Fibrous Glass Insulation: Health Hazard Question Resolved

Our plain-English summary of Fibrous Glass Insulation: Health Hazard Question Resolved, by J.M. Barnhart (1971).

The study

• Author: J.M. Barnhart
• Published: ASHRAE Journal, August 1971
• 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 1971 article in ASHRAE Journal was not a research study. Its author was executive secretary of the National Insulation Manufacturers Assn, a trade group of fibrous glass insulation makers. The article summarized earlier studies and reports by others on whether fibrous glass duct insulation is a health hazard. The author wrote that the health question had its roots in a jurisdictional dispute between two labor unions over installation work. Among the studies quoted, a 1969 study of fibrous glass manufacturing plants reported that fiber exposures in the asbestos textile industry were of the order of 20 times those in the fibrous glass industry. A 1967 University of Cincinnati study found no fibers in air leaving seven fibrous glass duct systems run at 3000 fpm for 136 hours. A 1970 follow-up found that settled dust near installed ducts generally contained some glass fibers. The article collected no new data of its own. The author concluded that studies over the past 30 years showed fibrous glass to be a biologically inert substance presenting no health risk greater than 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: Narrative review and position article by an official of an insulation manufacturers' trade association, quoting earlier published studies and reports; no original data
• Who was studied: No study population of its own; the article summarized other researchers' work on fibrous glass, including studies of workers, laboratory animals and air duct systems
• Exposure: Fibrous glass (glass fiber) insulation, especially duct liner and ducts made entirely of fibrous glass; asbestos appears only as a comparison in one cited study
• Main results:
  • The author reported that a cited 1969 study of fibrous glass manufacturing plants (Johnson, Healy, Ayer, Lynch) compared its results with an earlier study of the asbestos textile industry and stated that fiber exposures in the asbestos textile industry were of the order of 20 times those in the fibrous glass industry
  • The author reported that a cited 1967 University of Cincinnati study (Cholak and Schafer) found no fibers in the air stream leaving seven fibrous glass duct systems exposed to air at 3000 fpm continuously for 136 hours
  • The author reported that a cited 1970 University of California study (Cooper, Balzer, Fowler) of 13 air systems lined with fibrous glass found a decrease in glass fiber concentrations after the air passed through the systems
  • The author reported that a cited 1970 field study of installed fibrous glass ducts at six sites found no evidence of fiber erosion in outlet air samples, but dust that had settled or was wiped from walls near the sampling sites generally contained some glass fibers
  • The author reported that a cited 1968 chest X-ray study (Wright) of people with 10 to 25 years of exposure to airborne fibrous glass found no unusual pattern
  • The author reported that the American Conference of Governmental Industrial Hygienists, at its May 1969 meeting, changed the tentative threshold limit value for fibrous glass to the same value used for nuisance dust
• The authors' conclusion: The author concluded that medical and scientific studies over the past 30 years showed fibrous glass to be a biologically inert substance presenting no health risk greater than any other innocuous dust. The author also attributed the health concern to a labor union jurisdictional dispute.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Textile Industry, Settled Dust.

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