Pleural calcification in northwest Greece

Our plain-English summary of Pleural calcification in northwest Greece, by T. Bazas, D. Oakes, J.C. Gilson, et al (Environmental Research, 1985).

The study

• Authors: T. Bazas, D. Oakes, J.C. Gilson, B. Bazas, J.C. McDonald
• Journal: Environmental Research
• Published: 1985;38(2):239-47
• Cited by: 11 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. 001241).

Abstract

Mass miniature radiography in 1969 detected a high prevalence of pleural calcification in three villages in northwest Greece. In 1980 a survey of a 15% sample of the population over the age of 10 was carried out with a 80% response rate. Full-size radiographs, ventilatory capacity measurements, and a detailed questionnaire on respiratory symptoms, type of work, and residence were used. Independent classification of the 408 films by two readers using the ILO/UC scheme showed very few small opacities but a very high prevalence of pleural calcification first evident in young adults and rising to 70% in the elderly. The overall prevalence was 34.7% in men and 21.5% in women. A comparison with the 1969 survey showed a progression rate of 5% per annum. In neither sex was there a significant relation of pleural calcification to smoking, ventilatory capacity, nor type of work, though those classified as field croppers had a slightly higher prevalence. There was no obvious evidence of increased lung cancer or mesothelioma in the villages. The agent responsible for this apparently benign condition was not identified.

In plain English

This study surveyed three villages in northwest Greece where 1969 X-ray screening had found much pleural calcification (calcium deposits in the lining around the lungs). In 1980 the authors randomly selected 15% of residents over 10 who were born in the villages and had lived there most of their lives; about 80% took part. 408 people (222 males, 186 females) had chest X-rays, breathing tests and a questionnaire. Few films showed small lung opacities, but pleural calcification was found in 34.7% of males and 21.5% of females, rising to about 70% in the elderly. Calcification was not significantly linked to smoking, job or breathing capacity, though field croppers had somewhat higher rates. Among people X-rayed in both years, calcification progressed about 5% per year. One of two pleural specimens contained small proportions of tremolite fibers, the rest talc; the other contained no mineral. Death records for 1969 to 1978 showed no mesothelioma, though the authors were unsure of cancer rates. The authors concluded that a mineral dust, not necessarily asbestos, was the likely cause; the agent was not identified.

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 radiographic survey of a random population sample. It also compared the 1969 and 1980 chest X-rays of the same people to measure progression, and included tissue, water and death-record checks.
• Who was studied: A random 15% sample of people over age 10 in three villages in northwest Greece (Metsovo, Milea, Anilio). To be eligible, people had to have been born there, have lived there most of their lives, and be resident at the time. They were examined in July 1980. Response rates were 81.3% for males and 78.5% for females, and 408 people were X-rayed (222 males, 186 females).
• Exposure: An unidentified environmental agent. The ground contains serpentinite. Chrysotile asbestos is not known to occur in the area. There was no asbestos mining or processing within 200 km, and no villager had worked in mining, production or transport of asbestos. Occupations (mason, shepherd, field cropper, carpenter, woodcutter, nondusty jobs) and smoking were examined as possible factors.
• Main results:
  • Pleural calcification of any grade was found in 34.7% of males and 21.5% of females.
  • Prevalence rose with age, to about 70% in elderly men and women, and was higher in males than in females.
  • Small opacities in the lung were uncommon.
  • Calcification rates were similar in the three villages.
  • Among males, there was no relation of calcification to smoking after allowing for age.
  • Among males, 60.0% of those who had ever been field croppers had calcification, compared with 29.1% of those who never had (age-standardized odds ratio 1.71). No job category was statistically significant, even for males and females combined.
  • Lung function (FEV and FVC) in subjects aged 30 or over was lower in those with calcification than in those without, but the differences were not statistically significant.
  • In people X-rayed in both 1969 and 1980, calcification progressed at about 5% per year, regardless of its initial extent.
  • One of two pleural specimens contained small proportions of tremolite fibers, and its other fibers were talc. The second specimen contained no mineral material.
  • Death registrations for 1969 to 1978 did not suggest high proportional mortality from lung cancer and showed no case of mesothelioma.
  • Chemical analysis of drinking water gave no abnormal values.
• The authors' conclusion: The authors concluded that the similarity to calcification seen in asbestos workers points to a mineral dust as the cause, though not necessarily asbestos. They also concluded that, for practical purposes, the villagers' health was not impaired.
• Limitations the authors state:
  • No detailed study of the area's minerals or airborne dust had been made.
  • The authors could not be sure about lung cancer or mesothelioma rates.
  • No systematic search had been made for mesothelioma cases certified to other causes.
  • The readers differed in judging progression between the paired 1969 and 1980 films.
  • For a few subjects, identical names caused doubt about the correct pairing of 1969 and 1980 films.
  • Response was lowest in the 20 to 29 age group.
  • The occupational categories overlapped, especially shepherds and field croppers.
  • More human tissue was needed to analyze the lung and the pleural plaques.

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: Pleural Calcification, Lung Cancer, Mesothelioma.

Related studies

• Metsovo lung: pleural calcification and restrictive lung function in northwestern Greece. Environmental exposure to mineral fiber as etiology — S.H. Constantopoulos, J.A. Goudevenos, et al. (1985)
• Metsovo lung outside Metsovo. Endemic pleural calcifications in the ophiolite belts of Greece — S.H. Constantopoulos, P. Theodoracopoulos, et al. (1991)
• Pleural calcification associated with exposure to chrysotile asbestos in southeast Turkey — S. Yazicioglu (1976)
• Pleural effects of tremolite in north-west Greece — T. Bazas (1987)
• Tremolite whitewashing and pleural calcifications — S.H. Constantopoulos, N.A. Saratzis, et al. (1987)
• Decreasing prevalence of pleural calcifications among Metsovites with nonoccupational asbestos exposure — C. Manda-Stachouli, Y. Dalavanga, et al. (2004)

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