Occupational Medicine and Industrial Hygiene

Our plain-English summary of Occupational Medicine and Industrial Hygiene, by Rutherford T. Johnstone (1948).

The study

• Author: Rutherford T. Johnstone
• Published: St. Louis: The C. V. Mosby Company (1948)
• Type of article: Book excerpt
• 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 item is not a research study. It is part of a 1948 textbook, Occupational Medicine and Industrial Hygiene, by Rutherford T. Johnstone. The text supplied holds the front matter, table of contents and Chapter XXVIII on silicosis. The separate asbestosis chapter listed in the contents is not included. The silicosis chapter briefly described asbestos as fibrous silicate minerals. It quoted another writer, Gardner, who linked a hazy X-ray shadow with early asbestosis. Gardner wrote that the haze grew denser as the disease advanced, until a so-called 'ground glass' appearance marked fully mature asbestosis. Gardner also said diagnosis needed a history of exposure to fibrous asbestos dust, usually for six to eight years or more. The rest of the chapter covered silicosis: its causes, X-ray signs, pathology, tuberculosis as a complication, disability compensation, and aluminum powder treatment as reported by other researchers. It also gave two case reports. The first was a miner with advanced silicosis and tuberculosis of the larynx. The second was a disability claim by a barytes and bentonite grinder whose X-rays showed no evidence of pneumoconiosis. The author stated that no treatment for silicosis could be accepted as curative.

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: Textbook chapter (Chapter XXVIII, Silicosis) from a 1948 occupational medicine textbook, including the author's discussion of other writers' work and two case reports; not an original research study
• Who was studied: No study population. The chapter discusses silicosis in exposed workers in general and presents two case reports: a miner with silicosis, and a male adult claimant who had ground barytes and bentonite
• Exposure: Mainly free silica (silicon dioxide) dust. Asbestos is mentioned only briefly, as fibrous silicate minerals, and in a quoted passage on the X-ray appearance of asbestosis. Fiber types are not named; the text describes two varieties of hydrated magnesium silicate. Case 2 involved grinding barytes and bentonite.
• Main results:
  • The chapter described a longer-fibered, less heat-resistant variety of asbestos, coming principally from eastern Canada, that was woven into fireproof fabrics. It described a short-fibered variety used for packing steampipes and furnaces.
  • In a passage quoted from Gardner, a hazy X-ray shadow was described as associated with early asbestosis.
  • In the same quoted passage, the haze was described as becoming denser as the disease advanced. In fully mature asbestosis, vascular markings throughout two-thirds of the lungs were said to be obliterated by the so-called ground glass appearance.
  • In the same quoted passage, diagnosis of asbestosis was said to require a history of exposure to fibrous asbestos dust, usually for periods of six to eight years or more.
  • Case 1: a miner whose X-rays showed advanced silicosis was found on throat examination to have extensive tuberculosis of the larynx and hypopharynx, described as a complication of his silicosis.
  • Case 2: a claimant who ground barytes and bentonite had X-rays showing an old, healed left apical tuberculosis but no evidence of pneumoconiosis. X-ray diffraction analysis reported no evidence of uncombined silica in the samples, except that one barytes sample (El Portal) was slightly contaminated.
  • The chapter quoted another group's report (Crombie, Blaisdell and MacPherson) on aluminum powder treatment of silicosis. In that report, 19 of 34 cases studied showed clinical improvement. These are that group's results, not the author's.
• The authors' conclusion: The author stated that there is no treatment for silicosis that can be accepted as curative.

Topics

Medical terms in this study, explained in our Lexicon: Industrial Hygiene, Silicosis, Silicate, Pathology, Pneumoconiosis.

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