Comments on "Dimensions of elongated mineral particles with implications for pathogenicity and classification as asbestiform versus cleavage fragments"

Our plain-English summary of Comments on "Dimensions of elongated mineral particles with implications for pathogenicity and classification as asbestiform versus cleavage fragments", by M.M. Finkelstein (Ultrastructural Pathology, 2019).

The study

• Author: M.M. Finkelstein
• Journal: Ultrastructural Pathology
• Published: 2019;43(6):326-329
• Type of article: Letter, Comment
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Roggli and Green have reported their study of the dimensions of fibers extracted from the tissues of cases examined in their laboratory, and have drawn conclusions about the pathogenicity of Elongated Mineral Particles and their classification as asbestiform versus cleavage fragments. There are aspects of their methodology and discussion that would benefit from examination. Roggli and Green have relied upon a paper by Harper et al. for their definitions of asbestiform and cleavage fragments. Unfortunately, they have misinterpreted the work of those authors who have concluded that the best criterion is a particle width <1μm. Roggli and Green conclude that 'Our findings demonstrate the lack of pathogenicity of fibers less than 10 μm long or likelihood of cleavage fragments for fibers less than 10μm long and greater than 1.0μm in diameter has little or no effect on the classification of commercial amphibole fibers using our analytical methodology. On the other hand, both lack of pathogenicity and likelihood of cleavage fragments apply to a significant proportion of noncommercial amphiboles identified using our counting scheme.' This is not true. The study of Roggli and Green was a simple fiber counting study with no control population. The design of such a study does not allow the investigator to draw any conclusions about pathogenicity, or lack thereof.

In plain English

This article is a commentary, not a new study. The author critiqued a study by Roggli and Green that measured more than 570 fibers from more than 90 cases examined in their laboratory. Roggli and Green had used a length of at least 10 μm and a diameter under 1.0 μm to separate true asbestos fibers from cleavage fragments, and cited a paper by Harper and colleagues for that rule. The author argued that they misread that paper: according to the author, the ASTM and Harper and colleagues rejected that rule and favored a width under 1 μm alone. Harper and colleagues also stated this width cut-off was not a line between safe and unsafe. The author compared figures from the two studies. Roggli and Green found that 10% of tremolite and 14% of actinolite fibers were under 10 μm long and over 1.0 μm wide. Harper and colleagues reported 97% and 89% for crushed asbestos fibers. The author argued that fiber length largely reflects milling history. The author concluded that a fiber-counting study with no control population cannot support conclusions about whether fibers cause disease.

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 (critique of a previously published fiber-dimension study by Roggli and Green); no new data collected
• Who was studied: No population studied directly; the commentary discusses Roggli and Green's study of more than 570 fibers from more than 90 cases examined in their laboratory, and Harper and colleagues' laboratory study of crushed mineral specimens
• Exposure: Amphibole fibers and cleavage fragments: commercial amphiboles (amosite, crocidolite) and noncommercial amphiboles (tremolite, actinolite, anthophyllite), and the size criteria used to classify them as asbestiform or as cleavage fragments
• Main results:
  • The author stated that the ASTM and Harper and colleagues rejected the length-plus-diameter criteria used by Roggli and Green and instead adopted a width criterion of less than 1 μm
  • According to the author, Harper and colleagues stated that the 1 μm width criterion was not proposed as a dividing line between safe and unsafe
  • According to the author, Harper and colleagues noted that under the criteria adopted by Roggli and Green, the majority of actinolite asbestos and tremolite asbestos particles would be considered unlikely to be asbestos
  • The author reported that in Roggli and Green's study, 1% of crocidolite fibers and none of the amosite fibers met both length less than 10 μm and diameter greater than 1.0 μm. The author compared this with 69% of crocidolite and 85% of amosite fibers measured by Harper and colleagues. The author suggested the differences might reflect the small number of fibers counted, use of SEM rather than TEM, and fibers coming from lung tissue rather than straight from the mill.
  • The author reported that Roggli and Green found 10% of tremolite and 14% of actinolite fibers met both length less than 10 μm and diameter greater than 1.0 μm. The author stated that Harper and colleagues reported 97% of tremolite and 89% of actinolite asbestos fibers met those criteria. On that basis, the author said Roggli and Green's cleavage-fragment conclusion was not supported by their primary reference.
  • The author's Table 1 summarizes Harper and colleagues' data, with 300 particles counted in each cell. The percentages over 10 μm long and under 1 μm wide by TEM were: non-asbestiform tremolite 4.9%, asbestiform tremolite 2.7%, non-asbestiform anthophyllite 6.8%, and asbestiform anthophyllite 3.7%. The percentages under 1 μm wide were 24.4%, 27.2%, 50.4% and 37.5% respectively.
  • The author argued that fiber length depends on milling history. Commercial amphiboles (amosite, crocidolite), used largely in construction, were less heavily milled. Tremolite, actinolite and anthophyllite, which in the United States mostly occurred as contaminants of talc and Canadian asbestos, were usually heavily milled.
• The authors' conclusion: The author concluded that Roggli and Green's statement about the lack of pathogenicity of certain fibers is not true. Their study was a simple fiber-counting study with no control population, and in the author's view such a design cannot support any conclusions about pathogenicity or its absence.

Topics

Medical terms in this study, explained in our Lexicon: Asbestiform, Cleavage Fragment, Amphibole Group, Fiber Counting.

Related studies

• Dimensions of elongated mineral particles: a study of more than 570 fibers from more than 90 cases with implications for pathogenicity and classification as asbestiform vs. cleavage fragments — V.L. Roggli, C.L. Green (2019)
• Measuring EMPs in the lung what can be measured in the lung: Asbestiform minerals and cleavage fragments — V.L. Roggli (2018)
• Analysis and identification of elongated mineral particles in road coated aggregates — E. Leocat, C. Rielland, et al. (2018)
• Does qualitative examination of Elongated Mineral Particles (EMP) recovered from human and animal lungs provide reliable information on their carcinogenic and other effects? — B.W. Case (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)
• Pathogenic Potential of Respirable Spodumene Cleavage Fragments following Application of Regulatory Counting Criteria for Asbestiform Fibres — M. Gardner, M. Cross, et al. (2022)

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