Environmental asbestos exposure and malignant pleural mesothelioma

Our plain-English summary of Environmental asbestos exposure and malignant pleural mesothelioma, by M. Metintas, N. Ozdemir, G. Hillerdal, et al (Respiratory Medicine, 1999).

The study

• Authors: M. Metintas, N. Ozdemir, G. Hillerdal, I. Uçgun, S. Metintas, C. Baykul, O. Elbek, S. Mutlu, M. Kolsuz
• Journal: Respiratory Medicine
• Published: 1999;93(5):349-55
• Cited by: 50 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos-related benign and malignant pleural diseases are endemic in some rural parts of central Turkey because of environmental exposure to asbestos fibres. We report here epidemiological data on 113 patients with diffuse malignant pleural mesothelioma (DMPM) diagnosed in our clinic in Eskişehir, located in central Turkey. Of the 113 patients, 59 were men and 54 women (male:female ratio = 1). Ninety-seven patients (86%) had non-occupational asbestos exposure; all were living in villages. Their mean age was 56 years. As the patients had been exposed to asbestos from birth, the latency period was equivalent to the age of the patients. Twenty-eight patients (29%) had lived in villages their entire lives. The other 69 (71%) had been born in a village but migrated to the city or had given up white-soil usage for various reasons. The mean exposure time was 55 years for those with a long exposure period and 25 years for those with a short exposure period, but there was no significant difference between the age of the disease appearance for both groups (55 and 56 years, respectively). Thus, the latency time of mesothelioma due to environmental exposure to asbestos was longer than that due to occupational exposure, but independent of the length of exposure. Soil samples from 67 villages were analysed, comprising a population of 10,120 villagers. Tremolite and some other types of asbestos were found. In conclusion, DMPM in our region is due to mainly to environmental exposure to asbestos. The risk is substantial as a large proportion of the villagers are exposed. After smoking, asbestos exposure is one of the most serious health hazards in our rural population.

In plain English

This study, from a chest disease clinic in Eskişehir, central Turkey, prospectively recorded all 113 consecutive patients with diffuse malignant pleural mesothelioma confirmed by tissue diagnosis between May 1989 and December 1997 (59 men, 54 women). Ninety-seven patients (86%) were villagers exposed to 'white soil' used to whitewash house walls and insulate roofs. Four had occupational exposure and twelve had no known exposure. The authors analysed white soil from 67 randomly chosen villages by X-ray diffraction and found tremolite or other types of asbestos in 41 samples (61%). No asbestos was found in soil used as baby powder or for pottery. Among the 97 exposed patients, 50 were men and 47 women, and mean age at diagnosis was 55.8 years. Patients who had lived in villages all their lives (average exposure 54 years) did not differ significantly in age at diagnosis from those who had left or stopped using the soil (average 25 years). The authors concluded that mesothelioma in their region is due mainly to environmental asbestos exposure.

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 case series of consecutive patients, combined with X-ray diffraction mineral analysis of white-soil samples from randomly chosen villages
• Who was studied: 113 patients with diffuse malignant pleural mesothelioma (59 men, 54 women) diagnosed at the authors' clinic at Osmangazi University, Eskişehir, central Turkey, from May 1989 to December 1997. White-soil samples were taken from 67 villages.
• Exposure: Non-occupational (environmental) exposure from birth to local 'white soil', used mainly as whitewash for house walls and as roof insulation. Samples were found to contain tremolite, a tremolite-chrysotile complex, or combinations of actinolite, anthophyllite or chrysotile. Four patients had occupational exposure and twelve had no known exposure.
• Main results:
  • Of the 113 patients, 97 (86%) had white-soil exposure and all of them lived in villages. Twelve patients had no known asbestos exposure and four had occupational exposure.
  • Tremolite or other types of asbestos fibre were found in 41 of the white-soil samples (61%) collected from 67 randomly sampled villages.
  • The authors reported that 10,120 people live in villages determined to have asbestos-contaminated white soil.
  • No asbestos fibres were found in soil samples used as baby powder or in pottery-making. Asbestos was present only in soil used as plaster and/or paint and as roof insulation.
  • Among the 97 environmentally exposed patients, 50 were men and 47 were women.
  • Among the 97 environmentally exposed patients, mean age at diagnosis was 57.5 years for men, 54.0 for women and 55.8 years overall. The difference between men and women was not statistically significant. The authors treated age at diagnosis as the latency period because exposure began at birth.
  • The 28 patients who lived in villages all their lives had about 54 years of exposure on average, and the 69 who had left or stopped using white soil had about 25 years. Their ages at diagnosis did not differ significantly.
  • Mean age at disease onset was numerically lower in the continuous exposure group (54.6 years in Table 2) than in the partial exposure group (56.3 years), but the difference was not statistically significant.
  • Three villages, with a total population of about 1548, each produced four patients. Two of the patients were husband and wife.
  • Among the 97 environmentally exposed patients, 39 had epithelial, 18 mixed and 14 sarcomatous cell type. Mean exposure periods did not differ significantly between cell types.
  • Among all 113 patients, 78% of men and 6% of women were smokers.
• The authors' conclusion: The authors concluded that diffuse malignant pleural mesothelioma in their region is due mainly to environmental exposure to asbestos from white soil. They suggested that the duration of exposure matters less than reaching a threshold level of asbestos.
• Limitations the authors state:
  • Less accessible villages could not be surveyed, so the authors said the exposed population may be far greater than the number they counted.
  • Pathologists did not report a cell type for 26 of the 97 environmentally exposed patients.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Pleural Mesothelioma, Endemic, Environmental Exposure, Latency, Mesothelioma, Occupational Exposure, Tremolite.

Related studies

• Nonmalignant pleural lesions due to environmental exposure to asbestos: a field-based, cross-sectional study — M. Metintas, S. Metintas, et al. (2005)
• High-resolution computed tomography in cases with environmental exposure to asbestos in Turkey — F. Topçu, H. Bayram, et al. (2000)
• Diachronic study of pleural plaques in rural population with environmental exposure to asbestos — L. Sichletidis, D. Chloros, et al. (2006)
• Environmental asbestos exposure in rural Turkey and risk of lung cancer — S. Metintas, M. Metintas, et al. (2012)
• Malignant mesothelioma due to environmental exposure to asbestos: follow-up of a Turkish cohort living in a rural area — S. Metintas, M. Metintas, et al. (2002)
• Environmental asbestos-related pleural plaque in southeast of Turkey — G. Ates, T. Yildiz, et al. (2010)

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