Industrial Hygiene For Insulation Workers

Our plain-English summary of Industrial Hygiene For Insulation Workers, by J.L. Balzer (1968).

The study

• Author: J.L. Balzer
• Published: Journal Of Occupational Medicine 10(1):25-31, January (1968)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library, J-M no. 002730. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1968 paper reported preliminary findings from an industrial hygiene survey of insulation workers in San Francisco Local 16 of the insulators' union. The local had about 500 men in Northern California and Northern Nevada. The author estimated that these workers spent about 45% of their time with asbestos-containing products, mainly amosite and chrysotile, and about 45% with fibrous glass. Dust sampling was limited to jobs where asbestos materials were being applied. It found levels above the then-accepted limit of 5 million particles per cubic foot during prefabrication, tearing out and mixing, while the overall time-weighted average was reported to be below that limit. In membrane filter samples, 98% (plus or minus 2%) of the fibers counted were in the respirable size range. The paper also stated that radiographic changes indicative of asbestosis affected over 25% of the men with 20 years or more of work, a finding it attributed to unpublished data. The author concluded that the limit was not preventing asbestosis and was too high. The author recommended ventilation, substitution of materials, changed work habits, respiratory protection and worker education.

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: Industrial hygiene survey of the work environment (environmental sampling and observation), reported as preliminary environmental findings; presented at a conference in September 1967
• Who was studied: Members of San Francisco Local 16 of the International Association of Heat and Frost Insulation and Asbestos Workers, about 500 men covering Northern California and Northern Nevada. On a typical work day in summer 1967, 380 active members were surveyed and found employed: 220 in heavy industrial construction, 100 in commercial building and 60 in marine construction and repair.
• Exposure: Asbestos-containing insulating products, mainly chrysotile and amosite: 14 products from seven major producers, used about 45% of the time. Other exposures were fibrous glass (about 45% of the time), solvent-containing adhesives and coatings (5% of the time), heat, humidity and noise.
• Main results:
  • Midget impinger dust counts were highest and exceeded the TLV (5 million particles per cubic foot) in prefabrication, tearing out and mixing. The results section states these three areas account for less than 35% of the man's working time when applying asbestos materials.
  • The paper's summary states that the overall time-weighted average exposure to asbestos-containing materials was below the TLV of 5 million particles per cubic foot. It also states that the three work areas above the TLV account for less than 20% of total work time.
  • In membrane filter samples, 98% plus or minus 2% of fibers counted fell into the respirable category (diameter smaller than 3.5 microns), depending on working conditions.
  • Radiographic changes indicative of asbestosis were reported in over 25% of the union men with 20 years or more of work. The discussion cites unpublished data (Balzer and Cooper, 1967) for the radiologic changes.
  • None of the small number of solvent readings approached the TLV for the solvents listed.
  • Few areas had sustained noise readings above 90 dB, but readings above 100 dB were not uncommon when chippers, caulkers, riveters and grinders were used nearby.
• The authors' conclusion: The author concluded that the time-weighted average limit of 5 million particles per cubic foot for asbestos was not preventing asbestosis and was too high. The author stated that asbestosis and the risk of malignancies could be reduced by local and general ventilation, substitution of materials, changes in work habits, and personal respiratory protection combined with education of the men.
• Limitations the authors state:
  • The author stated that a classical time-weighted exposure for the insulator's changing work conditions was impossible to obtain; only the variability of exposures could be shown.
  • Because of manufacturer and contractor practices, it was impossible to reconstruct a working population with a pure exposure to one type of asbestos fiber.
  • Dust sampling was limited to areas where asbestos-containing materials were being applied.
  • Only a small number of solvent measurements had been made.
  • The impinger counting method behind the standard pools grains and fibers, and many asbestos fibers were below the resolving power of the light microscope.

Topics

Medical terms in this study, explained in our Lexicon: Industrial Hygiene, Insulator, Amosite, Chrysotile, Million Particles per Cubic Foot (mppcf), Time-Weighted Average (TWA), Habit, Respirator.

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