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Pulmonary Function Among Cotton Textile Workers: Appendix

Interestingly, chronic bronchitis was less predictive of 5-year lung function loss. This may have less to do with the pathophysiologic features of chronic airway disease due to cotton than to the variation in reporting chronic respiratory symptoms in this population.
There is evidence that cotton dust exposure leads to accelerated loss of lung function, though the magnitude of the effect and exposure-response relationships have not been well described.’’ The essential questions regarding chronic exposure and health remain: (1) Does cotton dust exposure lead to chronic loss of lung function? (2) Do the acute responses to cotton dust predict chronic loss of lung function? These results present no information with respect to question 1. Allergy medications more They do, however, provide evidence of an acute-chronic link. It is clear from cross-sectional studies that subjects with byssinosis symptoms have a higher prevalence of chronic bronchitis and lower levels of ventilatory function. It has remained unclear whether cotton textile workers with acute work-related symptoms and lung function drops actually have an accelerated loss of lung function. In contrast to cotton-exposed workers, those exposed to grain dust do exhibit such an acute-chronic link between across-shift drop in FEVi and chronic loss of FEVi.” In examining acute symptoms and across-shift changes prospectively, we need to examine the stability and reliability of these indicators. For example, symptom responses even on carefully standardized questionnaires are quite variable when asked about over time. Across-day spirometry may be influenced by tobacco smoking, age, initial level of FEVi, and diurnal variation.
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Pulmonary Function Among Cotton Textile Workers: Conclusion

Pulmonary Function Among Cotton Textile Workers: ConclusionIn this study, we used across-shift change in FEVi as a measure of specific airway responsiveness to cotton dust. This method of defining cotton dust responsiveness has been used in cross-sectional studies of cotton-exposed workers. The sources of variability in such bronchial responsiveness in the mill setting may include recent viral infection, pollen exposures, biologic variation in airway smooth muscle tone, differences in inhalation patterns of workers in various jobs, and varying exposure intensity of different textile jobs. Canadian family pharmacy read Thus, we expected some variability in the magnitude of across-shift change in FEVi among cotton textile workers. Those with consistent acute responses had the most accelerated loss in lung function over the 5-year period of observation.
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Pulmonary Function Among Cotton Textile Workers: Discussion

Berry and colleagues examined the data from one of these studies and reported the 3-year changes in pulmonary function in both cotton textile workers and synthetic fiber control workers. Cotton workers had an excess annual loss in lung function (54 ml) versus control workers (32 ml). However, the annual decline in lung function was not related to across-shift change in lung function or to symptoms of byssinosis or bronchitis, and information on symptom variability over time was not reported. Valic and Zuskin studied a small group of workers exposed to coarse cotton dust over 10 years and found that the prevalence of both byssinosis and nonspecific respiratory symptoms increased with the duration of exposure to cotton dust. Beck et al studied textile workers prospectively in a community-based study in South Carolina and reported a chronic effect of cotton dust exposure on lung function that was independent of cigarette use. Zuskin et al recently reported a follow-up study of a small group (n=66) of textile workers exposed to high levels of dust and examined over 10 years. Canadian neighbor pharmacy read more This group represented about 57 percent of the original cohort and were found to have an increasing prevalence of respiratory symptoms as well as progressive lung function decline.
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Pulmonary Function Among Cotton Textile Workers: Analysis of Missing Data

Pulmonary Function Among Cotton Textile Workers:  Analysis of Missing DataPreshift FEVi, on the resurvey adjusted for age, height, gender, and smoking, decreased similarly. The adjusted preshift FEVi for consistently positive responders at 94.4 percent contrasted with consistently negative responders whose adjusted FEVi was 98.3 percent. Subjects who responded both times with an across-shift drop of 5 percent or more lost 267 ml over 5 years versus 180 ml (t=1.72, p=0.05) for those who never experienced sharp drops. This effect persisted after adjustments for age, height, gender, and smoking by regression analysis (data not shown).
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Pulmonary Function Among Cotton Textile Workers: Acute and Chronic Ventilatory Changes

Symptom Persistence: When symptom consistency was examined in relation to pulmonary function, workers who consistently reported the presence of symptoms exhibited an accelerated decline in ventilatory capacity compared with those who never or inconsistently reported these symptoms (Table 3). As a group, those subjects with typical byssinosis, any chest tightness at work and chronic bronchitis, also tended to have more work years, higher dust exposure, and a higher prevalence of smoking. In addition, a high rate of loss (—139 ml/yr) was noted among the four subjects with byssinosis who reported typical byssinosis on both surveys (data not shown).
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Pulmonary Function Among Cotton Textile Workers: Environmental Assessment

Pulmonary Function Among Cotton Textile Workers: Environmental AssessmentCotton dust measurements revealed that most levels in all work areas exceeded the current Occupational Safety and Health Administration permissible exposure limit of 0.2 mg/m 8-h time-weighted average dust (Table 1). Median concentrations for dust ranged from 0.24 mg/m in fine spinning to 1.73 mg/m in cleaning. Canadian family pharmacy Click Here Endotoxin concentrations ranged from 0.004 Mg/m in fine spinning to 0.75 Mg/m in the drawing area. When dichotomized into exposure areas as just described, about half the cotton areas and a third of the endotoxin areas were in the lower category. There was moderately high correlation (Spearman’s test) between airborne VE dust and VE endotoxin levels (rs=0.66 for mill 1, p<0.01; rs=0.79 for mill 2).

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Pulmonary Function Among Cotton Textile Workers: Statistical Analysis

Characteristics of Airway Responsiveness (Symptoms): Byssinosis, chest tightness, chronic bronchitis, cough, and dyspnea 2+ were the symptoms of primary interest. Consistency of symptom reporting was defined as follows: Subjects were “always” responders if he or she reported the symptom in both surveys; “inconsistent” responders if they reported the symptom on one of the two surveys; and “never” responders if they did not report the symptom on either survey. Inconsistent responders included two potentially distinct groups, those who became symptomatic during the 5-year study and those who became asymptomatic.
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Pulmonary Function Among Cotton Textile Workers: Environmental Assessment

Pulmonary Function Among Cotton Textile Workers: Environmental AssessmentFemales: FEVi (L)= —0.024 age (years)+0.033 height (cm)—1.729 Males: FEVi (L)=—0.029 age (years)+0.055 height (cm) —0.008 smoking (pack-years)—4.742
Airborne cotton dust was collected using vertical elutriators (General Metal Works, Inc) designed to collect particles less than 15 microns in aerodynamic diameter. Multiple area samples were collected from each of the six different work areas in yarn preparation operations of the two mills. Canadian neightbor pharmacy read The dust samples were collected throughout the work shift at both surveys—1981 and 1986. The work areas for all phases of yarn preparation included: opening, cleaning, carding, drawing, roving, combing, and spinning. There was no change in the methods of cotton processing during the 5-year period with the exception that mill 1 began to blend Dacron with cotton continuously for 2 years before the follow-up survey. At the first survey, 130 air samples were collected. At the second survey, 192 air samples were collected. Sampling procedures were in accordance with the US National Institute for Occupational Safety and Health (NIOSH) recommended guidelines, with the exception that the height of the elutriators was set at approximately 1.6 m to compensate for the slightly lower average height of the work force. Samples were collected in the same areas on follow-up as in the initial survey, and there was no change in the handling or method of weighing the filters.
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Pulmonary Function Among Cotton Textile Workers: Pulmonary Function

Symptoms were defined as follows:
Byssinosis (all grades)=chest tightness or shortness of breath at work occurring on the first or other days of the workweek according to criteria of Schilling et al. Chronic bronchitis=sputum production occurring on most (>5) days of the week for at least 3 months a year for at least 2 consecutive years.
Chronic cough=cough without sputum for >5 days a week for at least 2 consecutive years.
Dyspnea grade 2+=having to walk slower than persons of the same age at an ordinary pace on level ground because of breathlessness.
Chest tightness at worktightness or constriction of the chest occurring anytime during the work shift and on any workday. Since the workers in these mills worked continual rotating shifts on an 8-day cycle with a 36-h rest at the end of rotation, we report chest tightness at work separately from the typical symptom periodicity which characterizes byssinosis.
Union of symptoms presence of any of any of the four symptoms noted previously.
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Pulmonary Function Among Cotton Textile Workers: Methods

Pulmonary Function Among Cotton Textile Workers: MethodsStudy Population
This study involved cotton textile workers enrolled in a longitudinal study of respiratory disease among textile workers in Shanghai, China. The baseline study in 1981 included 447 cotton textile workers (52 percent female). These represented 90 percent of workers employed more than 2 years and working in eligible jobs. The follow-up survey was performed 5 years later when all but 62 workers (37 female, 25 male) were restudied. Included in the lost worker category are six deceased workers, none of whom died of respiratory disease, and four others who were too ill to participate in the follow-up survey.
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