Is living close to ophiolites related to asbestos related diseases? Cross-sectional study

Our plain-English summary of Is living close to ophiolites related to asbestos related diseases? Cross-sectional study, by I. Döngel, M. Bayram, N.D. Bakan, et al (Respiratory Medicine, 2013).

The study

• Authors: I. Döngel, M. Bayram, N.D. Bakan, H. Yalçın, S. Gültürk
• Journal: Respiratory Medicine
• Published: 2013;107(6):870-4
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: To determine the rate of pleural plaques and malignant mesothelioma and other factors that affect people living close to ophiolites.

Methods: The study population was comprised of 2970 volunteers who resided <10 km from an ophiolitic unit. Control group comprised of 157 residents >25 km from ophiolites. Information gathered from the patients included presence of pleural plaques on chest X-ray, distance from ophiolites, gender, smoking status, duration of asbestos exposure, and body mass index (BMI). Mineralogical analysis of soil and rock samples was performed by X-ray diffraction.

Results: Among the 2970 study participants, those who lived close to ophiolites, 9.8% had asbestos related disease (3 malignant mesothelioma, 289 pleural plaques). No asbestos related disease (ARD) was identified in the control group. Male gender (OR: 2.63, 95% 1.9-3.5, p < 0.001), advanced age (5% increase for every year p < 0.001), residential proximity to ophiolites (for every 1 km proximity, a 12% increase p < 0.001), and low BMI (for every 1 unit decrease, 3.6% increase p < 0.001) were associated with increased risk of ARD.

Conclusion: The rate of ARD is higher in residents living close to ophiolites. Important risk factors for developing ARD were age, male gender, proximity to an ophiolite site, and low BMI.

Copyright © 2013 Elsevier Ltd. All rights reserved.

In plain English

This cross-sectional study in Sivas province, Turkey, asked whether living near ophiolites (rocks known to be sources of naturally occurring asbestos) was linked to asbestos-related disease. The authors examined chest X-rays of 2970 volunteers from 48 villages within 10 km of ophiolites and 157 residents of 6 villages more than 25 km away. Almost all were farmers or livestock keepers. Near ophiolites, 290 people had asbestos-related disease (287 pleural plaques, 3 malignant mesothelioma). That was a rate of 9.8% (17.1% of men, 5.2% of women); none was found in the distant group. Samples from nearby villages contained fibrous minerals, primarily chrysotile, with lesser tremolite/actinolite, though the authors also wrote that samples were not assessed for asbestos minerals. In the adjusted analysis, disease was associated with male sex (odds ratio 2.63, 95% confidence interval 1.9 to 3.5), older age, living closer to ophiolites and lower body mass index. Living in an adobe house and smoking were not statistically significant. The authors concluded that the disease rate is higher near ophiolites. They noted that chest X-rays can miss small plaques and no air sampling was done.

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 study with a control group of residents living far from ophiolites; chest X-ray screening plus X-ray diffraction analysis of plaster and soil samples
• Who was studied: 2970 volunteers (1140 male, 1830 female) from 48 randomly selected villages of Yildizeli district and Sivas center, Sivas province, Turkey, within 10 km of ophiolites; control group of 157 residents of 6 villages more than 25 km from ophiolites. Participants had to meet an age criterion of 35 years and to have lived more than 20 years in the village. Almost all worked in farming and livestock, with no reported occupational asbestos exposure. Study dates are not given.
• Exposure: Environmental (residential) exposure to naturally occurring asbestos from ophiolites, including the use of ophiolitic soil in homes. Exposure was measured as distance from the village to the nearest ophiolite and as living in an adobe house. Samples from villages near ophiolites contained fibrous minerals, primarily chrysotile, with lesser amounts of pectolite, brucite, hydrotalcite and tremolite/actinolite; the Discussion states that the samples were not assessed for asbestos minerals.
• Main results:
  • In the group living within 10 km of ophiolites, 290 people had asbestos-related disease: 3 with malignant mesothelioma and 287 with pleural plaques. No asbestos-related disease was found in the control group.
  • The rate of asbestos-related disease among participants from ophiolitic areas was 9.8% (Table 1: 17.1% in males, 5.2% in females; 0% in the control group).
  • Disease rates rose with age in the near-ophiolite group. The lowest rate was in the 35 to 45 age range (6.0% of males, 1.8% of females) and the highest in the oldest group, labelled 75 (28.6% of males, 16.7% of females).
  • In the multivariate analysis of the near-ophiolite group, male gender had an odds ratio of 2.63 (95% CI 1.9 to 3.5, p less than 0.001) for asbestos-related disease.
  • In the multivariate analysis, each additional year of age had an odds ratio of 1.05 (95% CI 1.04 to 1.06, p less than 0.001).
  • In the multivariate analysis, each 1 km farther from ophiolites had an odds ratio of 0.92 (95% CI 0.88 to 0.96, p 0.001); the authors describe this as an 8% decrease in risk per km of additional distance.
  • In the multivariate analysis, each 1-unit increase in body mass index had an odds ratio of 0.96 (95% CI 0.93 to 0.98, p 0.006).
  • In the multivariate analysis, living in an adobe house (odds ratio 1.27, 95% CI 0.96 to 1.66, p 0.083) was not statistically significant.
  • In the multivariate analysis, smoking (odds ratio 1.21, 95% CI 0.89 to 1.65, p 0.21) was not statistically significant.
  • Mineralogical analysis found fibrous minerals (primarily chrysotile) and lesser amounts of pectolite, brucite, hydrotalcite and tremolite/actinolite in villages close to ophiolites; no fibrous minerals were found in samples from the control villages.
• The authors' conclusion: The authors concluded that the rate of asbestos-related disease is higher in residents living close to ophiolites, and that males, older people and those living close to ophiolites are at highest risk for pleural plaques.
• Limitations the authors state:
  • Chest X-rays have low sensitivity and can miss small pleural plaques or pleural thickening, so plaques may be more common than found.
  • No ambient (indoor or outdoor) air sampling was performed.
  • Response rates differed by sex: 76.8% in females and 47% in males.
  • It is unclear whether low body mass index is a cause or a consequence of pleural plaque formation.
  • The authors state that the soil and plaster samples were not assessed for asbestos minerals.

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: Ophiolite, Pleural Plaques, Mesothelioma, Chest X-Ray, Asbestos Exposure, X-Ray Diffraction (XRD).

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