Chronic bronchitis in cotton textile workers. Evidence for addition of effect of cigarette smoking and occupational exposure

Our plain-English summary of Chronic bronchitis in cotton textile workers. Evidence for addition of effect of cigarette smoking and occupational exposure, by K. H. Kilburn, J. Merchant, J. Lumsden, et al.

The study

• Authors: K. H. Kilburn, J. Merchant, J. Lumsden, J. Hamilton
• Published: n.d.
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This short report, which is about cotton dust rather than asbestos, briefly presented the authors' studies of chronic bronchitis among workers at two textile mills in North Carolina, USA: a cotton thread plant and a woolen yarn plant, each employing slightly over 400 workers. Among women, less than 1% of non-smoking wool workers had chronic bronchitis. The figure was approximately 8% for non-smoking cotton workers, about 13% for smoking wool workers and 27% for smoking cotton workers. Among men, the rate was 3% for non-smoking wool workers and about 20% for non-smoking cotton workers. For smoking wool workers it was 12% below age 40 and 19% above, and smoking cotton workers averaged 25%. Chronic bronchitis was more common with more severe byssinosis. In a model cardroom with 12 men, the fall in lung function (FEV1) during work tracked chest symptoms, and washing or steaming the cotton reduced that fall. The authors concluded that cotton dust and smoking had an additive effect. They noted that workers with breathlessness, which they said represented more severe chronic bronchitis, quit work and were lost to the study.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Brief preliminary report by the authors of their own studies: a prevalence survey of chronic bronchitis in workers at a cotton mill and a wool mill, plus exposure experiments in a model cardroom. The full report was to be published elsewhere.
• Who was studied: Workers at two textile mills in small cities in North Carolina, USA: a cotton thread plant and a woolen yarn plant, each employing slightly over 400 workers. The model cardroom experiments used 12 men as test subjects.
• Exposure: Cotton dust (compared with wool work, unexposed to cotton dust) and cigarette smoking. In the model cardroom, cotton was carded untreated or after heating to 112°C, washing with water or steaming, with rayon as a synthetic control. Dust was measured with a cyclone separator, and the fine fraction was considered respirable.
• Main results:
  • Women who did not smoke and worked in wool, unexposed to cotton dust: less than 1% had chronic bronchitis.
  • Non-smoking women working in cotton (columns 3 and 4 of Fig. 1; the authors use the same column layout for men, where columns 3 and 4 are non-smoking cotton workers): chronic bronchitis prevalence of approximately 8%.
  • Women wool workers who smoked: a chronic bronchitis rate of about 13%.
  • Women working in cotton who smoked: 27% had chronic bronchitis. The authors described this as more than double the effect of cotton dust or cigarette smoking alone.
  • Men who did not smoke and were unexposed to cotton dust: chronic bronchitis rate of 3%.
  • Non-smoking male cotton textile workers: averaged about 20% with chronic bronchitis, and it was more prevalent in those above age 40.
  • Smoking male wool workers unexposed to cotton: averaged 12% below age 40 and 19% above age 40.
  • Smoking male cotton textile workers, exposed to both: chronic bronchitis prevalence averaged 25%.
  • In cotton workers, byssinosis and chronic bronchitis prevalence correlated best with fine respirable dust in dust samples taken at the same time.
  • In the model cardroom, the fall in FEV1 correlated with the number of workers with chest tightness or shortness of breath. The correlation coefficient for exposure to the five untreated types of cotton was r = 0.95, with the p value printed as "p<<0.005".
  • The model cardroom showed a correlation of r = 0.99 (p value printed as "p<<0.001"). The scanned text naming what was correlated is unreadable; the accompanying figure plots change in FEV1 against respirable dust level.
  • Washing and steaming the cotton reduced the fall in FEV1.
• The authors' conclusion: The authors concluded that their studies of cotton and wool textile workers showed a positive or additive effect of cotton dust exposure and cigarette smoking on chronic bronchitis. This contrasts with many studies that found no occupational effect once smoking was accounted for.
• Limitations the authors state:
  • Workers with breathlessness, whom the authors said represented more severe chronic bronchitis, quit work and are therefore lost to the study population.
  • Methods were not described in detail because they were to be published elsewhere.

Topics

Medical terms in this study, explained in our Lexicon: Occupational Exposure, FEV1.

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