Fibrous Glass Insulation Health Aspects

Our plain-English summary of Fibrous Glass Insulation Health Aspects, by NICA Outlook (1971).

The study

• Author: NICA Outlook
• Published: National Insulation Manufacturers Association Health and Safety Committee, November 1971
• Type of article: Trade 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 not a research study. It appeared in the trade publication NICA Outlook in November 1971, prepared by the National Insulation Manufacturers Association Health and Safety Committee. It quoted conclusions of earlier studies and official statements on the health effects of fibrous glass insulation. The subject is fibrous glass, not asbestos. It quoted a 1968 chest X-ray study by Wright that found no unusual pattern after 10 to 25 years of exposure. Another was a 1970 animal study by Gross and colleagues. It reported only small collections of macrophages (scavenger cells) in rats and hamsters exposed for 24 months to dust averaging somewhat over 100 mg/cu m. A 1969 government study by Johnson and colleagues reported fiber exposures in the asbestos textile industry of the order of 20 times those in the fibrous glass industry. In May 1969, the article noted, an industrial hygiene body changed its tentative threshold limit value for airborne fibrous glass to 15 mg/cu m, the nuisance dust value. The authors concluded that fibrous glass presents no health risk greater than any other innocuous dust.

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: Industry trade-publication article compiling quoted conclusions from earlier published studies and agency statements (a non-systematic review); no original research
• Who was studied: No study population of its own. The quoted sources included studies of fibrous glass workers, animal experiments in rats, guinea pigs and hamsters, and a government environmental survey of four fibrous glass insulation plants and one fibrous glass textile plant
• Exposure: Fibrous glass (glass fiber), in wool-type insulation products and textile yarn forms; asbestos is mentioned only as a comparison in one quoted study
• Main results:
  • The American Conference of Governmental Industrial Hygienists, at its May 1969 meeting, changed the tentative threshold limit value for airborne fibrous glass to 15 mg/cu m of air, the same as the nuisance dust value. The earlier value is unreadable in the scan.
  • A 1968 study by Wright, quoted in the article, examined chest X-rays of people with 10 to 25 years of exposure to airborne fibrous glass particles and reported no unusual pattern of radiologic densities
  • A 1970 study by Gross and colleagues, quoted in the article, reported that the lung response in rats and hamsters was relatively small accumulations of macrophages without significant stromal change. The animals had 24 months of exposure to fibrous glass dust at concentrations averaging somewhat over 100 mg/cu m.
  • A 1967 article by McCord, quoted in the article, stated that animal experiments with fiber glass particles introduced into the lungs had failed to provoke lung cancer, and that no clinical cases of lung cancer had been traced to fiber glass
  • A 1969 U.S. Department of Health, Education and Welfare study by Johnson and colleagues, quoted in the article, reported that fiber exposures in the asbestos textile industry were of the order of 20 times those in the fibrous glass industry
• The authors' conclusion: The authors concluded that published medical-scientific research over the past 30 years showed fibrous glass to be a biologically inert substance presenting no health risk greater than any other innocuous dust

Topics

Medical terms in this study, explained in our Lexicon: Chest X-Ray, Macrophage, Asbestos Textile Industry, Industrial Hygiene, Threshold Limit Value (TLV).

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