An Experimental Study on the Effects of Glass Wool on Animal Lungs

Our plain-English summary of An Experimental Study on the Effects of Glass Wool on Animal Lungs, by G.W.H. Schepers, A. Delhant (1955).

The study

• Authors: G.W.H. Schepers, A. Delhant
• Published: P.271-274 (1955)
• Type of article: Journal article
• 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 article described animal experiments with glass wool and glass cotton (not asbestos) done at the Saranac Laboratory from 1939 to 1947. First, three batches of glass wool with different fiber diameters (A, 3μ to 8μ; B, about 3μ; C, 3μ and less) were injected into guinea pigs' windpipes. Batch A appeared relatively inert: no animals died and lesions were minimal. With Batch B, foci of collapsed lung tissue (atelectasis) were the only early finding, but animals killed after the 75th week showed major lung damage. Batch C appeared to provoke mainly focal atelectasis. Second, 100 guinea pigs and 50 rats inhaled glass wool, later glass cotton, in experiments that ran 40 and 24 months, with animals killed in batches along the way. Seventeen of the 100 guinea pigs and 20 of the 50 rats died. Lung abscesses were relatively common in rats (10%) but not found in guinea pigs. No fibrosis was seen with the naked eye. The authors concluded the glass wool was not wholly inert. They cautioned against applying the results directly to the finer products sold when they wrote.

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: Animal experiments: intratracheal injection studies with three glass wool samples, plus a long-term inhalation experiment
• Who was studied: Guinea pigs in the intratracheal study (5 for Batch A, 8 each for Batches B and C). In the inhalation study, 100 guinea pigs in an experiment that ran 40 months and 50 white rats in one that ran 24 months, with animals killed in batches at intervals. The work was done at the Saranac Laboratory, 1939 to 1947.
• Exposure: Intratracheal study: glass wool given as three doses of 0.5 cc of saline suspension at weekly intervals. Inhalation study: glass wool with fibers of about 6μ diameter, changed to glass cotton at about the 20th month. Dust concentrations in the cages were 0.143 to 0.146 mg per cubic foot. Impinger counts were 1,400,000 to 2,200,000 particles.
• Main results:
  • Intratracheal study, glass wool type A (thickest fibers): relatively inert. No animals died and lung lesions were minimal.
  • Intratracheal study, glass wool type B: no early reactions except foci of atelectasis. Major pulmonary damage was found in animals killed after the 75th week.
  • Intratracheal study, glass wool type C (slender fibers): appeared to provoke mainly focal atelectasis.
  • Inhalation study: 17 of 100 guinea pigs and 20 of 50 rats died during the experiments.
  • Inhalation study: in all but a few instances, guinea pig deaths were attributed to pneumonia.
  • Inhalation study: lung abscesses were relatively common in the rats (10%) and looked like tumors on inspection. Comparable lung lesions were not found in the guinea pigs.
  • Inhalation study, guinea pigs: marginal atelectatic areas were present by the fourth month.
  • Inhalation study, rats: the lungs showed little evidence of dust pigmentation or reaction.
  • No macroscopic evidence of fibrosis was found.
• The authors' conclusion: The authors concluded that glass wool of the caliber and fiber length used was not wholly inert in animal lungs, although the fibers were not fibrogenic. They suggested a possible causal relation between the dust exposure and lung infection (particularly in rats) and focal atelectasis (particularly in guinea pigs).
• Limitations the authors state:
  • The authors cautioned against applying the findings too directly to the fiber industry. Technical changes had occurred since the experiments began, and the product commercially available when they wrote was considerably lighter in caliber than the material studied.

Topics

Medical terms in this study, explained in our Lexicon: Saranac Laboratory, Pneumothorax, Atelectasis, Fibrosis.

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