Lung function in relation to radiographic changes in asbestos workers

Our plain-English summary of Lung function in relation to radiographic changes in asbestos workers, by S. Zedda, G. Aresini, I. Ghezzi, et al (Respiration; International Review of Thoracic Diseases, 1973).

The study

• Authors: S. Zedda, G. Aresini, I. Ghezzi, E. Sartorelli
• Journal: Respiration; International Review of Thoracic Diseases
• Published: 1973;30(2):132-40
• Cited by: 17 articles, 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. 001325).

Abstract

A functional study involving VC, FEV 1.0 sec, RV, steady-state DLCO and fractional CO uptake at rest and, where possible, at two exercise levels (50 and 100 W), has been carried out on 724 male subjects exposed to asbestos dust inhalation. Subjects were divided into 5 groups according to UICC radiological classification of Cincinnati (1970): group I 0/0-0/1, with asbestos exposure of less than 10 years; group II 0/0-0/1, with asbestos exposure of more than 10 years; group III 1/0—1/1, group IV 1/2-2/1-2/2 and group V 2/3—3/2—3/3. The following results were obtained: obstructive ventilatory insufficiency was observed in a percentage of cases variable between 11.2 and 24.2% in the different groups; restrictive ventilatory insufficiency was observed in 5.6% of subjects in group I, 10.1 % in group II, and 31.1-41.9-69.2%, respectively, in groups III, IV and V; impairment of gas exchange at rest and during exercise (reference to the lowest values obtained in 123 normal male subjects) was found in 4.6-6.4% of subjects in group I, 9.6-19.2% of subjects in group II and in a percentage of above 20% (till 100%) in groups III, IV and V. Low values of DLCO in some cases of asbestos-exposed workers without radiological changes and without obstructive pulmonary disease suggest that the pulmonary damage induced by asbestos fibers may determine functional alterations of gas exchanges even in the preradiological stages.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This Italian study measured lung function in 724 men exposed to asbestos dust in mining, insulation, asbestos cement, asbestos manufacturing and friction materials work. Of these, 368 came from the Piemonte chrysotile mining industry. The authors grouped the men by chest X-ray category (UICC Cincinnati classification). They split those with normal or doubtful X-rays by exposure under or over 10 years and compared all groups with 123 unexposed men. Restrictive ventilatory insufficiency was found in 5.6% and 10.1% of the two normal or doubtful X-ray groups, and in 31.1%, 41.9% and 69.2% of the slight, moderate and severe asbestosis groups. Resting carbon monoxide diffusing capacity was below the lowest unexposed value in 6.4% of 109 and 19.2% of 125 men in the two normal or doubtful X-ray groups, and in 60.0% of 5 severe asbestosis cases. The groups differed significantly (p less than 0.001). Excluding men with airway obstruction did not substantially change these percentages. The authors concluded that asbestos damage may impair gas exchange before X-ray changes appear. Their reference values were not corrected for age, height or 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: Lung function survey (cross-sectional comparison) of asbestos-exposed workers grouped by chest X-ray category, with an unexposed reference group. Tests were spirometry, residual volume, and steady-state carbon monoxide diffusing capacity at rest and during bicycle exercise.
• Who was studied: 724 asbestos-exposed men. 356 were traced over the previous 10 years and given an asbestosis checkup. 368 were studied in the previous 2 years in a survey of the Piemonte chrysotile mining industry. Groups by X-ray category: 161 (0/0-0/1, exposure under 10 years), 228 (0/0-0/1, over 10 years), 215 (1/0-1/1, slight asbestosis), 107 (1/2-2/1-2/2, moderate), 13 (2/3-3/2-3/3, severe). The reference group was 123 normal men never exposed to dust (mean age 33).
• Exposure: Asbestos dust inhalation in asbestos mining (including chrysotile mining in Piemonte), insulating, asbestos cement, asbestos manufacturing and friction materials production. Mean exposure was 5.7, 21.2, 17.6, 18.0 and 20.1 years in the five groups.
• Main results:
  • Restrictive ventilatory insufficiency was found in 5.6% of group I (normal or doubtful X-ray, under 10 years' exposure) and 10.1% of group II (normal or doubtful X-ray, over 10 years). It was found in 31.1%, 41.9% and 69.2% of groups III, IV and V (slight, moderate and severe radiological asbestosis).
  • Obstructive disease (chronic bronchitis and emphysema) was found in 11% of the under-10-year group and 24% of the over-10-year group with normal or doubtful X-rays. In the slight, moderate and severe asbestosis groups it was 16%, 24% and 23%. The authors attributed this to very bad working conditions.
  • Mean resting DLCO in ml/mm Hg/min was 23.0 in the unexposed men. In the exposed groups it was 20.0 (under 10 years, normal or doubtful X-ray), 17.7 (over 10 years, normal or doubtful X-ray), 16.6 (slight asbestosis), 12.8 (moderate) and 9.8 (severe). A difference from normal was already appreciable in the under-10-year group.
  • Abnormal DLCO was defined as below the lowest values in the unexposed men: 11.6 ml/mm Hg/min at rest, 24.4 at 50 W and 31.0 at 100 W. The percentages below these values (rest, 50 W, 100 W) were: under-10-year group (109 men) 6.4, 4.6, 4.6; over-10-year group (125) 19.2, 9.6, 13.6; slight asbestosis (85) 24.8, 17.6, 22.4; moderate (26) 53.8, 42.3, 46.0; severe (5) 60.0, 100.0, 100.0.
  • The distribution of cases with reduced DLCO was correlated with radiological category, and the groups differed significantly (p less than 0.001).
  • Excluding all men with obstructive ventilatory insufficiency did not substantially change the percentages with impaired diffusing capacity. For example, at rest the figures were 6.0% of 100 men in the under-10-year group and 16.7% of 102 in the over-10-year group.
  • The reduction in fractional CO uptake was mainly due to the alveolar-capillary component, with no appreciable change in the ventilatory component.
• The authors' conclusion: The authors concluded that asbestos exposure frequently impairs diffusing capacity. A fairly large number of workers without radiological changes showed this impairment, more often those exposed over 10 years. They suggested that asbestos damage may alter gas exchange even in the preradiological stages. They stated that functional tests (VC, FEV 1.0 sec and DLCO) must be generalized in asbestos workers.
• Limitations the authors state:
  • The DLCO normal values were not corrected for age, height and smoking habit. For this reason the authors used the lowest values in their unexposed men as the cut-off for impairment.

Topics

Medical terms in this study, explained in our Lexicon: Diffusing Capacity (DLCO), UICC, Asbestos Exposure.

Related studies

• Lung function and radiographic change in chrysotile workers in Swaziland — M. McDermott, M.M. Bevan, et al. (1982)
• Radiographic changes and lung function in relation to activity of the glutathione transferases theta and mu among asbestos cement workers — K. Jakobsson, A. Rannug, et al. (1995)
• Spirometric impairments in long-term insulators. Relationships to duration of exposure, smoking, and radiographic abnormalities — A. Miller, R. Lilis, et al. (1994)
• Risk and significance of chest radiograph and pulmonary function abnormalities in an elderly cohort of former nuclear weapons workers — M.A. Mikulski, P.G. Hartley, et al. (2011)
• A systematic review of the association between pleural plaques and changes in lung function — L. Kopylev, K.Y. Christensen, et al. (2015)
• Decline in annual lung function in workers exposed to asbestos with and without pre-existing fibrotic changes on chest radiography — T. Nakadate (1995)

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