The assessment of a modification to the acetone/triacetin clearing technique as used in the measurement of airborne asbestos dust

Our plain-English summary of The assessment of a modification to the acetone/triacetin clearing technique as used in the measurement of airborne asbestos dust, by I.W. Furness, P.J. Reed (The Annals of Occupational Hygiene, 1985).

The study

• Authors: I.W. Furness, P.J. Reed
• Journal: The Annals of Occupational Hygiene
• Published: 1985;29(1):109-12
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This short communication from South Australia was a laboratory test of how asbestos fibres are counted in air samples, not a study of health effects. The standard Australian method makes the sampling filter transparent ("clearing") with acetone and triacetin, which takes up to 24 hours. The authors tested a faster version described by the Asbestos International Association, in which the mounted filter is heated to about 50°C for 15 minutes. They wanted to know whether heating made counts less accurate. They cut 25 field-collected filters in half, mostly from asbestos removal jobs. The samples held mostly amosite, and several held an amosite and chrysotile mix. One half of each filter was cleared the standard way and the other half the heated way. A single experienced counter counted each half twice. Statistical analysis found that the clearing technique was not a significant source of variation in the counts. The authors concluded that, for fibre loadings of about 25 to 1000 fibres per square millimetre, the heated procedure was an acceptable alternative that shortens clearing time.

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: Laboratory method-comparison study (short communication). Each filter was split in half and the two halves were cleared by different techniques, with duplicate counts analysed by analysis of variance.
• Who was studied: 25 cellulose ester membrane filters (25 mm, 0.8 µm pore size) carrying asbestos dust collected by field sampling, mostly from asbestos removal operations, by the Building Science Research Group, Public Buildings Department, South Australia. Fibre loadings ranged from about 0.2 to about 8 fibres per graticule area (about 25 to 1000 fibres per square millimetre). Dates of sampling are not given.
• Exposure: Airborne asbestos dust, mostly amosite only, with several samples of an amosite/chrysotile mixture. Two filter-clearing techniques were compared: the standard acetone/triacetin technique (counted after standing 24 hours) and the modified technique, in which the mounted filter is heated to approximately 50°C for 15 minutes.
• Main results:
  • Comparing the standard and the modified (heated) clearing techniques across the 25 filters, the difference between techniques was not a significant source of variation in fibre counts (F 0.84, P greater than 0.25, as printed in Table 2).
  • The interaction between filters and techniques was described by the authors as small. A significant interaction would have meant that the heated technique affected filters with different fibre loadings differently.
  • Differences between filters were a significant source of variation (P less than 0.001), which the authors attributed to the intentionally varied fibre loadings.
• The authors' conclusion: The authors concluded that, over fibre loadings of about 25 to 1000 fibres per square millimetre, heating as described by the Asbestos International Association did not introduce significant inaccuracy. They considered it an acceptable alternative to the standard technique in the Australian Code and an acceptable way to reduce clearing time.

Topics

Medical terms in this study, explained in our Lexicon: Triacetin.

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