Cumulative asbestos exposure as a key predictor of long-term pleuropulmonary outcomes: insights from decades of follow-up

Our plain-English summary of Cumulative asbestos exposure as a key predictor of long-term pleuropulmonary outcomes: insights from decades of follow-up, by L. Štěpánek, M. Nakládalová, M. Janošíková, et al (International Archives of Occupational and Environmental Health, 2025).

The study

• Authors: L. Štěpánek, M. Nakládalová, M. Janošíková, L. Štěpánek, A. Boriková
• Journal: International Archives of Occupational and Environmental Health
• Published: 2025;98(6):497-505
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Purpose: Occupational asbestos exposure was widespread before regulatory bans, and it remains a risk during renovations or demolitions of older buildings. While asbestos-related diseases are well-documented, less is known about minor radiological changes in exposed individuals. This longitudinal study aimed to identify predictors of pleural and parenchymal lung disorders in individuals with previous occupational asbestos exposure, focusing on both established asbestos-related diseases and minor radiological abnormalities.

Methods: The study tracked 445 former employees (334 men, 111 women) of two Czech asbestos-processing plants, who underwent regular examinations from the 1980s to December 2022. Cox proportional hazards regression models were employed to analyse predictors of asbestos-related diseases, as well as minor radiological findings alone.

Results: Over a median latency of 37 years, 127 participants (28.5%) developed asbestos-related diseases, mainly pleural mesothelioma (59 cases). An additional 168 participants (37.8%) exhibited minor radiological findings, predominantly pleural plaques (129 cases), while 150 (33.7%) had no abnormalities. Substantial cumulative exposure was a strong predictor for minor radiological findings (odds ratio [OR] 1.98, 95% confidence interval [CI] 1.18-3.35, p = 0.010) and any endpoint, including diseases (OR 1.89, 95% CI 1.18-3.02, p = 0.008). Respiratory symptoms and impaired spirometry results significantly increased the likelihood of endpoint occurrence. No significant differences emerged between settings with predominantly chrysotile exposure and those with a chrysotile-crocidolite mixture.

Conclusion: This study highlights the predictive value of cumulative exposure and the need for ongoing surveillance of occupationally exposed individuals to better understand radiological changes, their significance, and to refine risk assessment models.

© 2025. The Author(s).

In plain English

This longitudinal study followed 445 former employees (334 men, 111 women) of two asbestos-cement plants in the Olomouc region of the Czech Republic, with examinations from 1980 to December 2022. Plant A used 20% crocidolite and 80% chrysotile; Plant B used mainly chrysotile. By the end of follow-up, 127 people (28.5%) had asbestos-related diseases, most often pleural mesothelioma (59 cases); 168 (37.8%) had only minor radiological findings, mostly pleural plaques; and 150 (33.7%) had no abnormalities. Compared with mild cumulative exposure (a combined measure of years worked and dust level), substantial cumulative exposure was linked to higher odds of any endpoint (odds ratio 1.89, 95% CI 1.18 to 3.02) and of minor findings alone (1.98, 95% CI 1.18 to 3.35). Mild or severe spirometry impairment and respiratory symptoms were also associated with any endpoint. Endpoint occurrence did not differ significantly between workers from the chrysotile-crocidolite plant and the mainly chrysotile plant. The authors concluded that minor radiological changes may signal substantial past exposure and higher risk of future severe conditions. They noted missing precise dust measurements for some workers and possible selection bias from referral-based recruitment.

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: Longitudinal study of former asbestos workers under regular medical follow-up. Predictors were analysed with Cox proportional hazards regression with right censoring. There were two models: one for any endpoint, and one for minor radiological findings only.
• Who was studied: 445 former employees (334 men, 111 women) of two asbestos-processing plants in the Olomouc region, Czech Republic: Plant A (n = 255) and Plant B (n = 190). They attended follow-ups at the Department of Occupational Medicine, University Hospital Olomouc. Recruitment began in 1980 and data ran to December 31, 2022. Participants came through mandatory post-exposure examinations or through referrals for suspected occupational disease.
• Exposure: Plant A (1959–1993) made asbestos-cement pipes and boards from a mixture of 20% crocidolite and 80% chrysotile. Plant B (1910–1995) made asbestos-cement corrugated roofing sheets using asbestos containing up to 4% crocidolite until 1978, and only chrysotile after that. Cumulative exposure combined exposure duration with dust level (low or high, based on job role and historical hygiene assessments). It was classed as mild (less than 5 years at high dust levels, or only low dust levels) or substantial (at least 5 years at high dust levels).
• Main results:
  • By the end of follow-up, 127 of 445 individuals (28.5%) had developed asbestos-related diseases.
  • 168 individuals (37.8%) had only minor radiological findings, and the remaining 150 individuals (33.7%) had no detectable abnormalities.
  • Among the 127 with asbestos-related diseases, the diagnoses were pleural mesothelioma (59 cases, 46.5%), hyalinosis (32 cases, 25.2%), lung cancer (21 cases, 16.5%) and asbestosis (19 cases, 15.0%). Four people developed two different diseases. Under the Czech definitions used, hyalinosis means pleural plaques with restrictive ventilatory impairment.
  • In the minor-findings subgroup, 143 individuals (85.1%) had (PET/)CT scans. The most common finding was pleural plaques (129 cases, 76.8%).
  • The mean latency from first exposure to the endpoint was 37.4 years (median 37).
  • Substantial cumulative exposure, compared with mild, predicted any endpoint (asbestos-related disease or minor findings): OR 1.89, 95% CI 1.18 to 3.02, p = 0.008.
  • Substantial cumulative exposure, compared with mild, predicted minor radiological findings alone: OR 1.98, 95% CI 1.18 to 3.35, p = 0.010.
  • In the any-endpoint model, the following were associated with significantly higher odds than normal spirometry: mild ventilation impairment (OR 1.35, 95% CI 1.001 to 1.820, p = 0.049) and severe ventilation impairment (OR 1.93, 95% CI 1.007 to 3.693, p = 0.048). Moderate impairment was not significant (OR 1.523, p = 0.160). Spirometry was not a significant predictor in the minor-findings-only model.
  • Respiratory symptoms at examination predicted any endpoint (OR 1.40; 95% CI 1.035 to 1.891, p = 0.029). Symptoms were not significant in the minor-findings-only model.
  • Endpoint occurrence was not significantly associated with asbestos type. The comparison was chrysotile and crocidolite at Plant A versus chrysotile only at Plant B. For Plant B versus Plant A, any endpoint: OR 1.063, 95% CI 0.800 to 1.412, p = 0.675. The endpoint here was composite and combined malignant, non-malignant and minor radiological findings.
  • Kaplan-Meier curves showed that the effect of cumulative exposure on endpoints became apparent about 15 years after first exposure.
  • In the regression models, each additional year of exposure was associated with slightly lower odds of an endpoint: OR 0.982 for any endpoint and 0.969 for minor findings only. This contrasted with the descriptive data, where mean exposure duration was 20.5 years in those with diseases, 14.0 years in those with minor findings and 10.3 years in those without an endpoint. The authors attributed the difference to right-censored observations in the Cox model.
• The authors' conclusion: The authors concluded that cumulative exposure was a significant predictor of both asbestos-related diseases and minor radiological findings, whatever type of asbestos was processed. They called for continued monitoring of formerly exposed people, including those with only minor radiological changes, because such changes may indicate substantial past exposure and a higher risk of future severe conditions.
• Limitations the authors state:
  • Precise asbestos dust concentration data were unavailable for some participants. Workplace dust was assessed only intermittently, and dust levels for some individuals were estimated from their job roles.
  • Selection bias may have occurred because referral-based patients were included, so the sample may not fully represent the workforce of both plants.
  • Reasons for ending follow-up were not systematically documented, which creates uncertainty about right-censoring.
  • Dust level and exposure duration were reduced to binary variables to define cumulative exposure, which the authors say complicates comparison with similar studies.
  • The authors suggested that the lack of a difference by asbestos type likely reflected the composite endpoint approach, which did not separate malignancies from other findings.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Latency, Pleural Mesothelioma, Pleural Plaques, Cumulative Exposure, Odds Ratio, confidence interval, Spirometry.

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