Background
Occupational lung disease is a major concern and it has been listed as one of the priority problems in occupational health [
1,
2]. In developing countries, workers are important as tools in production, and their health is at risk due to exposure to occupational hazards [
2]. The textile industry is associated with a number of environmental problems such as water pollution, soil pollution, noise pollution, and air or dust pollution. Among these different textile pollutions, cotton dust pollution is the most important in terms of health effects on textile workers [
3]. Dust are solid particles with a range in size from below 1 micron (μm) up to at least 100 μm. They may be or become airborne depending on their origin, physical characteristics, and ambient conditions [
4].
The respirable dust is the fraction of the dust reaching the alveolar region of the lungs and it can penetrate beyond the terminal bronchioles to the gas exchange region of the lungs. Cotton dust is the dust present in the air during the handling or processing of cotton, which may contain a mixture of substances including ground-up plant matter, bacteria, fungi, soil, pesticides, and other contaminants [
5]. Inhalation of the dust depends on its aerodynamic diameter, the velocity of the surrounding air, and the persons’ breathing rate. The small aerodynamic diameter has a greater chance of deep penetration into the respiratory tract, and dust with an aerodynamic diameter > 10 μm is easy to reach the gas-exchange region of the lung [
4].
A large amount of dust was generated in different areas of the weaving section in the textile mill such as ginning, carding, and spinning operations [
6]. The spinning section might be exposed to cotton dust more than the other sections. The textile workers were exposed to heavy dust concentration in the first step of processing [
7]. The small dust particles entered into the alveoli of the lungs through inhalation. The capacity of retaining oxygen could be reduced by the accumulation of dust in the lymph causing damage to the alveoli [
8]. The initial pulmonary responses to the dust might be characterized by reversible respiratory symptoms and deterioration in lung functions [
9].
Exposure to occupational dust is implicated in the etiology of several occupational respiratory diseases with considerable socio-sanitary consequences [
10]. The textile workers exposed to respiratory dust might cause a variety of different respiratory health problems including byssinosis, chronic obstructive pulmonary disease, and respiratory irritation [
11,
12]. Cough, expectoration, and chest tightness were more prevalent in spinning and weaving workers [
13]. The typical symptoms caused by exposure to respiratory dust were chronic cough with or without phlegm, dyspnea, wheezing, nasal stuffiness, and chest tightness [
13‐
15]. The extent of chronic functional losses in textile workers was apparently affected by the consistency of reporting respiratory symptoms. It could be a stronger relationship between chronic respiratory diseases and spontaneous deteriorations in lung functions [
15,
16].
In every industry, a safe workplace is crucial to achieving the highest productivity level. Therefore, the promotion and protection of a safe workplace is the complementary element of industrial development [
17]. Finding and fixing workplace hazards before illness were the major concerns for safety and health at the workplace. Primary preventive interventions are important to reduce dust exposure in the workplace and remain vital for the elimination of the occupational lung disease burden [
18]. Although the major improvements in dust control have occurred in many textile industries, a considerable proportion of textile workers are at risk of developing lung diseases, even at very low dust concentration in the workplace.
The studies conducted in Taiwan and Pakistan found that increased cotton dust concentration led to a reduction of lung functions in textile workers [
8,
19]. In Myanmar, textile manufacturing is a labor-intensive industry and pivotal place in the economy. It represents one of the largest groups of manufacturing industries in terms of the value of production and source of direct employment to the people. However, the respiratory problems due to dust exposure is not well known and there is a limited scientific evidence for showing these kind of health issue in Myanmar. Therefore, the aim of the study was to assess respirable dust exposure and associated factors of lung functions among textile workers.
Discussion
This study has assessed the respirable dust exposure and associated factors of lung functions in textile workers. Almost all textile workers were female, and the male-female ratio was 1:10 in this study. It was similar to the result of the study carried out in Thailand stated that the majority of participants were female [
24], while the study conducted in Ethiopia reported that there was no difference in sex distribution [
25]. It might be due to different study areas and the nature of employment which means that the textile industry is generally or traditionally viewed as suitable employment for female workers in Myanmar. The mean age of textile workers was 38.8 years and it was consistent with the studies done in Thailand [
24] and Nigeria [
26] reported that the means age of participants were 39.7 and 36.9 years, respectively. In this study, most of the textile workers had a high school education level, but other studies conducted in the same constitution of India [
27] and Ethiopia [
28] stated that most of the participants were up to high school and illiterate, respectively.
For the duration of service in the current department, most of the textile workers had more than 15 years of service duration. In contrast, a study conducted in India reported that most participants had more than 20 years of service duration [
27] and, in an Ethiopia study, most of the participants were exposed to the dust in the current section for 20 to 30 years [
25]. In reported respiratory symptoms, 52.7% of textile workers had at least one respiratory symptom, and it was lower than the finding of a study done in Egypt showed that 59% of participants had respiratory symptoms. However, it was higher than the findings of the same studies conducted in Taiwan [
8] and Ethiopia [
29] reported that and 39.7 and 47.8% of participants had respiratory symptoms respectively.
The occupational lung diseases were rapid outsourcing of textile industries due to the long exposure period in the workplace and poor control measures. The textile workers who were exposed to dust reported respiratory symptoms as a result of hypersensitive airways and an acute reduction in FEV
1 [
30]. Most of the acute respiratory symptoms due to dust exposure in textile workers were chest tightness, cough, and dyspnea [
29]. In this study, breathlessness 34.3%, and phlegm 21.3% were the commonest respiratory symptoms reported by the textile workers. The reported respiratory symptoms of textile workers in the same occupational setting varied substantially from different studies. In contrast with other findings, a study conducted in Thailand revealed that there was a high prevalence of chest tightness 64.6% and phlegm 59.1% among the participants [
10]. A Pakistan study stated that the wheezing 20% and phlegm 20% were the most reported respiratory symptoms of textile workers [
19].
In this study, the mean respirable dust concentration was 3.30 mg/m
3, and 50.7% of textile workers were exposed to an increased level of respirable dust concentration. This finding was higher than the study done in Thailand showed that the mean respirable dust concentration was 0.53 mg/m
3 in sewing workers [
10]. It might be due to the fact that the textile workers in the weaving section exceeded occupational dust exposure. In this study, the mean respirable dust concentration in the twisting department was more than the other departments of the weaving section. In contrast, the carding department was an area of highest dust concentration in the studies done in Ethiopia [
25,
31] and Taiwan [
8]. Additionally, a similar study reported that the dust concentration was varied between the working departments and the level of dust concentration was higher in the cleaning department than in the spinning and weaving departments [
28]. This inconsistency in the results might be, in part, due to the methodological variation, the difference in an industrial setting, and the handling and processing of cotton.
In this study, the prevalence of reduced lung functions, 40.1%, among textile workers was higher compared with the other study done in Taiwan reported that 38.5% had reduced lung functions. Regarding spirometry patterns, 36.2% of textile workers had the restrictive pattern and it was lower than a similar study done in Nigeria found that the prevalence of restrictive pattern was 40.0% among textile workers [
26]. There were 3.9% of an obstructive pattern among textile workers in this study, but conversely, the studies conducted in Zimbabwe [
32] and Nigeria [
26] reported that 27.8 and 10.0% of study participants had the obstructive pattern. The mean value of FVC, 82.82%, was lower than the studies done in the same occupational setting at Thailand 106.0%, Greece 90.6%, and Pakistan 90.3% [
10,
12,
19]. The mean value of FEV
1, 83.64%, was coincided with the result of a study conducted in Pakistan [
19], however, it was lower than the studies done in Thailand 101.0%, Iran 88.8%, Turkey 96.2%, and Greece 91.7% [
10,
12,
33,
34]. This inconsistency of results might be attributable to the usage of different types of spirometers in these studies.
As a current working department, respirable dust concentration was highest in the twisting department, and the textile workers who were working in this department were the more likely to reduce lung functions compared with those who were working in other departments. The various conditions such as the quality of the cotton, the production rate, the ventilation system, the processing method, and the method of dust sampling and analysis might affect the concentration of dust in the working environment [
31]. The direct exposure to dust might contribute to reduced lung functions, and pulmonary diseases due to occupational exposure are mostly related to inhalation of dust and its deposition in the lungs [
13].
The duration of service in the current department was associated with lung functions and the textile workers who were exposed to dust > 5 years were more likely to reduce their lung functions than those who had ≤ 5 years of service duration. This finding was also in line with the study conducted in India reported that cotton mill workers with > 5 years of dust exposure were more likely to have spirometric abnormality [
29]. Consequently, the textile workers with long service duration and chronic exposure to dust were at high risk of developing chronic respiratory health problems [
35]. However, the studies conducted in the same constitutions of Egypt and Nigeria showed that there was no correlation between spirometric functions and duration of exposure to dust in the current section among cotton textile workers [
13,
26]. It might be due to the variation of the working environment and concentration of dust exposure in workplaces.
The textile workers with respiratory symptoms had 3.64 times more likely to reduce respiratory function than those who had no respiratory symptoms. The result of the current study was in agreement with a study done in Nigeria showed that the textile workers with respiratory symptom had low FEV
1 predicted value and a possibility of obstructive airway disease [
26]. This finding was also matched with the study done in India stated that spirometric abnormality was more prevalent in symptomatic workers and there was an association between spirometry results and respiratory symptoms in cotton mill workers [
29]. This might be due to increased dust exposure in the working environment and the accumulation of dust in the respiratory system. Dust particles or dust-containing macrophages causing injury to the lungs, and then fibrous lung tissue provided functional impairment.
The spirometric data of the current study showed a significant reduction of lung functions that occurred in most textile workers who were exposed to increased respirable dust concentration. It was consistent with the finding of the Taiwan study reported that more prevalence of impaired lung functions occurred in the cotton textile workers with higher exposure to dust [
8]. This finding also supported to the results of the study done in Pakistan showed that mean dust exposure level affects on lung functions of textile workers, and increased dust concentration led to more decline in lung functions of textile workers [
30]. This consistent finding provided strong evidence of increased respirable dust exposure that was an associated factor of reduced lung functions.
The smoking habit was not associated with lung functions in this study resulting from a low distribution of workers with smoking history. The results of this study might be generalized to elsewhere in which the workers are involved in the same occupational setting. However, the results might be varied depending on the diversity of basic characteristics, risk behaviors, respirable dust exposure, and implementation of occupational safety measures. There were some limitations to this study. The first was related to healthy worker effect which means that the workers who developed the respiratory symptoms may have quitted the job. Airborne endotoxin is more responsible for occupational respiratory diseases than respiratory dust itself and so, lack of the measurement of endotoxin exposure in the workplace was the second limitation of this study. Thirdly, the cross-sectional study could not determine the cause and effect relationship and therefore it would require further prospective studies in order to assess the causality and confirm the findings of this study. Finally, the interview by using the questionnaire method was another limitation because it may cause recall bias and interviewer bias. Despite all of these limitations, this study might be a reasonable source of information for occupational health and safety.
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