Measurement of asbestos exposure

Our plain-English summary of Measurement of asbestos exposure, by J.R. Lynch, H.E. Ayer (Journal of Occupational Medicine., 1968).

The study

• Authors: J.R. Lynch, H.E. Ayer
• Journal: Journal of Occupational Medicine.
• Published: 1968;10(1):21-4
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001451).

In plain English

This 1968 paper was not a disease study. It discussed methods for measuring asbestos dust, the first segment of a U.S. Public Health Service study of the asbestos products industry. The existing exposure limit, 5 million particles per cubic foot, was based on impinger measurements. From field sampling, the authors estimated that the impinger showed only about one in 100 airborne fibers seen in electron micrographs. Paired impinger and membrane filter samples from asbestos textile mills indicated that an impinger reading near that limit corresponded to about 50 total fibers per cc, 30 longer than 5 microns and 15 longer than 10 microns. No analytical method yet measured only fibrous asbestos amid associated rock. In the early plants surveyed, workplace airborne polynuclear aromatic hydrocarbon levels were not significantly above ambient air pollution levels. Significant amounts of nickel, chromium, cobalt and manganese were found, but the authors drew no conclusions. The authors concluded that membrane filter fiber counts were then the best method for estimating exposure related to asbestosis risk and for measuring airborne fibers as a factor in lung cancer risk.

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: Methods discussion paper on exposure measurement, forming the first segment of a U.S. Public Health Service epidemiologic study of the asbestos products industry
• Who was studied: No workers were examined in this paper. The measurement comparisons used large numbers of paired impinger and membrane filter air samples collected in asbestos textile mills (number not given).
• Exposure: Airborne asbestos dust in asbestos products plants. It was measured by the impinger, on which the existing exposure limit (TLV) was based, and by fiber counts on membrane filters.
• Main results:
  • From field sampling, the authors estimated that only about one in 100 airborne fibers seen in electron micrographs was seen in impinger samples.
  • When impinger samples averaged near the TLV of 5 mppcf (million particles per cubic foot), membrane filter samples would be expected to show (Table II) 50 total fibers per cc, 30 fibers per cc longer than 5 microns, and 15 fibers per cc longer than 10 microns.
  • A goal mentioned for English asbestos textile mills, 4 fibers longer than 5 microns per cc, would correspond to an impinger TLV on the order of 1 mppcf. The authors said a level that low would be so near the impinger's lower practical limit of sensitivity that accurate measurement would be impossible.
  • No analytical method had been developed to measure only fibrous asbestos when particles of associated rock were also present.
  • In the early plants surveyed, airborne polynuclear aromatic hydrocarbon levels in the work places were not significantly above ambient air pollution levels.
  • Trace metal analyses of high-volume air samples showed significant amounts of nickel, chromium, cobalt and manganese.
• The authors' conclusion: The authors concluded that, at present, fiber counts on membrane filters were the best method of estimating exposure as related to the risk of asbestosis, and of measuring airborne fiber concentration as a factor in the risk of lung cancer.
• Limitations the authors state:
  • The authors made the conversion from the English fiber goal to an impinger level conditional on the impinger-to-filter equivalence being only approximately valid.
  • The authors stated that no conclusions could be drawn from the trace metal data, because it was not known exactly which factor to measure for cancer risk.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Asbestos Exposure.

Related studies

• Measurement of airborne fibers: a review — P.A. Baron (2001)
• Techniques for the detection, identification and analysis of fibers — R.G. Keenan, J.R. Lynch (1970)
• Relative source contributions of diet and air to ingested asbestos exposure — J.N. Rowe (1983)
• A comparison of impinger and membrane filter techniques for evaluating air samples in asbestos plants — H.E. Ayer, J.R. Lynch, et al. (1965)
• Measurement of elongate mineral particles: What we should measure and how do we do it? — E.J. Chatfield (2018)
• Dust measurement and monitoring in the asbestos industry — C.G. Addingley (1965)

Browse more research in Journal of Occupational Medicine., or return to medical research.