Comments on Chesson et al. Interpretation of airborne asbestos measurements

Our plain-English summary of Comments on Chesson et al. Interpretation of airborne asbestos measurements, by K.S. Crump (Risk Analysis, 1991).

The study

• Author: K.S. Crump
• Journal: Risk Analysis
• Published: 1991;11(3):367-71
• Type of article: Comment, Letter
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004444).

In plain English

This was a letter to the editor, not a study of people. The author commented on a method that Chesson and colleagues had proposed for comparing airborne asbestos measurements in a setting needing a risk estimate with workplace settings where cancer potency had been estimated from epidemiological studies. The author proposed an alternative: count fibers 5 micrometers or longer by transmission electron microscopy (TEM) and apply that count to a cancer potency factor based on phase contrast microscopy (PCM). The method assumed that fibers shorter than 5 micrometers are nonpotent. The author acknowledged that this cannot be conclusively proven and that human data are largely unavailable. For a hypothetical nonoccupational exposure of 0.02 structures per cubic centimeter, with 96% of structures shorter than 5 micrometers, the alternative gave an upper-bound exposure of 0.0008 structures per cubic centimeter. The Chesson method gave an upper-bound exposure of 0.003 structures per cubic centimeter. The author concluded that the alternative is also conservative under given conditions, though less so, and needs no TEM data from the workplace setting.

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 method and proposing an alternative mathematical approach; no new data collected
• Who was studied: No people were studied; the methods were applied to a hypothetical nonoccupational exposure
• Exposure: Airborne asbestos fibers: concentration of fibers 5 micrometers or longer measured by TEM, applied to a cancer potency factor based on PCM measurements in an occupational setting
• Main results:
  • For the hypothetical exposure of 0.02 structures per cubic centimeter measured by TEM, 96% of structures were assumed shorter than 5 micrometers
  • The alternative method gave an upper-bound exposure estimate of 0.0008 structures per cubic centimeter for the hypothetical exposure
  • The Chesson et al. method gave an upper-bound exposure estimate of 0.003 structures per cubic centimeter for the same hypothetical exposure
  • The alternative method rests on the assumption that fibers shorter than 5 micrometers are nonpotent
  • As support for that assumption, the letter cited separate provisional analyses of animal inhalation data (a conference abstract). In both analyses the best estimate of the potency of fibers shorter than 5 micrometers was zero. The 95% upper confidence limits on their potency, relative to fibers longer than 20 micrometers, were 0.003 and 0.008.
  • Unlike the Chesson et al. method, the alternative does not require TEM data from the occupational setting
  • The author noted that among studies of exposure mainly to chrysotile, the larger lung cancer potency values came from textile mills, and suggested this may reflect a higher share of longer fibers
  • The author argued that direct TEM preparation is more appropriate than indirect preparation for risk assessment
• The authors' conclusion: The author concluded that, under given conditions, the alternative method is also conservative (tends to overestimate risk), though not as conservative as the Chesson et al. method
• Limitations the authors state:
  • The author stated that the assumption that short fibers are nonpotent cannot be conclusively proven
  • The author stated that evidence on short-fiber potency comes mainly from animal data because human data are largely unavailable; a reanalysis of the animal data was planned

Related studies

• Interpretation of airborne asbestos measurements — J. Chesson, J.D. Rench, et al. (1990)
• Mass concentrations of airborne asbestos in the non-occupational environment--a preliminary report of U.K. measurements — G.J. Burdett, J.M. le Guen, et al. (1984)
• The influence of external aerodymanic factors on the measurement of the airborne concentration of asbestos fibres by the membrane filter method — A.M. Johnston, A.D. Jones, et al. (1982)
• Airborne asbestos in public buildings — J. Chesson, J. Hatfield, et al. (1990)
• Real-time measurement of fibers using an HY-differential mobility analyzer with an optical particle counter (KOFAM) — S. Choi, K. Jang, et al. (2017)
• Airborne fiber concentration and size distribution of mineral fibers in area with serpentinite outcrops in Aichi prefecture, Japan — K. Sakai, N. Hisanaga, et al. (2001)

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