Glass Dust: A Study of its Biologic Effects

Our plain-English summary of Glass Dust: A Study of its Biologic Effects, by P. Gross, M.L. Westrick, J.M. McNerney (1960).

The study

• Authors: P. Gross, M.L. Westrick, J.M. McNerney
• Published: Archives of Industrial Health, Volume21. January 1960.
• 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 was an animal study of dust made from glass flakes. It did not test asbestos. The authors dusted the eyes of albino rabbits with milled glass. They fed young male rats diets containing 10% or 50% ground glass for one year. They injected coarse or fine glass dust into rats' windpipes, and they exposed rats and guinea pigs to fine glass dust in inhalation chambers for one year. Comparison animals received quartz or kaolin dust. No corneal damage was found. Rats eating glass showed no significant abnormality in their organs. In the lungs, glass dust produced small, scattered collections of dust-filled cells. The authors found no collagen formation from inhaled dust in guinea pigs, and only occasional thin collagen fibers around injected coarse glass. Quartz caused much more extensive and severe lung involvement. A lung fibrosis seen in glass-exposed guinea pigs also appeared in quartz and kaolin groups. The authors concluded that the lung changes from glass dust were minimal. They noted that iron had contaminated the dusts and that the exposures did not duplicate shop conditions.

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 experiment in three parts: eye irritation in rabbits, a one-year feeding study in rats, and lung studies (intratracheal injection in rats; inhalation in rats and guinea pigs) with quartz, kaolin and corn oil comparison groups
• Who was studied: Laboratory animals at the Industrial Hygiene Foundation, Mellon Institute. Groups were: six albino rabbit eyes in each of two eye experiments; four groups of 10 young male white rats in the feeding study; five groups of 15 rats for intratracheal injection; and three groups of 40 rats and three groups of 15 guinea pigs for inhalation. Study dates are not given.
• Exposure: Dust milled from glass flakes, given as a coarse dust and as a very fine dust. The fine dust picked up iron from a tool-steel baffle. Feeding groups received diets with 10% or 50% glass by weight for one year. Inhalation exposure was 6 hours a day, 5 days a week, for one year, followed by about another year without exposure. Quartz and kaolin dusts served as comparison dusts.
• Main results:
  • Rabbits: no corneal defects were found after the eyes were dusted with glass.
  • Feeding study rats: microscopic examination of the organs showed no significant abnormality.
  • Rats on the 50% glass diet almost doubled their daily food intake.
  • Guinea pigs that inhaled glass dust: no collagen formation attributable to the dust was found.
  • Rats that inhaled glass dust: microscopic signs of dust exposure were minimal, consisting of small scattered foci of dust-filled macrophages.
  • Rats injected with coarse glass dust: at 12 months, only occasional thin collagen fibers were found around the glass deposits.
  • Rats injected with fine glass dust: a few collagen fibers were noted in some dust foci.
  • Lung involvement from quartz was much more extensive and severe than from glass.
  • A lung fibrosis seen in guinea pigs exposed to glass dust (4 out of 16) was also found in animals exposed to kaolin and to quartz.
• The authors' conclusion: The authors concluded that lung changes in guinea pigs and rats exposed to fine glass dust were minimal, consisting of small collections of alveolar dust cells without fibrosis. They also concluded that no toxic or traumatic effect on the gastrointestinal tract was shown.
• Limitations the authors state:
  • The authors could not say how far the iron mixed into the dusts may have changed the lung response to glass dust.
  • The exposure conditions did not reproduce workplace conditions.
  • The cause of the lung fibrosis seen across all dust groups was not determined; the authors attributed it to an unknown factor in the technique.

Topics

Medical terms in this study, explained in our Lexicon: Collagen, Fibrosis.

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