Fibrous Glass Manufacturing and Health

Our plain-English summary of Fibrous Glass Manufacturing and Health, by H.M.D. Utidjian, R.T.P. DeTreville (1970).

The study

• Authors: H.M.D. Utidjian, R.T.P. DeTreville
• Published: 35th Annual Meeting of the Industrial Health Foundation, October 13-14, 1970
• Type of article: Conference paper
• 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 two-part conference report described a cross-sectional study of workers at what the authors called the oldest and largest fibrous glass manufacturing plant in the United States. It concerned fibrous glass dust, not asbestos. Workers were randomly selected by age group and by estimated dust exposure (light, medium or heavy), and 232 of the 261 selected were reported on. Part I said an earlier report on this sample found no relationship between degree of exposure and respiratory history, lung function or X-ray findings. Advancing age alone appeared related to chest symptoms and lower breathing capacity. Part II examined 30 of the oldest workers: 15 with the least exposure and 15 with the most. Breathing tests were abnormal in 6 of the 15 least-exposed and 3 of the 15 most-exposed workers. One worker in each group had a gas-transfer (diffusing capacity) value judged truly low, and the authors found the two groups nearly identical on this test. The authors concluded the evaluation failed to show that workers in dusty jobs were less healthy. They noted that lung cancer could not be ruled out in a study of actively employed workers.

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: Cross-sectional study of a stratified random sample of workers (Part I), with an in-depth hospital examination of a subsample of the oldest workers with the least and greatest exposure (Part II)
• Who was studied: Employees of one United States fibrous glass manufacturing plant with about 2,400 workers. 261 were selected in three age groups and three exposure categories, and 232 were reported on. The Part II subsample was 15 of the oldest workers with the least exposure (Group I) and 15 with the greatest exposure (Group III), examined at Licking County Memorial Hospital, Newark, Ohio.
• Exposure: Airborne dust from the manufacturing and processing of fibrous glass, graded by estimated time-integrated exposure as light, medium or heavy. No asbestos exposure was studied.
• Main results:
  • For the full sample, the earlier report suggested no relationship between degree of exposure and respiratory history, physiological or radiological findings. Advancing age alone appeared related to chest illness symptoms and reduced ventilatory capacity.
  • Least-exposed oldest workers (Group I): 6 of 15 had abnormal ventilatory (breathing) studies, four Class One and two Class Two. Nine had normal ventilatory studies and normal diffusing capacities.
  • Most-exposed oldest workers (Group III): pulmonary function was normal in ten, questionably abnormal in one, and abnormal in three (two Class I, one Class II).
  • Group I: one worker had a surely abnormal diffusing capacity, 11.3 ml/min/mm Hg against a predicted 16.5. This worker was a smoker of 40-plus pack-years, and the value was not below Social Security disability standards.
  • Group III: one worker had a low diffusing capacity judged significant, 9.5 ml/min/mm Hg. This worker had smoked 86 pack-years. The authors judged the diffusing capacity findings in the two groups nearly identical.
  • Respiratory questionnaire: Group I had 2 positive, 3 doubtful and 10 negative; Group III had 1 positive, 4 doubtful and 10 negative. The examiner saw no appreciable difference between the groups. 14 of 15 Group I and 12 of 15 Group III workers were smokers.
  • The examiner felt there was no significant difference between the two groups in their history of diseases.
• The authors' conclusion: The authors concluded that the medical evaluation failed to show any evidence supporting the hypothesis that workers with dusty jobs were less healthy than those with minimal dust exposure. They also found no measurable dust effect on gas diffusion across the lungs.
• Limitations the authors state:
  • Lung cancer cannot be fully excluded by a cross-sectional study of a 'survivor' population of actively employed workers.
  • Some selected workers were lost (resignations, military draft, one death, vacation, illness), with the greatest loss in the youngest age group.
  • The examiner did not know each worker's exposure group but could get a general idea of exposure level from the work history.

Topics

Medical terms in this study, explained in our Lexicon: Diffusing Capacity (DLCO), Lung Cancer.

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