Decreasing prevalence of pleural calcifications among Metsovites with nonoccupational asbestos exposure

Our plain-English summary of Decreasing prevalence of pleural calcifications among Metsovites with nonoccupational asbestos exposure, by C. Manda-Stachouli, Y. Dalavanga, G. Daskalopoulos, et al (Chest, 2004).

The study

• Authors: C. Manda-Stachouli, Y. Dalavanga, G. Daskalopoulos, C. Leontaridi, M. Vassiliou, S.H. Constantopoulos
• Journal: Chest
• Published: 2004;126(2):617-21
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Study Objectives: Twenty years ago, we reported on a very high prevalence of pleural calcifications (PCs) and malignant mesothelioma among inhabitants of Metsovo, in northwestern Greece. It was shown that both abnormalities were related to asbestos exposure from a whitewash containing tremolite. The fading use of this material has resulted in a decreased incidence of mesothelioma (one third of the original incidence). The aim of the present study was to examine whether PCs among Metsovites has followed a similar trend.

Design: Retrospective study.

Settings: University Hospital of Ioannina, a tertiary teaching hospital, "G. Hadjikosta" Hospital, a tertiary hospital in Ioannina, and Metsovo Health Center, a primary care center in the town of Metsovo.

Patients: Chest roentgenograms of 307 Metsovites, obtained between from 1998 to 2002 were examined. The prevalence of PCs was compared to the one noted 20 years ago.

Results: A significantly lower prevalence of calcifications was observed now among younger Metsovites (< 60 years of age). In both studies, there was an increasing rate of PC with age.

Conclusions: The findings of the present study strengthen the incrimination of the whitewash containing tremolite in the development of PCs in Metsovites. The withdrawal of its use in the area has resulted in a null prevalence of PCs in individuals < 40 years old.

In plain English

This retrospective study from Greece examined whether pleural calcifications (calcified pleural plaques seen on chest X-rays) had become less common in the Metsovo area. Residents there had been exposed outside work to tremolite asbestos in a whitewash called "luto", whose use gradually stopped. Two physicians read 307 chest X-rays taken from 1998 to 2002 of inhabitants of four villages. The X-rays came from the records of a local health center and two hospitals in Ioannina. The results were compared with a 1978 to 1982 survey of 214 people. Calcifications were significantly less common in the newer group at ages 30 to 39 (0 of 15 vs 6 of 21), 40 to 49 (22.2% vs 44.6%) and 50 to 59 (26.5% vs 65.5%). They were almost the same at ages 60 to 69 and 70 and over. Overall rates (58.0% vs 60.3%) did not differ significantly, and the newer group was older. In both periods, calcifications became more common with age. The authors noted that the two groups had to be selected differently. They concluded that the pattern further implicates the tremolite whitewash.

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: Retrospective study of chest X-ray records from 1998 to 2002, compared with an earlier survey of the same area from 1978 to 1982
• Who was studied: 307 people living in four villages of the Metsovo area, northwestern Greece (Metsovo, Milea, Anilio, Votonossi), whose chest X-rays from 1998 to 2002 were in the records of Metsovo Health Center, G. Hadjikosta General Hospital and Ioannina University Hospital. They were compared with 214 people examined from 1978 to 1982. Most came from Metsovo itself (82.7% now, 78.9% in the older study).
• Exposure: Nonoccupational exposure to tremolite asbestos from "luto", a whitewash used by practically all Metsovites from 1940 to 1950 and gradually abandoned. The article reports that its use fell from 88% of the population in 1950 to 15% in 1980 (figures from earlier work). It was crushed into powder at home.
• Main results:
  • Ages 30 to 39: no pleural calcifications in 1998 to 2002 (0 of 15), compared with 6 of 21 (28.6%) in 1978 to 1982. The difference was statistically significant.
  • Ages 40 to 49: 8 of 36 (22.2%) in 1998 to 2002 compared with 25 of 56 (44.6%) in 1978 to 1982. Ages 50 to 59: 13 of 49 (26.5%) compared with 38 of 58 (65.5%). Both differences were reported as significant.
  • In the older groups the rates were almost identical, and the differences were not significant. Ages 60 to 69: 71 of 101 (70.3%) now compared with 30 of 42 (71.4%) before. Ages 70 and over: 86 of 106 (81.1%) now compared with 30 of 37 (81.0%) before.
  • Overall prevalence was 178 of 307 (58.0%) in 1998 to 2002 compared with 129 of 214 (60.3%) in 1978 to 1982. This difference was not statistically significant. The newer group was much older: 67.4% were aged 60 or over, compared with 36.9% in the older study.
  • The youngest person with pleural calcifications was 42 years old in the present study, compared with 29 years old in the 1978 to 1982 study.
  • In the present study, calcifications were slightly more frequent in men (109 of 170, 64.1%) than in women (69 of 137, 50.4%) in every age group except the oldest. By age group, the difference was statistically significant only at ages 60 to 69 (men 46 of 59, 78.0%; women 25 of 42, 59.5%).
  • In both periods, the prevalence of pleural calcifications increased with age.
• The authors' conclusion: The authors concluded that the decreasing prevalence further incriminates the tremolite-containing luto whitewash, and specifically breathing it since childhood while crushing it into powder. They stated that its withdrawal has resulted in a null prevalence of pleural calcifications in people under 40. They also suggested that time since first exposure, or exposure from birth, was possibly more important than cumulative exposure for developing calcifications.
• Limitations the authors state:
  • The two study populations were necessarily different. A new general-population survey was not possible, so X-rays from health center and hospital records were used instead. The authors argued that this would, if anything, underestimate rather than overestimate the decrease.
  • Because of the age differences between the two groups, comparing total numbers is not appropriate; only comparisons within the same age groups are meaningful.
  • Chest X-rays allow only calcified plaques, not simple pleural plaques, to be identified with certainty.
  • Too few people from the smaller villages were examined to allow meaningful comparisons for those villages.
  • Whether people born after 1975 to 1980 are free of calcifications can be stated with certainty only once they are at least 30 years old.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Calcification, Asbestos Exposure, Malignant Mesothelioma, Whitewash, Tremolite, Mesothelioma.

Related studies

• Additional proteins in BAL fluid of Metsovites environmentally exposed to asbestos: more evidence of "protection" against neoplasia? — V. Galani, S. Constantopoulos, et al. (2002)
• Metsovo lung outside Metsovo. Endemic pleural calcifications in the ophiolite belts of Greece — S.H. Constantopoulos, P. Theodoracopoulos, et al. (1991)
• Tremolite whitewashing and pleural calcifications — S.H. Constantopoulos, N.A. Saratzis, et al. (1987)
• Lymphocytic alveolitis and pleural calcifications in nonoccupational asbestos exposure. Protection against neoplasia? — S.H. Constantopoulos, Y.A. Dalavanga, et al. (1992)
• Prevalence of pleural calcification in persons exposed to asbestos dust, and in the general population in the same district — M. Navrátil, F. Trippé (1972)
• 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)

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