The effect of cigarette smoking on the detection of small radiographic opacities in inorganic dust diseases

Our plain-English summary of The effect of cigarette smoking on the detection of small radiographic opacities in inorganic dust diseases, by P.D. Blanc, G. Gamsu (Journal of Thoracic Imaging, 1988).

The study

• Authors: P.D. Blanc, G. Gamsu
• Journal: Journal of Thoracic Imaging
• Published: 1988;3(4):51-6
• Type of article: Review
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000890).

Abstract

Whether cigarette smoking can cause radiographic opacities indistinguishable from those due to pneumoconiosis remains controversial. The situation becomes clearer when one limits the abnormalities to those that can be standardized under the International Labour Office (ILO) classification system. The bulk of the evidence indicates that, using the ILO system, cigarette smoking alone is not associated with radiographic opacities that would be mistaken for pneumoconiosis with sufficient frequency to be of any practical importance. The effects of cigarette smoking, as a cofactor, in conjunction with occupational dust exposure depend on the type of dust. No relationship has been convincingly demonstrated for coal dust or silica. Only with asbestos exposure does there appear to be a significant cigarette smoking-associated increase in the frequency of irregular radiographic opacities. This increase does not appear to translate into a restrictive impairment in pulmonary function. The limited information available indicates that the features of asbestosis on high-resolution computed tomography are not similarly related to cigarette smoking. Additional research is needed to substantiate the relationship between smoking and occupational exposure to dust of many types, and also the possible imaging and pathophysiologic significance of their interactions.

In plain English

This article was a review, not a new study. The authors examined published studies that scored chest X-rays with the International Labour Office (ILO) system, to see whether cigarette smoking causes or adds to small lung shadows (opacities) resembling dust-related lung disease (pneumoconiosis). In people without dust exposure, such findings were rare. In the largest reviewed study, 3 (0.21%) of 1,422 radiographs scored 1/0 or greater. In asbestos-exposed groups, several studies reported higher rates in smokers. In one study of 1,117 asbestos workers, abnormalities appeared in 365 (40.8%) of 894 smokers and 57 (25.6%) of 223 nonsmokers. The authors judged that no relationship had been convincingly shown for coal dust or silica, that a link with pleural abnormalities was not clearly established, and that the asbestos-smoking increase did not appear to translate into restrictive lung impairment. In their own unpublished study of 100 heavily exposed shipyard workers, they found no correlation between high-resolution CT signs of asbestosis and smoking. The authors concluded that smoking cannot be considered an independent factor in these X-ray abnormalities.

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: Review of published studies
• Who was studied: Published studies that used ILO chest X-ray criteria, covering populations not occupationally exposed to inorganic dust and populations exposed to asbestos, coal dust and silica
• Exposure: Cigarette smoking, alone and as a cofactor with occupational dust exposure (asbestos, coal dust, silica, plus other dusts such as perlite, carbon black, kaolin and synthetic vitreous fibers)
• Main results:
  • In the largest reviewed study of people not exposed to dust, 3 (0.21%) of 1,422 radiographs had ILO scores of 1/0 or greater
  • The authors estimated that X-ray abnormalities that could be confused with pneumoconiosis probably occur in less than 1% of employed, presumably healthy populations, regardless of smoking
  • In one reviewed study of 1,117 asbestos workers, 365 (40.8%) of 894 smokers and 57 (25.6%) of 223 nonsmokers had radiographic abnormalities consistent with pneumoconiosis (relative risk 1.6 for smokers)
  • A reviewed study of 367 vermiculite (asbestos) miners reported a significant smoking-associated excess risk (odds ratio 5.58)
  • The authors' own earlier research on shipyard workers found a significant smoking-associated relative risk of parenchymal opacities, highest (relative risk 13.0) in the heaviest smokers
  • In the authors' unpublished study of 100 heavily exposed shipyard workers, 45 had clinical asbestosis and 58 had HRCT abnormalities strongly suggestive of asbestosis; no correlation was found between these HRCT abnormalities and smoking history
  • Only with asbestos exposure did there appear to be a significant smoking-associated increase in irregular opacities
  • No relationship had been convincingly demonstrated for coal dust or silica
  • An association between smoking and ILO-scored pleural abnormalities had not been clearly established
  • The asbestos-related smoking increase did not appear to translate into restrictive impairment of lung function
• The authors' conclusion: The authors concluded that cigarette smoking cannot be considered an independent factor associated with X-ray abnormalities consistent with pneumoconiosis. As a cofactor with dust exposure, they found it appears to have a role in asbestos-related X-ray findings, but possibly not in asbestosis detected with HRCT.
• Limitations the authors state:
  • The ILO system was not designed as a clinical diagnostic tool or as a method to determine compensation
  • The authors acknowledged that relying only on ILO-based studies is not universally accepted
  • Data and analyses for coal dust and silica were weaker than for asbestos

Topics

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

Related studies

• Cigarette smoking and small irregular opacities — W. Weiss (1991)
• Characterization of the lower respiratory tract inflammation of nonsmoking individuals with interstitial lung disease associated with chronic inhalation of inorganic dusts — W.N. Rom, P.B. Bitterman, et al. (1987)
• Interaction of asbestos, age, and cigarette smoking in producing radiographic evidence of diffuse pulmonary fibrosis — K.H. Kilburn, R. Lilis, et al. (1986)
• Induction of thoracic malignancy in inorganic dust pneumoconiosis — J.C. Scatarige, F.P. Stitik (1988)
• Relative importance of cigarette smoking in occupational lung disease — P.C. Elmes (1981)
• Cigarette smoke, asbestos, and small irregular opacities — W. Weiss (1984)

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