Pneumoconiosis And Pulmonary Carcinoma

Our plain-English summary of Pneumoconiosis And Pulmonary Carcinoma, by A.J. Vorwald, J.W. Karr (1938).

The study

• Authors: A.J. Vorwald, J.W. Karr
• Published: American Journal Of Pathology 14(1):49-57, January (1938)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library, J-M no. 003183. The article is still under copyright, so we describe it here rather than post it.

In plain English

This article from the Saranac Laboratory asked whether inhaled industrial dust causes primary lung cancer. The authors combined published chest X-ray and autopsy reports with their own X-ray surveys, their own autopsies, and long-term dust-inhalation experiments in animals. Asbestos was one of many dusts listed in the animal work, but its separate results cannot be read in this copy. In published X-ray reports on 57,362 dust-exposed people, a lung tumor was mentioned in 3 (0.005 per cent). In the laboratory's own X-rays of 15,587 dust-exposed males, the rate was 0.019 per cent. Autopsies of 3,739 dust-exposed people, drawn from the literature and the authors' own series, showed 30 with lung cancer (0.8 per cent). The authors said this was lower than in routine autopsies of the general population. Of 3,338 animals, only 2 guinea pigs developed lung tumors, and both were benign adenomas. The authors concluded that inhaled dusts, except those containing recognized carcinogens such as radium and tar, cannot in general be considered causes of primary lung cancer.

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: Combined study: compilation of published X-ray and autopsy reports, the Saranac Laboratory's own chest X-ray surveys and autopsy series, and long-term dust-inhalation experiments in several animal species
• Who was studied: Dust-exposed workers: 57,362 people X-rayed in published reports; 444 people in published autopsy studies; South African gold miners autopsied in 1920-1925 (Miner's Phthisis Medical Bureau); 15,587 males X-rayed by the Saranac Laboratory; 178 males autopsied at Saranac who had been exposed for 1 to 46 years. Also 3,338 laboratory animals, including guinea pigs, rabbits, rats, mice, cats and chickens.
• Exposure: Various industrial dusts. The human groups included silica dust, iron and hematite mining, and coal. The animal experiments used heavy concentrations of dusts listed as chalcedony, quartz, granite, chert, hematite, marble, gypsum, fluorspar, carborundum, soft coal and asbestos. Counts for each dust are not readable.
• Main results:
  • In published X-ray reports on 57,362 dust-exposed individuals, pulmonary tumor was mentioned in only 3 (0.005 per cent).
  • In the Saranac Laboratory X-ray surveys of 15,587 dust-exposed males, the incidence of pulmonary tumor was 0.019 per cent. This was 1 of 1,357 silicotics (0.074%) and 2 of 14,230 non-silicotics (0.014%). All three had worked in iron mines.
  • Among South African autopsies for 1920-1925, primary lung carcinoma was found in 10 of 1,438 European miners with silicosis, 12 of 1,679 European miners without silicosis, and 13 of 1,595 European males never underground. The authors called lung carcinoma a rare complication of silicosis in these gold miners.
  • Of 178 males autopsied at Saranac, 2 had primary lung carcinoma. One had worked 27 years in hematite mines; the other had mined hard coal for 18 years. In the remaining 176, proliferation of the airway lining cells was not observed, even where dust fibrosis was massive.
  • Combining literature and their own autopsies, 30 of 3,739 dust-exposed individuals had lung carcinoma (0.8 per cent). The authors said this was lower than in routine autopsies of the general population.
  • Of 3,338 animals exposed to dusts, only 2 guinea pigs developed lung tumors (0.06 per cent overall), both benign adenomas. One had been exposed to ferruginous chert dust for 749 days; the other had been kept in a soft coal tipple.
  • Of 400 mice of a carcinoma-susceptible strain exposed to chalcedony for 3 to 12 months, none showed an unusual degree of epithelial proliferation in the lungs.
• The authors' conclusion: The authors concluded that inhaled dusts, except those containing recognized carcinogenic substances such as radium and tar, cannot in general be considered causes of primary lung cancer.
• Limitations the authors state:
  • The authors noted the difficulties of diagnosing lung tumors by X-ray in silicotic individuals.
  • None of the inhalation experiments was primarily planned to study lung carcinoma.
  • The authors raised the objection that the animal strains used might not have been susceptible to epithelial proliferation.

Topics

Medical terms in this study, explained in our Lexicon: Pneumoconiosis, Carcinoma, Saranac Laboratory, Lung Cancer, Chest X-Ray, Autopsy.

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