Roentgenologic Aspects Of Silicosis And Asbestosis

Our plain-English summary of Roentgenologic Aspects Of Silicosis And Asbestosis, by L.J. Bristol (1955).

The study

• Author: L.J. Bristol
• Published: Archives Of Industrial Health 11(3):189-195, March (1955)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library, J-M no. 001855. The article is still under copyright, so we describe it here rather than post it.

In plain English

This article is the text of a talk given at a Boston symposium on occupational lung diseases on October 2, 1953. In it, the author, a radiologist at the Trudeau-Saranac Institute, described how silicosis and asbestosis look on chest X-rays, using example cases rather than a defined study group. The author described three X-ray stages of asbestosis. Stage I was a fine network of shadows at the bases of both lungs. Stage III was dense shadowing that blurred the heart outline, the so-called "shaggy heart". The author wrote that breathing impairment in asbestosis, when present, is usually a "tight lung". The author added that physiological study of such cases usually shows a small total lung volume and no increase in residual air. Lung function tests on many men from the asbestos industry, done by Dr. George Wright, were compared with their X-rays. Some men with slight X-ray changes had definite functional impairment. The author contrasted this with simple silicosis, which the author said is usually not accompanied by impairment. The author concluded that not all cases of asbestosis involve a breathing problem.

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: Descriptive narrative presentation (symposium paper) on chest X-ray appearances of silicosis and asbestosis, illustrated with individual cases; not a formal study
• Who was studied: No defined study group. Illustrative cases included an iron-ore miner with silicosis. The asbestosis observations drew on lung function studies by Dr. George Wright of many men from the asbestos industry (number not stated).
• Exposure: Free crystalline quartz silica (silicosis), iron oxide (siderosis, for comparison), and asbestos fiber (type not specified)
• Main results:
  • Asbestosis was divided into three X-ray stages. Stage I was a fine network of increased densities at both lung bases with clear apices. Stage II had densities extending to the periphery of the middle and lower thirds, sometimes called "ground-glass". Stage III had considerable shadowing that could extend to the upper thirds, with the heart outline hard or impossible to make out ("shaggy heart").
  • In asbestosis, functional impairment when present was described as usually a "tight lung". Physiological study of such cases was said to usually reveal decreased maximum breathing capacity, a small total volume, and no increase in residual air. Expiration films or fluoroscopy were said to be of little help.
  • When Dr. George Wright's lung function findings in men from the asbestos industry were correlated with X-rays, some persons with slight X-ray changes had definite functional impairment. The author said this was not the case in simple nodular silicosis.
  • For silicosis, the author cited a study of 134 cases by Dr. George Wright. It showed a correlation between the ratio of residual air to total volume and the ratio of X-ray area at expiration to area at inspiration, with a correlation coefficient of 0.772.
  • The author stated that simple silicosis is usually not accompanied by pulmonary functional impairment, while complicated forms almost always show some departure from normal. In the iron-ore miner example, X-ray changes showed no progression over 17 years.
• The authors' conclusion: The author concluded that silicosis and asbestosis each produce a characteristic but different X-ray pattern. The author also concluded that not all cases of asbestosis involve a breathing problem, that when one is present it is due to a "tight lung", and that, unlike silicosis, some persons with slight asbestosis X-ray changes had definite functional impairment.
• Limitations the authors state:
  • The author stated the discussion was not a complete synopsis of pulmonary asbestosis and silicosis.
  • The author stated that no statistical data were known to confirm that all or most cases of simple silicosis progress.
  • The author stated that cases showing only a very slight departure from normal are the most difficult to diagnose and are classified as doubtful or uncertain.

Topics

Medical terms in this study, explained in our Lexicon: Silicosis, Occupational Lung Disease, Chest X-Ray.

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