Evaluation Of Airborne Asbestos Fiber Levels During Removal And Installation Of Valve Gaskets And Packing

Our plain-English summary of Evaluation Of Airborne Asbestos Fiber Levels During Removal And Installation Of Valve Gaskets And Packing, by W.N. Mckinnery, Jr, R.W. Moore (1992).

The study

• Authors: W.N. Mckinnery, Jr, R.W. Moore
• Published: American Industrial Hygiene Association Journal 53(8):531-532, August (1992)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library, J-M no. 004452. The article is still under copyright, so we describe it here rather than post it.

In plain English

This report described a simulation of past dry work practices: an asbestos worker removed and installed asbestos-containing valve gaskets and packing. The work took place in an isolated room built like an abatement enclosure. Gasket materials contained 50% to 60% chrysotile and packing materials 30% to 50% chrysotile. Air samples were analyzed by phase contrast microscopy (PCM, fibers/cc) and transmission electron microscopy (TEM, structures/cc). For gaskets, personal PCM levels ranged from 0.049 to 0.44 fibers/cc during removal and 0.131 to 0.29 during installation. The text gave TEM levels of 0.86 to 18.44 structures/cc for removal and 0.40 to 74.32 for installation, but the scrambled table appears to show a center-sample removal range of 0.29 to 28.22. For packing, PCM levels ranged from 0.04 to 1.01 fibers/cc for removal and 0.03 to 0.75 for installation. TEM levels ranged from 0.39 to 19.57 structures/cc for removal and 0.03 to 10.88 for installation. On numerous occasions, the authors reported, PCM levels exceeded the then-current permissible exposure limit of 0.2 fibers/cc. They called their conclusions preliminary. Their PCM-versus-TEM comparison is unreadable in this scan.

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: Controlled simulation study measuring airborne fiber levels during gasket and packing work in an isolated enclosure
• Who was studied: No people were studied as subjects. An Illinois-licensed asbestos worker removed and installed asbestos-containing materials. The materials were old valves obtained from a scrapyard that bought materials from industrial facilities, plus new sheet gasket and packing materials obtained from distributors.
• Exposure: Dry removal and installation of valve gaskets containing 50% to 60% chrysotile and packing materials containing 30% to 50% chrysotile. Asbestos content was measured by polarized light microscopy.
• Main results:
  • Gasket work, personal samples by PCM: 0.049 to 0.44 fibers/cc for removal and 0.131 to 0.29 fibers/cc for installation
  • Gasket work, TEM, as stated in the text: asbestos levels of 0.86 to 18.44 structures/cc for removal and 0.40 to 74.32 structures/cc for installation
  • Gasket work, TEM, from the scrambled Table II: a center-location removal row appears to show 23 samples ranging from 0.29 to 28.22 structures/cc. This range is wider than the removal range given in the text.
  • Packing work, PCM: 0.04 to 1.01 fibers/cc for removal and 0.03 to 0.75 fibers/cc for installation
  • Packing work, TEM: asbestos levels of 0.39 to 19.57 structures/cc for removal and 0.03 to 10.88 structures/cc for installation
  • On numerous occasions, PCM levels were observed to be higher than the then-current permissible exposure limit of 0.2 fibers/cc.
• The authors' conclusion: The authors gave preliminary conclusions comparing PCM with TEM results under these simulated working conditions, but the comparison itself is unreadable in the scanned text. They also stated that on numerous occasions PCM levels were higher than the then-current permissible exposure limit of 0.2 fibers/cc.
• Limitations the authors state:
  • The authors labeled their conclusions preliminary and stated that further data analysis was being conducted.

Topics

Medical terms in this study, explained in our Lexicon: Gasket, Abatement, Chrysotile, phase contrast microscopy (PCM), Transmission Electron Microscopy (TEM), Permissible Exposure Limit (PEL).

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