Asbestos Disease Among Career Insulators

Our plain-English summary of Asbestos Disease Among Career Insulators, by E.G. Comstock (1980).

The study

• Author: E.G. Comstock
• Published: Presented at the Annual Meeting of the American Academy of Clinical Toxicology, August 4-7. P. 1-7. (1980)
• 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 conference paper by E.G. Comstock reported clinical examinations of 93 career insulators whose first exposure to asbestos-containing insulation material was at least 15 years earlier. The insulators chose to come forward after union locals announced free evaluations. Two plaintiff attorney groups sponsored the examinations, which took place over 18 months. Each person had an interview, a physical examination and a series of chest X-rays, and lung function tests were done in many patients. Workers were grouped by years since first exposure. Shortness of breath on exertion was the most common symptom, rising from 70% in the 15-19 year group to 95% in the two longest groups. Crackling rales rose from 30% to 74%. Pleural thickening rose from 15% in the two groups under 25 years to 58% in the 35-or-more group. All three signs the author linked to asbestos (crackling rales, pleural thickening and parenchymal fibrosis) appeared in 5% of the youngest group and 42% of the oldest. The author stated that these signs were related to exposure and time since first exposure and were uninfluenced by smoking.

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 clinical examination series (symptoms, physical signs, chest X-rays, lung function and laboratory tests) of self-selected insulators; presented at a scientific meeting
• Who was studied: 93 career insulators, all at least 15 years since first exposure, who responded to an announcement to union locals offering free evaluation. They were examined over an eighteen month period and divided into five groups by years since first exposure: 15-19 (n=20), 20-24 (n=13), 25-29 (n=21), 30-34 (n=20), 35 or more (n=19). Location is not stated in the available text.
• Exposure: Occupational exposure to asbestos-containing insulation material, measured as years since first exposure (15 or more years). Fiber types are not named, and average exposure durations in Table 1 are unreadable in the scan.
• Main results:
  • Shortness of breath on exertion was the most prevalent symptom in all groups: 70% in the youngest (15-19 years since first exposure) group, 95% in the two oldest groups.
  • Crackling rales increased from 30% in the youngest group to 74% in the oldest group (table: 30, 38, 52, 60, 74%).
  • Pleural thickening on X-ray, by group from 15-19 to 35 or more years since first exposure: 15, 15, 48, 50 and 58%.
  • Basal linear scarring consistent with parenchymal fibrosis, by group: 30, 69, 57, 65 and 74%.
  • Pleural calcification appeared only in the groups 30 or more years since first exposure: 0, 0, 0, 10 and 11%.
  • Productive cough, by group: 65, 38, 43, 50 and 53%. Dry cough: 5, 15, 19, 25 and 11%.
  • Chest tightness, by group: 15, 31, 38, 35 and 16%. Pleuritic pain: 20, 23, 38, 30 and 32%.
  • Rhonchi and wheezing did not change appreciably among the groups. The author stated they appeared to be neither age nor dose related.
  • At least one of the three asbestos-associated signs (crackling rales, pleural thickening, parenchymal fibrosis): 55% of the youngest group to 89% of the oldest group.
  • Any two of the three signs: 15% of the youngest group to 63% of the oldest group.
  • All three signs: 5% of the youngest group to 42% of the oldest group.
• The authors' conclusion: The author stated that crackling rales, pleural thickening and parenchymal fibrosis are positively related to intensity of exposure, duration of exposure and time since first exposure, and are uninfluenced by smoking. The author also stated that the certainty of an asbestosis diagnosis increases with the number of these signs present in one patient.
• Limitations the authors state:
  • The population was self-selected: only insulators who took the initiative to present themselves after an announcement to union locals were examined.

Topics

Medical terms in this study, explained in our Lexicon: Insulator, Plaintiff, Chest X-Ray, Crackling Rales, Pleural Thickening, Interstitial Fibrosis.

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