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

MINISTRY OF EDUCATION AND

MINISTRY OF HEALTH

TRAINING

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: 52720103

Course 2015 2021

THESIS OF GRADUATION MEDICAL DOCTOR

Mentor:

Ass. Prof. Le Illi Tlianb Xu an

Hanoi- Year2021

nrdkn «s> ■>


ACKNOWLEDGE KENT

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. 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


SOCIALIST REPUBLIC OE VIETNAM

Independence - Freedom

Happiness

CONFIRMATION

To:
-

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 2021

Student
Pham Duy Thanh


LIST OF ABB RELATIONS

ILO

International Labor Organization

WHO

Worid Health Organization

-w .•* CN «G


TABLE OF CONTENTS

CONFIRMATION
ABSTRACT
INTRODUCTION

1

CHAPTER 1: LITERATURE REMEW

3

1.1.

Concepts associated with rhe employees. working environment and

& ãããằ-*<w la* a ãã aa ã aaô aa a •• ■••••• •••••••••> ••••••••••••••• •( aae a at a ãã ãã

1.1.1. I he employees...... -..............................

ttatttataatatatôtatằaa(aaaaaaaaaaaaaaaaaeaaaaaaaằ<

loiiiaaaaMiaMiaiaaateaaaaaaaiaaaaaaaitaaaiiaato

1.12. Working environment..........................

aaeta ãã a ttoitMitaatait ã ãããôããããããããããã>ã a*ae aãa3

113. Dust in labor.........................................

........................................................

4

1 1.4. Silica dust..............................................
4

115 Occupational diseases.........................
1.1 j6. Silicosis..................................................

............................................................................................................................................... 6

1.1.7. Diagnosis the silicosis.........................

....................................................... ..... ..................................................................................6

1.1.8. x-ray images of the silicosis..............

7

I I .9. Respiratory flinction evaluation parameters.

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.

Oveniew of the srndv sites

CHAPTER 2: RESEARCH SUBJECTS AND METHODOLOGY

18
18

«s> ■>


2.2. Research subjects........ ..............

19

2.3. Research nines....... ...................

20

2 .*1 • ReseaI

c 11 design

a...

1. a a. a. BM •M

.. a.0

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 • »• • ••• ••

REFERENCES

APPENDIX 1
APPENDIX 2
APPENDIX 3

APPENDIX 4

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51


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. 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 oftire 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


Table 3.15. The association between prevalence of silicosis and knowing

health services among employees..................

39

Table 3.16. The association between prevalence of silicosis and health status

anx> ng employees.............................................................................. 39
Table 3.17. The association between prevalence of silicosis and attitude to the

dangerous of silicosis among employees........... _............................40

Table 3.18. The association between prevalence of silicosis and some
associated factors (multivariate analysis)............

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40


LIST OF FIGI RES
Figure2.1: Study location....
Figure 2.2: Metallurigical coke and steel making process...-........................... 19

F igure 3.1. Rate of using various types of masks among employees
Figure 32. Ftequencv using masks among employees.................. ......

-w .ã* CN ôG

-........... 35
35

.Abstract
Silicosis is an occupational lung disease that causes lung fibrosis,

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.


1

INTRODUCTION

Silicosis is ail occupational lung disease that causes lung fibrosis,

progressive and irreversible in workers who inhale free silica dust [1], [2]. It
is incurable and the most common of all occupational diseases in developing
countries [5]. Exposure to large amounts of free silica may go unnoticed

because silica is odorless, does not cause irritation and does not cause any
immediate health effects. Chrome exposure to silica also increases the risk of
tuberculosis [4]. [5]. [6] - a major health problem in developing countlies,

including Vietnam.

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


2

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


3

Chapter 1

LITERATVRE REMEW

I. 1.

Concepts associated with the employees, working environment and
silicosis

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.


4

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 long­

standing 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


5

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 3sided 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.


6

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:


7

•

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 siikt

ã Small cloud:
-

Dimension cloud:

-w .ã* CN ôG


8

• 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.

• Large cloud:
-

Large cloud type A is a cloud with the size from 10.0 to 50mm or the

total size of the large fuzzies not exceeding 50mm.
•

Large cloud type B is a cloud of size over 50mm Ind not exceeding the

upper aiea of the right lung or the total size of the cloud is greater than 50mm
but not exceeding the upper area of the right lung.
-

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.

-w .ã* CN ôG


9

-

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].
Respiratory function evaluation parameters

J.J.9.

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-measure. 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.


10

•

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

ã

High: % FEV1 - 35 - 499ô of theoretical value

ã

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

11

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


12

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


13

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

14

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.


15

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 respiratorydisease 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].