Environmental considerations in surveillance of asbestos miners and millers

Our plain-English summary of Environmental considerations in surveillance of asbestos miners and millers, by G.W. Gibbs, R.S. du Toit (Annals of the New York Academy of Sciences, 1979).

The study

• Authors: G.W. Gibbs, R.S. du Toit
• Journal: Annals of the New York Academy of Sciences
• Published: 1979;330:163-78
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004030).

In plain English

This article reviewed dust measurement in South African and Quebec asbestos mines and mills and problems using those records for health studies. In South Africa, factors for converting konimeter and thermal precipitator counts to membrane filter counts had been developed; at 2 to 5 fibers per cubic centimeter they were about 2 for Cape crocidolite, 3 for Transvaal crocidolite, 4.5 for chrysotile and 5.5 for amosite. These factors fell as concentrations rose; processing past records this way was called formidable. In Quebec, no single conversion factor was found. Ratios of membrane filter fibers per cubic centimeter to midget impinger millions of particles per cubic foot, still under investigation, were mainly 1 to 5 and varied by mine and location. Some South African observations suggested mine person-weighted mean exposures ranged from 15% to four times the industry mean. Quebec mill fiber concentrations fell, though mid-1970s maxima exceeded 50 fibers per cubic centimeter. The authors concluded past exposure could be reconstructed, but with difficulty and limitations. They called for carefully designed surveillance and said the membrane filter method's validity remained questionable.

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: Descriptive review of environmental (dust) monitoring and its use in epidemiologic surveillance in the asbestos mining industries of South Africa and Quebec, drawing on the authors' experience
• Who was studied: Asbestos miners and millers in South Africa (approximately 30 mines, each with one or more mills) and in Quebec, Canada (five companies, eight open pits and two underground mines). Records date from 1940 onward in South Africa and from 1948 onward in Quebec.
• Exposure: Airborne dust from Cape crocidolite, Transvaal crocidolite, amosite and chrysotile mining and milling, measured with konimeters, thermal precipitators, membrane filters and (in Quebec) the midget impinger
• Main results:
  • South Africa: factors had been developed to convert konimeter or thermal precipitator counts to membrane filter counts. At 2 to 5 fibers per cubic centimeter, they were of the order of 2 for Cape crocidolite, 3 for Transvaal crocidolite, 4.5 for chrysotile and 5.5 for amosite.
  • South Africa: these conversion factors decreased as concentrations increased
  • South Africa: processing konimeter and thermal precipitator results recorded over a period of years into membrane filter concentrations was considered formidable
  • Quebec: no single conversion factor between midget impinger and membrane filter samples was found. Ratios of membrane filter counts (fibers per cubic centimeter) to midget impinger counts (millions of particles per cubic foot) were still under investigation. They were mainly 1 to 5 and varied by mine and by location in the mine or mill.
  • Quebec mills: median fiber concentrations showed a downward trend, but maxima in the mid 1970s exceeded 50 fibers per cubic centimeter
  • South African mines and mills: some observations suggested person-weighted mean exposure could be as low as 15% or as high as four times the industry mean. Short-period measurements ranged from 3% to 20 times the industrial mean.
• The authors' conclusion: The authors concluded that experience in the Canadian and South African mining industries showed past exposure can be reconstructed, but with difficulty and limitations. They concluded that a carefully designed environmental surveillance program could overcome some of these problems.
• Limitations the authors state:
  • Cumulative exposure indices were limited by small numbers of dust samples and long gaps between systematic surveys, particularly before 1964
  • The relationship between personal and fixed-station monitoring had not been examined in detail in either Quebec or South African mines
  • The validity of the membrane filter method for exposure assessment remained questionable

Topics

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

Related studies

• Long-term mortality experience of chrysotile miners and millers in Thetford Mines, Quebec — W.J. Nicholson, I.J. Selikoff, et al. (1979)
• Mortality in Canadian miners and millers exposed to chrysotile — J.C. McDonald, F.D. Liddell (1979)
• Combined effect of asbestos exposure and tobacco smoking on Finnish anthophyllite miners and millers — L.O. Meurman, R. Kiviluoto, et al. (1979)
• Magnetic lung measurements of relation to occupational exposure in asbestos miners and millers of Quebec — D. Cohen, T.S. Crowther, et al. (1981)
• Letter to the editor on commentary: malignant mesothelioma incidence among talc miners and millers in New York state by M M Finkelstein — R.P. Nolan, J.F. Gamble, et al. (2013)
• The morbidity and mortality of vermiculite miners and millers exposed to tremolite-actinolite: Part I. Exposure estimates — H.E. Amandus, R. Wheeler, et al. (1987)

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