Goal: To study migration of toxic chemicals from water containters into stored waterMaterial and Methods:Experimental study was carried out in the Health Reference laboratory of Public Health Institute. In the study, as examples of water containers that are commonly used among population, the samples of water containers narrow opened container intended for keeping oil, aluminium container, large blue container (plastic), and metal container were purchased from Narantuul market and container with volume of 1 liter for potable water was purchased from supermarket and were tested. For determination of heavy metal migration, dissolving soultion or 3% In the solution of 3% chloric acid and for determination of hygiene parameters 3% acidic acid were used, respectively. In the solution of 3% chloric acid 6 heavy metals including iron (Fe), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd) and manganese (Mn) were determined by Varian 210 D AAS-10 in accordance with the method stated in the standard of GOST 5370-50. In the solution of 3% chloric acide the content of formalyne was determined by qualitative method of Shiph and quantative titration methodr, ethylen and salicilic acid by qualitative method, oxidation of organic matters by bichromate titration method and formaldehyde by iodometer method, respectively. Results of analysis were processed by Origin 7.0 software.Conclusions:1. The migration of lead from oil container and large blue plastic container as used for water storage and carriage was detected 500-800 times higher in oil container and 60-72 times higher in large blue plastic container than the acceptable maximum limit of WHO reference level and drinking water standard MNS900:2005 (0.01mg/l). 2. The migration of formaldehyde from plastic containers to food products was 1800-3900 times higher in oil container and 3600-6900 times higher in large blue container than the acceptable maximum limit of formaldehyde migration (formaldehyde 0.1 mg/l). Also 27,0-39,17 mg/l of formalin were determined in the oil container and37,67-53,43 mg/l of formalin were measured in large blue plastic container and its concentration increased over time of storage. It shows that these plastic containers can not be used for keeping drinking water and food products. 3. Lead (122-250 times higher) and cadmium (10-53 times higher) migration from aluminum container was higher than the acceptable maximum limit of national standard NMS 900-2005.4. Iron (58-90 times higher), lead (240-360 times) and cadmium (33-70 times) migration from metal container were detected higher than the acceptable maximum limit of national standard NMS 900-2005.5. The migration of formaldehyde from pure water container was 2922-28000 times higher than the acceptable maximum limit of Russian’s hygienist direction approved in 1971 (reference level is 0.1mg/l of formaldehyde).

Bullying or peers violation is one of adolescent`s truly urgent issue but it is not public discussion topic. We conducted a study in 3 different schools which began from 6th of October, 2014 to 13th of October, 2014. There are total 167 subjects aged between 13-18 were from classes of junior and senior- high at: Orchlon school, School of 1 and School of 13. We used 53- item Questionnaire consisted of 4 sections for our study. We concluded 98(58.7%) participants from School of 1, 26(15.6%) participants from School of 13 and 43(25.7%) participants from Orchlon school who were aged between 13-17 (M=14.7±0.1) which comprise of 84 (50.3%)male and 83 (49.7%) female in our study We assessed correlation of depression and bullying by linear regression. The result of it shows 1 more score of depression measuring scale-CES-D can rise score of Aggression scale 1 by 0.33 point and also it can rise score of Aggression scale 2 by 0.84 point. There is a positive correlation between bullying and depression which confirms high risk of bullying is associated with majordepression in significantly. (p value 0.000) The findings of the study reveals that high levels of bullying associated with high levels of depression.

65 Non-bacterial originated tooth wear is a normal process which occurs throughout lif. If the rate of loss is likely to prejudice the survival of the teeth, or is a source of concern to the patient, then it may be considered ‘pathological’. Robb reported that the prevalence of pathological loss of tooth tissue in patients less than 26 years of age was greater than in many older age groups. Tooth surface loss was classified into 4 groups: attrition, erosion, abfraction and abrasion. To find the prevalence of four different types of tooth wear among patients visited Digital Dental Office, Ulaanbaatar, Mongolia and investigate their dental attrition severity. Methods: From total of patients visited Digital Dental Office clinic between September 2016 and September 2017 adults aged 16-62 who was found with any type of tooth wear were explored by 4 types. Those patients with attrition were chosen and severity was determined by Bardsley’s simplified tooth wear index (TWI). There were total of 5432 patients examined and treated during this period of time. From them total of 1002 patients aged 16-62 presented some degree of tooth hard tissue wear/dental attrition. Most of the patients were with combination of 4 types of tooth wear: attrition, abrasion, abfraction and erosion. Attrition (At) was found in 68 patients which was only 6.7%, Abrasion (Ab) in14 people-1.3%, Abfraction (Abf) in 4-0.3%, Erosion (Er) in 2 -0.1% alone. The combination of these types of tooth hard tissue was dominant. At+ab+abf+er in 59 patients of total 1002 (5.8%). At+ab+er in 58 (5.7%). Ab+abf in 29 (2.8%). At+er in 25 patients (2.4%). Er+ab in 27 (2,6%). At+abf+er in 264 people (26.3%). At+abf in 452 (45.1%), which was the most prevalent combination. Dental attrition severity in these 1002 patients were shown as following: -0-0- No loss of contour. -1-229 people (22.8%) - Loos of enamel surface characteristics. Minimal loss of contour. -2- 505 people (50.3 %) - Loss of enamel exposing dentine for less than one third of surface.Loss of enamel just exposing dentine. Defect less than 1 mm deep. -3- 211 people (21 %) - Loss of enamel exposing dentine for more than one third of surface.Loss of enamel and substantial loss of dentine. Defect less than 1-2 mm deep. -4-57 people (5.6%) - Complete enamel loss - pulp exposure - secondary dentin exposure.Pulp exposure or exposure of secondary dentine. Defect more than 2mm deep - pulp exposure - secondary dentine exposure. In this descriptive study showed patients with some degree of tooth wear were around 19% from total patients visited during 1 year of period. Four types of tooth hard tissue wear shown as a different combination, very low percentage was in these types alone. Most of the attrition patients were with mild to moderate degree of enamel loss. This kind of study should be continued to explore harmful dentofacial change

Background: To prevent and combat the spread of the COVID-19 pandemic, the Government of Mongolia has implemented measures such as movement and time restrictions, social distancing and isolation, closure of schools, kindergartens and public places, immunization, and others. It has caused adverse consequences for people, social relations, and the economy, causing health, social, economic, and humanitarian crises. Not only does this situation, medical students, as frontline healthcare workers, are more susceptible to virus infection. Vaccines against COVID-19 have been researched quickly due to the pandemic and are being used under emergency use authorization. In our country the approach of mixing vaccine doses from different manufacturers was used (fractional doses). Therefore, there is no study on the exposure of medical students to the COVID-19 infection and the adverse effects after receiving a dose of a heterologous vaccine. Objective: To study the exposure to the COVID-19 infection and vaccination status of medical students. Methods: The survey was conducted from November 2023 to December 2023 using a cross-sectional study design, and 170 students who study at ASUSU and live in the dormitory were included. Results: A total of 170 students participated in the study. 55.9% (n=95) of them were in the first year, 22.4% (n=38) were in the second year, 10% (n=17) were in the third year, 7.6% (n=13) were in the fourth year, 2.4% (n=4) were from the 5th year and 1.8% (n=3) were from the 6th year students. 88.2% (n=150) of students were female and 11.8% (n=20) were male. In this study, 37.1% of the students were infected by COVID-19 infection previously. Among them, 50% of the students were infected from family members, 16.7% from the school environment, and 15.2% did not know about the source of infection. 76.2% of the respondents were diagnosed with COVID-19 in a medical institution, and forty-one students answered that they were treated at the hospital. 83% of the cases were treated at home and were cured within 14 days. In contrast, 93.8% of the hospitalized students were treated within four months to 1 year. The current study demonstrates neurological, respiratory, sensory, cardiovascular, psychiatric, digestive, and dermatological symptoms were in 37.6%, 24.1%, 27.6%, 17.6%, 11.8%, 11.2%, and 10% of the students who participated in the study, respectively. For a year or more, symptoms of all organ systems were present, but neurological symptoms appeared to be the highest. 55.9% (n=115) of the enrolled students received 3 or 4 doses of the vaccine, 3.5% (n=6) did not receive the vaccine. In total, 35% (n=60) of the enrolled students experienced side effects and 65% (n=106) had no side effects. Conclusion In this study, 37.1% of the students were infected by COVID-19 infection previously. According to the current study, symptoms related to the nervous system was the most prevalent and 55.9% (n=115) of the enrolled students received 3 or 4 doses of the vaccine. In total, 35% (n=60) of the enrolled students experienced side effects.