Respiratory morbidity in workers exposed to asbestos in the primary manufacture of building materials

Our plain-English summary of Respiratory morbidity in workers exposed to asbestos in the primary manufacture of building materials, by T.G. Robins, M.A. Green (American Journal of Industrial Medicine, 1988).

The study

• Authors: T.G. Robins, M.A. Green
• Journal: American Journal of Industrial Medicine
• Published: 1988;14(4):433-48
• Cited by: 10 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. 000263).

Abstract

Former employees (214) of a plant that manufactured asbestos-containing building materials (wallboard and acoustic tile) from 1958 through 1974 were screened for asbestos-related pulmonary disease. Results are presented on 182 union members whose names appeared on a 1966 seniority list in one of six departments believed to have had substantial asbestos exposure. The study population demonstrated a high frequency of pulmonary abnormalities often associated with asbestos exposure: low mean forced vital capacity percent of predicted (FVC % predicted), low mean forced expiratory volume at one second percent of predicted (FEV1 % predicted), presence of parenchymal abnormalities (40.1% with profusion scores of 1/0 or higher), and 30.5% with bilateral pleural abnormalities on chest roentgenograms. In addition, râles in two or more locations were found in 22.8% on examination of the chest, 30.6% gave a history of chronic bronchitis, and 34.8% of dyspnea grade two or higher. Calculated asbestos exposure scores, based upon participant recall, were not found to be associated with these abnormalities. The abnormal findings were not adequately explained by potential confounders such as cigarette smoking. Other notable findings in this study include the presence of smoking-adjusted decrements in pulmonary function associated with moderate profusion scores (i.e., 1/0 and 1/1) and the presence of a substantial degree of obstructive lung disease (19.2%) in this population.

In plain English

This was a screening study of union members from the Conwed plant in Cloquet, Minnesota. The plant used asbestos in wallboard and acoustic tile from 1958 through 1974; South African amosite and chrysotile were believed used. Of 214 people screened, the analysis covered 182 men listed in 1966 as working in six departments thought to have high asbestos exposure. Based on the average of two X-ray readers, 40.1% had lung-tissue (parenchymal) abnormalities at a profusion score of 1/0 or higher, and 30.5% had pleural abnormalities on both sides. Obstructive lung disease was found in 19.2%, chronic bronchitis in 30.6%, and grade two or higher breathlessness in 34.8%. Asbestos exposure scores, based on workers' recall, showed no consistent dose-response relationship with any outcome. After adjustment for smoking and age, higher profusion scores were associated with larger shortfalls in lung capacity (FVC). The authors concluded that the findings were consistent with disease from asbestos alone or combined with other workplace hazards, and were not explained by smoking alone. They noted that recalled job histories raised serious questions about reliability, and that participation was voluntary.

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 respiratory screening study (questionnaire, spirometry, chest X-rays read by two B readers, physical examination)
• Who was studied: 182 male union members (ages 38 to 79, mean 56.1) of the Conwed plant, formerly Wood Conversion Company, in Cloquet, Minnesota. They were named on a 1966 seniority list in one of six departments believed to have high asbestos exposure. 214 were screened in total; 32 who contacted the investigators on their own were excluded from the main analysis.
• Exposure: Asbestos used as an ingredient in wallboard and acoustic tile manufacture, 1958 to 1974. South African amosite, chrysotile and perhaps other fiber types were believed used. Workers also reported exposure to silica (Celite, cristobalite) and to formaldehyde (Lo-tone resin). Exposure scores were based on participant recall.
• Main results:
  • 40.1% of the 182 participants had parenchymal profusion scores of 1/0 or higher (average of two B readers)
  • 30.5% of the 182 participants had bilateral pleural abnormalities on chest X-ray
  • Obstructive lung disease was found in 19.2% of the 182 participants (restrictive disease in 6.6%, per Table I)
  • Chronic bronchitis was reported by 55 participants (30.6%) and grade two or higher dyspnea by 62 (34.8%)
  • No outcome showed a consistent dose-response relationship with any measure of asbestos exposure
  • After adjustment for pack-years, current smoking and age, FVC decrement was significantly associated with average profusion score (0.229 L for 0/1 or less, 0.215 L for 1/0, 0.600 L for 1/1 or greater; p = .02), with rales, dyspnea and chronic bronchitis, but not with bilateral pleural disease
  • In a model including age, pack-years and current smoking, higher profusion scores were significantly associated with grade two or higher dyspnea (p = .01)
  • Pleural disease was not associated with pulmonary function decrements when profusion score was controlled for
  • Reported silica exposure was not associated with respiratory outcomes. Reported formaldehyde exposure was somewhat associated with dyspnea (38.0% vs 15.8%, p = .06) but not with other respiratory measures.
• The authors' conclusion: The authors concluded that these workers showed a significant degree of adverse respiratory outcomes consistent with pulmonary disease caused by asbestos alone or by asbestos mixed with other workplace hazards, not explained by cigarette smoking alone.
• Limitations the authors state:
  • Exposure estimates relied entirely on participant recall, with no air-monitoring data or job history records available. The authors' review of the recalled job histories raised serious questions about their reliability.
  • Only people with suspected high exposure were targeted, so the range of exposures may have been narrow
  • Locating methods favored people still employed in 1985, possibly introducing survivor bias
  • Voluntary participation meant a self-selected sample; self-referred people reported more dyspnea (54.8% vs. 34.8%, p = .03)
  • Workers had mixed exposures (silica, formaldehyde, rock wool, talc), and the questionnaire measured these only crudely

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, FEV1, Bilateral, Dyspnea, Obstructive Lung Disease.

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• Asbestos exposure and radiological abnormalities among maintenance and custodian workers in buildings with friable asbestos-containing materials — M. Matrat, J.C. Pairon, et al. (2004)
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• Exposure to airborne asbestos during abatement of ceiling material, window caulking, floor tile and roofing material — J.H. Lange, S.L. Sites, et al. (2008)

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