Asbestosis In Asbestos Cement Workers

Our plain-English summary of Asbestosis In Asbestos Cement Workers, by P.E. Enterline, H. Weill (1973).

The study

• Authors: P.E. Enterline, H. Weill
• Published: Biological Effects Of Asbestos (J.C. Wagner, Editor), Lyon: Iarc Scientific Publications, Volume 8, Pp. 179-183 (1973)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library, J-M no. 001301. The article is still under copyright, so we describe it here rather than post it.

In plain English

This was a review of asbestosis among workers making asbestos cement products, an industry using chrysotile and crocidolite asbestos in which workers are also exposed to silica. It summarized earlier reports and the authors' own studies. In 908 workers from two U.S. asbestos cement plants, chest X-ray changes of category 2/1 or above appeared after a total dust exposure of 1000 million particles per cubic foot-months. Workers with a moderately advanced profusion (category 2/1 or above) of irregular opacities tended to have lower lung volumes and diffusing capacity than those with rounded opacities. For this review, the authors tabulated deaths among 422 retired men who had worked with asbestos cement products. Their mortality was very similar to that of 926 other retired asbestos workers. The 106 cement pipe workers, all exposed to crocidolite, had a very high respiratory cancer death rate and no asbestosis deaths. The 316 shingle and sheet workers had all 6 asbestosis deaths. The authors concluded that this finding, though based on small numbers, supports other observations on the carcinogenic properties of crocidolite.

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: Review of published reports, including the authors' own studies, plus special tabulations of mortality data (observed and expected deaths, standardised mortality ratios) from the authors' study of retired asbestos workers
• Who was studied: 1348 U.S. asbestos workers who retired at age 65 during 1941-67 and were followed for deaths until 1969. Of these, 422 had worked with asbestos cement products (316 making rigid shingles and sheets, 106 making cement pipe) and 926 were other asbestos workers. The review also described a clinical study of 908 current, recently retired or separated workers from two U.S. asbestos cement plants.
• Exposure: Asbestos and silica dust in asbestos cement manufacturing. Chrysotile and crocidolite asbestos were used. All cement pipe workers had exposure to crocidolite, while rigid shingles and sheets rarely contained crocidolite. Exposure was measured as cumulative dust in million particles per cubic foot (mppcf)-months or mppcf-years.
• Main results:
  • In the study of asbestos cement plant workers, chest X-ray changes of category 2/1 or above appeared after a total dust exposure of 1000 mppcf-months.
  • Workers with a moderately advanced profusion of irregular opacities (well-established, category 2/1 or above) tended to have lower lung volumes and pulmonary diffusing capacity than workers with rounded opacities.
  • In the retired worker study, a linear relationship was found between time-weighted asbestos dust exposure and deaths from asbestosis.
  • The 422 retired asbestos cement workers and the 926 other retired asbestos workers had about the same mean time-weighted dust exposure at retirement (249 versus 247 mppcf-years). Their mortality was very similar for all causes and for the selected causes shown.
  • Among the retired asbestos cement workers, the cement pipe workers had a very high respiratory cancer death rate (10 respiratory cancer deaths observed) and no asbestosis deaths.
  • The rigid shingle and sheet workers (7 respiratory cancer deaths observed) had a respiratory cancer excess the authors called not remarkable. This group had all the asbestosis deaths among the cement workers (6 deaths).
• The authors' conclusion: The authors concluded that, in retired asbestos cement workers, those exposed to crocidolite showed no asbestosis but high respiratory cancer mortality. Those exposed mainly to chrysotile showed considerable asbestosis but moderate respiratory cancer mortality. In the authors' view this finding, though based on small numbers, supports other observations on the carcinogenic properties of crocidolite. They also concluded that the fibrotic lung effects appear related to cumulative dust exposure.
• Limitations the authors state:
  • The numbers of asbestos cement workers compared in Table 3 (pipe versus shingle and sheet workers) were small.
  • In the plant study, effects of silica and asbestos could not be separated, probably because only a limited range of exposures to these two materials was encountered in the plants.
  • Pipe workers started work later and had lower time-weighted exposure (228 versus 256 mppcf-years), which might account for their absence of asbestosis deaths.
  • Comparisons of working populations may be biased because the asbestos cement work force is younger and has had less exposure than other asbestos workers.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Chrysotile, Crocidolite, Chest X-Ray, Million Particles per Cubic Foot (mppcf), Diffusing Capacity (DLCO), Carcinogenic.

Browse return to medical research.