Nonmalignant pleural lesions due to environmental exposure to asbestos: a field-based, cross-sectional study

Our plain-English summary of Nonmalignant pleural lesions due to environmental exposure to asbestos: a field-based, cross-sectional study, by M. Metintas, S. Metintas, G. Hillerdal, et al (The European Respiratory Journal, 2005).

The study

• Authors: M. Metintas, S. Metintas, G. Hillerdal, I. Ucgun, S. Erginel, F. Alatas, H. Yildirim
• Journal: The European Respiratory Journal
• Published: 2005;26(5):875-80
• Cited by: 32 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The aim of the present study was to investigate the frequencies of asbestos-related benign pleural diseases in villagers environmentally exposed to asbestos and the factors affecting these frequencies. A field-based, cross-sectional study was designed. In total, 991 villagers from 10 villages, randomly chosen from 67 villages with known use of asbestos-containing white soil in central Anatolia (Turkey), were investigated. The type of asbestos in the white soil was determined for each village, as well as air-borne fibre concentrations. The villagers were investigated with small-size chest roentgenograms and epidemiological features were recorded. The air-borne fibre levels were generally low. Despite this, pleural plaques were found in 14.4% of the villagers, 10.4% had diffuse pleural fibrosis and 0.4% asbestosis. The significant variables for plaques were age, sex, type of asbestos fibre, e.g. actinolite and tremolite, and exposure duration, while there was a negative relationship with cumulative exposure. The variables affecting diffuse pleural fibrosis were age, exposure duration and cumulative exposure. In conclusion, villagers exposed to environmental asbestos have high frequencies of pleural plaques and diffuse pleural fibrosis, similar to occupationally exposed asbestos cohorts. Different types of asbestos appear to result in different frequencies of pleural lesions.

In plain English

This cross-sectional study examined non-cancerous pleural disease in Turkish villagers in Eskisehir county exposed to asbestos in local 'white soil' used to whitewash walls. Of 11 randomly chosen villages, one was dropped because of weather. In the other ten, 943 of 991 villagers aged 30 or over had small chest X-rays; 20 with disputed readings were excluded, leaving 923. Soil from seven villages contained actinolite and tremolite; from three, anthophyllite and chrysotile. Measured airborne fibre levels were low. Among them, 133 (14.4%) had pleural plaques, 96 (10.4%) diffuse pleural fibrosis and four (0.4%) asbestosis. Plaques were more common in males (19.0%) than females (10.2%), and with actinolite/tremolite than anthophyllite (19.8% and 7.9%). In the combined analysis, plaques were linked to male sex, longer exposure and actinolite/tremolite. Plaques were less common at estimated cumulative exposures of 5 fibre-years per mL or more; the authors said this could be false if diffuse fibrosis hid plaques. Diffuse pleural fibrosis was linked to exposure duration and cumulative exposure. The authors concluded that plaque and diffuse pleural fibrosis frequencies resembled occupational ones. They called their exposure measurement fairly crude and said X-rays undercount lesions.

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: Field-based cross-sectional study using chest X-rays, a questionnaire, soil mineral analysis and indoor and outdoor air fibre measurements
• Who was studied: Villagers aged 30 years or over in Eskisehir county, Turkey, from villages where asbestos-containing white soil was still used. Eleven of 41 asbestos-positive villages were randomly chosen. One (Kadıkuyusu) was excluded because weather prevented chest radiographs, leaving 10 villages. 991 villagers formed the study group, 943 (95%) took part, and 923 were included after 20 were excluded because the X-ray readers could not agree.
• Exposure: Lifelong environmental exposure to asbestos in white soil. Seven villages had actinolite and tremolite fibres and three had anthophyllite and chrysotile fibres. Cumulative exposure was estimated from indoor and outdoor air fibre counts and years lived in the village; it ranged from 0.19 to 14.61 fibre-years per mL.
• Main results:
  • Of the 923 villagers, 133 (14.4%) had pleural plaques, 96 (10.4%) had diffuse pleural fibrosis and four (0.4%) had asbestosis.
  • Airborne fibre concentrations were low. Indoor values had a mean of 0.089 fibres per mL and outdoor values a mean of 0.013 fibres per mL.
  • Pleural plaques were significantly more frequent in males (19.0%) than in females (10.2%).
  • Diffuse pleural fibrosis showed no difference between males (9.5%) and females (11.3%).
  • Pleural plaques were more frequent in villagers exposed to tremolite/actinolite (19.8%) than in those exposed to anthophyllite (7.9%). Diffuse pleural fibrosis did not differ by fibre type (10.7% and 10.0%).
  • Compared with those aged 30 to 39, plaques were about 6 times more frequent in males aged 60 to 69 (odds ratio 5.9, 95% CI 2.0 to 17.4) and 3.5 times more frequent in females aged 60 to 69 (odds ratio 3.5, 95% CI 1.1 to 10.7).
  • In the logistic regression, pleural plaques were linked to actinolite and tremolite compared with anthophyllite (odds ratio 4.84, 95% CI 3.06 to 7.65).
  • In the logistic regression, pleural plaques were linked to male sex compared with female sex (odds ratio 1.76, 95% CI 1.17 to 2.64).
  • In the logistic regression, pleural plaques were linked to exposure duration of 60 years or more compared with 20 to 39 years (odds ratio 7.73, 95% CI 3.78 to 15.78).
  • Pleural plaques were less likely at a cumulative dose of 5 fibre-years per mL or more than at less than 5 (odds ratio 0.33, 95% CI 0.17 to 0.67), an inverse relationship that the authors said could be a false finding because diffuse pleural fibrosis might obscure plaques.
  • Diffuse pleural fibrosis was linked to exposure duration of 60 years or more compared with 20 to 39 years (odds ratio 6.64, 95% CI 2.65 to 16.61).
  • Diffuse pleural fibrosis was linked to a cumulative dose of 5 fibre-years per mL or more compared with less than 5 (odds ratio 1.83, 95% CI 1.007 to 3.35).
• The authors' conclusion: The authors concluded that villagers exposed to environmental asbestos had frequencies of pleural plaques and diffuse pleural fibrosis similar to those in occupational exposure. They also concluded that the risk of diffuse pleural fibrosis depended on cumulative dose while plaques did not, and that tremolite/actinolite fibres appeared more prone to cause plaques than anthophyllite and chrysotile.
• Limitations the authors state:
  • Chest X-rays have low sensitivity, so the prevalence figures are minimums and the true figures should be higher.
  • The authors described their way of measuring exposure as fairly crude.
  • The few recent air measurements might not reflect historical exposures.
  • Peak exposures, such as during whitewashing or floor brushing, could not be reconstructed for individuals.
  • The inverse link between plaques and cumulative exposure might be a false finding, because diffuse pleural fibrosis could hide plaques.
  • Diffuse pleural fibrosis is less specific than plaques and may follow any type of pleuritis.

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: Environmental Exposure, Pleural Plaques, Fibrosis, Actinolite, Tremolite, Cumulative Exposure.

Related studies

• 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)
• Is living close to ophiolites related to asbestos related diseases? Cross-sectional study — I. Döngel, M. Bayram, et al. (2013)
• Environmental asbestos exposure in rural Turkey and risk of lung cancer — S. Metintas, M. Metintas, et al. (2012)
• Prevalence of anti-nuclear autoantibodies in subjects exposed to natural asbestiform fibers: a cross-sectional study — C. Ledda, R. Caltabiano, et al. (2018)
• Environmental asbestos exposure and malignant pleural mesothelioma — M. Metintas, N. Ozdemir, et al. (1999)
• Modelling prevalence and incidence of fibrosis and pleural plaques in asbestos-exposed populations for screening and follow-up: a cross-sectional study — C. Paris, A. Martin, et al. (2008)

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