10th Anniversary Critical Review: Naturally occurring asbestos

Our plain-English summary of 10th Anniversary Critical Review: Naturally occurring asbestos, by M. Harper (Journal of Environmental Monitoring, 2008).

The study

• Author: M. Harper
• Journal: Journal of Environmental Monitoring
• Published: 2008;10(12):1394-408
• Type of article: Review
• Cited by: 34 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos is a naturally occurring mineral in the Earth's crust, and it is not confined to the historic and current asbestos mining areas, but rather quite commonly encountered in certain geological environments across the world. That diseases developed as a result of high exposures suffered by miners and asbestos products workers is incontrovertible. In addition, asbestos contamination as a result of past production and use is considered a serious issue where remediation is normally required. However, the risk to health of living on soil and rock where asbestos is encountered as a result of the natural occurrence of small quantities of asbestos minerals is less obvious. The picture becomes even less clear when the minerals are subject to intensive investigation, since our generally accepted definitions of asbestos are themselves put to the test. The discovery of asbestos or related minerals has consequences beyond any immediate risks to health, including profound effects on the value of and ability to use or enjoy property. This review examines the issue of naturally occurring asbestos (NOA) as it has developed in the United States of America and elsewhere, including some superficial insights into the reactions of communities to the presence of NOA. These responses to 'contamination' by nature deserve further in-depth study.

In plain English

This article was a critical review of naturally occurring asbestos (NOA): asbestos and related fibrous minerals found in rocks and soils, not only in mining areas. It reported no new measurements or health data of its own. The author reviewed how these minerals are defined, including the Libby amphiboles (tremolite, winchite and richterite), erionite, fluoro-edenite, and non-asbestos 'cleavage fragments', whose toxicity the author called highly contentious. The review then described seven US locations: Fairfax County, Virginia; El Dorado Hills and the Clear Creek Management Area, California; Silver Bay, Minnesota; Sparta, New Jersey; Ambler, Alaska; and Swift Creek, Washington. For these places it drew on agency reports, such as air sampling taken while people played sports, cycled or rode vehicles. The author wrote that it is arguable whether a link between living on soils with natural fibrous minerals and lung cancer or mesothelioma has been firmly established. The author also wrote that methods for measuring NOA in soil are not yet standardized. The author concluded that such minerals are relatively common worldwide and that community responses have been unique in each case. The author noted that some cited sources were not peer-reviewed.

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: Critical review (narrative review of the literature, agency reports and community responses); no new data collected
• Who was studied: No study population. The review discussed reports from regions worldwide and seven US locations: Fairfax County VA, El Dorado Hills CA, Clear Creek Management Area CA, Silver Bay MN, Sparta NJ, Ambler AK and Swift Creek WA
• Exposure: Naturally occurring asbestos and related fibrous minerals in rocks and soils, including chrysotile, tremolite, actinolite, Libby amphibole (tremolite, winchite, richterite), erionite, fluoro-edenite and non-asbestiform amphibole cleavage fragments, disturbed by activities such as construction, farming, recreation and quarrying
• Main results:
  • After discussing other studies, including a California cancer registry study the author said may be criticized for failing to account for migration, the author wrote that a link between living on soils with natural fibrous minerals and asbestos-related disease is arguable rather than firmly established
  • The author described the toxicity of inhaled non-asbestos cleavage fragments and prismatic crystals as highly contentious, and summarized differing positions held by NIOSH and the US EPA
  • The review reported that EPA activity-based sampling at El Dorado Hills (simulated sports, running, biking, playground play and gardening) found fibers in nearly all samples
  • The review reported that a US EPA risk assessment for the Clear Creek Management Area indicated a lifetime lung cancer risk above acceptable levels with even one day per year of vehicle activity there, with children considered at greater risk
  • The review reported that 8% of the fibers in the EPA air samples at Clear Creek were considered amphibole (tremolite, actinolite or other) rather than chrysotile
  • Citing a Minnesota Department of Health update, the review reported that mesothelioma cases in the Minnesota taconite area had risen to 58, all in men
  • The author wrote that methods for measuring NOA in soil are not yet standardized, which can lead to uncertainty in risk assessment
• The authors' conclusion: The author concluded that asbestos and related hazardous minerals are relatively common around the world, that whether non-asbestiform amphibole particles are a hazard remains under debate, and that community responses and solutions have so far been unique in each case
• Limitations the authors state:
  • Several sources cited about community response were not from peer-reviewed scientific literature, and their accuracy is not assured
  • The insights into community reactions were described as only superficial
  • The relative potency of chrysotile versus amphibole asbestos (the 'Amphibole Hypothesis') was outside the review's scope

Topics

Medical terms in this study, explained in our Lexicon: naturally occurring asbestos (NOA), Asbestos, Discovery.

Related studies

• Evaluation of public and worker exposure due to naturally occurring asbestos in gravel discovered during a road construction project — R.A. Perkins, J. Hargesheimer, et al. (2008)
• Activity-Based Exposure Levels and Cancer Risk Assessment Due to Naturally Occurring Asbestos for the Residents Near Abandoned Asbestos Mines in South Korea — S. Lee, D. Kang, et al. (2021)
• Framework for assessment and phytoremediation of asbestos-contaminated sites — C. Gonneau, K. Miller, et al. (2017)
• Community responses to naturally occurring asbestos: implications for public health practice — M.R. Culley, J. Zorland, et al. (2010)
• Evaluation of the impact of asbestos wastes on soils in Emene-Enugu, Southeastern Nigeria — O. Igwe, O.V. Omonona, et al. (2014)
• Exposure to naturally occurring mineral fibers due to off-road vehicle use: A review — C. Wolfe, B. Buck, et al. (2017)

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