Spirometric abnormalities among asbestos insulation workers

Our plain-English summary of Spirometric abnormalities among asbestos insulation workers, by Y. Lerman, H. Seidman, S. Gelb, et al (Journal of Occupational Medicine., 1988).

The study

• Authors: Y. Lerman, H. Seidman, S. Gelb, A. Miller, I.J. Selikoff
• Journal: Journal of Occupational Medicine.
• Published: 1988;30(3):228-33
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000244).

Abstract

We studied the prevalence of spirometric changes among asbestos insulation workers to investigate when functional abnormalities appear during the course of asbestos employment and the influence of cigarette smoking. Of 1,249 eligible asbestos insulation workers in the New York-New Jersey metropolitan area, 1,117 (89.4%) were examined in the year 1963 to provide baseline pulmonary function status for long-term prospective observation. Forced vital capacity (FVC) was measured in all 1,117 workers and forced expiratory volume in 1 second (FEV1) in 613 workers (55%). Of 353 workers examined in the first 10 years after onset of exposure, 26 (7.4%) had FVC below 70% of predicted, a prevalence similar to that reported in nonexposed general populations. Prevalence increased with time from onset of exposure. Of the 117 workers examined 40 or more years after onset of exposure, 76 (55%) had FVC below 70% of predicted. A similar trend with time was shown for FEV1 and FEV1/FVC. Cigarette smoking had little influence on the prevalence of pure restrictive impairment. Cigarette smokers and non-cigarette smokers had much the same prevalence (28%) of moderate to severe reduction of FVC while the FEV1/FVC was normal. None of the non-cigarette smokers and five of the cigarette smokers had a predominantly obstructive pattern. One non-cigarette smoker and eight cigarette smokers showed reduction of both FVC and FEV1/FVC, consistent with a mixed ventilatory abnormality. The data demonstrate that asbestos alone without the additional effect of cigarette smoking has no measureable effect on the function of the large airways.

In plain English

In 1963 the authors examined 1,117 of the 1,249 (89.4%) members of the New York-New Jersey locals of the International Association of Heat and Frost Insulators and Asbestos Workers. This report analyzed those men's baseline breathing tests (spirometry), grouped by years since first asbestos exposure and by cigarette smoking. Forced vital capacity (FVC) was available for all 1,117 men and FEV1 for 613. Overall, 300 (26.9%) had FVC below 70% of predicted. Low FVC was uncommon early on (11 of 207 men in the first 5 years after exposure began) and more common later (76 of 117 men examined 40 or more years after onset). Smokers and non-cigarette smokers had similar rates of a pure restrictive pattern (27.8% and 27.3%). A predominantly obstructive pattern appeared in five of 613 men, all cigarette smokers. The authors concluded that asbestos alone had no measurable, or at most a minor, effect on the large airways, and that smokers had earlier and more frequent FEV1/FVC decreases. They noted that 1963 testing methods may be inadequate by current standards.

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: Retrospective analysis of baseline (1963) spirometry in a cohort of union insulation workers under long-term observation; cross-sectional comparison by time since onset of exposure and smoking status
• Who was studied: 1,249 members of Locals 12 and 32 (New York-New Jersey metropolitan area) of the International Association of Heat and Frost Insulators and Asbestos Workers on January 1, 1963. All were invited regardless of employment status, and 1,117 men (89.4%) were examined in 1963. Of these, 894 were cigarette smokers (including ex-smokers) and 223 were non-cigarette smokers.
• Exposure: Asbestos insulation work, measured as years since onset of asbestos exposure. No fiber types or doses are given. Cigarette smoking history was also studied.
• Main results:
  • Among all 1,117 workers, FVC was normal in 817 (73.1%) and decreased in 300 (26.9%): 193 (17.2%) moderate and 107 (9.7%) severe.
  • Early after onset of exposure, 11 (5.3%) of 207 workers in the first 5 years and 15 (10.3%) of 146 workers at 5 to 9 years had FVC below 70% of predicted. The authors stated similar prevalences have been reported in nonexposed general populations.
  • More than 40 years after onset of exposure, 22 (56.4%) of 39 non-cigarette smokers and 54 (69.2%) of 78 cigarette smokers had FVC below 70% of predicted. Severe FVC reduction was seen in 42 of the 117 workers (36%) in this group.
  • Of 309 workers examined 30 or more years after onset of exposure, 144 (46%) still had normal vital capacity.
  • Normal FVC was found in 648 (72.5%) of 894 cigarette smokers and 169 (76%) of 223 non-cigarette smokers. Abnormalities were consistently more common among smokers, but the difference was not statistically significant.
  • A pure restrictive pattern (normal FEV1/FVC with moderate to severe decrease in FVC) occurred in 27.8% of cigarette smokers and 27.3% of non-cigarette smokers.
  • A predominantly obstructive pattern was found in five (0.8%) of the 613 workers with both FVC and FEV1/FVC results, and all five were cigarette smokers. A mixed pattern was found in eight (1.6%) cigarette smokers and one non-cigarette smoker.
  • A normal FEV1/FVC ratio was found in 95.9% of non-smokers and 89.6% of cigarette smokers. All five non-cigarette smokers with a reduced ratio were examined 30 or more years after onset of exposure. By comparison, 20 (39.2%) of 51 cigarette smokers with a reduced ratio were examined less than 30 years after onset.
  • Among cigarette smokers, severe FEV1 reduction was found in 2 (1.6%) of 124 examined in the first 10 years after onset of exposure, compared with 31 (19.5%) of 159 examined 30 or more years after onset.
  • Vital capacity abnormalities were no more common among workers with a family history of asbestos exposure than among workers without one.
• The authors' conclusion: The authors concluded that asbestos alone, without cigarette smoking, had no measurable effect on large-airway function; the discussion describes this as a minor effect. They also concluded that cigarette smokers had earlier and more frequent decreases in FEV1/FVC than non-cigarette smokers.
• Limitations the authors state:
  • The data were analyzed retrospectively and depended on the equipment and testing procedures available about 20 years earlier.
  • FEV1 was available for only 54.8% of the study population.
  • The Vitalor device used in 1963 recorded vital capacity only up to 5.0 liters, and results may not be reproducible within 5%. For this reason the authors used 70% of predicted, rather than 80%, as the cutoff for normal.
  • The group with 25 to 29 years since onset was small (20 men). The authors attributed its higher abnormality rate to wartime hires who had been exempted from military duty and may have had other diseases such as tuberculosis.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Insulator, FEV1, FEV1/FVC Ratio, Obstructive Lung Disease.

Related studies

• Spirometric impairments in long-term insulators. Relationships to duration of exposure, smoking, and radiographic abnormalities — A. Miller, R. Lilis, et al. (1994)
• Railroad workers with pleural plaques: I. Spirometric and nitrogen washout investigation on smoking and nonsmoking asbestos-exposed workers — U. Hjortsberg, P. Orbaek, et al. (1988)
• Asbestosis: interstitial pulmonary fibrosis and pleural fibrosis in a cohort of asbestos insulation workers: influence of cigarette smoking — R. Lilis, I.J. Selikoff, et al. (1986)
• Symptomatic benign pleural effusions among asbestos insulation workers: residual radiographic abnormalities — R. Lilis, Y. Lerman, et al. (1988)
• Relation of spirometric function to radiographic interstitial fibrosis in two large workforces exposed to asbestos: an evaluation of the ILO profusion score — A. Miller, R. Lilis, et al. (1996)
• Lung function in insulation workers — J. Clausen, B. Netterstrøm, et al. (1993)

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