| Summary: | 碩士 === 國防醫學院 === 公共衛生學研究所 === 91 === The textile industry has been one of the most important basic industries in Taiwan. There are currently more than 7,000 textile factories with more than 240,000 employees in Taiwan. Many diseases and symptoms are known to be related to the cotton dust exposure, with byssinosis and declined pulmonary function being the most widely researched topics in the textile mills. In order to investigate the relationship between chronic changes of the pulmonary function and cotton dust exposure, a longitudinal study of the three-year changes of pulmonary function was designed. From 1998 to 2002, a total of 208 employees were included in this study with duplicated check－up. Both pulmonary function test and questionnaire about the respiratory symptoms were collected. IOM sampler were used to assess the regional cotton dust concentration in the working place and total dust sampler were used and combined with LAL（Limulus amebocyte lysate） method to evaluate the regional endotoxin concentration. GEE（Generalized estimating equation）model was used to analyze the longitudinal changes of pulmonary function and find out factors that may affect the pulmonary function.
The prevalence of chest tightness symptom had declined from 11.2% in 1988 to 7.2% in 2002, and the prevalence of respiratory irritative symptom had declined from 25.8% to 9.1%. The pulmonary function was also in this three－year period with FVC declining from 3.19 in 1998 to 3.06 liters in 2002 and FEV1 declining from 2.78 to 2.68 liters. However, the percentage of abnormal pulmonary functional pattern and chronic impaired pulmonary function were lower in 2002 than in 1998. The percentage of abnormal pulmonary functional pattern had declined form 13.2% in 1998 to 12.7% in 2002 and the percentage of chronic impairment of pulmonary function had declined from 15.8% to 14.3%.
The geometric mean of the regional cotton dust concentration had dropped from 0.89 in 1998 to 0.74 mg/m3 in 2002. The geometric mean of the regional endotoxin concentration was 1018.28 EU/m3. GEE model analysis revealed that the gender, age, body height, the abnormal pulmonary functional pattern and chronic impairment of pulmonary function influenced the longitudinal decline of the FVC and FEV1 over the three－year interval, while the byssinosis－related symptoms of chest tightness and respiratory irritation as well as the different working places did not affect the changes of pulmonary function . The smoking habit had more influence on the decline of FEV1 but not on the FVC. The workers who had WHO byssinosis－related symptoms of chest tightness or short of breathiness were more frequently to develop abnormal pulmonary function or chronic impaired pulmonary function than the workers who were asymptomatic. The log cumulative cotton and endotoxin concentrations did not affect the decline of the changes of pulmonary function. A possible “healthy worker effect” may bias these results since a portion of workers who were older, senior, with higher exposure, with poor pulmonary function as well as byssinosis－related symptoms, were not followed up in the current study.
The results of our study suggest that：（1）The dust collecting equipment should be improved in the work environment or using closure operation procedure to decrease the cotton dust in the working places.（2）The pulmonary function test should be included in the items of annual physical check－up.（3）Periodic monitoring the concentration of the cotton dust and endotoxin in the workplace and following up the respiratory illnesses among employees in the textile mills.（4）Further study is needed to examine the relationship between the cotton dust and endotoxin exposure and the prevalence of byssinosis, yearly decline in the pulmonary function and respiratory irritative symptoms.
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