The study of byssinosis in China: a comprehensive report

Cross-sectional studies were conducted during 1981-1983 among 861 textile workers in 3 cotton mills and 822 controls in 2 silk factories. Questionnaire and lung function tests were taken and inhalable dust concentrations were measured. Prevalence of byssinosis was 5.6%. Average dust concentrations were highest in carding rooms, 1.47-1.99 mg/m3. The correlations (r) between prevalence of byssinosis and dust concentrations was 0.64 (p less than 0.05). The prevalence of chronic bronchitis was 14.4% in cotton workers and 5.1% in controls (p less than 0.05). Acute FEV1 percent decrement (greater than 5%) was higher among cotton workers (32.1%) compared to controls (14.5%) (p less than 0.001). In one cotton blanket factory, the prevalence of byssinosis and chronic bronchitis was higher among workers in the high-dust work areas. Long-term effect studies included pulmonary function test among 173 cotton workers and 373 controls, retired 1-10 years, using the flow volume curve (FVC); chest X-rays of 140 pairs of cotton workers and controls with working tenures over 20 years; and examination of lobectomy specimens of 8 textile workers matched with 16 controls. In male cotton workers, only smokers had a prominent decrement of lung function indices, except FVC. For non-smoking females, there was no difference between the two groups. Additive effects were seen between smoking and dust exposure. According to the International Labor Organization (ILO) Pneumoconiosis Classification, the prevalence of abnormality (profusion greater than 1/0) was 4.3% and 8.7% in non-smoking controls and cotton workers. The interstitial changes on X-ray due to smoking would be much heavier. Additive effects also existed between smoking and dust exposures. No significant changes attributable to dust exposure were seen on pathological section of lobectomy specimens.     

Prevalence of byssinosis in Swedish cotton mills.

The prevalence of byssinosis and of chronic bronchitis was studied in a questionnaire investigation among workers in bale opening areas, carding rooms, and spinning rooms in five Swedish cotton mills. Airborne dust and Gram-negative bacteria was measured. Nineteen per cent of the interviewed workers reported symptoms of light byssinosis (grade 1/2). The prevalence of symptoms was not related to the duration of employment, and cases of byssinosis were found among people who had worked in cotton mills for only a few years. A significantly higher proportion of male than female workers reported symptoms. No difference in the extent of byssinosis was found between smokers and non-smokers, but the prevalence was significantly higher among those workers who had ceased smoking. The prevalence of byssinosis was related to the number of airborne viable Gram-negative bacteria as well as to the dust level in the different mills.     

棉纺车间空气中可吸尘,内毒素浓度与工人呼吸道反应

本文对338名棉工进行了呼吸道反应调查.并测定了车间空气中粉尘浓度及内毒素浓度.发现前纺车间可吸尘浓度在O.18～1.62m g/m~3,内毒素浓度在94.91～2682.18ng/m~3,棉尘有关症状(包括棉尘病症状和不典型症状)和慢性支气管炎患病率均比对照组高,且与车间粉尘和内毒素浓度呈正相关.与5年前比较,可吸尘或内毒素累积接触量高的男、女工人FEV_1下降均较累积接触量低者明显。     

Additive effect of smoking and cotton dust exposure on respiratory symptoms and pulmonary function of cotton textile workers

One hundred and sixty-nine and 175 cotton textile workers (CTWs) were enrolled in the first (1991) and second (1996) surveys to investigate the prevalence of byssinosis. The synergistic effect of smoking on cotton dust exposure was also evaluated. Although the difference in prevalence of abnormal pulmonary function between the first (38.5%) and second study (38.9%) was not statistically significant, smokers had significantly higher frequency than nonsmokers in both surveys. A significant trend existed between the cotton dust levels and the frequency of abnormal lung function. The significant trend was also noted in both smokers and nonsmokers. The frequency of respiratory symptoms and the prevalence of severe byssinosis in the second survey (14.9% and 12.6%, respectively) were significantly lower than that in the first survey (39.7% and 21.9%, respectively). The reduction of symptoms was due to remodeling of this old cotton mill. The prevalences of respiratory symptoms and byssinosis in smokers being significantly higher than in nonsmokers only found in the first survey, but not found in the second survey. These results indicate that smoking potentiates the effect of cotton dust exposure on respiratory symptoms and byssinosis. The second study reveals high prevalence of byssinosis still existed in Taiwanese cotton mill, although the prevalence was declining. Smoking was found to show an additive effect on cotton dust exposure. Anti-smoking campaign, occupational health program to reduce the dust exposure, and periodical medical examination are measures to prevent from byssinosis.     

An environmental and medical study of byssinosis and other respiratory conditions in the cotton textile industry in Egypt

This study was conducted in a typical Egyptian textile plant located in Alexandria. Male workers from all operations (N = 506) were examined and their dust exposures were assessed. Results showed that airborne dust concentrations were very high and that the plant fraction is mostly concentrated in respirable dust. Byssinosis prevailed in 21% of workers in opening and cleaning sections and in 13% in carding and combing rooms, but was found in none of the workers in drawing, twisting, and spinning operations, in only 1.1% in weaving, and in 3.1% of workers in other “auxiliary” occupations. The rare prevalence of byssinosis among the latter workers' groups was attributed to the workers' continuous exposure without fixed weekend interruption, the personal and family history of exposure to cotton, the low proportion of plant materials in dust evolved in related operations, the fine quality of Egyptian cotton, and/or the population characteristics of Egyptian workers. Reduction in FEV_1.0 at the end of the first work shift after absence from work occured more often than byssinosis, which indicates the importance of this test for the early detection of effects of cotton dust exposure. It is suggested that a nationwide study in the cotton textile industry is indicated.     

BYSSINOSIS IN COTTON GINNERIES IN GREECE

The prevalence of byssinosis in a sample of cotton ginnery workers in Greece was investigated. The respiratory symptoms, F.E.V._1·0, and V.C. of 70 male ginnery workers were recorded. No case of clinical byssinosis was found, but a statistically significant relationship exists between years of exposure to cotton dust and impairment of lung function. On the contrary no significant relationship exists between smoking and lung function, or between sputum production and lung function. The findings suggest the hypothesis that the cotton dust may exert, in the case of a prolonged exposure, a chronic deleterious action without producing the typical symptoms of clinical byssinosis.     

Respiratory symptoms and cotton dust exposure; results of a 15 year follow up observation

Aims: To determine chronic effects of long term exposure to cotton dust and endotoxin on incidence of respiratory symptoms and the effect of cessation of exposure.

Methods: Respiratory health in 429 Chinese cotton textile workers (study group) and 449 silk textile workers (control group) was followed prospectively from 1981 to 1996. Byssinosis, chest tightness, and non-specific respiratory symptoms were assessed by means of identical standardised questionnaires at four time points. Exposures to cotton dust and endotoxin were estimated using area samples collected at each survey. Incidence and persistence of symptoms were examined in relation to cumulative exposure and exposure cessation using generalised estimating equations (GEE).

Results: Among cotton workers, the cumulative incidence of byssinosis and chest tightness was 24% and 23%, respectively, and was significantly more common in smokers than in non-smokers. A high proportion of symptoms was found to be intermittent, rather than persistent. Among silk workers, no typical byssinosis was identified; the incidence of chest tightness was 10%. Chronic bronchitis, cough, and dyspnoea were more common and persistent in the cotton group than in the silk group. Significantly lower odds ratios for symptoms were observed in cotton workers who left the cotton mills; risk was also related to years since last worked. Multivariate analysis indicated a trend for higher cumulative exposure to endotoxin in relation to a higher risk for byssinosis.

Conclusion: Chronic exposure to cotton dust is related to both work specific and non-specific respiratory symptoms. Byssinosis is more strongly associated with exposure to endotoxin than to dust. Cessation of exposure may improve the respiratory health of cotton textile workers; the improvement appears to increase with time since last exposure.

     

Respiratory disease in a textile factory in Nicaragua

This is the first epidemiologic study conducted in a textile mill in Nicaragua using techniques and diagnostic criteria similar to those used in the United States and England. The prevalence of byssinosis and nonspecific respiratory symptoms were studied in 194 workers in a cotton mill in Managua. Limited environmental sampling, performed using a vertical elutriator in yarn preparation and weaving areas, indicated that exposures were similar to those reported in other parts of the developing world. A modified translated version of the Medical Research Council respiratory questionnaire was administered. Pulmonary function tests were performed before and after the Monday workshift to measure across-shift change in ventilatory function. The prevalence of byssinosis was 5.9% and all the cases occurred among exposed women. Nonspecific respiratory symptoms were also more prevalent among exposed workers. After adjusting for age, gender, smoking habit, and work tenure, the exposure odds ratios for usual cough and usual phlegm were 3.3 and 2.2, respectively. The association between exposure and across-shift decrement in FEV1 was not significant. Byssinotic workers, however, had greater decrements in FEV1% than those without byssinosis: 5.5% versus 1.8%. A consistent gender effect was observed in which both exposed and unexposed women were found to have greater across-shift decrements in FEV1 than men. The gender difference existed among long-term workers as well as workers who had been employed less than 2 years. Results are related to cotton dust exposure, as has been documented elsewhere. The poorer health status of the women in this study population deserves follow-up.     

A study of the prevalence of ventilatory obstruction in textile workers exposed to cotton dust

A study was conducted in a cotton spinning mill to assess the prevalence of respiratory impairment in 189 asymptomatic workers and 133 byssinotics drawn from various sections of the plant exposed to airborne cotton dust in the work environment. Eight-four healthy controls belonging to the same socioeconomic status and ethnic group having never been exposed to cotton dust or any other pollutant was also studied for the purpose of comparison. Of the 189 asymptomatic workers, 13 (6.8%) suffered from bronchial obstruction whereas only 2 (2.3%) among the control showed obstructive pulmonary impairment. The byssinotics showed a significantly higher prevalence (15.7%) of bronchial obstruction than that (6.8%) observed among the asymptomatic cotton workers (P less than 0.005). Byssinotics (grade II) showed significantly higher prevalence (31.5%) of bronchial obstruction than that (9.4%) observed in acute byssinotics (grade I). The effect of smoking on the prevalence of bronchial obstruction in the asymptomatic and byssinotics was quite discernible as smokers showed significantly higher prevalence than that observed among the nonsmokers (P less than 0.05). The asymptomatic cotton workers and those with different grades of byssinosis having more than 10 years of exposure showed significantly higher prevalence of bronchial obstruction than that observed in the group with less than 10 years of exposure (P less than 0.005). The healthy cotton workers and byssinotics engaged in the preparatory section (card, blow, and waste plant rooms) showed an insignificant higher prevalence of bronchial obstruction (11.3 and 24.4%, respectively) than among those who worked in the spinning, reeling, and winding sections of the mill. The mechanism responsible for causing ventilatory obstruction in the textile workers is discussed.     

Byssinosis: a follow-up study of cotton ginnery workers in the Sudan.

A follow-up study of lung function tests and dust measurements was undertaken in ginnery workers employed in five ginning factories. Respiratory symptoms and respiratory function tests (FEV1 and FVC) were first recorded in 1967 on a total of 382 workers (323 permanently employed ginnery workers, 35 seasonal farfara workers, and 24 fire brigade men as controls). In 1969 after a six-month break from ginning before the start of the season, a follow-up study of lung function tests was undertaken on 96% of the same workers (306 ginnery workers, 35 farfara, and 24 fire brigade men). Because of the lapse of two years a new adjustment for age and height was made so as to compare the FEV1 measured in the follow-up study. The fire brigade men showed an expected fall in FEV1 during the two-year period, whereas the ginnery workers showed a rise presumably because they had had no dust exposure during the previous six months. The differences between the degree of change in these groups were statistically significant. In 1967 only the fine dust (less than 7 mum) was measured, while in 1969 the concentration of fine and medium dust, that is, less fly was measured. The factories were divided into three groups according to dust concentration. Comparison between the three factory groups and farfara shows a positive association between the level of dust concentration less fly and the prevalence of cough and phlegm. Since age did not appear to be a significant factor in the prevalence of byssinosis, comparisons between permanent workers in these three groups of factories and farfara workers taken separately were made without age standardization. The overall differences were statistically significant. There was a marked trend showing a positive association between prevalence of byssinosis and level of cotton dust concentration in the factories. The correlation between dust levels and the prevalence of byssinosis was nearly perfect when the time factor was included.     

A comparative study of respiratory function in female non-smoking cotton and jute workers

Valić, F., and Žuškin, E. (1971).Brit. J. industr. Med.,28, 364-368. A comparative study of respiratory function in female non-smoking cotton and jute workers. To compare the effect of cotton and jute dust, respiratory symptoms were studied and respiratory function measured in 60 cotton and 91 jute non-smoking female workers of similar age distribution, similar length of exposure to dust, and exposed to similar respirable airborne dust concentrations. Cotton workers had a significantly higher prevalence of byssinosis, of persistent cough, and of dyspnoea (P < 0·01) than jute workers. Among cotton workers 28·3% were found to have characteristic symptoms of byssinosis, whereas none was found among jute workers.

Exposure to cotton but also to jute dust caused significant reductions of FEV_1·0, FVC, and PEF (P < 0·01) over the first working shift in the week. Functional grading of jute and cotton dust effects has shown that about 30% of cotton workers had functional grades F1 and F2, while only 13% of jute workers were found in the same grades (F1). It is concluded that cotton dust may be considered more active than jute though the latter cannot be considered inactive.

     

Cotton dust inhalation and upper respiratory tract disease

Summary An epidemiological study among 203 workers of whom 119 were exposed to cotton dust and 84 controls revealed the occurence of byssinosis among 20.1% of the exposed group. Radiological examination of nasal sinuses was performed and the diagnosis was made without previous knowledge of the state of exposure of the workers or their pulmonary diagnosis. The exposed group showed a significant difference in the occurence of chronic bacterial sinusitis which also increases in prevalence by the increased duration of exposure to cotton dust. Non specific respiratory disease was significantly higher in prevalence among exposed workers (14.3%). No significant difference of allergic sinusitis was observed in the two groups although the whole population examined showed noticeably high rates of sinus diseases. Most of the air-borne cotton dust is composed of large fibers which have a greater probability of retention in the nasal and upper respiratory passages. Chronic irritation from this dust and superadded infection may explain the higher ration of chronic bacterial sinusitis and non specific respiratory disease. There was no association between byssinosis and any form of sinusitis.     

Occupational-type exposure tests and bronchoalveolar lavage analyses in two patients with byssinosis and two asymptomatic cotton workers

Summary Two workers suffering from stage III byssinosis and claiming for compensation were examined. Bronchial obstruction was present in one case. MEF_25–75 values were significantly reduced and bronchial hyperreactivity was present in both subjects. Occupational-type exposure tests with cotton dust resulted in significant decreases in arterial oxygen pressure for more than 2 h and were associated with an obstructive ventilation pattern in one of the patients. Prolonged hypoxemia which is not paralleled by lung function changes is probably typical for byssinosis patients since we have never seen this in inhalative challenge tests with various environmental antigens and other occupational substances including flour dust. No specific IgE or IgG antibodies could be detected. In the two patients a hitherto unknown significant increase in CD23+ lymphocytes and granulocytosis were detected by bronchoalveolar lavage (BAL). Corresponding investigations in two cotton workers without any evidence of byssinosis revealed neither lung function changes after the exposure test nor striking BAL findings. Our results demonstrate the diagnostic value of specific challenge tests and BAL investigations in patients suffering from byssinosis, which is often difficult to diagnose.     

Respiratory disability in ex-cotton workers.

A high proportion of textile workers handling cotton and flax complain of respiratory symptoms and show a loss in lung function. These effects are reversible in the early stages but the degree to which they lead to permanent respiratory disability is unknown. Two surveys were therefore conducted in which respiratory function and symptoms were compared in ex-textile workers and in control subjects who had never been exposed to textile dusts. One survey was of ex-flax workers in Northern Ireland. The present survey was of ex-cotton workers in Lancashire. A survey of random population samples in Oldham and Bolton, in both of which cotton had formerly been the most important source of employment, was conducted. After allowing for age, height, and smoking, lung function was about 2-8% lower in the ex-textile workers than in controls who had never been exposed to any dust. Ex-textile workers were slightly shorter than the controls, suggestive of past social and nutritional deprivation which may have contributed to the decrement in lung function. There was evidence of a small but increasing decrement in lung function with an increase in a "dust exposure" score. For men, about 15 years of heavy dust exposure was associated with a loss in FEV1 equivalent to that shown by light or ex-smokers. For women, 15 years of heavy dust exposure appeared to be associated with a decrement in FEV1 about half that of light smoking.     

Respiratory disability in ex-cotton workers

A high proportion of textile workers handling cotton and flax complain of respiratory symptoms and show a loss in lung function. These effects are reversible in the early stages but the degree to which they lead to permanent respiratory disability is unknown. Two surveys were therefore conducted in which respiratory function and symptoms were compared in ex-textile workers and in control subjects who had never been exposed to textile dusts. One survey was of ex-flax workers in Northern Ireland. The present survey was of ex-cotton workers in Lancashire. A survey of random population samples in Oldham and Bolton, in both of which cotton had formerly been the most important source of employment, was conducted. After allowing for age, height, and smoking, lung function was about 2-8% lower in the ex-textile workers than in controls who had never been exposed to any dust. Ex-textile workers were slightly shorter than the controls, suggestive of past social and nutritional deprivation which may have contributed to the decrement in lung function. There was evidence of a small but increasing decrement in lung function with an increase in a "dust exposure" score. For men, about 15 years of heavy dust exposure was associated with a loss in FEV1 equivalent to that shown by light or ex-smokers. For women, 15 years of heavy dust exposure appeared to be associated with a decrement in FEV1 about half that of light smoking.     

Byssinosis among Winders in the Cotton Industry

In a mill spinning coarse cotton the prevalence of byssinosis and other respiratory symptoms, and the F.E.V._1·0, were measured in a group of 29 men and 117 women employed in the winding room. All the men and 95% of the women at risk were included.

Dust concentrations, measured with a modified Hexhlet at various work points in the winding room, ranged from 1·65 to 6·05 mg./m.³ total dust. These concentrations are higher than 1·0 mg./m.³, which is the threshold limit value for cotton dust recommended by the American Conference of Governmental Industrial Hygienists. The mean dust concentration was 3·48 mg./m.³ compared with 2·85 mg./m.³ in the card room of the same mill.

The prevalence of byssinosis was 18·8% among the women and 13·8% among the men. A comparison among the women showed that those with symptoms of byssinosis had, on the average, significantly lower F.E.V.s than women of similar age without such symptoms. Four women and one man with moderately severe symptoms of byssinosis showed evidence of permanent respiratory disability with effort intolerance and a substantial diminution in F.E.V._1·0. Further studies should be carried out in other winding rooms because, if these findings are repeated elsewhere, they would indicate the necessity for medical surveillance, dust control, and extending the compensation scheme to include winding room workers.

     

Role of histamine in the aetiology of byssinosis. I Blood histamine concentrations in workers exposed to cotton and flax dusts

The formation or the accumulation, or both, of histamine in the lungs may be potentiated by agent(s) present in cotton dust at higher level(s) than in flax dust and negligible in cottonseed dust. It has been suggested that such potentiation may be due to the activation of the ability of the lung to produce histamine and/or produce or recruit mast cells; this may present an acceptable explanation of the mechanism by which the propagation of the chronic effect of the dust proceeds in cotton and flax workers. Histamine accumulated in the lung over the weekend is released on exposure to dust causing the symptoms of byssinosis. The difference in the rate of histamine metabolism relative to the rate of histamine formation in byssinotic subjects leads to a more prolonged histamine accumulation than in symptom free subjects, with the consequent appearance of the symptoms of byssinosis. Continuous exposure to dust, without weekend interruption, leads to equivalent rates of histamine formation and metabolism with non-considerable histamine accumulation in the lungs and consequent absence of the symptoms of byssinosis.     

Role of histamine in the aetiology of byssinosis. I Blood histamine concentrations in workers exposed to cotton and flax dusts.

The formation or the accumulation, or both, of histamine in the lungs may be potentiated by agent(s) present in cotton dust at higher level(s) than in flax dust and negligible in cottonseed dust. It has been suggested that such potentiation may be due to the activation of the ability of the lung to produce histamine and/or produce or recruit mast cells; this may present an acceptable explanation of the mechanism by which the propagation of the chronic effect of the dust proceeds in cotton and flax workers. Histamine accumulated in the lung over the weekend is released on exposure to dust causing the symptoms of byssinosis. The difference in the rate of histamine metabolism relative to the rate of histamine formation in byssinotic subjects leads to a more prolonged histamine accumulation than in symptom free subjects, with the consequent appearance of the symptoms of byssinosis. Continuous exposure to dust, without weekend interruption, leads to equivalent rates of histamine formation and metabolism with non-considerable histamine accumulation in the lungs and consequent absence of the symptoms of byssinosis.     

A chemical and engineering analysis of dust in textile mills

Proximate chemical analysis was conducted on the carding, spinning and weave rooms of textile mills. The dust was found to be composed of inorganic, cellulosic and noncellulosic organics in carding and spinning. The percentage of noncellulosic organic (the component of cotton dust considered to be responsible for byssinosis in cotton textile workers) in ring spinning was found to be one-half the percentage composition of the card room dust. The cellulosic percentage of spinning room dust is elevated above that found in card rooms. In weave rooms the composition of dust is a function of the fabric being produced, environmental control systems, and machinery. In all weave rooms where dust levels were sufficiently above background, all components of the dust were accounted for by the proximate chemical analysis without the presence of a noncellulosic organic component. The card room, spinning room and weave room produce dusts that are very different in composition, to the extent that the proximate chemical analysis could identify the area of origin of dust samples from a textile mill.     

Respiratory problems among cotton textile mill workers in Ethiopia.

This study was conducted to investigate the prevalence of respiratory problems, in particular byssinosis, and to explore factors associated with their occurrence among a group of 595 randomly selected workers representing 40.5% of those exposed to dusty operations in a typical Ethiopian cotton textile mill. A standard questionnaire on respiration was administered and pre and postshift forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were determined for each worker; workers found to have byssinosis and other respiratory diseases were compared with workers having no respiratory diseases in terms of the level and duration of exposure to cotton dust and other variables. Multiple area air samples from different sections were analysed for elutriated cotton dust concentrations (0.86-3.52 mg/m3). The prevalence of byssinosis was 43.2% among blowers and 37.5% in carders in comparison with four to 24% among workers in other sections. Prevalence of chronic bronchitis ranged from 17.6 to 47.7% and bronchial asthma from 8.5 to 20.5% across all sections. Significant across shift decrements in FEV1 and FVC were seen in those workers with respiratory tract diseases compared with those workers without such diseases. A significant dose response relation for pulmonary function and respiratory illnesses was also found by regression analysis. Preventive measures are proposed. Further research including a nationwide survey of textile mills is suggested. This is the first epidemiological study of the textile industry in Ethiopia.