Report of Preliminary Dust Investigations for Asbestos Textile Institute June 1947

Our plain-English summary of Report of Preliminary Dust Investigations for Asbestos Textile Institute June 1947 (1947).

The study

• Published: Industrial Hygiene Foundation of America p1-28 (1947)
• 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 1947 report by the Industrial Hygiene Foundation of America described a preliminary survey of the asbestosis problem in textile plants of Asbestos Textile Institute members. Over three months, investigators visited all member plants but one, reviewed existing dust count records, took a few samples, and examined dust with an electron microscope. Some plants had brought dust down to five million particles per cubic foot or lower, the commonly used limit. Four plants materially exceeded that limit in carding. Only five plants had made any medical x-ray surveys of workers. Reported figures included about three to four per cent with asbestosis in one plant and about 20 per cent (recorded or potential cases) in two others. Electron microscope pictures showed that the 'cubical' particles seen in dust counts were bundles of fibers. They also showed that some long, very thin fibers were invisible to the usual counting microscope. The authors concluded that keeping dust at five million did not positively ensure that no asbestosis would develop over a long working life. They recommended medical and x-ray examinations of all exposed workers.

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: Preliminary industrial hygiene survey (plant visits, review of existing dust count records, a few dust samples, electron microscope study of airborne dust, review of plant medical practices), with recommendations; prepared for an industry trade association
• Who was studied: Textile plants of members of the Asbestos Textile Institute: all member plants except one (plants A to J in the report's table), visited during the three months before June 1947; textile employment is given only for some plants (for example around 150 at Plant D and 300 at Plant I)
• Exposure: Asbestos dust in textile operations (preparation, carding, mule and ring spinning, twisting, weaving, spooling and winding), measured as dust counts in millions of particles per cubic foot; the fiber type is not named
• Main results:
  • Mechanical dust control methods in one or more plants brought dust concentrations down to five million or lower in all operations, with one or two exceptions
  • In carding rooms, concentrations well below three million were obtainable with good enclosure and exhaust of the machines, but four of the plants visited materially exceeded the five million limit
  • Mule spinners' exposure ranged from two to eight million, ring spinning from one to five million, and twisting from two to eight million
  • Only five plants had made any medical x-ray surveys of employees
  • At Plant A, recorded cases diagnosed as asbestosis came to about 20 per cent, and over the past nine years the plant had compensated on average two cases per year
  • At Plant C, a recent systematic survey estimated asbestosis incidence at about three to four per cent
  • At Plant D, an incomplete survey of volunteers found four cases, in a total textile employment of around 150; one case had been compensated in about 10 years and three more were pending
  • At Plant I, with a textile employment of 300, the physician found five or six cases a year believed to show early changes due to asbestos
  • At Plant J, potential cases of asbestosis amounted to about 20 per cent, comparable with Plant A
  • The plants without systematic x-ray surveys had no information on incidence among their employees, and none of them had had cases requiring compensation
  • At the two North Carolina plants, where the state had examined workers periodically for 10 years, the authors could find no employee who had been removed from work or compensated for asbestosis
  • Non-fibrous particles made up 80 to 95 per cent of the total dust seen in dust counting in most textile operations
  • Electron microscope samples from a card room with good dust control showed that the 'cubical' particles seen by light microscope were bundles of fibers
  • The same samples showed many fibers of considerable length, some fully 50 microns, whose width was only a fraction of a micron, making them invisible in the dust counting microscope; some fibers a few microns long were only 0.01 to 0.02 microns in diameter
• The authors' conclusion: The authors concluded that eliminating dust to five million particles per cubic foot does not positively ensure that no asbestosis will develop in some workers after a long working life (greater than 20 to 25 years), and that the available information did not permit complete assurance that five million is safe. They strongly recommended medical and x-ray examinations of all exposed workers, a diagnostic panel, statistical studies of existing medical records, and further dust studies.
• Limitations the authors state:
  • Dust count data for preparation room operations were highly variable and considered much less reliable than those for other departments; the same applied to spooling and winding data
  • Relatively extreme values in the dust table indicate too few data to permit a closer estimate
  • Occasional high values in ring spinning and twisting may partly reflect the sampling procedure rather than the worker's exposure
  • The authors had no complete data on employment history and labor turnover in the plants
  • There were not enough data from the attempt to measure dust in roving to draw conclusions

Topics

Medical terms in this study, explained in our Lexicon: Industrial Hygiene, Million Particles per Cubic Foot (mppcf), Carding.

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