Fibre release from asbestos garments

Our plain-English summary of Fibre release from asbestos garments, by G.W. Gibbs (The Annals of Occupational Hygiene, 1975).

The study

• Author: G.W. Gibbs
• Journal: The Annals of Occupational Hygiene
• Published: 1975;18(2):143-9
• Cited by: 2 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. 001127).

In plain English

This study measured airborne fibres in the breathing zones of men who wore asbestos safety garments at work in two ore reduction plants. At plant 1, the blast furnace section of a large steel plant, men wore asbestos coats, hoods and mittens. At plant 2, a small plant making elemental phosphorus, men also wore leggings. Fibres at least 5 micrometres long were counted by optical microscopy, and some samples were also examined by scanning electron microscopy. At plant 1, the mean of 39 tests was 2.0 fibres/cm3, and 13 tests exceeded 2 fibres/cm3. The 8-hour time-weighted average at plant 1 ranged from 0.1 to 1.1 fibres/cm3. At plant 2, all samples exceeded 5 fibres/cm3 and all but one exceeded 10, giving an estimated 8-hour average of 4.7 fibres/cm3. Electron microscopy showed substantial numbers of fibres that optical counting did not detect. The author did not know why the plants differed but noted that the plant 2 coats and mittens were untreated. The author concluded that fibre release from asbestos garments needs to be identified and reduced, including by testing garments before sale.

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: Workplace exposure survey using personal breathing-zone air sampling, with optical (phase contrast) fibre counts and some scanning electron microscopy counts
• Who was studied: Men at two ore reduction plants where asbestos safety garments were worn routinely. Plant 1 was the blast furnace section of a large steel plant, where all workers on two neighbouring furnaces were studied. Plant 2 was a small elemental phosphorus plant, where four men ran two furnaces and two shifts were studied. The location of the plants and the dates of the surveys are not stated.
• Exposure: Asbestos safety garments from three sources: coats, hoods and mittens at plant 1, plus leggings at plant 2. Most cloths were 'Underwriters' grade, described as 80-85% asbestos. Some plant 1 garments were acrylic-resin treated and hoods were aluminized. The asbestos fibre type of the garments is not stated.
• Main results:
  • Plant 1: the mean breathing-zone concentration over 39 tests was 2.0 fibres/cm3 (standard error 0.4).
  • Plant 1: 13 of the 39 tests exceeded 2 fibres/cm3.
  • Plant 1: assuming two casts per day, the 8-hour time-weighted mean was 0.4 fibres/cm3 (range 0.1 to 1.1). No 8-hour weighted exposure exceeded 2 fibres/cm3.
  • Plant 1: concentrations were similar across different occupations.
  • Plant 1: the correlation between garment age and fibre concentration was 0.4 overall, and 0.68 after one 12-week-old coat was excluded. The author said this suggested fibre release increased with garment age up to 8 weeks.
  • Plant 2: breathing-zone concentrations exceeded 5 fibres/cm3 in all cases, and exceeded 10 fibres/cm3 in all but one case, over exposure periods of 15-47 minutes.
  • Plant 2: based on about 2 hours 45 minutes of garment wear per day, the estimated 8-hour time-weighted average was 4.7 fibres/cm3.
  • Electron microscopy: in the six samples examined, fibres at least 5 micrometres long made up 32, 16.5, 2.3, 26, 28 and 23% of all airborne fibres.
  • Electron microscopy found substantial numbers of fibres at least 5 micrometres long that were not visible by optical counting.
  • The reason for the difference between the plants was not known. The author noted that coats and mittens at plant 2 were untreated and that leggings were also worn there.
• The authors' conclusion: The author concluded that fibre release from asbestos garments needs to be identified and decreased, to prevent workers being exposed to concentrations that may be hazardous or exceed present and likely future standards. The author suggested new manufacturing and treatment processes, and testing garments for fibre release (including submicroscopic fibre) before sale.
• Limitations the authors state:
  • Ambient air in the work areas could not be sampled because of safety rules. The author relied on assurances from management that there were no other sources of fibrous dust.
  • Full details of the cloths used to make the garments could not be obtained in all cases.
  • It could not be determined whether the fibres came from the coat, the gloves or the hood.
  • The optical and electron microscope samples being compared were not taken at the same time. The author said this probably explains the large variation between them.
  • The garment-age analysis had wide scatter, few measurements, and a correlation too low to reliably predict fibre release.

Related studies

• Heat stress associated with the use of vapor-barrier garments — W.S. Beckett, J.E. Davis, et al. (1986)
• Penetration of overall hoods by water-borne crocidolite fibres — R. Goode, T. Waldron (1977)
• Physiological and subjective responses to working in disposable protective coveralls and respirators commonly used by the asbestos abatement industry — M.K. White, T.K. Hodous, et al. (1989)
• Protection of dockyard workers against asbestosis — P.G. Harries (1970)
• Water-cooled suit for protection against hot environments — J.W. Hill (1970)
• Asbestos-stimulated tumour necrosis factor release from alveolar macrophages depends on fibre length and opsonization — K. Donaldson, X.Y. Li, et al. (1992)

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