A Chemical and Hierological Study of Insulation Materials

Our plain-English summary of A Chemical and Hierological Study of Insulation Materials, by G.W. Gibbs (1974).

The study

• Author: G.W. Gibbs
• Published: A Final Report to The Insitute of Occupational and Environmental Health, March (1974)
• Type of article: Report
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This was a final report from McGill University's Department of Epidemiology and Health, dated March 1974, on the chemical and mineralogical makeup of insulation materials. The available text is mostly the report's conclusions. It names techniques such as microscopy and infrared studies, but it gives no detailed methods or sample sizes. The author reported that most used insulation samples from oil refineries and a dockyard contained amosite, and that 85% magnesia was the most common material in the refineries. After long use on hot pipes, amosite fibres turned from colourless or white to dark brown. Infrared studies showed that asbestos decomposed when temperatures were high enough and use lasted long enough. Benzo(a)pyrene was not found in any sample, and polycyclic aromatic hydrocarbons appeared in only a few samples, at very low levels. Among insulation workers, rates of respiratory symptoms were similar to those of Quebec chrysotile miners and millers, except that wheezing was considerably higher. The author stated that the meaning of this is not known. The author concluded that the study showed the extreme difficulty of defining insulation workers' exposure.

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 chemical and mineralogical study of new and used insulation materials, with air sampling during insulation removal and a comparison of respiratory symptoms (detailed methods are not included in the available text)
• Who was studied: Used insulation samples collected at oil refineries and a dockyard; construction workers removing asbestos insulation at an oil refinery; members of the Heat and Frost Insulation Workers in Montreal. The available text gives no numbers.
• Exposure: Insulation materials, chiefly amosite-containing 85% magnesia, plus diatomaceous silica, organic material, and trace metals (iron, nickel, cobalt, manganese) in insulation and in airborne dust
• Main results:
  • Most used insulation samples from oil refineries and a dockyard contained amosite. 85% magnesia was the most common material in refineries where insulation had been in use for up to 40 years.
  • The ratio of ferrous to ferric iron in insulation on pipes tended to be greater at the inner surface.
  • Amosite fibres changed from colourless or white to dark brown after long-term use on hot pipes. Haematite in some used samples suggested that the amosite had decomposed.
  • Infrared studies showed that asbestos decomposed when the temperature was high enough and the period of use long enough. Pipes were often heated to temperatures up to 650°C.
  • Polycyclic aromatic hydrocarbons were found in only a few insulation samples, at very low concentrations. Benzo(a)pyrene was not detected in any sample. Total organic content of used insulation ranged from 1.0 mg per 100 g up to a figure that is partly illegible in the scan. Commercially milled Canadian chrysotile ranged from 0.5 to 20 mg per 100 g.
  • Nickel and cobalt contents of the insulation materials were similar to or lower than those of commercially milled Canadian chrysotile. Iron content was considerably higher, mostly because of amosite. Manganese was higher in amosite-containing materials.
  • Among workers removing insulation at an oil refinery, airborne trace metal concentrations were lower than in the Quebec asbestos mining and milling industry, but the trace metal content of the dust was considerably higher. Oxy-acetylene welders had the highest dust exposure, but this was not to asbestos.
  • Rates of respiratory symptoms in insulation workers were similar to those in Quebec chrysotile miners and millers, except for wheezing, which was considerably higher in insulation workers.
  • For Montreal Heat and Frost Insulation Workers, the most common non-asbestos materials were fibreglass, rubber and foam plastic. Amosite was the most common type of asbestos encountered.
• The authors' conclusion: The author concluded that the study showed the extreme difficulty of characterizing and defining insulation workers' exposure to either used or new materials.
• Limitations the authors state:
  • The author stated that the significance of the higher rate of wheezing among insulation workers is not known.

Topics

Medical terms in this study, explained in our Lexicon: Epidemiology, Amosite, 85% Magnesia, Insulator, Quebec Chrysotile.

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