Environmental exposure to asbestos: from geology to mesothelioma

Our plain-English summary of Environmental exposure to asbestos: from geology to mesothelioma, by M. Bayram, N.D. Bakan (Current Opinion in Pulmonary Medicine, 2014).

The study

• Authors: M. Bayram, N.D. Bakan
• Journal: Current Opinion in Pulmonary Medicine
• Published: 2014;20(3):301-7
• Type of article: Review
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose Of Review: This article aims to review the geological background of environmental asbestos exposure and the distribution of asbestos-related disease (ARD) in association with naturally occurring asbestos (NOA), and discusses the potential health risks associated with exposure to non-occupational asbestos.

Recent Findings: With the motion of continental and oceanic plates, in some parts of the world serpentinites in the lower layer of the oceanic plate move into the continental plate and form the so-called ophiolites. Ophiolites consist of soil and rocks containing serpentine-type asbestos. There is an increase in ARDs in regions close to ophiolites. Indoor exposure and outdoor exposure to NOA, outdoor exposure to industrial asbestos and mines, urbanization and construction works in NOA regions are the known sources and types of environmental asbestos exposure.

Summary: Although there is an expectance of decline in ARDs caused by industrial exposure to asbestos, the environmental exposure to asbestos is still a challenge waiting to be overcome.

In plain English

This article was a review, labeled a special commentary, rather than a report of a new epidemiological study. The authors explained how ophiolites form: ocean-floor rock, including serpentinite, is pushed into continental crust, bringing asbestos to the surface. They wrote that serpentinite belts contain mainly chrysotile, with a few percent of tremolite/actinolite and anthophyllite. They summarized published studies linking nearness to such rock with disease. In one study from California, mesothelioma risk fell by 6.3% for every 10 km farther from a naturally occurring asbestos source. In an earlier case-control study by these authors in Sivas, Turkey, the risk of malignant mesothelioma or pleural plaques was halved with every additional 5 km between birthplace and ophiolites. The review also described exposure from house plaster and whitewash made with asbestos-containing soil, industry and mines, farming, and construction. A figure reported that X-ray diffraction of samples from a roadside quarry in Sivas Province showed serpentine. The authors noted that the distance studies could not prove that patients had inhaled the fibers. They concluded that environmental exposure remains a challenge waiting to be overcome.

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: Review (published as a special commentary) of geology and published studies on environmental asbestos exposure; not a report of a new epidemiological study, though one figure includes satellite views, photographs and an X-ray diffraction finding for soil-quarry samples from Sivas Province
• Who was studied: No study population of its own. The review drew on published studies of environmental asbestos-related disease in places including Turkey, Greece, Cyprus, New Caledonia, China, Corsica and California, and on studies from Italy, Japan, Australia, Bulgaria and Libby, Montana
• Exposure: Non-occupational (environmental) asbestos exposure. The main focus was naturally occurring asbestos in ophiolites, whose serpentinite belts contain mainly chrysotile with a few percent of tremolite/actinolite and anthophyllite. The review also covered exposure from industrial sources and mines (including the Libby vermiculite mine and the Wittenoom crocidolite mine), farming and construction, and exposure to erionite (a fibrous zeolite, not asbestos) in Cappadocia
• Main results:
  • In the cited study by Pan et al. in California, mesothelioma risk decreased by 6.3% for every 10 km farther from a naturally occurring asbestos source
  • In the authors' earlier case-control study in Sivas province, Turkey (a separate publication), the risk of malignant mesothelioma or pleural plaques was halved with every additional 5 km between birthplace and ophiolites
  • A cited cross-sectional study from Sivas found an 8% decrease in risk of asbestos-related disease for every 1 km of additional distance from ophiolites
  • A cited study reported mesothelioma risk 300 times higher in Metsovo, a Greek village where whitewashing with asbestos-containing soil was extensive
  • In a cited study, indoor airborne asbestos fiber concentrations from whitewash or wall plastering ranged from 0.0042 to 1.24 fibers/cm3
  • In a cited study near an industrial source of asbestos, pleural mesothelioma risk was higher in residents living less than 500 m from the source
  • In Wittenoom, Australia (crocidolite mine), 24 mesothelioma patients were reported in 1992 among 4890 residents who never worked in the mine. By the end of 2002 the number had risen to 67
  • A cited report on farmers described a Bulgarian town of 3225 inhabitants, 10 km from an asbestos mine, where 110 people were confirmed to have asbestos-related disease
  • Figure 3 reported that X-ray diffraction of samples from a soil quarry next to a road in Sivas Province showed that they contain serpentine
• The authors' conclusion: The authors concluded that indoor exposure, outdoor exposure to naturally occurring asbestos, environmental exposure from industrial or mining sources, and exposure from agriculture and urbanization in rural areas remain challenges, even though asbestos-related disease from industrial exposure is expected to decline
• Limitations the authors state:
  • The authors noted that the distance-based studies from Sivas could not prove that patients had inhaled naturally occurring asbestos. They cited separate lung-fluid studies on this point
  • The authors stated that no estimates are available of how much asbestos is released into the air from natural sources

Topics

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

Medical terms in this study, explained in our Lexicon: Environmental Exposure, Mesothelioma, Asbestos Exposure, naturally occurring asbestos (NOA), Serpentinite, Ophiolite, Serpentine Group.

Related studies

• Observations on environmental asbestos exposure in a high risk area — U. Sahin, O. Ozturk, et al. (2009)
• High risk of malignant mesothelioma and pleural plaques in subjects born close to ophiolites — M. Bayram, I. Dongel, et al. (2013)
• A review of scientific literature examining the mining history, geology, mineralogy, and amphibole asbestos health effects of the Rainy Creek igneous complex, Libby, Montana, USA — B.R. Bandli, M.E. Gunter (2006)
• Assessment of environmental asbestos exposure in Turkey by bronchoalveolar lavage — P. Dumortier, L. Coplü, et al. (1998)
• Environmental exposure to crocidolite and mesothelioma: exposure-response relationships — J. Hansen, N.H. de Klerk, et al. (1998)
• Occurrence, behaviour, and human exposure pathways and health risks of toxic geogenic contaminants in serpentinitic ultramafic geological environments (SUGEs): A medical geology perspective — W. Gwenzi (2020)

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