

Conclusion. The revealed features of the COVID-19 incidence in Moscow help establish the factors influencing the development of the epidemic process in the city and give an accurate prediction of the COVID-19 situation for the future.

Introduction. Enterobiasis remains a predominant invasion in the structure of parasitic diseases. At the same time, judging by the incidence rates of enterobiasis, the activity of the epidemic process differs significantly from one region to another and even between cities of one and the same region. The purpose of our study was to assess the intensity of the epidemic process of enterobiasis based on incidence rates and pinworm testing coverage in children aged 3 to 6 years at­tending preschools and schoolchildren aged 7 to 14 years in the Tyumen Region.

Materials and methods. We analyzed data on the incidence of enterobiasis (per 100 thousand population) and pinworm testing coverage (%) per 100 children of two age groups (3 to 6 and 7 to 14 years old) by municipalities of the Tyumen Region in 2013–2017. The interval data were analyzed using methods of variation statistics. To test the hypothesis that the differences between samples were random, a univariate analysis of variance was used. Additionally, the mean difference was calculated and its 95 % confidence interval was deter­mined. The strength of the relationship between two variables was measured using the coefficient of determination, i.e. the square of the Pearson correlation coefficient.

Results. We gave a comparative characteristic of the intensity of the epidemic process of enterobiasis based on the incidence and pinworm testing coverage data in 3 to 14-year-old children attending educational institutions of the Tyumen Region in 2013–2017 and assessed the deterministic relationship between the inci­dence rates of enterobiasis and the commitment of healthcare workers to pinworm detection testing in organized groups of children.

Conclusions. We established that the incidence of pinworm infection in the child population of the Tyumen Region differed significantly between the administrative territories. It should be noted, however, that a relatively high incidence of enterobiasis in some areas was mainly attributed to a high pinworm testing coverage of children while in other areas a low coverage underestimated the incidence rate of enterobiasis and created a false impression of epidemiological welfare.

Summary. We studied the impact of meteorological factors including atmospheric pressure, relative and absolute humidity, air temperature, wind speed, and precipitation quantity on COVID-19 incidence and mortality rates in Moscow during the first wave of the pandemic from 1st April to 25th June 2020 using a correlation analysis. The calculations created new scientific knowledge about the effects of fluctuations in average daily values of weather parameters on the dynamics of the COVID-19 pandemic and demonstrated their statistical significance. We es­tablished that meteorological factors had a greater influence on the incidence than on mortality from the novel coronavirus disease. Atmospheric pressure and wind speed had the strongest effect on incidence and mortality rates of Muscovites while air temperature and precipitation quantity demonstrated the least impact. Correlation coefficients of 0.50–0.70 enabled us to assert that the meteorological factors start influencing the incidence and mortality 6 to 8 weeks before the disease onset. Based on empirical data, we also estimated that the most likely period between the disease onset and death of COVID-19 patients ranged from 8.63 to 22.13 days, the average be­ing 12.63 days. The resulting statistical patterns demonstrate high convergence with actual data and international experience and allow determination of the degree of influence of meteorological conditions on the development of the COVID-19 pandemic in different periods and prognosis of the worst scenarios in the city enabling appropriate and timely preventive measures.

Introduction. In the Karachay-Cherkess Republic (KCR), dysentery and salmonellosis rank high in the etiological structure of intestinal infections and arose interest in studying the incidence of shigellosis in the republic. Our objective was to analyze the incidence of bacillary dysentery, to study Shigella landscape in the territory of the KCR in 2005–2019, and to compare the findings with similar variables in other regions of the Russian Federation.

Materials and methods. We analyzed data of the Center for Hygiene and Epidemiology in the Karachay-Cherkess Republic on the incidence of shigellosis and Shigella isolates obtained from human stool samples in the KCR in 2005–2019 and compared them with available results of similar studies conducted in other parts of the country.

Results: When analyzing the curves of the incidence of dysentery in the KCR and the Russian Federation, we found that they were asynchronous. In the KCR, the curve rose twice (in 2005–2006 and 2011–2014), while in the Russian Federation, the incidence rates demonstrated a gradual decrease. Over the whole observation period, only in 2018–2019 the incidence of shigellosis in Karachay-Cherkessia was 1.3–1.8 times lower than in the country as a whole. We also established that, in contrast to the Russian Federation, Shigella sonnei represented by the biochemical variant IIg prevailed in the structure of shigellosis in the republic. The analysis of the relationship between the number of detected samples of dairy products of poor microbial quality and the incidence rate of Sonne dysentery showed that those two variables did not always correlate. Molecular genotyping of Shigella sonnei strains by pulsed-field gel electro­phoresis (PFGE) allowed us to assume the imported nature of the pathogen. The import could have occurred during the Hajj to Mecca and Medina of KCR residents in 2012.

Conclusion. Shigella sonnei strains differing in the presence of tetracycline and chloramphenicol (levomycetin) resistance determinants are circulating in Karachay-Cherkessia. No bacteria resistant to ciprofloxacin were isolated in the republic in 2005–2019.

Background. The article presents an overview of foreign and Russian scientific data on possible natural reservoirs of the COVID-19 causative agent, SARS-CoV-2 transmission routes, and measures taken to combat it in an aquatic environment. The objective of this review is to determine the possibility and features of SARS-CoV-2 dissemination through the aquatic environment, taking into account statistical significance of the results obtained and the compliance of scientific research with the criteria of evidence-based medicine.

Methods. We used keywords “COVID-19”, “wastewater”, “treatment facilities”, and “river water” to search the electronic databases, including Web of Science, Scopus, PubMed, eLIBRARY, and ResearchGate, for journal articles on the topic. Out of 109 search results, we chose 85 papers and, having analyzed them, selected 55 most rel­evant articles for this review. The presence of the COVID-19 causative agent has been shown in various environmental objects including water supply systems, wastewater, and surface waters. Methods for detecting SARS-CoV-2 particles based on the detection of strains of other viruses in environmental objects have been determined. They demonstrated that the independent entry of the virus into the ecosystem occurs due to its absorption by various fomites. The review presents the results of studies conducted in a number of countries during the pandemic, confirming the presence of SARS-CoV-2 in river water. Some stud­ies indicate the resistance of viral particles present in environmental objects to disinfectants, which, in its turn, determines the relevance of in-depth studies from the standpoint of ensuring sanitary and anti-epidemic regimen at water treatment plants.

Conclusions. The analysis of the world experience enabled us to establish the SARS-CoV-2 survival ability in the aquatic envi­ronment of urbanized areas and to identify its alternative transmission routes in the environment. In modern conditions, due to a poor efficiency of sewage treatment plants in terms of virions, the spread of SARS-CoV-2 in the environment posing a potential risk of the coronavirus disease is quite possible. Our findings will help develop new preventive measures to maintain safety of water bodies and sanitary protection zones. Their implementation will contribute to improvement of the epidemic situation in our country.

Introduction. Disability resulting from diseases of the respiratory system is a complex problem for the health care and social security systems. The prevalence of chronic lung diseases keeps growing.

Our objective was to analyze the rates of initial and recurrent respiratory disability in the adult population of the Rostov Region in 2014–2018 and to compare them with those registered in the Southern Federal District and the Russian Federation.

Material and methods. We used information about initial and recurrent respiratory disability in adults from the electronic database of the unified information and analytical system of medical and social expertise of the Rostov Region and digests of the Federal Bureau of Medical and Social Expert Examination of the Ministry of Labor and Social Protection of the Russian Federation for 2014–2018. We applied methods of data copying, descriptive statistics (estimation of extensive and intensive indicators, significance tests (p)), analytical and comparative anal­ysis.

Results. The analysis of adult respiratory disability in the Rostov Region in 2014–2018 showed a decrease in the number of adults with initial and recurrent disability. The proportion of initial cases tended to decrease and was similar to the Russian average rate but exceeded that in the Southern Federal District while the proportion of recurrent disability cases increased. The rates of initial respiratory disability in the adult population of the Rostov Region and the Russian Federation were comparable. The regional proportion of young people with respiratory disability was 42.2 % in contrast to the Southern Federal District and the Russian Federation where elderly cases prevailed (42.0 % and 48.7 %, respectively). In terms of severity of disability, grade II disability cases prevailed (50.4 %) in the Rostov Region as opposed to the Southern Federal District and the Russian Federation with higher proportions of persons with disability grade III (62.3 % and 72.0 %, respectively). The recurrent disability rate showed a rising trend and was higher than the intensive indicator in the Southern Federal District but lower than that in the Russian Federation. The majority of regional cases with recurrent respiratory disability were young and middle-aged (40.5 % and 40.2 %, respectively); the proportion of young cases tended to increase while that of the middle-aged showed a downward trend. In the Southern Federal District and the Russian Federation, most recurrent cases were middle-aged or elderly (37.8 % and 35.3 %) and elderly or middle-aged (39.0 % and 35.1 %), respectively. The rate of recurrent respiratory disability among young people in the Rostov Region was twice as high as in the Southern Federal District and the Russian Federation. In terms of severity of recurrent respiratory disability, grade III disability was most prevalent in all territories but in the Rostov Region its proportion was lower than in the areas of comparison. The proportion of people with grade II disability tended to decrease but was still higher than in the Southern Federal District and the Russian Federation.

Conclusions. Our findings will allow a more accurate assessment of severity of impairments and vital activity limitations in adults with respiratory disability and help plan appropriate age and sex-specific rehabilitation measures contributing to effective rehabilitation and habilitation actions and successful social integration of a disabled person.

Background. Food safety is one of the prerequisites for a healthy diet of the population of the Russian Federation. At the same time, successful functioning of modern agricultural complexes is almost impossible without a wide­spread use of various agrochemicals, including nitrogen-containing fertilizers. The objective of our study was to conduct a comparative assessment of the nitrate content of vegetables grown on commercial and subsistence farms located in industrially contaminated areas of the region and used as local food.

Materials and methods. The research was carried out in the summer and autumn periods of 2017–2019 in a number of polluted areas of the Saratov Region. Nitrate concen­trations in local vegetables were measured by a potentiometric method.

Results. We established that the nitrate content of vegetables grown in most environmentally disadvantaged areas varied greatly. Concentrations of this contaminant depended on the type of vegetables, growing conditions and region; yet, they did not exceed the maximum permissible level in any vegetable sample tested. At the same time, the level of nitrates in crops grown on commercial farms was significantly higher than that in vegetables grown in private gardens (p < 0.05) due to a more extensive application of nitrate fertilizers in the form of commercially produced ammonium nitrate. Private gardeners, on the opposite, use biomass species, usually legumes, contributing to a better conversion of nitrates into proteins and preventing their ex­cessive accumulation in the produce.