Metsovo lung: pleural calcification and restrictive lung function in northwestern Greece. Environmental exposure to mineral fiber as etiology

Our plain-English summary of Metsovo lung: pleural calcification and restrictive lung function in northwestern Greece. Environmental exposure to mineral fiber as etiology, by S.H. Constantopoulos, J.A. Goudevenos, N. Saratzis, et al (Environmental Research, 1985).

The study

• Authors: S.H. Constantopoulos, J.A. Goudevenos, N. Saratzis, A.M. Langer, I.J. Selikoff, H.M. Moutsopoulos
• Journal: Environmental Research
• Published: 1985;38(2):319-31
• Cited by: 45 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. 002558).

Abstract

Pleural calcifications are described in 122 of 268 (45.5%) inhabitants of four villages (Metsovo, Anilio, Milea, and Votonosi) in a small area of northwestern Greece (total population about 5000). All affected individuals are of one ethnic group, Vlachi. Calcifications were not noted in any of the 103 persons in the control group made up of 73 non-Vlachi inhabitants from the same and neighboring villages and 30 Vlachi from distant villages. The calcifications were seen in both sexes, equally, and their frequently increased with age, from 28.6% between 30 and 39 years to 81.0% in individuals over 70 years of age. When plaque development was extensive, a small restrictive pulmonary function defect was noted. Because of its prevalence in the Metsovo area we call this clinical pattern Metsovo lung. The identification of tremolite, related amphibole fibers, and traces of chrysotile fiber in settled dusts and soil specimens and of identical fibers in tissue specimens obtained at lung biopsy from 8 people with plaques supports the hypothesis that abestiform minerals are the agents responsible for these disease processes. Further, reports of the occurrence of mesothelioma and benign pleural effusions in inhabitants in the Metsovo area, along with the striking similarities to disease patterns observed in the Karain area of Turkey, add further weight to the hypothesis that mineral fiber(s) in the environment of the four villages are agent(s) in the etiology of Metsovo lung.

In plain English

Researchers in northwestern Greece read chest X-rays of 268 residents of four villages (Metsovo, Anilio, Milea and Votonosi) and of 103 comparison people. Pleural calcifications appeared in 122 of the 268, all of them of the Vlachi ethnic group. None were seen in 73 residents of neighboring villages or in 30 Vlachi from distant villages. The share affected rose with age, from 28.6% at ages 30 to 39 to 81.0% over 70. Breathing tests showed a slight restrictive loss of lung volume as plaques became more extensive. Electron microscopy found occasional chrysotile fibrils and traces of amphibole in local soil and house dust. In five of eight small lung biopsies it found mostly tremolite-like amphibole fibers, with rare chrysotile. The authors also noted five pleural mesothelioma cases in the area within two years. They concluded that the findings suggest mineral fiber as at least one cause of the condition, which they named "Metsovo lung." They cautioned that biopsies may not reflect the fibers at the pleura, and that fiber amounts were not measured.

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 survey: chest X-ray readings, clinical examination and spirometry in a subset, plus mineral analysis of soil, settled dust and lung biopsy tissue
• Who was studied: Chest X-rays of 246 inhabitants of Metsovo, Anilio and Milea plus 22 Vlachi inhabitants of Votonosi (268 total), and 103 controls (73 from neighboring villages, 30 Vlachi from distant villages), in northwestern Greece. 98 people had a full clinical evaluation and 55 attempted spirometry. Nine lung biopsies came from Metsovo inhabitants with 'Metsovo lung'; eight were analyzed.
• Exposure: Environmental (nonoccupational) exposure to mineral fibers from local soils and rock. Soil and dust contained occasional chrysotile fibrils and trace amphibole, including fibers with the chemistry of iron-poor tremolite.
• Main results:
  • Pleural calcifications were seen in 116 of the people from Metsovo, Anilio and Milea (47.2%) and in 6 of 22 people from Votonosi (27.3%). All 122 affected people were Vlachi.
  • No calcifications were seen in the 30 Vlachi from distant villages or the 73 inhabitants of the three neighboring villages.
  • The frequency of calcifications rose with age, from 28.6% among those aged 30 to 39 to 81.0% among those over 70.
  • In people without plaques (group A), mean FVC and FEV1 were 92.3% and 96.6% of predicted. In people with stage III plaques they were 81.0% and 88.3%, and with stage IV plaques 75.5% and 80.5%. The authors described this as a slight restrictive decrease.
  • Respiratory symptoms or history were reported by 52 of 61 people with plaques (85%), compared with 20 of 37 without (56%). The groups differed in age and sex.
  • Fibers were found in five of the eight lung biopsy preparations. Amphibole fibers, tending to be tremolitic and asbestiform, were much more frequent than chrysotile.
  • Of the 98 people with known clinical histories, 26 had had episodes of benign pleural effusion.
  • In the discussion, the authors reported five cases of pleural mesothelioma in a population of about 5000 over 2 years, based on hospital cases. None of these patients had pleural calcification.
• The authors' conclusion: The authors concluded that the dust and tissue studies suggest mineral fiber as at least one of the agents causing these diseases. They proposed the term 'Metsovo lung' and called for a quantitative case-control study of lung tissue.
• Limitations the authors state:
  • Transbronchial biopsies reflect dust near the airways and may not reflect fibers at the pleura, where the injury occurs.
  • Tissue samples were small and variable, so fiber amounts were not quantified.
  • Fibers may have been found in only five of eight specimens because of the small amounts of tissue.
  • Groups with and without plaques were not comparable in age or sex.
  • For 273 of the people studied, the only clinical data were X-ray films.

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: Metsovo Lung, Pleural Calcification, Restrictive Lung Disease, Environmental Exposure, Mineral Fiber, Etiology, Tremolite, Amphibole Group.

Related studies

• Metsovo lung outside Metsovo. Endemic pleural calcifications in the ophiolite belts of Greece — S.H. Constantopoulos, P. Theodoracopoulos, et al. (1991)
• Pleural calcification in northwest Greece — T. Bazas, D. Oakes, et al. (1985)
• Association of Metsovo lung and pleural mesothelioma with exposure to tremolite-containing whitewash — A.M. Langer, R.P. Nolan, et al. (1987)
• Evidence Suggesting the End of Universal Domestic Asbestos Exposure in Metsovo, NW Greece — A. Gogali, E.E. Ntzani, et al. (2017)
• 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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