Occupational Exposure to Inhalable Cotton Dust, Endotoxin and Health Problems Associated with Workers of Ethiopian Integrated Textile Industry

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Addis Abeba University


Background: Exposure to workplace hazards is a significant risk to workers' health in the textile and garment. Objective measurement of personal inhalable dust and endotoxin level and the effects of exposure to workers' health in this sector was not adequately investigated in Ethiopia. Objectives: This study aimed to measure personal inhalable cotton dust and endotoxin concentration, examine lung function capacity, and analyze registered diseases and injuries of workers in the integrated textile factories of Ethiopia. Methods and materials: Three independent studies were conducted to achieve the stated objectives. Personal inhalable cotton dust and endotoxin level, cross-shift lung function status with chronic respiratory symptoms and registered diseases and injuries are outcomes of the three studies. The overall study objectives were crafted within the framework of the three levels of occupational exposure: external exposure consider (inhalable dust and endotoxin), internal exposure (cross-shift lung function) and effect (diseases and injuries). An institution-based crosssectional and comparative cross-sectional design was employed. The study settings were at three industrial zones in two regions of the country: Amhara Regional State and Tigray Regional State. The study involved three integrated textile factories (Factory 1, Factory 2 and Factory 3) and two soft drinks and water bottling factories as comparison groups. In the first study, ninety-six (96) repeated air samples were collected from sixty-four (64) workers’ breathing zone to analyze the personal inhalable cotton dust and endotoxin exposure levels. The samples were collected from seven work sections or seven similar exposure groups (SEG) from an integrated textile at Factory 1. The seven work sections are Carding, Open-end, Ring frame, Preparatory, Fabric making, Batching and Sewing found in the four production departments (spinning, waving, finishing and garment). Dust samplings were performed for a shift using a conductive plastic inhalable conical sampler mounted with a 37mm glass-fibre filter. The pump operated at a flow rate of 3.5 l. min -1 . The Time Weighted Average cotton dust level was determined by gravimetrical analysis and reported in mg.m -3 . Endotoxin was extracted from the cotton dust samples and analyzed using a quantitative kinetic chromogenic Limulus Amebocytes Lysate test and reported as EU. m In the second study, cross-shift lung function tests and chronic respiratory symptoms assessment were performed among 306 workers from an integrated textile Factory 1 and 156 non-cotton exposed workers. The lung function test was conducted before and after the work shift using a portable spirometer (SPIRARE 3 sensor model SPS 320) for the parameters: Forced Expiratory Volume in one second (FEV 1 ) and Forced Vital Capacity (FVC). Moreover, the prevalence of chronic respiratory symptoms was assessed through a face-to-face interview using a standardized questionnaire adopted from the American Thoracic Society. In the third study, a one-year registration of diseases and injuries of 7,992 workers were collected from the three integrated textile factories (Factory 1, Factory 2 and Factory 3). Data were retrieved from both the registration of factory clinics and human resources. Each worker has a chart/card in the clinic, labelled with the name and unique worker's identification number, similar to the one used in the human resource department database. All clinical consultations of workers during March 2016 to February 2017 were extracted from the health archives of the factory’s clinic. Exposure measurement, lung function and registered diseases data were entered into a Micro Soft Office excel template, whereas the data of the respiratory symptoms were entered using epidemiological information package (Epi-Info) version 7.1. All types of data were exported to SPSS for analysis. Missing values, incomplete recording, outliers and inconsistent records were checked and managed accordingly. The exposure assessment was described by the arithmetic mean, standard deviation, geometric mean (GM), and geometric standard deviation (GSD). The cross-shift change in FEV 1 (∆FEV 1 ) and FVC (∆FVC) was calculated by subtracting the after-shift value from the before-shift value. The Global Lung Initiative Quanjer GLI-2012 multi-ethnic reference value for the African American ethnicity was used to estimate the predicted value and the proportion of subjects with FEV 1 and FVC below the Lower Limit Normal (LLN). Prevalence, percentage and proportion were used to describe the respiratory symptoms and the registered disease conditions as categorical variables. The independent t-test was performed to analyze exposure differences between work sections and to compare the cross-shift difference FEV 1 and FVC among the textile and non-cotton exposed workers. A paired-samples t-test was performed to compare the pre- and post-shift difference of lung function parameters. The correlation between inhalable dust and endotoxin concentrations was analyzed using Pearson's correlation test. Analysis of Variance (ANOVA) was also performed to compare the GM of personal inhalable dust, endotoxin exposure level, and endotoxin ratio to dust between departments and work sections. The Pearson Chi-square test or Fisher's exact test, if the expected value was less than 5, was used to testing the difference between the groups regarding the categorical variables. Logistic regression analysis was used two times in the study by adjusting confounding variables: 1) to compare the chronic respiratory symptoms between the integrated textile workers and control and 2) to identify work and personal factors associated with the registered work-related diseases and injuries. Furthermore, the amount of reduced cross-shift lung function capacity among the integrated textile workers was estimated using multiple linear regressions. Results: In the external exposure measurement, the overall Geometric Mean (Geometric Standard Deviation) of cotton dust and endotoxin level was 0.75 mg·m −3 (2.6) and 831 EU· m (5.4), respectively. The highest dust and endotoxin concentrations were observed in the carding section found in spinning department (1.34 mg· m −3 ) and (6,381 EU· m −3 ), respectively; while the lowest cotton dust (0.46 mg· m −3 ) and endotoxin levels (76 EU· m −3 ) were found in the garment department. There was a moderate linear relationship between personal inhalable dust and endotoxin exposure (r = 0.45, p < 0.001). In the internal exposure assessment, the cross-shift lung function reduction among textile workers (123 mL for FEV 1 and 129 mL for FVC) was significantly higher than the control group (14 mL for FEV 1 and 12 mL for FVC) at p < 0.001. The prevalence of chronic respiratory symptoms was significantly higher among textile workers (54 %) than the controls (28 %). Breathlessness was the most prevalent chronic respiratory symptom with the highest adjusted odds ratio of 9.4 (95 %; CI: 4.4–20.3). The prevalence of respiratory diseases was highest (34 %), followed by musculoskeletal disorders (29 %), gastrointestinal infection (21 %), peptic ulcer (19 %) and injury (17 %); the injury was the leading cause of sick leave. About 69 %, 65 % and 60 % of textile, garment and support workers, respectively, were diagnosed with a disease in one year. In the effect measurement, 27,320 consultations for different disease diagnoses were made by 5,276 (66 %) workers; claimed 16,993 workdays lost due to sick leave annually. Work-related and personal factors were associated with diseases and injuries; textile department, females, older and workers with low educational status had a significantly higher risk for most diseases than the support, male, young and workers with higher educational level. Conclusions: We found a high level of personal inhalable dust and endotoxin in external exposure from workplaces. Eleven percent of the dust samples were higher than the Workplace Exposure Limit set by the Health and Safety Executives (HSE) of the United Kingdom and 89 % higher than the Dutch experts' recommendation for endotoxin exposure. A lower level of inhalable dust exposure does not guarantee safe exposure to endotoxin in work sections. The textile workers had a higher level of cross-shift lung function reduction in the internal exposure, which could be related to external exposure. The prevalence of chronic respiratory symptoms was also higher among textile factory workers compared to control. Majorities of the workers were diagnosed with different types of diseases and injuries as an effect. The textile and garment production workers had a higher risk of acquiring diseases than the support process workers, indicating that some diseases might have resulted from the external exposure and development of internal exposure at the workplace. Thus, factory clinics seem to be an essential source of evidence to understand the burden of occupational diseases and injuries. Further, the study showed the link between exposure and effect. Recommendations: A comprehensive workplace hazard exposure assessment and worker's health protection program in the integrated textile factories should be strengthened. The occupational health and safety programs should be prioritized and focused on addressing the specific gaps and needs of high-risk workers. Besides, factory management, occupational health and safety practitioners, policy and regulatory bodies should be part of the program. Further research is required to assess exposure measurement to other hazards, including cotton dust and endotoxin, by tracking workers' exposure profiles to estimate cumulative exposure and relationship to disease outcome. The occupational diseases and injuries study may be extended to compare the results with the general population using a standard and similar diagnosis tool, the International Classification of Diseases (ICD) code. .



Integrated textile factory; cotton dust; endotoxin; cross-shift lung function; respiratory symptoms; diseases and injuries