Survey in Seventeen cement plants of Atmospheric Dusts in Two Hundred Employees

Our plain-English summary of Survey in Seventeen cement plants of Atmospheric Dusts in Two Hundred Employees, by L.U. Gardner, T.M. Durkan, D.M. Brumfiel, et al (1939).

The study

• Authors: L.U. Gardner, T.M. Durkan, D.M. Brumfiel, H.L. Sampson
• Published: The Journal of Industrial Hygiene and Toxicology, Volume 21 No7. September 1939
• Type of article: Journal article
• 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 1939 article reported an engineering survey of airborne dust in 17 United States portland cement plants. It also reported physical and chest X-ray examinations of all 2278 employees in 11 of those plants, of whom 1979 worked where they were exposed to dust. The study concerned cement dust and raw-material dusts containing free silica. It did not study asbestos. In 17 samples of finished cement, one from each plant, the highest free silica content was 0.12%. Eight employees showed X-ray evidence of nodular fibrosis. The authors attributed six of these to silica exposure in earlier jobs and two to sandstone dust in special operations within the cement industry. Well-marked (second-degree) linear exaggeration of lung shadows, which was not associated with any symptoms, was most frequent in men with considerable raw mill exposure. Four cases of active tuberculosis were found among the 2278 employees. The authors concluded that, compared with hard rock mining, the dust problem in the cement industry was trivial. They noted that exact correlation with dust type was impossible because many employees had worked in several departments.

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: Cross-sectional survey: engineering measurements of dust in 17 cement plants, plus physical and chest X-ray (roentgenographic) examinations of the employees of 11 plants, with plant workers compared against less-exposed controls and a group of rock miners
• Who was studied: 2278 employees of 11 United States portland cement plants (in states including New York, Pennsylvania, Indiana, Alabama, Iowa, Missouri, Kansas, Texas and California). 1979 worked in plant areas with dust exposure. The remainder (299) worked in relatively dust-free jobs and served as controls.
• Exposure: Cement plant dusts: finished portland cement dust, in which the maximum free silica content among 17 samples (one per plant) was 0.12%, and mixed raw mill dusts (limestone, shale, clay, sandstone and similar materials) containing varying amounts of free silica. No asbestos exposure was studied.
• Main results:
  • 8 of the 2278 employees showed nodular fibrosis attributable to dust. In 6 of these, silica exposure in previous employment was presumed responsible.
  • Only 2 individuals, both exposed to sandstone dust in special operations, showed nodulation resulting from their cement industry employment
  • Second-degree linear exaggeration was most frequent in men with considerable raw mill exposure to mixed dusts containing free silica. In all cement employees its frequency was about one-thirteenth of that in a group of rock miners. The reaction was not associated with any symptoms.
  • The authors found that prolonged inhalation of finished cement dust produced so slight a reaction that little or no abnormality was seen on the X-ray
  • Among all 2278 employees, only 4 cases of active tuberculosis were found. The authors reported the incidence of tuberculosis and other chronic lung infections as lower than in the general population.
  • Slight (first-degree) linear exaggeration of lung shadows was attributed mainly to non-specific factors related to advancing age rather than to dust
• The authors' conclusion: The authors concluded that, compared with hard rock mining and other silica industries, the dust problem in the cement industry was trivial. They also concluded that prolonged inhalation of cement dust had no unfavorable influence on susceptibility to tuberculous infection.
• Limitations the authors state:
  • Exact correlation between dust type and lung findings was impossible because many employees had worked in several departments
  • Technical obstacles prevented exact determination of how much airborne silica was in inhalable form
  • Only a single X-ray examination was made on most of the men, so the study could not answer questions about how tuberculosis developed
  • Bronchitis and respiratory infection figures were based on the men's own statements and may be subject to error

Topics

Medical terms in this study, explained in our Lexicon: Chest X-Ray, Fibrosis.

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