Pulmonary Hazards from Exposure to Glass Fibers

Our plain-English summary of Pulmonary Hazards from Exposure to Glass Fibers, by A.N.M. Nasr (1967).

The study

• Author: A.N.M. Nasr
• Published: Journal of Occupational Medicine, Volume 9 No7. July 1967
• 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 1967 article was a review of animal experiments and reports on people about lung hazards from glass fibers (fibrous glass). The author separated fibrous glass from mineral wool, Fiberglas Reinforced Plastic and Plexiglass. Among the animal studies, one found fine glass dust caused no more severe a lung reaction than kaolin dust, though that dust contained iron and was flake-shaped. Another set of experiments had no control animals, and the author judged their findings uncertain. Saranac Laboratory inhalation tests over 19 months were negative. Among the human studies, one found no detectable functional impairment in 6 workers exposed to glasswool and rockwool, while findings in asbestos-exposed workers deviated from normal. The author judged that infection played the major role in three reported cases of inflammatory lung disease after glass fiber exposure. Other workplace air contaminants were not assessed in those cases or in a reported asthma case. The author concluded that available evidence indicated fibrous glass was a relatively inert material with no fibrogenic or other significant toxic properties.

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: Review (critical evaluation of published animal experiments and human reports)
• Who was studied: Published animal experiments (rats, guinea pigs) and human case reports and small worker studies found in the American and European literature
• Exposure: Glass fibers (fibrous glass, glass wool, glass dust). The author distinguished these from mineral wool, Fiberglas Reinforced Plastic and Plexiglass. One reviewed study also included workers exposed to rockwool and a comparison group exposed to asbestos.
• Main results:
  • In the Gross et al. animal experiments, the lung reaction to inhaled fine glass dust was no more severe than the reaction to equally fine kaolin dust. The author noted that the dust's high iron content and its flake or plate shape might have influenced the result.
  • The Schepers studies in rats and guinea pigs reported lung changes after glass fiber injection and inhalation. The author noted that no control animals were studied, so assessing the significance of the findings would be conjecture.
  • Saranac Laboratory inhalation experiments in animals showed negative results over 19 months of daily exposure.
  • In the Bjure et al. study, no detectable functional impairment was observed in the 6 workers exposed to glasswool and rockwool. Findings in the asbestos-exposed group appreciably deviated from normal.
  • The author questioned the name "fiber glass pneumoconiosis" given by Murphy to the case of a 50-year-old electrical worker with hemorrhagic bronchiolitis. That worker had a right lower lobe removed.
  • The author judged that in three reported cases of inflammatory lung disease after glass fiber exposure (Murphy, Kahlan, Bezjak), the illness was acute and infection played the major role.
  • Among 25 workers examined by Cirla, there was slight upper respiratory irritation but no clinical evidence of lung involvement. X-rays showed fibrous opacities in 5 workers, with no further evaluation reported.
• The authors' conclusion: The author concluded that available evidence indicated fibrous glass was a relatively inert material with no fibrogenic or other significant toxic properties.
• Limitations the authors state:
  • The author noted that in all four case reports, no appraisal was made of other air contaminants that may have been present in the work environment.
  • The author noted that the human function studies covered only a limited number of workers.

Topics

Medical terms in this study, explained in our Lexicon: Saranac Laboratory, Fibrogenic.

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