Regulated Asbestos Analysis: EPA Polarized Light Microscopy Method and the Implications for Reported Fiber Sizes

Our plain-English summary of Regulated Asbestos Analysis: EPA Polarized Light Microscopy Method and the Implications for Reported Fiber Sizes, by T.G. Laubenthal (New Solutions, 2020).

The study

• Author: T.G. Laubenthal
• Journal: New Solutions
• Published: 2020;30(2):83-85
• Type of article: Letter
• Read it: PubMed · Publisher

In plain English

This was a letter to the editor, not a research study, and it reported no new data. The author commented on a review by Egilman et al. about censored elongated mineral particles and the detection limits of laboratory methods. The letter focused on polarized light microscopy (PLM) analysis of asbestos in bulk building materials. The author stated that EPA method EPA/600/R-93/116 (the "93 method") was not the method required for compliance with EPA's asbestos NESHAP and AHERA rules. The required method, Appendix E to Subpart E of 40 CFR Part 763, was not listed in the review's Table 11. According to the author, that required method defines asbestos fibers only by an aspect ratio greater than 3:1 plus positive mineral identification, with no length or width requirements. The 93 method's criteria, by contrast, would not take shorter fibers into account. The author also noted the required method's caution that grinding amphiboles may produce cleavage fragments with aspect ratios greater than 3:1. The author concluded that interpretations focusing only on the 93 method dismiss smaller fibers, resulting in "censoring."

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: Letter to the editor commenting on a published review; no new data
• Who was studied: No study population. The letter comments on the review "Health Effects of Censored Elongated Mineral Particles, a Critical Review" by Egilman et al.
• Exposure: Laboratory methods for detecting asbestos in bulk building material samples by polarized light microscopy (PLM): EPA/600/R-93/116 (the "93 method") compared with Appendix E to Subpart E of 40 CFR Part 763
• Main results:
  • The author stated that the 93 method is not the method required for EPA compliance under the asbestos NESHAP and AHERA rules
  • The author stated that the required method is Section 1 of Appendix E to Subpart E of 40 CFR Part 763, which was not listed in Table 11 of the Egilman et al. review
  • In the required method, asbestos fibers are defined as having an aspect ratio greater than 3:1 and being positively identified as one of the listed minerals
  • According to the author, the required method has no fiber length requirements and no discussion of fiber widths
  • According to the author, the 93 method's fiber geometry criteria would not take shorter fibers into account
  • The required method cautions that grinding amphiboles may separate fiber bundles or produce cleavage fragments with aspect ratios greater than 3:1. The author considered this caveat in line with the review's censorship premise.
• The authors' conclusion: The author concluded that interpretations focusing only on the 93 method dismiss smaller fibers. In the author's view, this would not comply with existing EPA rules and results in "censoring" of smaller fibers that may be present.

Topics

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

Medical terms in this study, explained in our Lexicon: Regulated Asbestos, Polarized Light Microscopy (PLM).

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• Determination of mineral fibre in human lung tissue by light microscopy and transmission electron microscopy — A.J. Rogers (1984)

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