Malignant pleural mesothelioma from nonoccupational asbestos exposure in Metsovo (north-west Greece): slow end of an epidemic?

Our plain-English summary of Malignant pleural mesothelioma from nonoccupational asbestos exposure in Metsovo (north-west Greece): slow end of an epidemic?, by K. Sakellariou, V. Malamou-Mitsi, A. Haritou, et al (The European Respiratory Journal, 1996).

The study

• Authors: K. Sakellariou, V. Malamou-Mitsi, A. Haritou, C. Koumpaniou, C. Stachouli, I.D. Dimoliatis, S.H. Constantopoulos
• Journal: The European Respiratory Journal
• Published: 1996;9(6):1206-10
• Cited by: 42 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Inhabitants of the Metsovo area, north-west Greece have been exposed since childhood to inhalation of asbestos, from a material containing tremolite, used for whitewashing ("luto soil"). This has resulted in endemic pleural calcifications (47% of adult population) and increased incidence of malignant pleural mesothelioma (MPM). In 1987, we reported that the incidence of MPM between 1981-1985 was around 300 times higher than expected in a nonasbestos exposed population (seven cases in 5 yrs in a population of 4,000-5,000). The present study is an updated report regarding this "mesothelioma epidemic", in conjunction with the diminished use and final abandonment of "luto soil" in the early 1980s. It appears that the incidence of MPM in Metsovo has dropped considerably since our first report. Between 1985-1994, we diagnosed six such cases (incidence rate = 1.4 cases per 10,000 person-years), whilst between 1980-1984 eight cases had been diagnosed (incidence rate = 3.7 cases per 10,000 person-years). Although, because of the small number of cases, this did not reach statistical significance (p = 0.08), we note that the incidence is now considerably lower than before. Had it remained unchanged, we would have expected 17 cases of MPM instead of six. This drop follows the diminished use of "luto" whitewash (by 92% of the population in 1950 and only 18% in 1980). If we take into account a 30-40 year latency period for mesothelioma, we expect that the "Metsovo mesothelioma epidemic" will fade away by the year 2020-2030, since the material has not been used since 1985.

In plain English

This study followed up malignant pleural mesothelioma in four villages of the Metsovo area, north-west Greece (4,250 people in 1981 and 4,494 in 1991). Residents there had used a tremolite-containing whitewash called "luto". Its use fell from practically all inhabitants until 1950 to 18% by 1980. The authors compared six cases diagnosed from 1985 to 1994 with eight cases from 1980–1984. The incidence was 3.7 cases per 10,000 person-years in 1980–1984 (95% CI 1.6–7.3) and 1.4 in 1985–1994 (95% CI 0.5–2.9). The earlier rate was 2.8 times the later one (relative risk 2.8, 95% CI 1.0–7.7). This difference was not statistically significant (p=0.08), mainly because of the small number of cases. Had the earlier rate continued, the authors would have expected 17 cases rather than six. The rates were crude because the population's age structure was unknown. The authors noted that the timing alone does not establish that reduced whitewash use caused the drop. They concluded the drop was genuine and expected the epidemic to fade by 2020–2030.

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: Follow-up comparison of crude mesothelioma incidence rates in two time periods (1980–1984 and 1985–1994) in one population, with a description of the six recent cases
• Who was studied: Total population of four villages (Metsovo, Milia, Anilio, Votonossi) in the Metsovo area, Ioannina, north-west Greece, followed 1980–1994. Census populations were 4,250 (1981) and 4,494 (1991), giving 21,372 person-years for 1980–1984 and 44,574 person-years for 1985–1994.
• Exposure: Nonoccupational exposure to a tremolite-containing whitewash ("luto" soil) used in homes. It was used by practically all inhabitants until 1950 and by 18% in 1980, and its use has now practically ceased. Exposure was not measured for individuals in this study.
• Main results:
  • Six malignant pleural mesotheliomas were diagnosed from the four villages between January 1985 and December 1994, compared with eight in 1980–1984.
  • Incidence was 3.7 cases per 10,000 person-years in 1980–1984 (95% CI 1.6–7.3) and 1.4 cases per 10,000 person-years in 1985–1994 (95% CI 0.5–2.9).
  • The relative risk for the 1980–1984 period compared with 1985–1994 was 2.8 (95% CI 1.0–7.7). The difference was not statistically significant (p=0.08, Fisher's exact test), mainly because of small numbers.
  • If the earlier incidence had remained the same, 17 cases would have been expected in 1985–1994 instead of the six observed.
  • The authors stated that the rate was still very high compared with non-exposed populations, including their own experience of two cases in 10 years from a non-exposed population of 400,000.
• The authors' conclusion: The authors considered the drop in incidence genuine. They expected a further decline in the following decades and hoped the disease would disappear in Metsovo by 2020–2030.
• Limitations the authors state:
  • The age structure of the population was not available, so the rates could not be standardized and are crude.
  • The match in timing between declining whitewash use and declining incidence does not establish cause. The authors also said the drop appears too abrupt to be due only to reduced luto use.
  • Some cases may have been missed between 1985 and 1994, and it is unknown whether cases occurred before 1980.
  • The predicted decline still needs to be tested with continued follow-up.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Asbestos Exposure, Tremolite, Luto, Endemic, Pleural Calcification, Mesothelioma, Incidence.

Related studies

• Metsovo lung outside Metsovo. Endemic pleural calcifications in the ophiolite belts of Greece — S.H. Constantopoulos, P. Theodoracopoulos, et al. (1991)
• Pleural effects of tremolite in north-west Greece — T. Bazas (1987)
• Evidence Suggesting the End of Universal Domestic Asbestos Exposure in Metsovo, NW Greece — A. Gogali, E.E. Ntzani, et al. (2017)
• Malignant mesothelioma in Metsovo, Greece, from domestic use of asbestos: 30 years later — A. Gogali, C. Manda-Stachouli, et al. (2012)
• 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)
• Cancer morbidity of residents living near an oil refinery plant in North-West Italy — C. Salerno, P. Berchialla, et al. (2013)

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