Dietary intake and physical activity of elementary school children in ha nam and dien bien provinces in 2020

HANOI MEDICAL UNIVERSITYPHAM DUY THANI1 THE PREVALENCE AND SOME ASSOCIATED FACTORS OF SILICOSIS AMONG EMPLOYEES WORKING IN ON E FACTORY IN THAI NGUYEN PROVINCE,2020 Specialization: Preve

HANOI MEDICAL UNIVERSITY

PHAM DUY THANI1

THE PREVALENCE AND SOME ASSOCIATED FACTORS OF SILICOSIS AMONG EMPLOYEES WORKING IN ON E FACTORY

IN THAI NGUYEN PROVINCE,2020

Specialization: Preventive Medicine

Code: 52720103Course 2015 2021

THESIS OF GRADUATION MEDICAL DOCTOR

Mentor:

Ass Prof Le Illi Tlianb Xu an

Hanoi- Year2021

Department of Occupational Health School of Preventive Medicine and Public Health Hanoi Medical University for her exemplary guidance, monitoring and constant encouragement throughout the course of this thesis I

am also indebted to members of Department of Occupational Health allowing

me to use a parr of data as my thesis I also wish to take this opportunity to express a deep sense of gratitude to the Board of Directors Training Department of School of Preventive Medicine and Public Health for their cordial support, valuable information and guidance which helped me in completing litis task through curious stages I would like to express my deepest thanks to the Maraging Board Department of Training, Hanoi Medical University who had created a favorable and wonderful environment

in the sclfcjol for the past 6 years 1 wish to thank all the teachers in the Department of Occupational Health School of Preventive Medicine and Public Health Hanoi Medical University for their valuable information provided by them in their respective fields I am grateful for their cooperation during the period of my assignment Lastly I would like to express my deepest thanks to my loving family relatives and friends for their constant encouragement without them this thesis would not be possible

Hanoi, May 2021 Student Pham Duy Thanh•

- Management Board of Hanot Medical University

- Department of Undergraduate Trailing Management and Department

of Student Affairs Hanoi Medical University

- Institute for Preventive Medicine and Public Health Hanoi Medical University

- Department of Occupational Health Hanoi Medical University

- Examination Committee for Graduation Thesis 2020-2021

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 my participation The data handbag and analysis were objectively completed with honesty The results of this study have not been published in any document

Hanot May 2021StudentPham Duy Thanh

WHO Worid Health Organization

ABSTRACT

INTRODUCTION

CHAPTER 1: LITERATURE REMEW

1.1 Concepts associated with rhe employees working environment and

I I 9 Respiratory flinction evaluation parameters

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1.1.1 I he employees -

ttatttataatatat«tat»aa(aaaaaaaaaaaaaaaaaeaaaaaaa»< loiiiaaaaMiaMiaiaaateaaaaaaaiaaaaaaaitaaaiiaato 1.12 Working environment aaeta •• a ttoitMitaatait • •••«•••••••••••>• a*ae a• a3 113 Dust in labor 4

1 1.4 Silica dust

115 Occupational diseases 4

1.1 j6 Silicosis 6

1.1.7 Diagnosis the silicosis 6

1.1.8 x-ray images of the silicosis 7

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

1.3 Some factors associated with the prevalence of silicosis among

1.4 Oveniew of the srndv sites

18

1

3

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 27

2.9 Data entry and analysis 27

2.10 Research ethical consideration 28

CH APTER 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 ỉ ha ỉ ^^gu\*en Ờ 0 .a 31 3.3 Some factors associated with tlie prevalence of silicosis working in Coc factory in Thai Nguyen 2020 — 36

CH APTER 4; DISCX'SION——~ 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 • •• •••»•»» *• w • »• • ••• •• »wwwwww»nwmimwn51 REFERENCES

APPENDIX 1

APPENDIX 2

APPENDIX 3

APPENDIX 4

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 The prevalence of silicosis among employers 31

Table 3.4 Peicentage of employees with decreased respirator}.’ function 32

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

Table 3.6 Rate of respiratory dysfunction in employees — 33

Table 3.7 Level of damage on chest X-ray of employees according to ILO classification

Table 3.8 The rate of enỊÌoyees using masks with tire prevalence of silicosis 34

Table 3.9 The association between tire prevalence of silicosis and the employees’s gender 36

Table 3.10 The association between the prevalence of silicosis and the age group of employees - _ 36 Table 3.11 The association between the prevalence of silicosis and the occupational age of tire employees - 37

Table 3.12 The association between prevalence and the employees's smoking history 37

Table 3.13 The association between prevalence of silicosis and the employees’s history of respiratory disease 38

Table 3.14 The association between pievalence of silicosis and accessing information of silicosis among employees _ 38

anx> ng 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

Figure 2.2: Metallurigical coke and steel making process - 19

F igure 3.1 Rate of using various types of masks among employees - 35 Figure 32 Ftequencv using masks among employees — 35

progressive and iiTeveisibte in workers who inhale free silica dust Coc factory is a manufacturing industry that also generates a lot of silicon dust, which significantly affecting the health of employees, especially problems related to occujMtional pulmonary dust respiratory disease Therefore, the health protection and prevention of occupational diseases for employees is very necessary.

We conduct the tope ’ The prevalence and some associated factors of silicosis among employees working in one factory in Thai Nguyen province 2020* with two following specific objectives; identify ing the prevalence of silicosis among employees and analysing some factors associated with the prevalence of silicosis among employees working in Coc factory in Thai Nguyen province 2020

A cross-sectional study was applied All employees of Coc factory were working directly in the production lines matching with inclusion criteria

as above All qualified employees to participate ill tile research, agreed to participate in the study and fully examined the research items were recruited

In totaL we selected 336 workers among 341 employees of the company at the study’ time

.After analysing, tile prevalence of silicosis in workers at Coc Factory in Thai Nguyen in 2020 was 10.1% Gender was the statistically significant factor related IO silicosis of workers The prevalence of silicosis in male workers was 4.32 times higher tlian tliat of female workers (95% Cl was 1.60 - 11.6) When analyzing multivariate regression, the rate of silicosis in male workers was 3.14 times higher than that of female workers (95% CI was 1.05-1.24), the comparison was statistically significant with p <0.05 No statistically significant association between other factors and silicosis was found

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

In developed countries, due to good labor protection, silicosis tends to decrease gradually In deseloping countries, according TO the consulting conference of silicon pneumoconiosis Geneve 1989: due to ineffective measures to prevent dust, high concentrations of respiratory dust, workers often have to work hard, making them be dangerous As a result, the risk of silicosis increases among those workers [8] According to tlw Work! Health Organization (WHO), the prevalence of silicosis in developing countries among workers exposed to silica dust was about 20-50% Incidence rates also varied between countries and occupations [9] In Vietnam, as of 201<5 there

w ere 34 occupational diseases entitled to social insurance, of which silicosis was recognized for compensation since 1976 and is rhe most common occupational lung disease [1Ớ] The disease accounted for 885Ó of all occupational diseases assessed in Vietnam in the period 1976-1997 (9) [11], According to the summary data of the National Institute of Occupational Health and Environment - Ministry of Health in 2ƠI5 out of a total of 28.659

cases of occupational diseases detected across the country silicosis was accounted for 7629% (12).

Thai Nguyen is a province in northeastern Vietnam bordering Hanoi capital Thai Nguyen is a major socio-economic center of the Northeast and the Northern Midlands and Mountains region In 2008 the Department of Preventive Medicine and Environment, the Ministry of Health directed the investigation of status and n$k factors for occupational pneunxjconiosis ’ silicosis in five key industrial cities 1 provinces in including Thai Nguyen Besides high-tech zones Thai Nguyen still has mam industrial zones operating with old and outdated technological lines, including the metallurgy industry

Coc factory was established on September 6 1963 as an auxiliary unit

in the metallurgical line of Thai Nguyen Iron and Steel Joint Stock Company Tire factory's main task is producing metallurgical coke as taw material for iron production

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

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

1 To identify the piw aleuce of silicosis among employees working in Coc factory in Thai Nguyen province 2020

2 To analyse some factors associated with the prevalence of silicosis among employees working in Coc factory in Thai Nguyen province 2020

Chapter 1LITERATVRE REMEW

I 1 Concepts associated with the employees, working environment andsilicosis

J ] J Thf tmpỉợyen

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 13bor contract paid and subject to management, of the employer

According to Law No 84/2015 / QH13 - Law on Occupational Safety and Hygiene, an employee IS defined as an officer, public servant employee, person of the J>eople’s aimed forces and those who work under compliance co-labor: probationer: apprentices and apprentices to work for the employer and for those who do not work under labor contracts

J.u Working eniironmenl

Working environment is the space of tile working area in which employees work together with means of serving labor Workers' health and the environment also have a close relationship A polluted working environment will impair the workers' health, possibly even death Worker’s health status is a general measure of working environment [1Ị

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

J ỉ3 Dust bi tabor

Dust ill the working environment is generated from the production process Dust is a collection of many molecules of small size and long­standing in the air as flying dust, settling dust and multi-phase aerosol systems of vapor, smoke and mist formed from the debris of objects substances caused by natural forces or by manufacturing processes Dust less than 0.1 Jim suspended in the air do not stay in the alveoli Dust from 0.1 Jim

to 5Jim in size stays in the lungs accounting for 80-90% Dust from 5 to 10

pm enters the lungs but is retamed in ’die bronclu and transported by the hails

of the bronchial ceils to the throat Dust greater than lOum collects in the nasal wall Thanks to the respiratory system, humans can block and eliminate 90% of dust over 5 pm in size The harmfill effects of dust to the respiratory system are highly dependent on the particle size, chemical composition and sedimentation rate The most dangerous harmful effect of dust is causing lung fibrosis It is a hallmark of lung diseases (14 ]

Ị.13 Silica riwt

Free silica dust has the chemical symbol of SĨO2 S1O2 also known as silica, is a common mineral in the earth's crust, accounting for 27.7% It is found abundantly in nature in tile form of sand or quartz, is a major component of some types of glass and is the main substance in concrete [15].Silica rarely exists in atomic form, it is often combined with oxygen in the form of silicon dioxide ($102) consisting of 2 bodies:

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

disease The crystalline form accounting for 90% is the pathogenic form The common 01 det is alpha, quartz cristobalite, and tridi ante.

Structural and surface activity characteristics are related to dust toxicity: quartz has a four-sided structure with high fibrosis potential, while 3- sided cristóbatite does not cause fibrosis

The hydration properties of tree silicon lead to the formation of OH groups oil the dust surface and this bond reacts with the phospholipids of the cell membrane causing damage to this cell If lire surface of die silica is surrounded by aluminum salts, substance p204 the toxicity of SÍO2 will be reduced Silica dust containing aluminum salts did not cause experimental silicosis

Combination form: is silicon dioxide (SÌO2) 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 of dust containing Silicon (free silicon dioxrde - SÍO2) and assessment of dust pollution containing silicon in the air of the working environment in Decision 3735 2002 J QD-BYT [16]

Ỉ.U Occupational diseases

According to the Law on Safety Hygiene and Labor 2015 occupational disease is a disease caused by harmful working conditions of the occupation affecting the employee [19] In Vietnam, by May 2016 there were

34 diseases recognized as occupational diseases and entitled to the insurance regime, divided into 5 main groups, including:

Group 1: 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 Ji Silicosis

The term Silicosis was firstly used by Visconti when he found SÍO2 in cadaveric lungs 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 as SÌO2 and defined: "Silicosis is a lung conditjon caused by breathing in silicon bioxide (SiO2) or free silicon Anatomically characterized by fibrosis and growth of granules in the two lungs, clinically difficult to breathe, and radio graphically tbe lungs have a distinctive image of damage" [2]

In the opinion of the ILO expert group at the Fourth International Conference on Pneumoconiosis (Bucarest 1971) pneumoconiosis is defined as: "Dust accumulation in the lungs and the response of the organization with ingress of dust" Thus, silicosis is a diffuse fibrosis occupational lung disease, which develops and does not recover in employees who breathe in dust containing silicon every day and the silicon coiuent in rocks is also very different, as in sandstone The content of agar, granite and shale ranges from

20 TO nearly 100% Classification according to ICD-9 silicosis has code 502 and according toICD- 10 codes are J62.0 [2],

Ỉ.Ỉ.7 Diagnosis Uie silicosis

According to Circular IS'2016 I TT • BYT on occupational diseases

and social insurance, guidelines for diagnosis of silicosis are as follows:

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

• Minimum exposure: respiratory dust concentration containing free silicon is greater than 0.1 mg / mỉ for 8 hours (or according to cutrent regulations).

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

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

- Clinical feature: may have the following symptoms:

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

• Chest pain, cough and sputum production;

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

- Subelinical feature:

• 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 opacities denoted $, t u or ideal large blur A B c (according to the sample film of the International Labor Organization (ILO) 2000 or the 2011 ILO digital sample film)

+ Can see emphysema, cavity necrosis, eggshell calcification

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

• Lung CT scanner when needed

J J J X-ray bnaRrt oftftf siikứỉỊt

• Small cloud:

- Dimension cloud:

• Regular round opacities: the symbols of p q r are used: small cloud p is

a cloud with size less than 15mm; small cloud q is a cloud of size from 1.5 to 3.0 mm; small haze r is a cloud of sizes between 3.0 and 10.0 mm

• Son-circular opacities: the symbols s t and u are used; small uneven opacities cloud s is the opacities cloud with the largest spot size up to 1.5mm: small uneven cloud t is a cloud with the widest spot size from 1.5mm to 3.0mm; small uneven cloud u is the opacities cloud with the widest spot size from 3.0 to 10.0 nun

- I'he density of the cloud: depending on the density of the cloud, the classification of ILO - 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 the right lung or the total size of the opacities exceeding the area

on the right lung

Other 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

- Lime of the hilum or mediastinal lymph nodes.

- Lymph node lung enlargement

- Image of blur red bands and lines on the lung parenchyma

- Pictures of gas spillage, pleural effusion

- Other diseases or abnormalities [10] [21]

J.J.9 Respiratory function evaluation parameters

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

• Some key respiratory indicators:

- FEV1 (Forced Expiratory Volume in One Second): The volume of air tliat can be exhaled for tlie first 1 second of exertion is the volume of air that can be exhaled during the first second of forced expiration FEV1 is an important, easy-to-mea sure low-volatility index used to determine and evaluate the degree of obstruction

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

- VC (Vital capacity): living capacity VC is an important indicator of restrictive syndrome identification

- Tiffi neau FEV1 / VC i s normal è 70%

Carlisle: FEV1 / FVC index is normally 2 70%

Diagnose the degree of limitation according to the standard of ATS 7 ERS based on Fl c Ị22Ị:

• Low: % FVC = 60 • <80% of theoretical value

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

• High: % F VC - <40% of Theorem cal value

Diagnosis of ainvay obstruction according to ATS / ERS based on EEll Ị22Ị:

• Low: % FEV1 £ 70% of tlrecreti cal value

• Average: 0 0 FEM = 60 - 69° « of the theoretical value

• Little high: % FEM ■ 50 - 59% of theoretical valve

• High: % FEV1 - 35 - 499« of theoretical value

• Very high: % FEVI ■ <35® 0 of theoretical value

Diagnosis of obstruction is based on GOLD 2014 standards (FEU value after bronchodilator test) Ị23Ị.

• Stage 1 - Low: FEVI 2 80?% of theoretical value

■ Stage 2 • Average: 50% £ FEVI <80% of theoretical value

• Stage 3 - High: 30% £ FEM <50% of theoretical value

• Stage 4 - Verv high: FEVl <30% of theoretical valve

1.2 1 he prevalence in silicosis among employees exposed to silica dust

1.2J Global

The first international conference on pneumoconiosis was held in 1930

in Johannesburg - South Africa, to discuss the pres ention of silicosis that is very common among mining workers The ILOheld pneumococcal disease conferences over tire past eight decades have contributed greatly to the advancement of respiratory medicine worldwide [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 be the primary cause of death with 16305 which

98” 0 of whom are male Between 1968 and 2002 rhe number of deaths from silicosis decreased from 1157 to MS or 93% respectively [24].

According to the SWORD program in the L'K in the 22-year period from 1996 to 2017 there were 216 reported cases of silicosis belonging to 8 occupational groups in direct contact with silica dust in the labor environment, of which the metal production and quanying accounted for the highest percentages of 21% and 19% respectively The median age of those reported was 61 years (between 23-89), and 989« were male [25]

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

In 2014 a study in Spain by Perez-Alonso A et al Showed that the use

of new building materials such as quartz increases the incidence of silicosis due to occupational exposure Specifically, 46 men were diagnosed with the disease with an average age of 33 years and an average age of 11 years [27]

A 2014 study of agate grinder respiration in Iran found tliat: Onyx grinding workers are ar risk of resparatoiy diseases, especially silicosis and chronic bronchitis The rate of silicosis in onyx workers was 12.9%: 43.3% of subjects had limited ventilation disorder [28]

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

In 201Tsao V c et al Conducted a descriptive study on the clinical characteristics and history of silicon dust exposure of workers in several Taiwan ceramics manufacturing facilities The results showed that: 78.7% of

suBjeets with small opacities lesions had density of main subgroups 1 and 2 and 21.3*0 of subjects with small opacities lesions had density of main subgroups 3 and lesions, large opacities haze on x-ray There are 32.9% of subjects with limited RLTK with FVC <80% 49.3% with FEV1 <80% For airway obstruction 49.3% had peedicted an FEV1 <80%.25.8% had an FEV /

F VC ratio <75% and 29.6% had predicted an MMEF <60% (30)

India is a country with a large mining industry In 1999 tire Indian Medical Research Council repotted that about 3.0 million workers had a high risk of exposure to silicon; Of which about 1.7 million workers were ill the quarrying industry 0.6 million were in the production of non-metal products (refractory bricks, clay, glass, mica ) and 0.7 million were in the metal industry There was very little epidemiological research on silicosis in India where the incidence of silicosis varies from 3.5% in the material manufacturing factories to 54.6% in the shale pencil industry (31)

In 2015 Prabodh Panchadhyayee et al conducted a study on pneumoconiosis in Indian among jewelry polishing workers The results showed that silicosis in jewelry polishing workers was found to be more severe and progressive than that of other occupational exposures silicosis Specifically, die exposure rime to silica dust of jewelry polishers was significantly less than that of other workers (3.4 ± 1.7 vs 93 X 4.1; p = 0.001) the mean duration (months) of jewelry polishers was also less than other workers (14.9 ± 5.8 with 28.5 ± 16.5; p - 0.04) (32)

In 2017 another study in India also showed that workers in stone crushing units were at risk of silicosis, with rales greater tlian 8% In which, the average age of diagnosis was 42.5 (from 35-49 years old) 75% of workers with the disease have been working in stone crushing units for 18-30 years X-ray images of patients with the disease showed that; small, round cloudy

image accounted for 87.5%: Eggshell calcification occurs in 50% of cases and pleural thickening was 62% [33].

In 2003 Xiao GB et aTs stud}' on dr}- sludge exposure at Tatami carpet production in China showed that: the average free silicon content in the settling dust in the workplace was 25.6% There are 2.57% of subjects with a cloud density of I/O or more on x-ray [34]

1.2J In I letnam

In 2003, research by author Nguyen Tlu Rich Lien on clinical symptoms and CNHH exploration on 83 quarry workers in Bmh Dinh with the age op> 5 years showed that: foe rate of silicosis was 9.6% with the majority (50%) having mild illness (1 '0 p); 1.2% had silicosis combined with tuberculosis; there are 2 prominent fiinctional symptoms: chest pain (80.7%) and difficulty breathing (75.9%) followed by sputum production, coughing and coughing up blood [37],

According to a study by Nguyen Bach Ngoc et al in 2003 on Silicosis among quarry workers in Binh Dinh 19 workers were found and diagnosed with silicosis, accounting for 3.23% and mainly in the I/O p form 100% of cases are at work age> 5 years [38]

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

A study was done by tb? authors Huynh Thanh Ha and Trinh Hong Lan (2008) found that the rate of silicosis of workers working in some construction materials manufacturing facilities in Binh Duong was 11.97%

Of which, the rate of workers in die stone quarrying and processing workshop was much higher Ilian that in the brick production area ip <0.05) 22.13% of the employees had abnormal development results, in which the mixed

ventilation disorders accounted for rhe highest percentage of 11.27% and only 0.64*0 were jammed ventilatory disoidets [40].

According to authors Nguyen Van Thuyen and Hoang Viet Phuong (2014) the rate of general respiratory disorders among workers in some factories of repairing arid building defense ships in the south was 22.88^0 mainly limited ventilatory disorders accounting for 15.47% mixed ventilatory disorders were 5.01%, and rhe remaining 2.4% were jammed ventilatory disorders The rate of occupational silicosis was 21.35% of which 17.43% was pure silicosis, and silicosis combined with tuberculosis accounts for 3.92% Research has also 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 in some facilities exploiting, processing stone and producing braiding materials in Binh Dinh province showed that: the overall prevalence rate is 44.5% of which the incidence of suspected infection (0/1 1/0) is 37.2%, incidence rate 1/1 p/por nxneis 7,3% [42],

Research on the state of silicosis of workers in some iron-smelting factories in 2018 by Ta Thi Kim Nhung and Nguyen Ngoe /\nh shows that the incidence of silicosis of two iron refining factories in Tliai Nguyen province was 11.5% and 123% respectively [43J

1.3 Some factors associated with the prevalence of silicosis among employ co exposed to silica dust

There liave been many studies conducted showing that the arạ? sex occupational age Instory of chronic respiratory disease, smoking exposure history, and the degree of use of dust protection measures among employees related to respiratory' disease in general and silicosis in particular of workers

in direct contact with silica dust hl the labor environment

Ỉ.3J CiiabaJ

Akgun eĩ al (2008) showed dial the risk and severity of silicosis correlated with seniority (r = 0.48; p <0.001) exposure time (r = 0.25; p

<0.011 and number of working places (r = 0.32; p <0.01) [36]

Sillicosis in onyx grinder workers in Iran (2014) mainly occurs in workers* 40 years old and those with exposures* 25 years, and the disease was also linked IO unsecured personal protective measures [28]

A study by Oizzaw z et al in Ethiopia in 2015 showed that gender, age education level, work position, age smoking, history of chronic respiratory- disease and training knowledge about occupational hygiene to prevent respiratory diseases are factors related to chronic respiratory symptoms that the workers of Dejen Cement Factory suffer The relationship 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); workers aged 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 higher than the group with higher education (95% CI: 1.86-8.92); workers working in the cement department have a risk of 3.72 times higher Ilian that of raw pans (95 tà CI: 1.92-7.21); workers with the occupational age

of more than 5 years ha\e a risk of 5.44 times higher than that 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 higbet risk of contracting than a non-smoker grwp (95% CI: 1.42-20.39); workers with a history of chronic respiratory disease were 7.'9 times more likely to be infected than workers with no history of the disease, workers who were not named in occupational hygiene to prevent respiratory diseases were at risk of 2.73 times higher than that of trained workers (95% CI; 1.41-5.29) [44]

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

The 2019 study of respiratory’ disease incidence among iron production workers in India found an association with the history of family chronic respiratory disease (OR w 0.47% 95% CI: 0.24-0.91) and worker education level (OR 0.34; 95’0 CI: 0.12-0.94) literate people had the I ate of disease towel than the illiterate [45 J

/.J-2 In I frtna/n

Research by the author Dao Xuan Vinh et al (2006) in the building material manufacturing facilities whose working time was exposed to the labor environment with the concentration of silicon dust exceeding the permitted standaid at least 5 consecutive yea IS shows that there was a correlation between the incidence of silicosis with occupational groups, in particular, the group of quarry workers, producing refractory bricks with silicosis accounted for the highest rate of 6.4% followed by’ is the group of cement producers and the lowest was 3.8% in the group of casting, concrete drilling, mechanical [46],

According to research by author Nguyen Ngoc Son Le Hoai Cam on workers suffering from silicosis at the Saigon Shipyard ill 2012 The study indicates that the higher age, tire higlier the proportion of workers with pulmonary’ disease The rate of workers with occupational age i 5 years has

tine rate of ventilatory disorders of 13.8% increasing to 23.1’0 in the age grcxip 5-10 years and the highest is 37.7% in the age group 2 10 years The

higher The occupational age plus The dust pollution level, the greater the prevalence of silicosis [47].

Authors Nguven Van Thuyen and Hoang Viet Phuong (2014) researching on workers with silicosis at some shipbuilding and repair factories in the south showed that the higher tile occupational age The higher the rate of silicosis Specifically, the occupational age group £ 10 years has

11k lowest rate of disease (10.86%) increases to 22.06% in the age group 11-

20 years and tile highest is 35% in the age group* 20 years [41I

A study by Nguyen Ngoc Anh and Ta Thỉ Kim Nhung (2018) also showed a correlation bet wen 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 Mud) sites

Thai Nguyen is a province in northeastern Vietnam, bordering Hanoi capital Thai Nguyen is a major socio-economic center of the Northeast and the Northern Midlands and Mountains region In 2008 the Department of Preventive Medicine and Environment, the Ministry of Health directed tile investigation of status and risk factors for occupational pneumoconiosis - silicosis in five key industrial cities / provinces, in including Thai Nguyen Besides high-tech zones Thai Nguyen still has many industrial zones operating with old and outdated technological lines, including the metallurgy industry Coc factory is a manufacturing industry that also generates a lot of silicon dust, which significantly affecting the health of employees, especially problems related to occupational pulmonaiy dust respiratory disease Therefore, the health protection and prevention of occupational diseases for employees is very’ necessary

Coe factory was established on September 6 1963 as an auxiliary unit

in the metallurgical line of Thai Nguyen Iron and Steel Joint Slock Company Tlte factory's main task is jxoducmg metallurgical coke as law material for iron production

Currently, the company has 341 workers

The main products of company: metallurgical coke, steel widgets biTumen, naphthalene, phenol

HẢM OÓ HẢMI < MIMI IỈMI ill Al MỈVYÊ*

Figure 2.1; study location

2.2 Research subjects

Employees were working in Coc factory

Inclusion criteria:

- 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 leseaich

• 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 pregnant female employees

Metallurgical coke makingprocers:

Figure 2.2: MetaUurigical coke and steel making process

Dust, noise, sHtca dust

ultra tfuxt, toxic gas,

metal vapor, high

re trip er autre

Steel makingprocess:

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 entire sample was selected

All employees of Coe factory were wotting directly in die production lines matching with inclusion alteria as above

• Sampling

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

w orkers among 341 employees of the company at the study time

2.6 Variables and indicators

Demographic characteristics: age gender, specialized work

fable 2.1 List of variables and indicators among employees of Coe factory

General information

Age

Number of years horn birth to 2020 (according to solar calendar) including 5 age groups under 20 from 20-29 from 30-39 from 40-49 and over 50 yean old

Face-to face interview bv•Questionaire

indicators Definition, Variable Type

Technique for data collection

Questionable

Occupational age

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

Questionair e

Educational level

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

Number of employees with thr history

of chronic respiratory disease totalnumber of employees participating in the study

Quesionairc

indicator*

Definition, Variable Type Technique for

data collection

Objective 1: Describe the pm lienee of silicosis among employees

norking in Coe factory in Thai Nguyen 2020

Questionaire and 2011 ILO radiograph results

FVC

The proportion ofemployees with reduced FVC according to each level total number of employees participating

in the research

- Gaensler indicator

• Percentage of employees with disabilities

- Rate ofdisabilities

Measuring respiratory function

indicators Definition, Variable Type

Technique for data collection

employees Tilth reduced FEV1 according to each level total number of employees participating

Radio graphILO 2011

Rate of types injury lungs according to 1LO 2011

RadiographILO 2011

Objective 2: Analyse some factors associated with the prevalence of silicosis among workers working in Coc factors- In Thai Nguyen 2020

The prevalence of The relevance between the situation of Odds ratio

Odds ratioOR

Odds ratioOR

Odds ratioOR

2.7 Tool and technique for data collection

• Data collection process:

• Stage 1: Preparation

• Coordinated with the Provincial Preventive Medicine Center in Thai Nguyen to contact the factory leaders to get approval for conducting research

• obsenvd and learnt about the production process and the factory's labor environment characteristics - teseaich sites, select eligible subjects and agree

to participate in research

• Developed research records and necessary' forms for recording respiratory function measurements and x-rays based on the variables developed-

- Stage 2: Infortnation gathering

• Sign up for a visit

• Face-to face interview with workers

• Clinical examination according to research records

• Measuring respiratory' function

• X-ray of the lungs according to Ito standards

• Sdrtnit a checklist of completion of the examination IO the check-in desk

• Spiro Analyzer pulmonary function measurement technique:

• Press tlx* "ID” button, load the subject's parameters using tile numeric keys: age (year) height (cm), weight (kg), sex (I - male 2 • female), race (race 4) After each parameter is loaded, press "Enter" Before measuring, check the exact parameters of the object loaded into the machine, if wrong, proceed to recharge

- Instruct the object manipulation to perform:

• Press the "FVC" key

’ Wlmi the subject is ready, prnch 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 tube through the mouth, do not block the tube, not let the ah escape

• Press lire "Start" button

• 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, sưongly and last until the end or when the examiner stops talking trying to last for about 6s.

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

• Press tl*e "Print" key to print the Jesuits

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

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

• Must have a good starting point

• FVC measurement time lass 6 seconds

• Ensure constant exertion and speed for each measurerrvni

• Tile difference between FVC andFEVl’s 2 best exertion attempts should not exceed 5%

• Perform no more than 6 tunes 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

I Ire 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 than 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 breah completely.

- Step fi: press the button

2.8 Potential Errors and Solutions

- Error recall: should specify' which information or variables

Solution: using words that are easy to understand, clear, and suitable to lite target Cross-check the infomation by repeating the question dining 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, weight and 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 Tian 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 Ỡ software

- Data were then analyzed using Stata 15 software

• Descriptive statistics were used to present frequency, percentage for quantitative variables (eg gender, age group) or mean SD for qualitative variables (e.g occupational age) 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 X SD or median

and quartile interval, when considering the association between the morbidity status (silicosis: Yes.No) and several factors such as: gender, age group, workplace, smoking I pipe tobacco history, history of chronic respiratory-

diseases and frequency of using masks of employees, using both univariate and multivariate logistic regression models to calculate the odds ratio OR the

p value <0.05 is considered a statistically significant relationship

2.10 Research ethical consideration

This study is a part of die State-level project tilled "Research on molecular epidemiological characteristics, risk factors and application of advanced technology in early diagnosis of silicosis in Vietnam", code: K.C10 /

1620 by Prof Le Thi Huong conducted from 2018 to 2020 (attached to the Ethical Council's approval, code 4218/HMƯIRB dated November 16 2018) The author was allowed to participate in the process of collecting data, processing, analyzing data and using Illis data to write a university graduation thesis

Tbe research conducted with the permission of the liead of the research facility, the consent and voluntary’ participation of the subject Research issues do not affect the health or other problems of the subjects Information collected from the subjects is for research purposes only Research results will be fed back to research facility and research subjects

Chapter 3FINDINGS AND RESULTS

3.1 Demographic characteristics OÍ study participants

Table 3.1 General characteristics of research subjects

to smoke but now quit and currently smoking) 11 6% of employees had die history

of chronic respiratory disease