The studies conducted in 2001 and 2010 included permanent residents of indigenous nationalities dwelling in the villages of Uelen and Kanchalan of Chukotka Autonomous Okrug. We assessed health risks from exposures to polychlorinated biphenyls (PCBs), DDT insecticides, lead, and mercury according to Guidelines R 2.1.10.1920-04 and U.S. EPA methods; a health survey was also conducted based on questionnaires. Health risks posed by ingestion of PCBs were mainly related to consumption of traditional foodstuffs contributing 84 % to the risk profile. Secondary contamination of food products from indoor surfaces accounted for 56 % of DDT-related health risks. For people of traditional occupations (hunters, fishermen, and reindeer herders) the risks of adverse health effects of PCBs were 5 times higher than for those of other occupations. Low income of the local population, high consumption of sea animal fat, alcohol abuse and ignorance of preventive measures resulted in 5-14 times increase in health risks posed by PCB exposures. Low socioeconomic status may significantly modify the health risks caused by bioaccumulation of persistent contaminants and heavy metals, its maximum impact being observed in the coastal areas of Chukotka and mainly in relation to PCBs. For the residents of Uelen, the predicted carcinogenic risk (up to 1.0 x 10^-3) should be considered unacceptable.

Background. The mastectomy (ME) frequency does not decrease. ME has an adverse psychological effect on patients. Breast reconstruction (BR) is an important stage in rehabilitation of breast cancer (BC) patients but the method of choice of BR (immediate or delayed) is still a point at issue. Thus, the assessment of BR results after ME in breast cancer patients is an essential task. Methods. A retrospective cohort study was conducted. From the database of the Saint Petersburg Medical Information and Analytical Center we selected data about the women who were diagnosed with BC and came through ME in 2011-2012 and BR in 2011-2017. The study included information about all BC and BR surgeries in St. Petersburg female BC patients in 2011-2017. We used Statistica 12.0 for Windows and the information from the Population Cancer Register for statistical data processing. The differences were considered statistically significant at p < 0.05. Results. Delayed BR was 1.5 times more frequent than the immediate one (p = 0.0003). The average age of patients who underwent delayed BR was 5 years less than that in the immediate surgery group (p = 0.0017). In 127 (77.4 %) cases, BR after ME was done in women of working age. Cases of stage I BC prevailed in the study groups - 46.2 % (30/65) and 35.4 % (35/99), respectively. Conclusion. BR after ME was more prevalent in working-age women with stages I and II BC. Immediate BR was more frequent in cases with the tumor size less than 2.0 cm. There were no statistically significant differences in the 5-year survival rates in immediate and delayed BR groups (83.1 % and 81.8 %, respectively, p = 0.83). BR surgeries, both immediate and delayed, in BC patients pose no risk of cancer.

The analysis of multicomponent chemical composition of atmospheric air and the air of residential and public premises, including school indoor air, is an urgent task of modern hygienic studies devoted to environmental quality and risk assessment of adverse health effects of dangerous chemicals. The priority sources of air pollution inside classrooms are finishing materials (linoleum, wallpaper, varnishes, paints, etc.) and emissions of monomers from furniture made of chipboards processed with polymer resins. The article demonstrates the results of screening tests establishing the levels of airborne toxic organic compounds (phenol, formaldehyde, benzene, toluene, ethylbenzene, and xylene) both inside and outside educational premises affected by various environmental exposures (conditional areas of observation and comparison). To assess the chemical body burden, blood levels of certain chemicals were measured in schoolchildren dwelling in the observation (study) and comparison (control) areas. Blood tests were accompanied by indoor and outdoor air monitoring in the educational establishments. We examined the total of 424 children including 231 students from primary, secondary and high schools of the city of Perm (observation area) and 193 schoolchildren of grades 1-11 living in the town of Kungur (comparison area). We established that the average daily concentrations of phenol and formaldehyde in indoor air in Perm were 2.4 and 5.6 times higher (р < 0.05) than those in Kungur. Outdoor concentrations of phenol and formaldehyde in Perm were 2.6 and 3.7 times higher than those in Kungur. The analysis of blood levels of certain organic compounds in the primary, secondary and high school children in Perm showed significantly higher concentrations of phenol, benzene, and toluene (p < 0.05) (1.5, 1.1, and 1.2 times, respectively). The average blood concentration of formaldehyde in the study group was 1.3 times higher (p < 0.05) than that in children of the comparison area. No significant differences between the comparison and observation groups (p < 0.05) were found in blood levels of xylene and ethylbenzene. Children's blood concentrations of the identified organic compounds indicate the presence of external sources of exposure to these toxicants.

Nowadays, tobacco smoking is an acute social problem, especially among young people. As a rule, the habit of using tobacco products forms at the school age. The current trend in developing tobacco addiction is not only the decrease in the age at onset of the tobacco use, but also the prevalence of smoking among school-age girls. In combination with other environmental factors, this can not only lead to the development of diseases but also affect their reproductive health in the future. The article describes the results of a sociological study of adolescent schoolchildren, Grades 9-11, of a lyceum in the city of Voronezh and an evaluation of the nicotine intake and exposure among schoolchildren of different ages. The number of cigarettes smoked per day was used as the basis for health risk assessment (age at risk, risk groups, and the time of risk acceleration) according to MR 2.1.10.0033-11, Health risk assessment of lifestyle factors. We established that the age at risk of addiction was 15 years while adolescents smoking more than 10 ± 1 cigarettes per day formed the risk group and the time of the risk acceleration was 3-4 years. Based on the results of our research, we proposed comprehensive actions aimed at the promotion of a healthy lifestyle among adolescents in educational institutions including interaction of schoolchildren with universities, future employers, and parents using mass media, the Internet, and outreach events. The article develops the scientific direction of establishing a method approach to assessing tobacco smoking as a health risk factor for schoolchildren aged 15-18.

Drinking water of proper chemical and organoleptic quality, epidemically and radiologically safe and in sufficient quantity is one of the principal determinants of public health. Currently, the requirements for chemical water quality of the centralized drinking water supply in the Russian Federation are established by SanPiN 2.1.4.1074-01 and GN 2.1.5.1315-03. Despite the fact that both regulatory documents apply to drinking water, they contain different maximum permissible concentrations (MPC) of many chemicals. This ambiguity impedes the choice of standard values and leads to inconsistencies in drinking water quality assessment. Both national and foreign water quality standards have a single regulatory principle but the number and list of regulated chemicals and their standard values in different countries vary considerably. It is essential to develop hygienic standards that combine national and international experience in regulating drinking water quality. We compared Russian hygienic standards for chemical drinking water contaminants with appropriate foreign standards in order to resolve the issue of the necessity and possibility of their optimization.

Introduction. Oxidizing methods are most widely used for water disinfection with such reagents as chlorine, chlorine dioxide, sodium, and calcium hypochlorite. However, the regulatory instruments of the sanitary and epidemiologic legislation do not fully reflect the requirements for monitoring of their use. Materials and methods. We analyzed the research, regulatory and methodological literature concerning water disinfection issues in the process of water treatment and the parameters of water disinfection efficiency as well as the quality of drinking water of three water treatment stations based on production control data (Perm, Russia) and the results of own research (the towns of Nizhny Tagil (Russia) and Curitiba (Brazil)). Results. A comparative analysis of regulatory documents governing the parameters of the efficacy and safety of drinking water disinfection with chlorine in different years showed that, after the completion of the disinfection process of drinking water, residual free chlorine should be kept within 0.3-0.5 mg/L after 30 minutes of contact or residual bound chlorine - within 0.8-1.2 mg/L after 60 minutes of contact. With the simultaneous presence of free and bound chlorine in water, their total concentration should not exceed 1.2 mg/L. When analyzing the production control data for drinking water in the city of Perm, where chloramination was used for water treatment, we established that the concentration range of 1.04-1.44 mg/L of only the residual bound chlorine ensured high efficiency of water disinfection according to microbiological indicators. The examples of water treatment plants in the towns of Nizhny Tagil and Curitiba demonstrated that water treatment with 0.3 and 0.4 mg/L of chlorine dioxide formed no new dangerous organo-chlorine compounds but the disinfected drinking water contained residual amounts of chlorine dioxide, as well as chlorite and chlorate anions. Conclusion: These indicators should be included in the regulatory documents to monitor the safe use of chlorine dioxide for water disinfection.

The review presents the analysis of effects of different ranges of ultraviolet (UV) radiation on physicochemical and organoleptic properties of certain types of fruits, vegetables, and mushrooms, as well as on changes in their storability. It provides the results of experimental studies and information from patent descriptions demonstrating significant changes in the properties and composition of plant objects after UV-treatment: an increase in the concentration of phenolic compounds, anthocyanins, quercetin glycosides, chlorogenic and ascorbic acids, and an increased antioxidant activity. Available data allow us to conclude on the efficiency of applying UV radiation, both as an independent type of product treatment during storage and processing of plant raw materials, and as part of combined methods using other physical processing techniques (microwave radiation, fast electron processing, Y-radiation, sonication, thermal treatment, etc.). The effectiveness of UV radiation significantly depends on its range and processing modes. UV radiation, along with the sterilizing effect, has a thermal effect on the treated objects. This means that a long-term exposure to UV radiation causes significant heating, which must be taken into account when processing plant objects having a temperature below the ambient one as it can potentially amend their storability. The review discusses the issues of choosing optimal UV treatment modes (radiation dose and processing time) that improve storability of fruits, vegetables, mushrooms and other plant species while preserving their physicochemical and organoleptic quality parameters. In conclusion, the efficiency of the radiation dose is determined by the radiation power flux density, parameters of radiation sources and their location relative to the processed objects. Determination of the optimal conditions (radiation dose and processing time) of UV treatment of plant raw materials, depending on the goals, is an important scientific and technological task.

Background. Enterovirus infection is widely spread around the world. It has different epidemiologic and clinical manifestations. However, to date, the amount of accumulated information on the epidemic process of enterovirus infection in different constituent entities of the Siberian Federal district of the Russian Federation is insufficient. Objectives. Our objectives were to investigate characteristics of the enterovirus infection epidemic process in Siberian constituent entities subjected to surveillance using the innovative molecular genetic analysis. Materials and methods. The analysis of long-term enterovirus infection incidence in the investigated constituent entities of Siberia was performed. The total number of 237 enterovirus strains circulating during 2017-2018 epidemic seasons in the analyzed regions were isolated using sequencing technique. A phylogenetic analysis of the obtained nucleotide sequences was performed. Results. The epidemiologic situation related to enterovirus infection was unfavorable in the majority of the Siberian constituent entities in the past two years. A significant increase in incidence rates was registered in the Irkutsk Region, Zabaykalsky Krai and Altai Republic. We distinguished major manifestations of the enterovirus infection epidemic process including a years-long excess of the national average and a rising trend in the annual incidence rate, prevalence of herpangina, exanthema and enterovirus meningitis in the clinical course of the disease among children aged 3-6. Prevalence of Coxsackievirus A-6 and Coxsackievirus A-9 in the landscape of circulation was revealed in a number of Siberian regions. Group incidence and imported cases were also registered. Discussion. Our results demonstrated the importance of molecular genetic monitoring of circulating enteroviruses as part of the epidemiologic surveillance. This state-of-the-art approach can reveal potential epidemiologic links between cases of the disease.

Objective. Our objective was to study the prevalence of toxoplasmosis among various groups of population in the Omsk Region. Materials and methods. We analyzed statistical data and the results of our own serological tests carried out in 2000-2017. Antibodies to Toxoplasma were determined in 1,926 people (769 citizens and 1,157 villagers). The blood serum was used as the test material. For the detection of IgG and IgA antibodies to toxoplasma, we used locally produced ELISA test systems ("Vector-Best", Novosibirsk). Results. Antibodies to toxoplasmas were found in residents of all landscape areas of the Omsk Region. In the northern parts of the forest zone, 45.9 % of people had antibodies to toxoplasma; in the southern steppe zone, 64.6 % of people had those antibodies. Urban residents were infected in 17.7 % of cases. There were significant age-related differences in toxoplasma infection in the population of the Omsk Region. The maximum rates of invasion in older age groups were more than 50 % among urban residents and over 70 % in rural areas. Rates of seropositivity of rural children under 15 were 5 times higher than those in urban children. Serological markers of toxoplasmosis were detected in 52.8 % of rural women of childbearing age and in 33.9 % of urban women. Conclusion. The research results indicated the unfavorable epidemic situation for toxoplasmosis in the Omsk Region. Taking into account the risk of infection for people with immunodeficiency and pregnant women and the possibility to reactivate the invasion even in an immunocompetent organism, it is necessary to study distinctive features of the toxoplasmosis epidemic process in different areas of the Omsk Region and to develop regulatory and procedural documents on prevention of Toxoplasma infection in the population.

Research objective. Differentiation of natural focal areas of Western Siberia by integral incidence rates of ticK-borne infectious diseases for determination of the strategy and tactics of their comprehensive prevention. Materials and methods. A retrospective analysis of official statistics for the period 2002-2018 for eight sub-federal units in the context of administrative territories was carried out. The criteria of differentiation were determined by means of three evaluation scales, including longterm mean rates of tick-borne encephalitis, tick-borne borreliosis, and Siberian tick-borne typhus. As a scale gradation tool, we used the number of sample elements between the confidence boundaries of the median. The integral assessment was carried out by the sum of points corresponding to the incidence rates for each of the analyzed infections. Results. The areas of low, medium, above average, high and very high risk of tick-borne infectious diseases were determined. Recommendations on the choice of prevention strategy and tactics were given. In areas of very high and high incidence rates, a combination of population-based and individual prevention strategies is preferable while in other areas a combination of high-risk and individual strategies is recommended. Discussion. Epidemiologic zoning should be the basis of a risk-based approach to determining optimal volumes and directions of preventive measures against natural focal infections. It is necessary to improve the means and methods of determining the individual risk of getting infected and developing tick-borne infectious diseases in case of bites, in view of mixed infection of vectors, as well as methods of post-exposure disease prevention (preventive therapy).

The urgency of the problem of hepatitis B is related to its significant economic damage, epidemiologic, medical and social significance, widespread infection, severity, high frequency of adverse outcomes, and active involvement of working-age people in the epidemic process. The objective was to assess population immunity to hepatitis B virus among citizens of the european part of Russia (based on the example of the Nizhny Novgorod Region) in the context of planned vaccination. We analyzed disease incidence and vaccination of the population using official statistics and laboratory test results. The prevalence of serological markers of hepatitis B (anti-HBs, anti-HBcor IgG) among the conditionally healthy population aged 1-55 was determined by enzyme immunoassay. Epidemiologic efficiency of mass vaccination against hepatitis B in the population of the Nizhny Novgorod Region was established: the absence of officially registered cases of acute hepatitis B among children aged 0-14 since 2013, as well as a significant reduction in the incidence rates in the adult population from 52.2 0/0000 in 2000 to 1.30/0000 in 2018. An inverse correlation dependence of the average power between the incidence rates of the AHB and the vaccination coverage of children and adults was established. The article presents the results of studying duration and intensity of post-vaccination immunity to the hepatitis B virus in the population of the Nizhny Novgorod Region in 2000-2018. Serological monitoring allows evaluation of efficacy of vaccination and the level of specific population immunity to the hepatitis B virus, which, in its turn, contributes to timely management decisions about the need and timing of booster immunization of specific categories of the population.

The article presents the results of the examination of relatives of the patients with chronic H. pylori-assoe ciated gastritis. The genes of H. pylori pathogenicity were investigated by PCR to determine possible intrafamilial transmission of the infection. We established that in families of the patients with chronic gastritis, H. pylori was found in more than 60 % of relatives. The most similar spectrum of the genes of H. pylori pathogenicity was found in the samples of spouses, as well as in the mothers and the children. The study of H. pylori genovariant helps es-a tablish the mechanisms and ways of transmission of the infection, identify people infected with the microorganism with the most pronounced pathogenic potential and requiring therapy.