Inert Dusts

Our plain-English summary of Inert Dusts, by R.T. Johnstone (1948).

The study

• Author: R.T. Johnstone
• Published: OCCUPATIONAL MEDICINE AND INDUSTRIAL HYGIENE, ST. LOUIS: C.V. MOSBY, PP. 386-401 (1948)
• Type of article: Book excerpt
• Our copy: from Johns-Manville's own medical library.

In plain English

This textbook chapter reviewed dusts the author grouped as inert. It opened with benign pneumoconiosis, a lung condition from dusts said, unlike free silica and asbestos, to cause no symptoms or disability. It also described allergic and other respiratory illness from cotton, grain and bagasse dust. Asbestos appeared only in passing, as a comparison. Other topics included iron dust in welders, cement, carbon, tobacco, mica and fibrous glass, mostly through other investigators' work. The author reported a case of a cotton sampler (once called a sorter) with twenty-eight years of exposure and night-time attacks of shortness of breath. His chest X-rays showed whirlpool-like shadows at the bases of both lungs, especially the left. The radiologist and a consultant described them as not suggestive of, or not appearing to be, tuberculosis. The author concluded these markings were not the result of cotton dust itself, and suggested repeated allergic asthma with years of dust inhalation might have caused them. At follow-up he was free of symptoms but his films were unchanged. The scanned text is badly damaged.

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 reviewing published work on so-called inert dusts, including case descriptions by the author (notably a cotton sampler, and a malt-company weighman with grain or malt fever)
• Who was studied: Various worker groups described from other reports (welders, cotton workers, cement workers, tobacco workers, grain workers, glass-fiber workers). The author's main case was one Black man who had worked as a cotton sampler (once called a sorter in the text), in the South and later in Los Angeles. His age is unreadable in the scan.
• Exposure: Iron-containing dust, cotton dust, Portland cement dust, calcium and magnesium carbonates, carbon dust, tobacco dust, grain dust and smuts, malt dust, bagasse, mica and fibrous glass. Asbestos was not studied; it was mentioned only in passing, as a comparison.
• Main results:
  • The chapter reported that eighty-three welders in one plant were screened after several were rejected by the army. A number of them, unreadable in the scan, showed varying degrees of siderosis.
  • The chapter described cotton dust as inert in the sense of causing no appreciable fibrosis. It said the illness in cotton workers was due to allergens or fungi.
  • For bagasse, the chapter described men developing a cough with foul-smelling sputum, shortness of breath and often pain behind the breastbone after several months of exposure.
  • In the author's case, the cotton sampler had been exposed for twenty-eight years.
  • The sampler's chest films showed concentric whirlpool-like shadows in the bases of both lung fields, especially the left.
  • The radiologist's reading stated the findings were not suggestive of pulmonary tuberculosis.
  • A consulting expert (Dr. Sampson) wrote that the shadows suggested a nontuberculous process.
  • After the sampler was no longer exposed to cotton dust and was followed periodically, he was free of symptoms but his chest films remained unchanged.
  • The author also described a weighman at a malt company's grain elevator in Los Angeles who reported recurrent attacks of an odd malaise that he attributed to malt dust.
  • For cement dust, the chapter cited studies made in eleven plants involving 2278 employees.
  • For tobacco dust, the chapter reported that the investigator Long studied 2251 persons, of whom 1,216 had been exposed to tobacco dust at work, and concluded that pneumoconiosis (tabacosis) does not develop in tobacco workers.
  • For mica, the chapter attributed silicosis-like findings in mica miners probably to free silica in the earth from which the mica is procured.
  • For fibrous glass, the chapter reported that an examination of approximately two hundred employees in Newark found significant skin irritation in only one worker, a man who had begun work in the plant four days earlier.
• The authors' conclusion: The author concluded that the lung markings in the cotton sampler were not the result of cotton dust itself. The author suggested that repeated allergic asthma, together with continuous dust inhalation over many years, may have produced chronic bronchitis-type lung changes.
• Limitations the authors state:
  • For grain or malt fever, the author stated that the condition came to the author's attention after printing of the book had begun, so there was not enough time for thorough laboratory investigation.

Topics

Medical terms in this study, explained in our Lexicon: Pneumoconiosis, Mica, Chest X-Ray.

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