Diachronic study of pleural plaques in rural population with environmental exposure to asbestos

Our plain-English summary of Diachronic study of pleural plaques in rural population with environmental exposure to asbestos, by L. Sichletidis, D. Chloros, N. Chatzidimitriou, et al (American Journal of Industrial Medicine, 2006).

The study

• Authors: L. Sichletidis, D. Chloros, N. Chatzidimitriou, I. Tsiotsios, D. Spyratos, D. Patakas
• Journal: American Journal of Industrial Medicine
• Published: 2006;49(8):634-41
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: The progress of pleural plaques in persons exposed to environmental asbestos in Almopia, Greece were studied prospectively.

Methods: During a 15-year period, 198 individuals, in whom pleural plaques had been observed during the period 1988-1990 were followed. Respiratory function was initially evaluated in 23. All were inhabitants of seven villages of Northern Greece, where rocks with high concentration in asbestos fibers were used for whitewashing until 1935.

Results: Out of this population, 126 survived and underwent chest X-ray in 2003 while respiratory function was retested in 18. New radiological findings were compared to previous ones using digital technology. Furthermore, the cause of death of the remaining 72 was recorded. Deterioration of X-ray findings was observed in all survivors. Not only did the surface area of previous plaques increase (8.66 +/- 12.6 cm2, mean value +/- SD) but new ones also appeared. Total lung capacity decreased from 95.6 +/- 14.8 in 1998 to 76.5 +/- 9.3% predicted in 2003. It was found that out of 72 deaths, 11 people died of malignant lung neoplasm, and 4 of mesothelioma.

Conclusions: Radiological appearance of pleural plaques and respiratory function of people previously exposed to asbestos environmental pollution worsens over the years. Prevalence of mesothelioma was found to be higher than expected.

Copyright 2006 Wiley-Liss, Inc

In plain English

The authors followed 198 people over age 40 from seven villages in Almopia, Northern Greece, whose chest X-rays had shown pleural plaques in a 1988–1990 survey. Rocks from a nearby ravine, containing asbestos fibers (especially chrysotile and tremolite), had been used there for whitewashing until 1935. In 2003, 126 survivors had new chest X-rays, which were compared with their earlier films. Causes of death for the other 72 came from death certificates. In survivors, mean plaque area rose from 8.52 to 17.18 square centimetres and new plaques appeared, with no X-ray signs of lung tissue damage. In 18 people tested both times, total lung capacity fell from 95.65 to 76.48 percent of predicted, a statistically significant drop. Greater plaque growth was correlated with greater loss. During follow-up, 4 people developed mesothelioma and 11 malignant lung neoplasm, and all 15 had died by 2003. The authors concluded that plaques worsen over time, breathing shows a mild restrictive defect, and mesothelioma was very common, which they mainly attributed to tremolite. They said smoking could not be excluded as a factor in the lung neoplasms.

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: Prospective follow-up (longitudinal) study of people with pleural plaques identified in an earlier survey, with repeat chest X-rays, repeat lung function tests in a subgroup, and death certificate review
• Who was studied: 198 inhabitants over age 40 of seven villages of Almopia, Pella county, Northern Greece, found to have pleural plaques in 1988–1990 (out of 1,086 who took part in that survey from 3,901 inhabitants). In 2003, 126 were alive and had chest X-rays and 72 had died. 18 of the 23 originally tested had repeat lung function tests (14 men, 4 women, mean age 72.7).
• Exposure: Environmental (non-occupational) exposure from whitewashing material taken from rocks in a nearby ravine, used until 1935. Earlier work in the same project found the rocks contained 50–90% asbestos fibers, especially chrysotile and tremolite.
• Main results:
  • Among the 126 survivors, mean pleural plaque surface area was 8.52 plus or minus 11.4 square centimetres in 1988–1990 and 17.18 plus or minus 19.24 square centimetres in 2003, and new plaques had appeared
  • Total plaque area in the 126 survivors increased from 1,073.4 to 2,164.5 square centimetres
  • Plaque area was larger on the left side of the chest than the right at both examinations (792.1 vs 281.3 square centimetres at first, 1,485.6 vs 678.9 at second)
  • No X-ray sign of damage to the lung tissue itself was seen in the survivors
  • In the 18 people retested, total lung capacity fell from 95.65 to 76.48 percent of predicted between 1988 and 2003. Forced vital capacity also fell, from 94.74 to 80.12 percent of predicted. Both decreases were statistically significant (P less than 0.001).
  • In the 18 people retested, the FEV1 ratio (%FEV1) rose from 79.84 to 84.95 (P less than 0.01). The authors described this as a relative increase in expiratory flow rates.
  • In the 18 people retested, the authors reported a statistically significant negative correlation (P = 0.041) between growth in plaque area and reduction in total lung capacity
  • Among the 198 people with plaques, 4 cases of mesothelioma and 11 of malignant lung neoplasm were diagnosed during 1988–2003. All 15 had died by the time of re-examination.
  • The authors calculated that 4 mesotheliomas among 198 people over 15 years was about 1,300 times the expected number, using an expected rate of 1 per 1,000,000 per year taken from another publication
• The authors' conclusion: The authors concluded that pleural plaques from environmental asbestos exposure worsen over the years, as with occupational exposure. They said respiratory function was slightly affected, showing a mild restrictive ventilatory defect. They found mesothelioma prevalence very high and mainly attributed it to the high concentration of tremolite in the local rocks.
• Limitations the authors state:
  • Only a relatively low share of the target population took part in the original 1988–1990 survey
  • Some of the loss of lung volume may have come from lung tissue damage that chest X-rays could not detect. The authors said more sensitive methods such as high-resolution CT should be used in future studies.
  • Smoking as a co-existing cause of the lung neoplasms could not be excluded

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Environmental Exposure, Chest X-Ray, Total Lung Capacity (TLC), Neoplasm, Mesothelioma.

Related studies

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• Pleural plaques and exposure to mineral fibres in a male urban necropsy population — A. Karjalainen, P.J. Karhunen, et al. (1994)
• Nonmalignant pleural lesions due to environmental exposure to asbestos: a field-based, cross-sectional study — M. Metintas, S. Metintas, et al. (2005)
• Environmental pleural plaques in residents of a Quebec chrysotile mining town — A. Churg, L. DePaoli (1988)
• Malignant pleural mesothelioma caused by environmental exposure to asbestos or erionite in rural Turkey: CT findings in 84 patients — A.A. Sahin, L. Cöplü, et al. (1993)
• Pulmonary abnormalities as a result of exposure to Libby amphibole during childhood and adolescence-The Pre-Adult Latency Study (PALS) — J. Szeinuk, C.W. Noonan, et al. (2017)

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