Some Observations On Asbestosis

Our plain-English summary of Some Observations On Asbestosis, by G.L. Leathart, J.T. Sanderson (1963).

The study

• Authors: G.L. Leathart, J.T. Sanderson
• Published: Annals Of Occupational Hygiene 6(2):65-74, April-June (1963)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library, J-M no. 001568. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1963 paper from King's College, Newcastle-upon-Tyne, examined British certification figures for asbestosis and the work of insulators, called laggers. The authors reported that certifications had not shown a satisfactory fall in recent years and might be increasing. Over the same period the asbestos industry grew from 10,000 workers in 1935 to 18,700 in 1958. Of 67 cases certified in 1960 and 1961, 32 were employed on insulating or asbestos spraying. During installation of a new heating system in a local hospital, the authors sampled air dust, counting fibrous particles 5 to 50 microns long. Counts rose above the official limit of 177 particles per cm³ while dry magnesia/asbestos plaster was mixed with water, but this was a localized cloud. Sweeping up stripped lagging gave 2 to 23 particles per cm³. The authors stressed that their measurements were limited to one building. They concluded that asbestosis was occurring among insulation workers and that prevention probably depends on substituting an innocuous material for asbestos. They judged dust masks unlikely to be effective in the hot conditions they recorded.

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 report: review of national asbestosis certification figures and asbestos industry statistics, plus a small set of air dust measurements during lagging work in one hospital
• Who was studied: British asbestosis certifications from 1931 to 1961, including 67 cases certified in 1960 and 1961 grouped by occupation. Laggers (thermal insulators) installing a heating system in one local hospital in the Newcastle area.
• Exposure: Asbestos dust in insulation (lagging) work: mixing dry magnesia/asbestos plaster with water, stripping and sweeping old lagging, and asbestos cloth made from chrysotile asbestos. Mixing took 5 to 15 minutes and was repeated every 2 to 4 hours.
• Main results:
  • National certifications of asbestosis had not shown a satisfactory fall in recent years and might be increasing
  • The asbestos industry employed 10,000 workers in 1935 and 18,700 in 1958
  • Among asbestos products, the greatest percentage increase was in insulating materials
  • Of 67 asbestosis cases certified in 1960 and 1961, 32 were employed on insulating or asbestos spraying
  • In the authors' part of the country, fewer than 500 men did insulation work, and the author had personally seen 18 cases of asbestosis among them. Nationally, the authors estimated the number of insulators at about 5000.
  • At the hospital, the dust count rose above the official limit (M.A.C.) of 177 particles per cm³ during mixing of magnesia/asbestos plaster, but this was a localized dust cloud
  • During sweeping up of stripped lagging in a duct, counts of 2 to 23 particles per cm³ were recorded
  • The authors judged from the dust counts that prolonged exposure to high concentrations was not occurring at this site, although asbestosis was occurring among men on similar work
  • Corrected effective temperatures as high as 89 °F were recorded during lagging work in the hospital
  • In the published discussion, a participant proposed 30 particles per cm³ as a more realistic limit for fibrous particles. The author accepted this figure and agreed that the dust hazard was greater than previously implied.
• The authors' conclusion: The authors concluded that asbestosis is occurring among workers in the insulating industry and that steps should be taken to deal with this. They suggested closer health supervision of laggers, perhaps by extending the Medical Arrangements Scheme. They judged that prevention probably depends on substituting an innocuous material for asbestos, that reducing handling of dry asbestos plaster might help, and that respirators are less likely to be effective because of the hot, humid conditions.
• Limitations the authors state:
  • The dust observations were not extensive, were limited to one building, and need confirmation in other situations
  • Certification figures must be interpreted cautiously because diagnostic accuracy and the law (including the 1952 benefit scheme) changed over the period
  • The incidence of asbestosis among insulators is unknown, and the total number of insulators was only estimated
  • Diagnosis was occasionally being made before X-ray changes appeared. The author said it was not known how far this influenced the certification figures.

Topics

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

Browse return to medical research.