Dietary intake and physical activity of elementary school children in Ha Nam and Dien Bien provinces in 2020

Some factors associated with the prevalence of silicosis working in Coc factory in Thai Nguyen.. Some factors associated with the prevalence of silicosis among employees working in Coc f

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I -am indebted to my tutor Ass Prof Le Till Thanh Xuan from the Department

of Occupational Health School of Preventive Medicine and Public Health HanoiMedical University for her exemplaiy guidance, monitoring and constantencouragement throughout the course of this thesis I am also indebted to members ofDepartment of Occupational Health allowing me to use a part of data as my thesis Ialso wish to take this opportunity to express a deep sense of gratitude to the Board ofDirectors Training Department of School of Preventive Medicine and Public Health fortheir cordial support, valuable information and guidance which helped me incompleting this task through various stages I would like to express my deepest thanks

to the Managing Board Department of Training Hanoi Medical University who hadcreated a favorable and wonderful environment in the scliool for the past 6 years I wish

to thank all the teachers in the Department of Occupational Health School ofPreventive Medicine and Public Health Hanoi Medical University for their valuableinformation provided by them in their respective fields I am gratefill for theircooperation during the period of my assignment Lastly I would like to express mydeepest thanks to my loving family, relatives and friends for their constantencouragement without them this thesis would not be possible

Hanoi May 2021

Student Pham Duv Thanh

Independence-Freedom - Happiness

CONFIRMATION

To:

- Department of Undergraduate Training Management and Department of StudentAffairs Hanoi Medical University

- Institute for Preventive Medicine and Public Health Hanoi Medical University

I here by declare that this research was originally done by myself and was a part

of national research on silicosis where the principal investigator approved for myparticipation The data handling and analysis were objectively completed with honesty.The results of this stud}’ have not been published in any document

Hanoi May 2021

Student

Pham Duy Thanh

•

International Labor OrganizationWorld Health OrganizationILO

WHO

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CONFIRMATION

ABSTRACT

INTRODUCTION

CHAPTER 1: LITERATURE REMEW , .3

1.1 Concepts associated with the employees, working environment and silicosis 3

1.1.1 The employees 3

1.12 Working environment 3

1.13 Dust in labor 4

1.1.4 Silica dust 4

1.13 Occupational diseases 5

1.1.6 Silicosis 6

1.1.7 Diagnosis the silicosis 6

1.1.8 X-ray images of the silicosis 7

1.1 p Respiratory' function evaluation parameters 9

1.2 The prevalence in silicosis among employees exposed to silica dust 10

1.2.1 Global 10

1.22 In Vietnam 13

1.3 Some factors associated with the prevalence of silicosis among employees exposed to silica dust 14

1.3.1 Global 15

1.32 In Vietnam 16

1.4 Overview of the study sites 17

CHAPTER 2: RESEARCH SUBJECTS AND METHODOLOGY 18

2.1. Research sites 18

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2.3. Research times 20

2.4. Research design 20

2.5. Sample size and sampling 20

2.6. Variables and indicators 20

2.7. Tool and technique for data collection 24

2.8. Potential Errors and Solutions 4 27

2.9. Data entry and analysis 27

2.10. Research ethical consideration 28

CHAPTER 3: FINDINGS AND RESULTS 29

3.1 Demographic characteristics of study participants 29

3.2 The prevalence of silicosis among employees working in Coc factory in Thai Nguyen, 2020 31

3.3 Some factors associated with the prevalence of silicosis working in Coc factory in Thai Nguyen 2020 36

CHAPTER 4 DISCUSION - -43

4.1 The prevalence of silicosis among employees working in Coc factory in Thai Nguyen 2020 43

4.2 Some factors associated with the prevalence of silicosis among employees working in Coc factory in Thai Nguyen 2020 48

CONCLUSION 50

RECOMMENDATION 51

REFERENCES APPENDIX 1 APPENDIX 2 APPENDIX 3 APPENDIX 4 LIST OF TABLES Table 2.1 List of variables and indicators among employees of Coc factory in 2020 20

Table 3.1 General characteristics of research subjects 29

Table 3.2 Percentage of employees diagnosed with silicosis and received occupational disease book previously 31

Table 3.3 Tire prevalence of silicosis among employees 31

Table 3.4 Percentage of employees with decreased respirators- funct ion 32

Table 3.5 The degree of decline in FVC and FEV1 among employees 33

Table 3.6 Rate of respirators7 dysfunction in employees 33 Table 3.7 Level of damage on chest X-iay of employees according to ILO

group of employees 36Table 3.11 The association between the prevalence of silicosis and the

occupational age of the employees 37Table 3.12 The association between prevalence and the employees's smoking

history 37Table 3.13 The association between prevalence of silicosis and the

employees's history of respiratory disease 38Table 3.14 The association between prevalence of silicosis and accessing

information of silicosis among employees 38 Table 3.15 The association between prevalence of silicosis and knowinghealth services among employees 39Table 3.16 The association between prevalence of silicosis and health status

among employees 39Table 3.17 The association between prevalence of silicosis and attitude to the

dangerous of silicosis among employees 40Table 3.18 The association between prevalence of silicosis and some

associated factors (multivariate analysis) 40

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Figure 2.1: Study location 18

Figure 2.2: Metal lurigical coke and steel making process 19

Figure 3.1 Rate of using various types of masks among employees 35

Figure 3.2 Frequency using masks among employees 35

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Silicosis is an occupational lung disease that causes lung fibrosis, progressiveand irreversible in workers who inhale free silica dust Coc factory is a manufacturingindustry that also generates a lot of silicon dust, which significantly affecting the health

of employees, especially problems related to occupational pulmonary dust respiratorydisease Therefore, the health protection and prevention of occupational diseases foremployees is very necessary

We conduct the topic "The prevalence and some associated factors of silicosisamong employees working in one factory in Thai Nguyen province 2020" with twofollowing specific objectives: identifying the prevalence of silicosis among employeesand analysing some factors associated with the prevalence of silicosis amongemployees working in Coc factory in Thai Nguyen province 2020

A cross-sectional study was applied All employees of Coc factory wereworking directly in the production lines matching with inclusion criteria as above Allqualified employees to participate in the research, agreed to participate in the study andfrilly examined the research items were recruited In totaL we selected 336 workersamong 341 employees of the company at the study time

After analysing, the prevalence of silicosis in workers at Coc Factory in ThaiNguyen in 2020 was 10.1% Gender was the statistically significant factor related tosilicosis of workers The prevalence of silicosis in male workers was 4.32 times higherthan that of female workers (95% CI was 1.60 - 11.6) When analyzing multivariateregression, the rate of silicosis in male workers was 3.14 times higher than that offemale workers (95% CI was 1.05-1.24 X tire comparison was statistically significantwith p <0.05 No statistically significant association between other factors and silicosiswas found

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INTRODUCTION

Silicosis is an occupational lung disease tíiat causes lung fibrosis, progressiveand irreversible in workers who inhale free silica dust [1], [2] It is incurable and themost common of all occupational diseases in developing countries [3] Exposure tolarge amounts of free silica may go unnoticed because silica is odorless, does not causeirritation and does not cause any immediate health effects Chronic exposure to silicaalso increases the risk of tuberculosis [4] [5] [6] - a major health problem indeveloping countries, including Vietnam

According to the ILO International Labor Organization, it is estimated that everyyear about 2.2 million people die from occupational diseases, equivalent to about 5.500deaths per day [7]

In developed countries, due to good labor protection, silicosis tends to decreasegradually In developing countries, according to the consulting conference of siliconpneumoconiosis Geneve 1989: due to ineffective measures to prevent dust, highconcentrations of respiratory dust, workers often have to work hard, making them bedangerous As a result, the risk of silicosis increases among those workers [8].According to the World Health Organization (WHO), the prevalence of silicosis indeveloping countries among workers exposed to silica dust was about 20-50%.Incidence rates also varied between countries and occupations [9] In Vietnam as of

2016 there were 34 occupational diseases entitled to social insurance of which silicosiswas recognized for compensation since 1976 and is the most common occupationallung disease [10] The disease accounted for 88;% of all occupational diseases assessed

in Vietnam in the period 1976-1997 [9] [11] According to the summary' data of theNational Institute of Occupational Health and Environment - Ministry of Health in

2015 out of a total of 28.659 cases of occupational diseases detected across thecountry, silicosis was accounted for 76.29% (12]

Thai Nguven is a province in northeastern Vietnam bordering Hanoi capital.Thai Nguyen is a major socio-economic center of the Northeast and the Northern

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Midlands and Mountains region In 2008 the Department of Preventive Medicine andEnvironment, the Ministry' of Health directed the investigation of status and risk factorsfor occupational pneumoconiosis - silicosis in five key industrial cities / provinces, in

zones operating with old and outdated technological lines, including the metallurgyindustry’

Coc factory was established on September 6 1963 as an auxiliary unit in themetallurgical line of Thai Nguyen Iron and Steel Joint Stock Company The factory'smain task is producing metallurgical coke as raw material for iron production

Coc factory is a manufacturing industry that also generates a lot of silicon dust,which significantly affecting the health of employees, especially problems related tooccupational pulmonary dust respiratory disease Therefore, the health protection andprevention of occupational diseases for employees is very necessary'

Therefore, we conducted the topic "The prevalence and some associated factors ofsilicosis among employees working in one factory in Thai Nguyen province 2020"with two following specific objectives:

1 To identify- the prevalence of silicosis among employees working in Coc factory inThai Nguyen province 2020

2 To analyse some factors associated with the prevalence of silicosis amongemployees working in Coc factory In Thai Nguy en province, 2020

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Chapter 1 LITERATURE REMEW

According to clause 1, article 3 of the Labor Code 2012 defines an employee as

a person aged full 15 years or older, capable of working, working under a laborcontract, paid and subject to management, of the employer

According to Law No S4/2015 / QH13 - Law on Occupational Safety andHygiene, an employee is defined as an officer, public servant, employee, person of thepeople’s aimed forces and those who work under compliance co-labor: probationer:apprentices and apprentices to work for the employer and for t hose who do not workunder 1 abor contracts

l.u Working environment

Working environment is the space of the working area in which employees worktogether with means of serving labor Workers' health and the environment also have aclose relationship A polluted working environment will impair the workers' healthpossibly even death Worker’s health status is a general measure of workingenvironment [1]

Working environment includes physical, chemical, microbiological psychosocialand accidental factors Workers working in different occupations are exposed todifferent factors of the working environment, and thus suffer from different impacts anddisease patterns

1.13 Dust in labor

Dust in the working environment is generated from the production process Dust

is a collection of many molecules of small size and longstanding in tire air as flying

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dust, settling dust and multi-phase aerosol systems of vapor, smoke, and mist formedfrom the debris of objects substances caused by natural forces or by manufacturingprocesses Dust less than 0.1 urn suspended in the air do not stay in the alveoli Dustfrom 0.1pm to 5pm in size stays in the lungs, accounting for 80-90% Dust from 5 to 10

pm enters the lungs but is retained in the bronchi and transported by tile hairs of thebronchial cells to the throat Dust greater than 10pm collects in the nasal wall Thanks

to the respiratory system, humans can block and eliminate 90% of dust over 5um insize The harmful effects of dust to the respiratory system are highly dependent on theparticle size, chemical composition and sedimentation rate The most dangerousharmful effect of dust is causing lung fibrosis It is a hallmark of lung diseases [14]

1.1.4 Silica (lust

Free silica dust lias the chemical symbol of SÌO2 SĨO2 also known as silica,

is-a common mineris-al in the eis-arth's crust, is-accounting for 27.7% It is found is-abundis-antly innature in the form of sand or quartz, is a major component of some types of glass and isthe main substance in concrete [15]

Silica rarely exists in atomic form it is often combined with oxygen in the form ofsilicon dioxide (SĨO2) consisting of 2 bodies:

The unconjugated silicon form is called free silicon (or silicon oxide, silicondioxide, anhydric silicon, quartz, free silica) in two forms: polymorphic crystal (freecrystalline silica) or amorphous (amourphous silica) In which: 10% amorphous form,inactive, less toxic and not cause

disease The crystalline form accounting for 90% is the pathogenic form The commonorder is alpha, quartz, cristobatite and tridi mite

Structural and surface activity characteristics are related to dust toxicity'.- quartzlias a four-sided structure with high fibrosis potential, while S- sided cristobatite doesnot cause fibrosis

The hydration properties of free silicon lead to the formation of OH groups Oil

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the dust surface and this bond reacts with the phospholipids of the cell membrane,causing damage to this cell If the surface of the silica is suirounded by aluminum salts,substance p204 the toxicity of SĨO2 will be reduced Silica dust containing aluminumsalts did not cause experimental silicosis

Combination form: is silicon dioxide (SĨO2) combined with other cations such

as Mg Ca Na, K Fe to form silicates such as Feldspars (K Na Ca) Kaolin Mica

The standard allows to be applied in the determination of the concentration ofdust containing silicon (free silicon dioxide - SĨO2) and assessment of dust pollutioncontaining silicon in tile air of the working environment in Decision 3733/2002 / QD-BYT [16]

According to the Law on Safety Hygiene and Labor 2015 occupational disease

is a disease caused by harmful working conditions of the occupation affecting theemployee [19] In Vietnam by May 2016 there were 34 diseases recognized asoccupational diseases and entitled to the insurance regime, divided into 5 main groups,including:

Group I: Occupational pulmonary and bronchial diseases

Group 2: Occupational poisoning diseases

Group 3: Occupational diseases caused by physical factors

Group 4: Occupational skin diseases

Group 5: Occupational diseases caused by microorganisms

1.1.6 Silicosis

The term Silicosis was firstly used by Visconti when he found SÍO2 in cadavericlungs in 1871 [20] In 1915, Colis et al showed that quartz was the cause of silica dust.The 1930 International Conference in Johannesburg identified the cause of silicosis asSĨO2 and defined: “Silicosis is a lung condition caused by breathing in silicon bioxide(SĨO2) or free silicon Anatomically characterized by fibrosis and growth of granules ill

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the two lungs, clinically difficult to breathe, and radio graphically the lungs have adistinctive image of damage” [2]

In the opinion of the ILO expert group at the Fourth International Conference onPneumoconiosis (Bucarest 1971) pneumoconiosis is defined as: “Dust accumulation inthe lungs and the response of the organization with ingress of dust" Thus, silicosis is adifluse fibrosis occupational lung disease, which develops and does not recover inemployees who breathe in dust containing silicon every day and the silicon content inrocks is also very different, as in sandstone The content of agar, granite and shaleranges from 20 to nearly 100% Classification according to ICD-9 silicosis lias code

502 and according to ICD - 10 codes are J02.0 [2]

1.1.7 Diagnosis tlie silicosis

According to Circular 15/2016 / TT - BYT on occupational diseases and socialinsurance, guidelines for diagnosis of silicosis are as follows:

- Occupational risk factors: Workers must work in dust exposure occupations whoseconcentration, quantity and size of particles, free silicon content exceed the permissiblelimit Specifically:

• Minimum exposure: respiratory dust concentration containing free silicon isgreater than 0.1 mg / m3 for 8 hours (or according to current regulations)

• Minimum exposure time: 3 months for acute cases: 5 years for chronic cases

• Guarantee period: for acute silicosis, the maximum duration of illness aftercessation of exposure is 1 year For chronic silicosis, maximum onset of illness altercessation of exposure: 35 years

- Clinical feature: may have the following symptoms:

• Difficulty breathing with exertion, then frequent difficulty in breathing:

• Civ st pain, cough, and sputum production;

• There maybe explosive rales, moist rales (possibly acute)

- Subclinical feature:

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• Images of lesions on a straight chest x-ray (film and digital film);

+ There are small opacities round notes denoted p, q r: small uneven opacitiesdenoted s t u or ideal large blur A B c (according to the sample film of theInternational Labor Organization (ILO) 2000 or the 2011 ILO digital sample film)

• Can see emphysema, cant)' necrosis, eggshell calcification

• Respiratory dysfunction (if any): Restricted or obstructive pulmonary ventilation(when bronchitis is present), or mixed

• Lung CT scanner when needed

l.l s X-ray images of th e si licosis

• Small cloud:

- Dimension cloud:

size less than 1.5mm; small cloud q is a cloud of size from 1.5 to 3.0 nun: small haze r is acloud of sizes between 3.0 and 10.0 mm.

• Non-circular opacities: the symbols s t and u are used: small uneven opacities cloud

s is tlie opacities cloud with the largest spot size up to 1,5mm: small uneven cloud t is acloud with the widest spot size from 1.5mm to 3.0mm; small uneven cloud u is the opacitiescloud with the widest spot size from 3.0 to 10.0 nun

- The density of tile cloud: depending on the density of the cloud, the classification ofILO - 2000 is divided into 4 main groups: 0 1 2 3; Each main sub-category includes 3 sub-categories

- The large cloud of type c is the haze having dimensions greater than the area of theright lung or the total size of the opacities exceeding the area on the right lung

Oilier abnormalities that can be seen on x-rays include:

- Aortic loop atherosclerosis

- Thick pleura in the apical region

- Small cloud adhesion

- Oxidation of the pleura

- Heart failure

- Tensile organs in the chest

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- Lime of the hilum or mediastinal lymph nodes

- Lymph node lung enlargement

- Image of blurred bands and lines on the lung parenchyma

- Pictures of gas spillage, pleural effusion

- Other diseases or abnormalities [10] (21 ]

1.1.9 Respiratory junction evaluation parameters

Respiratory function measurement is a technique commonly used in the diagnosis,assessment of severity and treatment monitoring of respirator}' diseases The tecliniquehelps to record parameters related to lung function, thereby helping to evaluate ventilator}'disorders: obstruction, restriction and mixed

• Some key respirator}' indicators:

- FEV1 (Forced Expiratory Volume in One Second): Tire volume of air that can beexhaled for the first 1 second of exertion is the volume of air that can be exhaled during thefirst second of forced expiration FEV1 is an important, easy-to-measure low-volatilityindex used to determine and evaluate the degree of obstruction

- FVC (Force vital capacity): forced vital capacity is the total volume of forcedexhalation air in one breath

- VC (Vital capacity): fixing capacity VC is an important indicator of restrictivesyndrome identification

- TifTmeau FEV1 / VC is normal ằ 70%

Gaensler FEV’l / FVC index is normally t> 70%.

Diagnose the degree of limitation according to the standard of A TS / ERS based on FVC[22J:

• Low: % F VC = 60 - <80% of theoretical value

• Medium: % F VC = 40 - <60% of theoretical value

• High: % FVC = <40% of theoretical value

Diagnosis of airway obstruction according to 4 TS / ERS based on FEV1 [22]:

• Low: % FEV1 £ 70% of theoretical value

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• Average: % FEV1 = 60 - 69% of the theoretical value

• Little high: % FEV1 = 50 - 59% of theoretical value

• High: % FEV1 = 35 - 49% of theoretical value

• Very high: % FEV1 = <35% of theoretical value

Diagnosis of obstruction is based on GOLD 2014 standards (FEM value after bronchodilator test) [23].

• Stage 1 - Low: FEV1 £ so% of theoretical value

• Srage 2 - Average: 50% s FEV1 <80% of theoretical value

• Stage 3 - High: 30% ắ FEV1 <50% of theoretical value

• Stage 4 - Very high: FEV1 <30% of theoretical value

The first international conference on pneumoconiosis was held in 1930 inJohannesburg - South Africa, to discuss the pres ention of silicosis that is very commonamong mining workers The ILO-held pneumococcal disease conferences over tire pasteight decades have contributed greatly to the advancement of respiratory medicineworldwide [8]

In the US according to the 2005 Morbidity and Mortality (MMWR) weekly report,

in the period 1968 - 2002 out of 74 million death certificates, silicosis was reported to bethe primary cause of death with 16305 which

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98% of whom are male Between 1968 and 2002 the number of deaths from silicosisdecreased from 1157 to 148 or 93% respectively [24]

According to the SWORD program in the UK in the 22-year period from 1996 to

2017 there were 216 reported cases of silicosis belonging to 8 occupational groups in directcontact with silica dust in the labor environment, of which tire metal production andquarrying accounted for the highest percentages of 21% and 19%ụ respectively The medianage of those reported was 61 years (between 23-89) and 98% were male [25]

A 2011 Italian study of a workshop using mostly artificial stones reported silicosiswith a prevalence rate of 54.5% (6 out of 11 workers), where The largest dust comes fromthe cutting and polishing of football [26]

In 2014 a study in Spain by Perez-Alonso A et al Showed that the use of newbuilding materials such as quartz increases tire incidence of silicosis due to occupationalexposure Specifically 46 men were diagnosed with the disease with an average age of 33years and an average age of 11 years [27],

A 2014 study of agate grinder respiration in Iran found that: Onyx grinding workersare at risk of respiratoiy diseases, especially silicosis and chronic bronchitis The rate ofsilicosis in onyx workers was 12.9%: 43.3% of subjects had limited ventilation disorder[2S]

Another study in Australia in 2016 showed that in the 5 years from 2011-2016 therewere 7 cases of silicosis related to artificial stone - a new material present in Australia sincethe 2000s exposure to artificial rock dust until symptoms were 7.3 years All 7 people havesymptoms of cough, difficulty breathing increases gradually with exertion [29]

In 2017 Tsao Y c et al Conducted a descriptive study on the clinical characteristicsand history of silicon dust exposure of workers in several Taiwan ceramics manufacturingfacilities Tire results showed that: 78.7% of subjects with small opacities lesions haddensity of main subgroups 1 and 2 and 21.3% of subjects with small opacities lesions haddensity of main subgroups 3 and lesions, laige opacities haze on x-ray There are 52.9% ofsubjects with limited RLTK with FVC <80% 49.3% with FEV1 <80% For airwayobstruction 49.3% had predicted an FEV1 <80% 25.8% had an FEV / FVC ratio <75% and

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29.6% had predicted an MMEF <60% [30]

India is a country with a large mining industry In 1999 the Indian Medical ResearchCouncil reported that about 3.0 million workers had a high risk of exposure to silicon: Ofwhich about 1.7 million workers were in the quanying industry 0.6 million were in theproduction of non-metal products (refractory bricks, clay, glass, mica ) and 0.7 millionwere in the metal industry There was very little epidemiological research on silicosis inIndia where the incidence of silicosis varies from 3.5% in the material manufacturingfactories to 54.6% in the shale pencil industry [31]

In 2015 Prabodh Pancliadhvayee et al conducted a study on pneumoconiosis inIndian among jewelry polishing workers The results showed that silicosis in jewelrypolishing workers was found to be more severe and progressive than that of otheroccupational exposures silicosis Specifically, tire exposure time to silica dust of jewelrypolishers was significantly less than that of other workers (3.4 X 1.7 vs 9.3 X 4.1: p =0.001) the mean duration (months) of jewelry polishers was also less than other workers(14.9 X 5.8 with 28.5 ± 16.5: p = 0.04) [32]

In 2017 another study in India also showed that workers in stone crushing unitswere at risk of silicosis, with rates greater than 8% In which, the average age of diagnosiswas 42.5 (from 35-49 years old) 75% of workers with the disease have been working instone crushing units for 18-30 years X-ray images of patients with die disease showed that:small, round cloudy

In Vietnam

In 2003 research by author Nguyen Thi Bich Lien on clinical symptoms and CNHHexploration on 83 quarry workers in Binh Dinh with the age of> 5 years showed that: therate of silicosis was 9.6% with the majority (50%) having mild illness (1/0 p); 1.2% hadsilicosis combined with tuberculosis; there are 2 prominent functional symptoms: chest pain(80.7%) and difficulty breathing (75.9%) followed by sputum production, coughing andcoughing up blood [37],

According to a study by Nguyen Bach Ngoc et al in 2003 on silicosis among quarryworkers in Binh Dinh 19 workers were found and diagnosed with silicosis, accounting for3.23% and mainly in the 1/0 p form 100% of cases are at work age> 5 years [38]

According to authors Nguyen Lieu and Pham Van To (2004), among the diseasesacquired by coal mining workers in Quang Ninh, lung and bronchial diseases account forthe highest proportion at 40.8% [39]

A study was done by the authors Huynh Thanh Ha and Trinh Hong Lan (2008)found that the rate of silicosis of workers working in some construction materialsmanufacturing facilities in Binh Duong was 11.97% Of which, the rate of workers in thestone quarrying and processing workshop w as much higher than that in the brickproduction area (p <0.05) 22.13% of the employees had abnormal development results, inwhich the mixed ventilation disorders accounted for the highest percentage of 11.27% andonly 0.64% were jammed ventilatory disorders [40]

According to authors Nguyen Van Thuyen and Hoang Viet Phuong (2014) the rate

of general respirator.- disorders among workers in some factories of repairing and buildingdefense ships in the sou til was 22.ss% mainly limited ventilatory disorders accounting for15.47% mixed ventilatory disorders were 5.01% and the remaining 2.4% were jammed

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ventilator}’ disorders The rate of occupational silicosis was 21.35% of which 17.43% waspure silicosis, and silicosis combined with tuberculosis accounts for 3.92% Research hasalso shown that there was an association between occupational age and risk of disease [41]

In 2016 a study by author Trinh Van Tuan on the current situation of Silicosis insome facilities exploiting, processing stone and producing building materials in Binh Dinhprovince showed tliat; the overall prevalence rate is 44.5% of which the incidence ofsuspected infection (0/1 1/0) is 37.2% incidence rate 1/1 p / p or more is 7 3% [42]

Research on the state of silicosis of workers in some iron-smelting factories in 20IS

by Ta Till Kim Nhung and Nguyen Ngoc Anh shows that the incidence of silicosis of twoiron refining factories in Tliai Nguyen province was 11.5% and 12.3%, respectively [43].1.3 Some factors associated with the prevalence of silicosis among employees exposed tosilica dust

There have been many studies conducted showing that the age sex occupationalage history of chronic respiratory disease, smoking, exposure history, and the degree of use

of dust protection measures among employees related to respirator}' disease in general andsilicosis in particular of workers in direct contact with silica dust in the labor environment

Sillicosis in onyx grinder workers in Iran (2014) mainly occurs in workers> 40 yearsold and those with exposures> 25 years, and tile disease was also linked 10 unsecuredpersonal protective measures [28].

A study by Gizzaw z et al in Ethiopia in 2015 showed that gender, age educationlevel, work position, age smoking, history of chronic respiratory disease and trainingknowledge about occupational hygiene to prevent respirator.’ diseases are factors related tochronic respirator)’ symptoms that the workers of Dejen Cement Factory suffer Therelationship was significant for both univariate and multivariate analysis (p <0.05).specifically, men had a risk 2.07 times higher than women (95% CI; 1.18-3.63); workersaged 45 and over had a 4.02 times higher risk of contracting workers under 30 years old(95% CI: 1.94-9.12); workers with education below grade 8 have a risk of 4.07 times higherthan the group with higher education (95% CI: 1.86-8.92); workers working in the cementdepartment have a risk of 3.72 times higher than that of raw parts (95% CI: 1.92-7.21);workers with the occupational age of more than 5 years have a risk of 5.44 times higher thanthat of the group with the occupation age less than or equal to 5 years (95% CI: 3.09-9.59);smokers had a 5.38 times higher risk of contracting than a non-smoker group (95% CI: 1.42-20.39); workers with a history of chronic respirator)’ disease were 7.79 times more likely to

be infected than workers with no history of the disease: workers who were not trained inoccupational hygiene to prevent respiratory diseases were at risk of 2.73 times higher thanthat of trained workeis (95% CI: 1.41-5.29) [44]

In 2016 a study of coal workers in Australia concluded that symptoms andmanifestations of occupational pneumoconiosis varied depending on the composition of theinhaled dust, duration of exposure, stage of illness, and other factors related to the subject'sgeomorphology [29]

The 2019 study of respiratory disease incidence among iron production workers in

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India found an association with the history of family chronic respiratory disease (OR =0.47% 95% CI: 0.24-0.91) and worker education level (OR = 0.34; 95% CI: 0.12-0.94).literate people had the rate of disease lower than the illiterate [45]

1.32 In Vietnam

Research by the author Dao Xuan Vinh et al (2006) in die building materialmanufacturing facilities whose working time was exposed to the labor environment with theconcentration of silicon dust exceeding the permined standard at least 5 consecutive yearsshows that there was a correlation between the incidence of silicosis with occupationalgroups, in particular, the group of quarry workers, producing refractory bricks with silicosisaccounted for the highest rate of 6.4% followed by is the group of cement producers and thelowest was 3.8% in the group of casting, concrete drilling, mechanical [46]

According to research by author Nguyen Ngoc Son Le Hoai Cam on workerssuffering from silicosis at the Saigon Shipyard in 2012 The study indicates that the higherage the higher the proportion of workers with pulmonary disease The rate of workers withoccupational age £ 5 years lias the rate of ventilatory disorders of 13.8% increasing to23.1% in the age group 5-10 years and the highest is 37.7% in the age group 2 10 years The

A study by Nguyen Ngoc Anh and Ta Thi Kim Nhung (2018) also showed acorrelation between silicosis and age (95% CI: 1.7-11.3) and history of respiratory disease,chronic absorption of employees (95% CI: 1.6-114.3) [43],

1.4 Overview of the study sites

•Thai Nguyen is a province in northeastern Vietnam, bordering Hanoi capital ThaiNguyen is a major socio-economic center of the Northeast and the Northern Midlands andMountains region In 2008 the Department of Preventive Medicine and Environment theMinistry of Health directed the investigation of status and risk factors for occupationalpneumoconiosis - silicosis in five key industrial cities f provinces, in including ThaiNguyen Besides high-tech zones Thai Nguyen still has many industrial zones operatingwith old and outdated technological lines, including the metallurgy industry Coc factory is

a manufacturing industry’ that also generates a lot of silicon dust, which significantlyaffecting the health of employees, especially problems related to occupational pulmonarydust respiratory disease Therefore, the health protection and prevention of occupationaldiseases for employees is very necessaiv

Chapter 2 RESEARCH SUBJECTS AND METHODOLOGY 2.1 Research sites

The study was done in Coc factory Cam Gia ward Thai Nguyen province

Coc factors- was established on September 6 1963 as an auxil iary unit in die

metallurgical line of Thai Nguyen Iron and Steel Joint Stock Company The factory's main

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task is producing metallurgical coke as raw material for iron production

Currently, the company lias 341 workers

The main products of company: metallurgical coke, steel widgets, bitumen,

- Directly exposure to silica dust

- The employee fully participated in the examination items required by the study,including attending questionnaire, clinical examination Xray film and respiratory functions

- Agreed to participate in research

- Working time at the company at least one year at the study time

Exclusion criteria:

Those working in the administrative department of the company, the pregnantfemale employees

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2.3 Research times

- The study was conducted from June 2020 to May 2021

- Data were aggregated in November 2020

2.4 Research design

A cross-sectional study was applied

2.5 Sample size and sampling

• Sample size: The entile sample was selected

All employees of Coc factory were working directly in the production linesmatching with inclusion criteria as above

• Sampling

A list of all employees directly engaged in production was made All qualified employees toparticipate in the research, agreed to participate in the study and fully examined the researchitems were recruited In total, we selected 336 workers among 341 employees of the

Metallurgical coke making process: Steel making process:

Figure 2.2: Metallurigical coke and steel making process

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company at the study time

2.6 Variables and indicators

Demographic characteristics: age gender, specialized work

Table 2.1 List of variables and indicators among employees ofCoc factory

in 2020

Variables,

Technique for data collection General information

Age

Number of years from birth to 2020(according to solar calendar), including 5age groups: under 20 from 20-29 from 30-

39 from 40-49 and over 50 years old

Face-to face interview by Questionaire

Specialized

work

Including: construction materials; mining and processing ores: exploiting,

manipulating stone, metallurgy; production

of ceramics, porcelain and glass; exploitinggranite stone; other

Questionaire

Occupational age

Years of working at the factory (from the beginning to 2020) including 4 groups: <5 years 5-9 years 10-19 years and £ 20 years

Questionaữe

Educational level

The highest level of education of the employees, including all levels of education: Primary Secondary High School Junior Intermediate College University

Questionaire

Rate of employees

who smoke pipe

tobacco, tobacco

Number of employees who smoke pipe

employees participating in the study

Quesionaire

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Objective 1: Describe the prevalence of silicosis among employees working in

Coc factory in Thai Nguyen 2020

employees diagnosed with the disease

participating in the study

Questionaireand 2011 ILOradiographresults

FVC

employees with reducedFVC according to eachlevel total number ofemployees participating

in the research

- Gaenslerindicator

- Percentage ofemployees withdisabilities

- Rate ofdisabilities

Measuringrespữatoryfunction

employees with reducedFEV1 according to eachlevel total number ofemployees participating

RadiographILO2011

Damage level of lung

injury according to

(should specify here)

Rate of types injury lungs according to ILO2011

RadiographILO2011

Objective 2: Analyse some factors associated with the prevalence of silicosis

among workers working in Coc factor)' in Thai Nguyen 2020

of silicosis with

the age of

employees

The relevance between the current situation

of silicosis and the age of employees

Odds ratioORThe prevalence

silicosis with the

Odds ratioOR

The prevalence of

silicosis with the

employee's history of

respiratory disease

The relevance between the current situation

of silicosis and die employee's history ofrespiratory disease

Odds ratioOR

Odds ratioOR

2.7 Too! and technique for data collection

* Data collection process:

- Stage 1: Preparation

contact the factory leaders to get approval for conducting research

• Observed and leamt about the production process and the factory’s labor environment

characteristics - research sites, select eligible subjects and agree to participate in research

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• Developed research records and necessary' forms for recording respiratory function

measurements and X-rays based on the variables developed

- Stage 2: Information gathering

• Sign up for a visit

• Face-to face interview with workers

• Clinical examination according to research records

• Measuring respirator)' function

• X-ray of the lungs according to ILO standards

• Submit a checklist of completion of the examination to the check-in desk

• Spiro Analyzer pulmonary function measurement technique:

- Press the "ID" button, load the subject's parameters using the numeric keys: age(year), height (cm), weight (kg), sex (1 - male 2 - female), race (race 4) After eachparameter is loaded, press "Enter" Before measuring, check the exact parameters of theobject loaded into the machine, if wrong, proceed to recharge

- Instruct the object manipulation to perform:

• Press the "FVC" key.

• When the subject is ready, pinch the nose, put the tube into the mouth through the

teeth round the lips and close the tube, breathe normally for a few times through the tubethrough the mouth, do not block the tube, not let the air escape

• Press the "Start" button.

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• When the device receives the receiving signal, ask the subject to inhale slowly, as

quickly as much as possible, then exhale 1 breath very quickly, strongly, and last until the end or when the examiner stops talking, trying to last for about 6s

• Press the “display” key to view the result (including number plate and graph).

• Press the “Print" key to print the results.

Note: Do not get figures for non-cooperative subjects.

Three acceptable waste items must comply with the ATS (American Thoracic Society) standards

• Must have a good starting point

• F VC measurement time lasts 6 seconds

• Ensure constant exertion and speed for each measurement

• Tlte difference between FVC and FEVl’s 2 best exertion attempts should not exceed

5%

• Perform no more than 6 times in a row

• Occupational lung disease X-ray procedure:

- Step 1: Instructed the employee to stand close to his chest against the shield, stand up straight, with his eyes straight ahead, with his hands on the sides The two patient elbows must be brought forward as much as possible

- Step 2: Adjusted the distance between the x-ray ball and the position of the person being photographed to be 1.5m

- Step 3: The central ray shined directly on the 5th vertebrae for men and on the 6th vertebra for women

- Step 4: set the shooting constant: the shutter speed must be less titan 0.1 second, the best use voltage is from 60-70kV depending on the thin or fat person and the amperage ranges from 200-300mA good the most is 300mA

- Step 5: guided the workers to breathe in as much as possible and hold the breathcompletely

- Step 6: press the button

2.8 Potential Errors and Solutions

- Error recall: should specify which information or variables

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Solution: using words that are easy to understand, clear, and suitable to the target.

Cross-check the information by repeating the question during data collection

- Error collection

Solution: comply with the regulations of the Ministry of Health prescribed by

professional doctors and technicians Standardized techniques for measuring height, weightand recording

- Error entered

Solution: read the forms collected, clean before inputting Check the data after each

entry to ensure that the correct and adequate information is collected Train data entry users,analyze data thoroughly, and closely monitor the data entry and analysis process

2.9 Data entry and analysis

- Data were cleaned, encrypted and then was entered using SPSS 20.0 software

- Data were then analyzed using Stata 15 software

- Descriptive statistics were used to present frequency, percentage for quantitativevariables (e.g gender, age group) or mean SD for qualitative variables (e.g occupationalage) Using univariate and multivariate logistic regression model to analyze related factors

- The results are presented in tabular form, the figure showing the frequency,percentage by group of variables as well as mean ± SD or median

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and quartile interval When considering the association between the morbidity status(silicosis: Yes/No) and several factors such as: gender, age group, workplace, smoking /pipe tobacco history, history of chronic respiratory diseases and frequency of using masks ofemployees, using both univariate and multivariate logistic regression models to calculate theodds ratio OR the p value <0.05 is considered a statistically significant relationship

2.10 Research ethical consideration

This study is a part of the State-level project titled "Research on molecularepidemiological characteristics, risk factors and application of advanced technology in earlydiagnosis of silicosis in Vietnam", code: KC10 / 1620 by Prof Le Thi Huong conductedfrom 2018 to 2020 (attached to the Ethical Council's approval, code 421&TÍMƯIRB datedNovember 16 2018) Tlie author was allowed to participate in the process of collectingdata, processing, analyzing data and using this data to write a university graduation thesis

The research was conducted with the permission of the head of the research facility,the consent and voluntary participation of the subject Research issues do not affect thehealth or other problems of the subjects Information collected from the subjects is forresearch purposes only Research results will be fed back to research facility and researdisubjects

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Chapter 3 FINDINGS AND RESULTS

3.1 Demographic characteristics of study participants

Table 3.1 General characteristics of research subjects

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According to table 3.1 among 336 subjects, there were 202 males (60.1%) and

134 females (39.9%) Mean of age was 40 27 The percentage of people aged 40-49 wasthe highest, while the opposite was true for the group aged 20-29 (27.40%) There is noemployee under 20 years old The percentage of employees with elementary educationaccounted for the highest rate at 37.8% and the lowest one was primary level with 0.3%.The majority of employees are in Metallurgical (59.8%) The average occupational age ofthe employee was 15.22 years Most of the employees worked for 5-9 years (42.9%).while the figure of employees worked for under 5 years had the lowest percentage (3.3%).There were 40.5% of employees who smoke cigarettes pipe tobacco (including allemployees who used to smoke but now quit and currently smoking) 11 6% of employeeshad die history of chronic respirator.- disease

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3.2 The pievalence of silicosis among employees working in Coe factors in Thai Nguyen, 2020

Table 3.2 Percentage of employees diagnosed ait II silicosis and received

occupational disease book previously

According to table 3.2 There were 5 employees previously diagnosed withsilicosis accounted for 1.5% Among them 4 were granted occupational disease books

Table 3.3 The prevalence of silicosis among employees

Diagnosed with silicosis