Elongate mineral particles in the natural environment

Our plain-English summary of Elongate mineral particles in the natural environment, by M.E. Gunter (Toxicology and Applied Pharmacology, 2018).

The study

• Author: M.E. Gunter
• Journal: Toxicology and Applied Pharmacology
• Published: 2018;361:157-164
• Type of article: Review
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

When considering elongate mineral particles (EMPs) in the natural environment it is important to first: 1) define what an elongate mineral is and 2) present what we as mineralogists and geologists know about their distribution. However, it is often very difficult to define the natural world, instead we physical scientists resort to describing it. For instance, we used 1,419 words spread over two pages of our mineralogy textbook (Dyar and Gunter, 2008) to describe a mineral. On the other hand, elongate has a rather simple non-quantitative definition as a particle longer than it is wide; however, to quantify it, we must select an aspect ratio. Cleary the term EMP was coined with the hopes to simplify some of the confusion resulting in the differing "meanings" of such words as asbestos, asbestiform, acicular, and most importantly "fiber" in the natural vs. built environment, especially when applied to amphiboles (Gunter, 2010), and non-regulated asbestiform amphibole species. This paper draws on three sources: 1) the USDA-NRCS soil database (Thompson et al., 2011), 2) soil mineralogical data from USGS (Smith et al., 2013), and 3) the mineral database created in conjunction with the Dyar and Gunter (2008) textbook in an attempt to show issues created by use of the term EMP.

Copyright © 2018 Elsevier Inc. All rights reserved.

In plain English

This article is a commentary by a mineralogist on the term "elongate mineral particle" (EMP). It did not study people or disease. The author drew on three existing sources: a U.S. Department of Agriculture soil database, a U.S. Geological Survey soil survey, and a database of 369 mineral species built for the author's mineralogy textbook. Work by Thompson and colleagues found amphiboles in 13% of 34,326 soil sample locations in the USDA database. The USGS survey by Smith and colleagues found amphiboles in 16% of 4,802 soil samples, at an average of 0.4%. The author wrote that soil amphiboles were more widespread than the locations of amphibole-bearing rock would predict. Of the 369 textbook minerals, 10% could occur in an acicular habit and 20% in a fibrous habit. Grain mounts of 156 minerals were viewed under a polarized light microscope, and 74% showed EMPs using a 3:1 length-to-width ratio. The author concluded that if the term EMP is used, it needs a more thorough description than a 3:1 ratio, because that ratio alone would make most natural soils and rocks "contaminated" with EMPs.

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: Commentary by a mineralogist drawing on two existing soil datasets and a mineral database built for the author's textbook; not a study of human health
• Who was studied: No people were studied. The sources were: 34,326 soil sample locations in the USDA-NRCS database (Thompson et al., 2011); 4,802 USGS soil samples from across the USA (Smith et al., 2013); and 369 mineral species in the textbook database, 156 of which were photographed as grain mounts
• Exposure: No human exposure was studied. The subject is the shape of mineral particles, especially amphiboles in soils, and how elongation is defined by length-to-width (aspect) ratios such as 3:1 or 5:1
• Main results:
  • In the USDA-NRCS soil database (Thompson et al., 2011), 13% of 34,326 soil sample locations contained amphiboles, based on a 300 point count with a polarized light microscope
  • In the USGS dataset (Smith et al., 2013), 16% of 4,802 soil samples from the A horizon contained amphiboles by X-ray diffraction, with an average amphibole content of 0.4%
  • The author reported that soil amphiboles were more widespread across the USA than the locations of rock likely to contain amphiboles
  • Of the 369 minerals in the textbook database, 10% could occur in an acicular habit and 20% in a fibrous habit
  • Of 156 minerals selected for polarized light microscope grain mount photos, 74% had EMPs, using a 3:1 aspect ratio
• The authors' conclusion: The author concluded that if the term EMP is to be used, it requires a more thorough description than a 3:1 aspect ratio, because that ratio would make most natural mineral-containing materials such as soils and rocks "contaminated" with EMPs

Topics

Medical terms in this study, explained in our Lexicon: elongate mineral particles (EMPs), Mineralogy, Aspect Ratio (Length-to-diameter ratio), Asbestiform, Acicular, Amphibole Group.

Related studies

• A comparison of asbestos fiber potency and elongate mineral particle (EMP) potency for mesothelioma in humans — D.H. Garabrant, S.T. Pastula (2018)
• Dosimetry of inhaled elongate mineral particles in the respiratory tract: The impact of shape factor — B. Asgharian, T.P. Owen, et al. (2018)
• Measurement of elongate mineral particles: What we should measure and how do we do it? — E.J. Chatfield (2018)
• The epidemiologic evidence for elongate mineral particle (EMP)-related human cancer risk — P. Boffetta, K.A. Mundt, et al. (2018)
• Differential responses of murine alveolar macrophages to elongate mineral particles of asbestiform and non-asbestiform varieties: Cytotoxicity, cytokine secretion and transcriptional changes — T.O. Khaliullin, E.R. Kisin, et al. (2020)
• OSHA and elongate mineral particles — D.T. Crane (2018)

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