Fiberglass Exposure in the Workplace

Our plain-English summary of Fiberglass Exposure in the Workplace, by D.L. Adams, K. Kassim (1981).

The study

• Authors: D.L. Adams, K. Kassim
• Published: HMMJ p21-27 March-April (1981)
• 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 was a review, not a new study. The authors summarized published evidence on workplace fiberglass exposure and made recommendations. In one California series, 653 of 691 fiberglass cases were attributed to effects on the skin and eyes. In rat experiments, fine glass fibers placed in the chest cavity produced tumors; the authors said these routes are not appropriate to workplace exposure. A study of 416 retired men found lower mortality than U.S. white males, no mesothelioma deaths, and excess retirements due to chronic bronchitis. A cohort of 1,448 white males at a small diameter fiberglass plant found lower overall mortality, except for excess nonmalignant respiratory disease deaths, not counting influenza and pneumonia. The authors concluded that these two studies indicated excess risks of chronic bronchitis and of nonmalignant respiratory disease deaths (excluding influenza and pneumonia) among exposed white males. They recommended a limit of 3 fibers per cubic centimeter as a time-weighted average for fibers 3.5 microns or less in diameter and at least 10 microns long. They also recommended a limit of 5 milligrams per cubic meter for total fibrous glass, protective equipment and annual examinations.

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 of published medical, animal and epidemiological evidence on fibrous glass, with the authors' recommendations for work practices and medical surveillance
• Who was studied: No original study population. The authors reviewed published case reports, surveys, rodent experiments and epidemiological studies of workers exposed to fibrous glass, mainly in the United States.
• Exposure: Fibrous glass (fiberglass), including wool and textile fibers and fiberglass reinforced plastics (FRP), along with the resins, binders and other chemicals used with them
• Main results:
  • In California occupational disease summaries reviewed by the authors, 653 of 691 fiberglass cases were attributed to effects on the skin and eyes.
  • In a reviewed rat experiment by Wagner et al., fiberglass was placed inside the chest cavity (intrapleural). Mesotheliomas occurred in 4 of 32 rats given fine fibers and in none of the controls or the rats given coarse fibers.
  • In the reviewed Stanton et al. rat implantation studies, fibers 1.5 microns or less in diameter and longer than 8 microns produced the highest incidence of pleural sarcoma.
  • In a reviewed postmortem study by Gross et al., enlarged air spaces from alveolar destruction were found in 13 of 20 fibrous glass workers and in 19 of 26 urban controls.
  • In the reviewed Enterline et al. study of 416 retired men, there were no deaths from malignant mesothelioma, and there was an excess of retirements due to chronic bronchitis.
  • The reviewed Bayliss et al. retrospective cohort studied 1,448 white males employed at a plant producing small diameter fiberglass. It found lower overall mortality, except for an excess risk of nonmalignant respiratory disease deaths (excluding influenza and pneumonia).
  • The fibrous glass standard described by the authors limited exposure to 3 fibers per cubic centimeter, as a time-weighted average, for fibers 3.5 microns or less in diameter and 10 microns or more in length. It set a separate time-weighted average limit of 5 milligrams per cubic meter for total fibrous glass.
• The authors' conclusion: The authors concluded that the two well-designed epidemiological studies indicated excess risks of chronic bronchitis and of nonmalignant respiratory disease deaths (excluding influenza and pneumonia) among white males exposed to workplace fiberglass. They recommended keeping airborne fiberglass within the exposure limit of 3 fibers per cubic centimeter. In the standard they described, this limit is a time-weighted average for fibers 3.5 microns or less in diameter and 10 microns or more in length. They also recommended protective equipment and annual examinations that include chest x-rays and pulmonary function tests.
• Limitations the authors state:
  • Most animal studies used rodents, and the authors cautioned against applying the results directly to humans.
  • Very few epidemiological studies were available to show a definite pattern of human response.
  • Most available epidemiological studies were cross-sectional studies of current employees and did not consider discharged and retired employees.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, Fibers per Cubic Centimeter (f/cc), Time-Weighted Average (TWA).

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