Respiratory health in Turkish asbestos cement workers: the role of environmental exposure

Our plain-English summary of Respiratory health in Turkish asbestos cement workers: the role of environmental exposure, by I. Akkurt, B. Onal, A.U. Demir, et al (American Journal of Industrial Medicine, 2006).

The study

• Authors: I. Akkurt, B. Onal, A.U. Demir, D. Tüzün, H. Sabir, L. Ulusoy, K.O. Karadağ, N. Ersoy, L. Cöplü
• Journal: American Journal of Industrial Medicine
• Published: 2006;49(8):609-16
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Aim: Benign and malignant pleural and lung diseases due to environmental asbestos exposure constitute an important health problem in Turkey. The country has widespread natural deposits of asbestos in rural parts of central and eastern regions. Few data exists about the respiratory health effects of occupational asbestos exposure in Turkey. A cross-sectional study was conducted to investigate respiratory health effects of occupational asbestos exposure and the contribution of environmental asbestos exposure.

Methods: Investigations included asbestos dust measurements in the workplace and application of an interviewer-administered questionnaire, a standard posteroanterior chest X-ray and spirometry. Information on birthplace of the workers was obtained in 406 workers and used to identify environmental exposure to asbestos, through a map of geographic locations with known asbestos exposure.

Results: Asbestos dust concentration in the ambient air of the work sites (fiber/ml) ranged between 0.2 and 0.76 (mean: 0.25, median: 0.22). Environmental exposure to asbestos was determined in 24.4% of the workers. After the adjustment for age, smoking, occupational asbestos exposure, and potential risk factors environmental asbestos exposure was associated with small irregular opacities grade > or = 1/0 (44.2% vs. 26.6%, P < 0.01), FVC% (97.8 vs. 104.5, P < 0.0001), and FEV1% (92.4 vs. 99.9, P < .0001). Occupational exposure to asbestos was associated with small irregular opacities grade > or = 1/0 (OR: 2.0, 95% CI: 1.3-3.1, per 1 unit increase in the natural logarithm of fiber/ml) and FEV1/FVC% (beta: 1.1, SEM: 0.54; P < 0.05, per 1 unit increase in the natural logarithm of fiber/ml).

Conclusions: Environmental exposure to asbestos could increase the risk of asbestosis and lung function impairment in workers occupationally exposed to asbestos, independent from occupational exposure and smoking.

Copyright 2006 Wiley-Liss, Inc.

In plain English

This cross-sectional study enrolled 424 of 474 workers at six Turkish asbestos cement factories using chrysotile asbestos, and assessed them with questionnaires, chest X-rays and breathing tests. Workers born where environmental asbestos disease is endemic (99 of 406, 24.4%) were classed as possibly environmentally exposed. Among the 334 with acceptable X-rays, small irregular opacities graded 1/0 or higher, the authors' X-ray definition of asbestosis, were found in 38 possibly exposed workers (44.2%) versus 66 others (26.6%). Possibly exposed workers averaged 97.8 percent of predicted forced vital capacity, versus 104.5 for others. Pleural thickening or plaques did not differ significantly (20.9% versus 13.8%). Possible environmental exposure was associated with opacities 1/0 or higher (odds ratio 2.4, 95% CI 1.4 to 4.1). Some models added workplace dust and were limited to 260 workers with workplace exposure. In those models, dust was associated with these opacities (odds ratio 2.0, 95% CI 1.3 to 3.1, per unit increase in log fiber level), but the environmental association was not statistically significant (odds ratio 1.8, 95% CI 0.9 to 3.6). The authors concluded both exposures suggested increased risk of asbestosis and lung function abnormality. They noted the cross-sectional design limits causal interpretation.

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 study using an interviewer questionnaire, chest X-rays, spirometry and workplace dust measurements
• Who was studied: 424 of 474 (89%) active workers at six asbestos cement factories in different cities of Turkey, all using chrysotile asbestos. Of these, 406 gave their birthplace, and 334 of those had acceptable chest X-rays. Study dates are not given.
• Exposure: Occupational exposure was workplace chrysotile dust, with site and factory means assigned by job title. Possible environmental exposure was defined by birthplace in areas where environmental asbestos diseases are endemic.
• Main results:
  • The authors defined asbestosis on chest X-ray as small irregular opacities graded 1/0 or higher.
  • Possible environmental exposure was identified in 99 of 406 workers (24.4%).
  • Of the 406 workers who gave their birthplace, 334 (82.3%) had acceptable chest X-rays. The X-ray findings refer to these workers.
  • Among workers with acceptable X-rays, small irregular opacities graded 1/0 or higher were found in 38 workers (44.2%) with possible environmental exposure and 66 (26.6%) without.
  • Small irregular opacities were more common in workers with possible environmental exposure than in those without:
• grade 1/0 or higher: 44.2% vs 26.6%, p less than 0.01
• grade 1/1 or higher: 25.6% vs 9.7%, p less than 0.0001
  • Among workers with acceptable X-rays, pleural thickening or plaques were found in 18 workers (20.9%) with possible environmental exposure and 34 (13.8%) without. The difference was not statistically significant.
  • Workers with possible environmental exposure had lower lung function than those without (both p less than 0.0001):
• FVC, percent of predicted: mean 97.8 (SD 15.6) vs 104.5 (SD 14.7)
• FEV1, percent of predicted: mean 92.4 (SD 16.7) vs 99.9 (SD 14.6)
  • Restrictive lung function (FVC below 80% of predicted) was found in 12.1% of workers with possible environmental exposure vs 3.3% of those without (p less than 0.01).
  • In logistic regression, possible environmental exposure was associated with small irregular opacities:
• 1/0 or higher: OR 2.4 (95% CI 1.4 to 4.1)
• 1/1 or higher: OR 3.7 (95% CI 1.8 to 7.4)
  • The models that included workplace dust were restricted to the 260 workers who had workplace exposure during the survey and had lung function results.
  • In these models restricted to 260 workers, the environmental exposure OR was:
• 1/0 or higher: 1.8 (95% CI 0.9 to 3.6), not statistically significant
• 1/1 or higher: 3.2 (95% CI 1.4 to 7.6)
  • In these models restricted to 260 workers, the OR for small irregular opacities per 1-unit increase in the natural logarithm of workplace dust concentration was:
• 1/0 or higher: 2.0 (95% CI 1.3 to 3.1)
• 1/1 or higher: 2.0 (95% CI 1.1 to 3.5)
  • After adjustment for workplace dust, the coefficients linking environmental exposure to FVC and FEV1 (percent of predicted) decreased, but both remained statistically significant:
• FVC: 4.3 (SEM 2.07), p less than 0.05
• FEV1: 4.6 (SEM 2.14), p less than 0.05
  • Workplace dust was significantly associated with the FEV1/FVC ratio: coefficient 1.1 (SEM 0.54) per 1-unit increase in the natural logarithm of dust concentration, p less than 0.05.
  • Median worksite asbestos dust concentration was 0.22 fiber per cubic centimetre of air.
• The authors' conclusion: The authors concluded that the study suggested an increased risk of asbestosis and lung function abnormality due to both occupational and environmental asbestos exposure.
• Limitations the authors state:
  • The findings apply only to active workers; retired workers and those who left for health reasons were not included.
  • The cross-sectional design limits interpretation of causality and risk assessment.
  • Dust measurements taken at the time of the study probably underestimate past occupational exposure.
  • Diseased workers who had left work or changed jobs could not be reached (healthy worker effect), which may underestimate the effect.
  • Workers excluded for unacceptable X-rays were older and had worked longer, so they could have had more opacities.
  • The reference group did not contain only unexposed workers.
  • Birthplace gives no information on how long or how intensely a person was exposed in the environment.
  • Some workers born in exposed regions may never have been exposed at all.
  • No mineralogical examination of bronchoalveolar lavage fluid was done to confirm fiber presence or type.
  • Chest X-ray rather than HRCT was used; HRCT could have shown a higher prevalence of asbestosis.

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-Cement, Environmental Exposure, Asbestos Exposure, Chest X-Ray, Spirometry, FEV1, Occupational Exposure, FEV1/FVC Ratio.

Related studies

• An 11-year longitudinal study of the occupational dust exposure and lung function of polyvinyl chloride, cement and asbestos cement factory workers — A. Siracusa, A. Forcina, et al. (1988)
• Respiratory health of workers exposed to metal dusts and foundry fumes in a copper refinery — G. Ostiguy, C. Vaillancourt, et al. (1995)
• Regarding "absence of radiographic asbestosis and the risk of lung cancer among asbestos-cement workers: extended follow-up of a cohort", by Murray Finkelstein, American Journal of Industrial Medicine 2010 — R.M. Ross (2011)
• Vapor, dust, and smoke exposure in relation to adult-onset asthma and chronic respiratory symptoms: the Singapore Chinese Health Study — T.D. LeVan, W.P. Koh, et al. (2006)
• Health and environmental consequences of the world trade center disaster — P.J. Landrigan, P.J. Lioy, et al. (2004)
• Survival in cohorts of asbestos cement workers and controls — M. Albin, V. Horstmann, et al. (1996)

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