Byssinosis and lung health among cotton textile workers: baseline findings of the MultiTex trial in Karachi, Pakistan.

OBJECTIVES: To assess the association of exposure in cotton mills in Karachi with different definitions of byssinosis and lung health. METHODS: This cross-sectional survey took place between June 2019 and October 2020 among 2031 workers across 38 spinning and weaving mills in Karachi. Data collection involved questionnaire-based interviews, spirometry and measurements of personal exposure to inhalable dust. Byssinosis was defined using both WHO symptoms-based (work-related chest tightness), and Schilling's criteria (symptoms with decreased forced expiratory volume in 1 s (FEV1). Values of FEV1/forced vital capacity ratio below the lower limit of normality on postbronchodilator test were considered as 'chronic airflow obstruction' (CAO). RESULTS: 56% of participants had at least one respiratory symptom, while 43% had shortness of breath (grade 1). Prevalence of byssinosis according to WHO criteria was 3%, it was 4% according to Schilling's criteria, and likewise for CAO. We found low inhalable dust exposures (geometric mean: 610 µg/m3). Cigarette smoking (≥3.5 pack-years), increasing duration of employment in the textile industry and work in the spinning section were important factors found to be associated with several respiratory outcomes. CONCLUSION: We found a high prevalence of respiratory symptoms but a low prevalence of byssinosis. Most respiratory outcomes were associated with duration of employment in textile industry. We have discussed the challenges faced in using current, standard guidelines for identifying byssinosis.

Respiratory impairment in cotton-ginning workers exposed to cotton dust.

Dust generated during the handling and processing of cotton causes ill health of ginning workers. The purpose of this study was to determine the prevalence of respiratory symptoms among cotton-ginning workers. This study involved 188 workers of 10 cotton-ginning factories. Forced vital capacity (FVC), peak expiratory flow rate (PEFR), and forced expiratory volume in 1 s (FEV1) declined significantly with increasing duration of exposure (p < .001) of the cotton-ginning workers. Results of a standard respirator medical evaluation questionnaire indicated that, depending on duration of exposure, 51%-71% of cotton-ginning workers suffered from chest tightness, 55%-62% experienced chest pain, while 33%-42% of the workers reported frequent cough. Blood tests of the workers showed higher values of erythrocyte sedimentation rate, eosinophils, and white blood cells when exposure was longer. Byssinosis symptoms were observed among the workers. We recommend regular periodical medical check-ups, compulsory use of personal protective equipment, and proper ventilation at the workplace.

Effect Of Cotton Dust Exposure On Respiratory Health Outcomes Among Textile Workers.

BACKGROUND: Cotton dust is generated during various textile manufacturing processes. Only a few studies from Pakistan assessed cotton dust exposure and explored the relationship of duration of work in the textile industry with respiratory health outcomes. We aimed to assess cotton dust exposure and its association with lung function and respiratory symptoms among textile workers in Pakistan. METHODS: We report findings from the baseline survey of the larger study, MultiTex, among 498 adult male textile workers from six mills conducted between October 2015-March 2016 in Karachi, Pakistan. Data collection included the use of standardized questionnaires; spirometry, and area dust measurements through UCB-PATS. Multivariable logistic and linear regression models were developed to assess the association of risk factors with respiratory symptoms and illnesses. RESULTS: We found the mean age of workers to be 32.5 (±10) years; around 25% were illiterate. The prevalence of COPD, asthma, and byssinosis was 10%, 17%, and 2%, respectively. The median cotton dust exposure was 0.33 mg/m3 (IQR: 0.12-0.76). Increased duration of work among non-smokers was associated with a decline in lung function, FVC (-245 ml; 95% CI: -385.71, -104.89) and FEV1 (-200 ml; 95% CI: -328.71, -841.1). Workers with certain job titles (machine operators, helpers, and jobbers), those with greater duration of work, and higher dust exposure, were more likely to report respiratory symptoms and illnesses. CONCLUSIONS: We report a high prevalence of asthma and COPD and a low prevalence of byssinosis. Cotton dust exposure and duration of employment were associated with respiratory health outcomes. Our findings highlight the need for preventive interventions in the textile industry in Pakistan.

Monitoring of cotton dust and health risk assessment in small-scale weaving industry.

The present study describes the estimation of particulate matter (cotton dust) with different sizes, i.e., PM(1.0), PM(2.5), PM(4.0), and PM(10.0 µm) in small-scale weaving industry (power looms) situated in district Hafizabad, Punjab, Pakistan, and the assessment of health problems of workers associated with these pollutants. A significant difference was found in PM(1.0), PM(2.5), PM(4.0), and PM(10.0) with reference to nine different sampling stations with p values <0.05. Multiple comparisons of particulate matter with respect to size, i.e. PM(1.0), PM(2.5), PM(4.0), and PM(10.0), depict that PM(1.0) differs significantly from PM(2.5), PM(4.0), and PM(10.0), with p values <0.05 and that PM(2.5) differs significantly from PM(1.0) and PM(10.0), with p values <0.05, whereas PM(2.5) differs non-significantly from PM(4.0), with a p value >0.05 in defined sampling stations on an average basis. Majority of the workers were facing several diseases due to interaction with particulate matter (cotton dust) during working hours. Flue, cough, eye, and skin infections were the most common diseases among workers caused by particulate matter (cotton dust).

Contemporary Prevalence of Byssinosis in Low- and Middle-Income Countries: A Systematic Review.

We aimed to identify the contemporary prevalence of byssinosis through a systematic review. Medline, Web of Science, Embase, and Global Health databases were used to identify studies published in any language between 2000 and 2019, reporting primary data on byssinosis among adults. We used the Joanna Briggs Institute checklist to estimate the risk of bias in studies and undertook a qualitative, narrative data analysis. The review considered the prevalence of byssinosis, chest tightness, and airflow obstruction in textile workers in low- and middle-income countries (LMICs). We found 26 relevant studies that included 6930 workers across 12 countries. Most of the studies (n = 19) were from Asia, and seven from African countries. Twenty-five studies were cross-sectional surveys while one was a cohort study. The prevalence of byssinosis was reported by 18 studies, and ranged from 8% to 38%, without any clear associations, at the group level, between the prevalence of byssinosis and durations of workers' exposures. Prevalence of chest tightness ranged between 4% and 58% and that of airflow obstruction between 10% and 30%. A strong correlation (r = 0.72) was found between prevalence of byssinosis and cotton dust levels. Our findings indicate that byssinosis remains a significant, contemporary problem in some parts of the textile sector in LMICs.

Health Concerns of Textile Workers and Associated Community.

BACKGROUND: Workers in the textile industry risk developing various respiratory and pulmonary diseases due to exposure to cotton dust. The particles from the cotton lint are inhaled by the workers and results in the breathing problems including asthma, shortness of breath, cough and tightness in the chest. The poor health of labor contributes to the low productivity of the labor and in serious cases loss of jobs leading to the poverty. OBJECTIVE: To assess the prevalence of respiratory symptoms among the textile workers and associated community. To contrast the health profiles of the textile workers, associated community and the control group to factor out any confounding factors. METHODS: This study explores the health profiles of the textile workers and associated community and contrast them against the health profile of the control group to factor out any confounding factors. The study is conducted on cotton industry in Kasur, Pakistan. We interviewed 207 workers, 226 people from associated community (living in vicinities of weaving units) and 188 people for control group (from areas far away from weaving units and people are not associated with weaving industry) based on stratified random sampling technique. We employed descriptive methods and logistic regression to explore the association between respiratory diseases and weaving workers. RESULTS: Overall, prevalence of postnasal drip, byssinosis, asthma, and chronic bronchitis were 47%, 35%, 20%, and 10%, respectively, among the workers. These percentages are significantly higher than the control group. An additional year of work increase the risk of postnasal drip, byssinosis, asthma, and chronic bronchitis by 5-6%. Among workers, 43% and 21% feel difficulty in hearing against noisy background and at low volume, respectively. Due to bad light arrangements at workstations, 21% and 31% workers are suffering from myopia and hyperopia, respectively. Proportions of the workers suffering from continuous headache, skin infection, depression, and low back pain are 28%, 29%, 27%, and 44%, respectively. Chi-square test results confirms that no confounding factor like air pollution is involved in this cause-and-effect study implying the association between the cotton dust and associated diseases is not spurious. CONCLUSION: Respiratory symptoms were statistically significantly more common in the weaving workers compared to control group. Better environment at workstations, use of protective gears and education are the factors which reduce the risk of associated diseases among workers.

Epidemiology of respiratory diseases and associated factors among female textile workers in Pakistan.

Objective. The study aimed to estimate the prevalence of byssinosis and other respiratory symptoms among women textile workers and the associated risk factors in 18 spinning mills of Faisalabad and Lahore districts of Punjab, Pakistan. Method. In this case-control study of 1054 female workers, we used the dose-response function to measure the association between dust level and respiratory disorders in cotton textile workers. Results. Working overtime and long working hours per week are significantly associated with self-reported symptoms of byssinosis. Women's age, marital status and wages were significantly associated with mitigating actions (seeing the doctor), while the education of the women was significantly associated with averting action (use of a mask). Conclusion. Regulating working hours and ensuring employees' compliance with the safety standards are expected to mitigate the health problems of female workers.

Long-term effects of work cessation on respiratory health of textile workers: a 25-year follow-up study.

RATIONALE: The degree to which chronic respiratory health effects caused by exposures to cotton dust and endotoxin is reversible after cessation of textile work is unknown. OBJECTIVES: To investigate changes in lung function and respiratory symptoms after cessation of textile work and to determine whether past exposure to cotton dust and endotoxin or smoking history modify the associations. METHODS: We performed a prospective cohort study consisting of 447 cotton textile workers exposed to cotton dust and 472 unexposed silk textile workers, with a 25-year follow-up. Spirometry testing and respiratory questionnaires were conducted at 5-year intervals. Generalized estimated equations were used to model the average 5-year change in FEV(1) and odds ratios of respiratory symptom prevalence. MEASUREMENTS AND MAIN RESULTS: Years since cessation of textile work was positively associated with 11.3 ml/yr and 5.6 ml/yr gains in 5-year FEV(1) change for cotton and silk workers, respectively. Among male cotton workers, smokers gained more FEV(1) per year after cessation of exposure than did nonsmokers, and the risk of symptoms of chronic bronchitis and byssinosis was larger for smoking than for nonsmoking male cotton workers. CONCLUSIONS: Cessation of textile work was significantly associated with improvement in lung function and respiratory symptoms. The positive effect of work cessation was greater for cotton workers than for silk workers. For cotton workers, the improvement in lung function loss after cessation of textile work was greater among smokers, but no differences were observed for silk workers.

Byssinosis and tuberculosis amongst "home-based" powerloom workers in Madhya Pradesh State, India.

BACKGROUND: Byssinosis is an occupational lung disease observed among workers exposed to cotton, flax, and hemp dust. The severity and extent of Byssinosis are well recognised in the high-income countries and control measures have been implemented to prevent the disease. In India, there are conflicting evidence on burden estimation of the disease, followed by inadequate prevention and control of Byssinosis. DESIGN/METHODS: We did a cross-sectional study to assess the prevalence of Byssinosis in "home-based" power-loom workers in Mominpura, an administrative ward of Burhanpur Municipality with 2800 population in the state of Madhya Pradesh, India. 290 adults working from "home-based" power loom units were randomly selected, profiled and screened for Byssinosis like symptoms with the help of a semi-structured questionnaire and simple hand-held peak expiratory flow monitor. For epidemiological purposes the symptoms were classified based on Schilling's classification. Chest x-rays were done for selected subjects. Sputum smear microscopy for detecting TB was done for those who had Byssinosis like symptoms. RESULTS: Prevalence of Byssinosis among "home based" powerloom workers was found to be 98% [n = 283, 95 CI (95.65-98.96)]. Peak expiratory flow rate (PEFR) was reduced in 44% (n = 124), of which 81 (29%) had more than 50% PEFR reduction, and of these, 69 (29%) were in early stage of Byssinosis (Grade 0.5). 11% of study participants who had Byssinosis like symptoms, also had TB. CONCLUSIONS: Byssinosis is highly prevalent in "home-based" power loom units in Madhya Pradesh. Adequate advocacy on awareness and prevention; prompt diagnosis and linkages to treatment services in "home-based" power loom units are urgently required to address Byssinosis at an early disease stage.

Byssinosis: as seen in cotton spinning mill workers of Karachi.

OBJECTIVE: To identify Byssinosis in cotton spinning mill workers, probable associations of disease with factors such as different work areas, safety gadget usage and overtime and to ascertain proportions of byssinosis to accidental injuries. METHODS: This study was conducted in a spinning mill of Karachi in June 2006. Mill workers who had worked for a period of minimum 5 years were selected. A sample size of 83 conveniently selected workers participated in the research study. Data collection was done via questionnaire, and pulmonary function tests. RESULTS: The mean age of the sample was 30 +/- 6.9 years. Of all the workers 72% used safety gadgets (masks) while working and 50% availed overtime. Smokers amounted to 31% of the total subjects. Around 35% workers complained of having respiratory ailments of which 19% (16 workers) closely matched byssinotic symptoms. Pulmonary Function Tests (PFTs) confirmed 13 of 16 workers to be byssinotics, with the remaining being labeled as Probables. The overall proportion of Byssinotics in the mill was 19.28% (95% C.I. 11-27) and that of accidental injuries was 22.9%. The association of byssinosis with respect to work areas was significantly high in Ring area (O.R. = 2.04) followed by carding (O.R. = 1.3). The association of byssinosis was also high in workers who did not use safety gadgets, e.g. dust masks (O.R = 4.89) and in people who worked overtime (O.R. = 1.82). Associations with respect to duration of employment and smoking could not yield significant results. CONCLUSION: Results indicate a very high probability of association of disease to non-usage of safety gadgets and overtime working. Studies comprising of a greater sample size would show precisely the overall prevalence of the disease.

Prevalence of byssinosis and other respiratory problems among textile mill workers in Asaba, Nigeria.

OBJECTIVES: This study was conducted to determine the distribution and severity of byssinosis and other respiratory problems in the different operation sections in a textile mill industry in Asaba. PATIENTS AND METHODS: This is a cross-sectional and analytic study in which workers directly exposed to cotton dust are compared with those not directly exposed to cotton dust at one point in time. RESULTS: A total of 735 workers were interviewed and 437 workers had respiratory examinations carried out on them. Byssinosis was diagnosed in 8 out of 405 workers (prevalence of 1.98%) who were not directly exposed to cotton dust, and 21 out of 330 workers (prevalence of 6.36%) who were directly exposed to cotton dust. The difference was found to be statistically significant (chi2 =9.25; df=1; 0.01

Byssinosis and COPD rates among factory workers manufacturing hemp and jute.

OBJECTIVES: Prior studies have been performed on cotton textile plants throughout the world. This study was planned to identify the rate of byssinosis and chronic obstructive pulmonary disease (COPD) in hemp and jute workers and those who worked with both of them. MATERIAL AND METHODS: The study was realized in a factory which consecutively processed hemp and jute. The study enrollment included 266 people, 164 of whom were active workers and 102 were retired. A questionnaire, plain chest X-rays, physical examination and pulmonary function tests were performed. Dust levels were measured in various sections of the factory during 8 h work shifts. Endotoxin levels of various quality hemp fibers and dusts were measured. RESULTS: The rate of byssinosis (28.2%) was higher among the workers that who exposed to both jute and hemp dust. The frequency of chronic bronchitis in retired workers who previously smoked was higher (20%) as compared to currently smoking workers (17%). High dust levels were measured in some parts of the factory (mean (M) = 2.69 mg/m3). Working in dense dust areas, active smoking, being older than 40 years of age, being an ex-smoker, and working in the factory for a period exceeding 15 years were significantly associated with bronchitis and emphysema development. High endotoxin levels were determined for fine hemp dust (605 EU/mg), coarse hemp dust (336 EU/mg) and poor quality hemp fibers (114 EU/mg), whereas in fresh hemp stalks the level of endotoxin was determined to be lower (0.27 EU/mg). CONCLUSIONS: Because of high exposures to jute and hemp dusts that are associated with high byssinosis rates, personal protection and environmental hygiene is crucial to prevention of byssinosis.

[Other obstructive diseases: byssinosis, chronic bronchitis and occupational COPD and eosinophilic bronchitis]. / Otras enfermedades obstructivas: bisinosis, bronquitis crónica y EPOC de origen laboral y bronquitis eosinofílica.

Besides occupational asthma and diseases derived from acute inhalation, other obstructive diseases also have an occupational origin. Although at present byssinosis is a rare disease in Spain, we describe its characteristics because of its historical interest amongst occupational respiratory diseases and because it is still relevant in developing countries. Chronic bronchitis can also be related to exposure at work to dust and smoke, and is often referred to as "industrial bronchitis". Historically, the relation of CPOD to occupation has been subject to controversy, but nowadays this relationship is accepted; we describe the present evidence supporting this relationship. Finally, we describe eosinophilic bronchitis without asthma, an entity that was described for the first time in 1989 and that can sometimes have an occupational origin, sharing aetiological agents with occupational asthma.

Metal fume fever and polymer fume fever.

INTRODUCTION: Inhalational exposure to metal-containing fumes generated by welding and related processes may result in the development of the clinical syndrome known as "metal fume fever." Polymer fume fever is a separate and distinct but related disorder that has been associated with inhalational exposure to specific fluorinated polymer products, such as polytetrafluoroethylene or Teflon(®). We undertook a review of the peer-reviewed medical literature as it relates to these two disease entities in order to describe their epidemiology, pathophysiology, clinical presentation, diagnosis, treatment, prevention, and prognosis. METHODOLOGY: We performed a search of the PubMed ( www.pubmed.com ) and Ovid MEDLINE (ovidsp.tx.ovid.com) databases for keywords "metal fume fever," "polymer fume fever," and "fume fever," covering the period 1946 to September 2014, which resulted in a total of 141 citations. Limiting the search to articles published in the English language yielded 115 citations. These 115 articles were manually reviewed for relevance. In addition, the reference lists in each article retrieved were reviewed for additional relevant references. This left 48 relevant citations. EPIDEMIOLOGY: Metal fume fever occurs most commonly as an occupational disease in individuals who perform welding and other metal-joining activities for a living. It is estimated that 1,500-2,500 cases of metal fume fever occur annually in the United States. Polymer fume fever was initially identified as an occupational disease but increased regulations have resulted in decreased incidence in the occupational setting. Overheating of Teflon(®)-coated cookware is one of the more common mechanisms for exposure. PATHOPHYSIOLOGY: While the precise pathophysiology associated with the development of metal fume fever is yet to be elucidated, suggested pathophysiologic mechanisms include pro-inflammatory cytokine release, neutrophil activation, and oxygen radical formation. The pathophysiologic mechanism for polymer fume fever has not been definitively elucidated but may involve similar mechanisms to those proposed for metal fume fever. CLINICAL PRESENTATION: Metal fume fever typically presents with generally non-specific complaints including influenza-like symptoms, fever, shaking chills, arthalgias, myalgias, headache, and malaise. Onset of symptoms typically occurs 4-10 h following the exposure to metal-containing fumes. While metal fume fever is typically benign and self-limited, severe cases of the disease have been reported. In patients with ongoing metal fume exposure over the course of a workweek, tachyphylaxis occurs resulting in improvement in symptoms over the course of the workweek and maximal symptoms occurring after an exposure-free period such as a weekend. The clinical presentation of polymer fume fever is indistinguishable from metal fume fever, with an exposure history being necessary to distinguish the two entities. DIAGNOSIS: Chest radiographs are typically normal in cases of metal fume fever and polymer fume fever; however, mild vascular congestion may be demonstrated and severe cases may feature diffuse patchy infiltrates. Laboratory studies are typically not necessary but may demonstrate leukocytosis with leftward shift or an elevated erythrocyte sedimentation rate. TREATMENT: The primary treatment for both metal fume fever and polymer fume fever is supportive and directed at symptom relief. Oral hydration, rest, and the use of antipyretics and anti-inflammatory medications (e.g., non-steroidal anti-inflammatory drugs and aspirin) are recommended. A careful workplace exposure assessment analysis conducted by an occupational medicine specialist or clinical toxicologist in concert with a qualified industrial hygienist should be performed. PREVENTION: A careful workplace exposure assessment including measurement of ambient zinc and other metal (e.g., chrome, nickel, copper and manganese) fume concentrations or concentrations of fluorocarbon polymer decomposition products at different locations within the workplace should be performed. PROGNOSIS: Metal fume fever is typically a benign and self-limited disease entity that resolves over 12-48 h following cessation of exposure. CONCLUSIONS: Metal and polymer fume fevers generally follow a benign course with spontaneous resolution of symptoms, though both have the potential to be serious, especially in those with significant preexisting cardiorespiratory disease.

Compensation for byssinosis in Great Britain.

Byssinosis first became compensatable in Great Britain in May 1941. The claimants were examined by a specially constituted board consisting of chest physicians and medical specialists from the Manchester area. Following the Industrial Injuries Act of 1946, which became operative in July 1948, the examinations were taken over by the Manchester Pneumoconiosis Medical Panel. At first only men who had worked for at least 20 years up to and including cotton carding processes could claim. They had to be permanently and totally incapacitated by the disease. Women workers were included from July 1948, and the disablement required was reduced from total to 50 percent in December 1948. As experience with the diagnosis was gained, the law was changed to cover any degree of disablement in 1956, and in 1974 those with byssinosis grade II was accepted. In 1956 ten years replaced the 20-year qualifying period in the cotton industry, reduced to five years in 1974 and to any period in 1979. In 1951 insurance against the disease was extended to workers in the waste cotton industry and in 1965 to workers in the flax industry. In 1974 the scheduled area in the mill was extended from the carding process up to and including beaming and winding.

A longitudinal study of pulmonary function in cotton gin workers in the San Joaquin Valley.

In a previous study we found no significant effects of acute exposure to the cotton gin environment on FEV1 in San Joaquin Valley gin workers compared with concurrent control subjects, nor was there an excess of obstructive lung disease among the same gin workers. The present study looked at the mean annual decline in FEV1, FEV1/FVC, and FEF25-75% in San Joaquin Valley cotton gin workers vs concurrent control subjects over four years. The FEV1 of gin workers completing all four years of the study declined 27.3 ml vs 35.5 ml in control subjects (p = 0.37); FEV1/FVC declined 0.21 percent in gin workers and 0.23 percent in control subjects (p = 0.86); FEF25-75% declined 0.058 L/s in gin workers and 0.066 L/s in control subjects (p = 0.68). Also, the mean annual rate of change of FEV1 was less among the gin workers who did not complete all four years than the gin workers completing all four years. The presence of "byssinosis" symptoms did not significantly influence the results. This prospective, longitudinal study failed to find any detrimental effect of the cotton gin environment on the rate of decline of FEV1, FEV1/FVC, and FEF25-75%. This result was independent of "byssinosis" symptoms and the effect of "dropouts."

Pulmonary function among cotton textile workers. A study of variability in symptom reporting, across-shift drop in FEV1, and longitudinal change.

Longitudinal variability in respiratory responses, including symptom reporting and across-shift change in ventilatory function, were examined in relation to long-term loss of ventilatory function in a group of 447 cotton textile workers in Shanghai, China. The study used a standardized respiratory questionnaire and standardized spirometric testing before and after a work shift on the first day of the workweek. Prediction equations for FEV1 were generated from a group of silk textile workers from the same city. Environmental samples included both vertical elutriated cotton dust and endotoxin levels. There was considerable variability in symptom reporting between the baseline and 5-year follow-up survey for all symptoms. However, subjects who consistently reported symptoms had a significantly accelerated 5-year loss in FEV1 compared with those who never reported symptoms. Subjects with symptoms of chest tightness or dyspnea at one survey lost FEV1 at a rate intermediate between the never or both groups. Moreover, subjects with an across-shift change in FEV1 of more than 5 percent at both surveys had the greatest loss in FEV1 over 5 years (-267 ml) when compared with one-time responders (-224 ml), and nonresponders (-180 ml), though the differences were not significant. Workers with chest tightness and chronic bronchitis in both surveys were overrepresented in the high dust and endotoxin areas. Our results indicate that even with substantial survey-to-survey variability in responses, there is important information contained in both questionnaires and across-shift spirometry. Among cotton workers, consistent responders to either symptom questionnaire or across-shift FEV1 decrements of > or = 5 percent appear to be at increased risk for lung function impairment.

The use of pulmonary function testing and questionnaires as epidemiologic tools in the study of occupational lung disease.

Pulmonary function testing and questionnaires are valuable tools in epidemiologic studies of occupational lung disease. Accurate equipment and standardized methodology are vital to obtain reproducible responses. For spirometry, the FVC and FEV show the least intrasubject variability and on questionnaires, occupational and smoking history are more reproducible than symptoms. The limitations of any method used to define a lower limit of normal should be kept in mind and, whenever possible, groups should be compared by use of the distribution of observations in the two groups--not just the prevalence of "abnormal" findings.

Some observations on epidemiologic studies in Egyptian gins, cotton pressing plants and cottonseed oil extraction plants.

The follow-up studies presented in this report wee conducted to evaluate the impact of the relative technical improvements that took place in the cotton processing industries of Egypt in the last 10-15 years on the health of the workers. Results have indicated tha: 1) the health status of the workers has been relatively improved; however, their work environment is far from being safe. 2) The prevalence of byssinosis and reduction in FEV1 during the first day of work after the weekend are related to the duration of exposure, level of dustiness and content of plant debris in dust. 3) Chronic effect of exposure to cotton dust, demonstrated as reduction in predicted FVC, develops in workers continuing exposure for long durations, even if the classic symptoms of byssinosis and reduction in FEV1 do not occur. 4) Women workers are more liable to be affected by cotton dust exposure than the men. 5) "Cottonseed dust" may not be a "byssinnogenic" dust; however, it is capable of producing ventilatory function effects similar to those produced by cotton dust.

The respiratory effects of cotton dust.

It is apparent that occupational exposure to cotton dust, and in vivo exposure to its components, may result in a number of cellular and humoral events. These include specific antibody formation, mediator release, complement activation, endotoxin effects, and related phenomena. The role of these, either singly or in combination, in the pathogenesis of cotton dust-induced lung disease awaits elucidation. Provocative inhalation challenge studies, using well-characterized standard cotton dusts with careful monitoring of physiologic effects, and in vitro assays will provide answers to some of these questions. Development of a suitable animal model would prove to be invaluable for studying the etiology of the disease and might permit evaluation of the relationship of the acute disease to any chronic effects. It is likely that several pathogenetic mechanisms may be found to be operative and that other, as yet untested, effects such as activation of arachidonic acid metabolism may play an important role in the development of this disease.