Vital capacity and one-second forced expiratory volume in Australian male asbestos cement workers

Our plain-English summary of Vital capacity and one-second forced expiratory volume in Australian male asbestos cement workers, by L.N. Balaam, S.F. McCullagh (The Annals of Occupational Hygiene, 1975).

The study

• Authors: L.N. Balaam, S.F. McCullagh
• Journal: The Annals of Occupational Hygiene
• Published: 1975;18(2):133-41
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004061).

In plain English

This study measured lung function in 955 men making asbestos-cement products at an Australian factory that began production in 1917. The second author was the company's chief medical officer. At the time of the study, raw materials were 11.6% asbestos, mostly chrysotile with less amosite, but had varied over the years. Each man's vital capacity (VC, the most air he could breathe out) and one-second forced expiratory volume (FEV1) were measured. Three long-serving company officers used job histories to place 952 men into five exposure categories. The authors could not express exposure as accurate numbers. As a group, they had lower VC and FEV1 than non-asbestos workers studied separately, a difference that was not statistically significant. VC declined more steeply with age in higher exposure categories: 1.98 ml more per year for each category step. FEV1 results were less consistent. Smoking habit did not significantly alter how either measure related to age and height. The authors noted that exposure was partly confounded with age. They concluded that exposure considerably influenced how VC and FEV1 related to age and height.

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 spirometry survey of a factory workforce, analysed with regression equations relating lung function to age, height and assessed exposure category
• Who was studied: 955 male workers of European race at an asbestos-cement factory in Australia, drawn from a male workforce (including some clerical workers) of about 1100. Exposure categories were available for 952 of them. The date of data collection is not stated.
• Exposure: Manufacture of asbestos-cement pipes and building products. At the time of the study, raw materials were 11.6% asbestos (by far mostly chrysotile, the lesser part amosite), 39.5% silica and 46.5% cement, plus a small amount of cellulose pulp. Different products used different combinations, and these had varied over the years. Each man's exposure was assessed from his job history by three company officers and placed in one of five categories. No quantitative doses were given.
• Main results:
  • As a whole group, the asbestos-cement workers had lower VC and FEV1 than non-asbestos workers in a parallel study, but the difference was not statistically significant.
  • The authors interpreted the lack of a significant whole-group difference as meaning that too few workers were affected for the effect to be detected when all the data were treated together. They stated that this did not mean asbestos exposure does not reduce VC.
  • The regression equations for VC differed significantly among the five exposure groups, both in position and in their coefficients.
  • The decline in VC with age became steeper with higher exposure group. The age coefficient changed by -1.98 ml per year for each step up in exposure group by the first method, and by -2.10 by the second method.
  • For FEV1, there was no consistent trend between the age coefficients and exposure group. The height coefficients did show a strong linear relationship with exposure group, changing by -4.97 per exposure group (-4.26 by the second method).
  • The three smoking habit categories (smoker, ex-smoker, non-smoker) did not produce significant differences in the intercepts or slopes of the equations relating VC or FEV1 to age and height.
  • Body weight had little effect in determining VC, and a similar result was found for FEV1.
• The authors' conclusion: The authors concluded that asbestos exposure had a considerable influence on the relationship between age, height, VC and FEV1 in these workers. They also stated that more sensitive and more acceptable methods of examination must be devised.
• Limitations the authors state:
  • Exposure could not be expressed in quantitative terms with acceptable accuracy, so only five assessed categories were used.
  • Older men generally had longer and greater exposure, so the effect of increasing exposure was partly confounded with age.
  • The authors suggested the inconsistency between the VC and FEV1 results probably arose because FEV1 is affected much more than VC by factors other than asbestos exposure.
  • A planned approach of following each worker's VC over the years became impractical because a majority of employees became unwilling to perform the spirometry properly.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement.

Related studies

• Expiratory and inspiratory forced vital capacity and one-second forced volume in asymptomatic never-smokers in Norway — A. Gulsvik, T. Tosteson, et al. (2001)
• Diffusing capacity and forced vital capacity in 5,003 asbestos-exposed workers: relationships to interstitial fibrosis (ILO profusion score) and pleural thickening — A. Miller, R. Warshaw, et al. (2013)
• Auscultated forced expiratory time as a clinical and epidemiologic test of airway obstruction — D.G. Kern, S.R. Patel (1991)
• Maximal expiratory flow volume curves in workers exposed to asbestos — R. Rodriguez-Roisin, J.E. Merchant, et al. (1980)
• Pulmonary function of nonsmoking female asbestos workers without radiographic signs of asbestosis — X.R. Wang, E. Yano, et al. (1998)
• Relations between vital capacity, CO diffusion capacity and computed tomographic findings of former asbestos-exposed patients: a cross-sectional study — A.M. Preisser, K. Schlemmer, et al. (2020)

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