Dust exposure and mortality in an American factory using chrysotile, amosite, and crocidolite in mainly textile manufacture

Our plain-English summary of Dust exposure and mortality in an American factory using chrysotile, amosite, and crocidolite in mainly textile manufacture, by A.D. McDonald, J.S. Fry, A.J. Woolley, et al (British Journal of Industrial Medicine, 1983).

The study

• Authors: A.D. McDonald, J.S. Fry, A.J. Woolley, J.C. McDonald
• Journal: British Journal of Industrial Medicine
• Published: 1983;40(4):368-74
• Cited by: 84 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M nos. 000692, 001709).

Abstract

This report describes the second in a series of three parallel cohort studies of asbestos factories in South Carolina, Pennsylvania, and Connecticut to assess the effects of mineral fibre type and industrial process on mortality from malignant mesothelioma, respiratory cancer, and asbestosis. In the present plant (in Pennsylvania) mainly chrysotile, with some amosite and a small amount of crocidolite, were used primarily in textile manufacture. Of a cohort of 4137 men comprising all those employed 1938-59 for at least a month, 97% were traced. By the end of 1974, 1400 (35%) had died, 74 from asbestosis and 70 from lung cancer. Mesothelioma was mentioned on the certificate in 14 deaths mostly coded to other causes. All these deaths occurred after 1959, and there were indications that additional cases of mesothelioma may have gone unrecognised, especially before that date. The exposure for each man was estimated in terms of duration and dust concentration in millions of dust particles per cubic foot (mpcf) from available measurements. Analyses were made both by life table and case referent methods. The standardised mortality ratio for respiratory cancer for the whole cohort was 105.0, but the risk rose linearly from 66.9 for men with less than 10 mpcf.y to 416.1 for those with 80 mpcf.y or more. Lines fitted to relative risks derived from SMRs in this and the textile plant studied in South Carolina were almost identical in slope. This was confirmed by case referent analysis. These findings support the conclusion from the South Carolina study that the risk of lung cancer in textile processing is very much greater than in chrysotile production and probably than in the friction products industry. The much greater risk of mesothelioma from exposure to processes in which even quite small quantities of amphiboles were used was also confirmed.

In plain English

This cohort study followed men employed at least a month in 1938-1959 at a Pennsylvania asbestos plant making mainly textiles. The plant used mainly chrysotile, some amosite and a little crocidolite. Of 4137 men, all but 113 were traced, and 1400 of the traced men (35%) had died. Each man's cumulative dust exposure was estimated from workplace measurements, in millions of particles per cubic foot times years (mpcf.y). For deaths at least 20 years after first employment, the cohort's standardised mortality ratio (SMR) for respiratory cancer, against Pennsylvania death rates, was 105.0. Counting exposure up to 10 years before death, it rose from 66.9 in men with under 10 mpcf.y to 416.1 in men with 80 mpcf.y or more. The rise in respiratory cancer risk with exposure had a nearly identical slope to that in a South Carolina chrysotile textile plant. Mesothelioma appeared on 14 death certificates, 10 pleural and 4 peritoneal. Some deaths coded to unspecified cancers looked consistent with unrecognised peritoneal mesothelioma. The authors concluded that even quite small proportions of amphibole, here mainly amosite, carried a special mesothelioma risk.

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: Retrospective cohort mortality study with individual dust exposure estimates. Deaths were compared with Pennsylvania death rates (life table method), and a case-referent (Mantel-Haenszel) analysis was also done. This is the second of three parallel plant studies.
• Who was studied: 4137 men employed for at least a month between 1938 and 1959 at an asbestos plant in Pennsylvania, USA. 97% were traced. The 998 women in the cohort are not covered in this paper.
• Exposure: Mainly chrysotile, with some amosite and a small amount of crocidolite, used primarily in textile manufacture (friction products and packings were also made). Dust exposure was estimated in millions of particles per cubic foot (mpcf) and as cumulative exposure (mpcf.y).
• Main results:
  • All but 113 of the 4137 men were traced. Of the traced men, 1400 (35%) had died.
  • The SMR analyses by exposure covered male deaths at least 20 years after first employment, with dust exposure accumulated up to 10 years before death.
  • Respiratory cancer SMR for the whole male cohort was 105.0, for deaths at least 20 years after first employment. It rose from 66.9 in men with less than 10 mpcf.y to 416.1 in men with 80 mpcf.y or more.
  • SMR for all causes rose from 93.1 in men with under 10 mpcf.y to 215.2 in the highest exposure category (80 mpcf.y or more).
  • Respiratory cancer relative risk rose with exposure along nearly identical lines in the two plants: RR = 1 + 0.059 mpcf.y in South Carolina and RR = 1 + 0.051 mpcf.y in Pennsylvania.
  • Mesothelioma was specified on 14 death certificates: 10 pleural and 4 peritoneal.
  • Mesothelioma accounted for 14 of 1392 male deaths (1%) in Pennsylvania, compared with 1 of 867 (0.1%) in the South Carolina plant.
  • Of 30 deaths coded to unspecified cancer sites (ICD 199), the diagnosis in many was consistent with unrecognised peritoneal mesothelioma.
  • The authors stated that the similar exposure-response findings in this and the South Carolina plant supported their earlier conclusion that respiratory cancer and asbestosis risks differ between chrysotile production (mining and milling) and textile manufacture.
• The authors' conclusion: The authors concluded that this study again showed a special mesothelioma risk from exposure to even quite small proportions of amphibole, in this plant predominantly amosite.
• Limitations the authors state:
  • The dust estimates did not include some short but very heavy exposures, such as cleaning in the dust house.
  • SMRs may be distorted because the cohort may not be comparable with the Pennsylvania state population.
  • Smoking data covered few men, so no firm conclusion could be drawn about smoking differences.
  • About 5% of cases were missing from the case-referent analysis because matching controls were not found.
  • Some mesothelioma cases may have gone unrecognised, especially before 1959.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Amosite, Asbestos textiles, Chrysotile, Crocidolite.

Medical terms in this study, explained in our Lexicon: Chrysotile, Amosite, Crocidolite, Malignant Mesothelioma, Lung Cancer, Mesothelioma, Relative Risk, Friction Products.

Related studies

• Dust exposure and mortality in an American chrysotile textile plant — A.D. McDonald, J.S. Fry, et al. (1983)
• Dust exposure and mortality in an American chrysotile asbestos friction products plant — A.D. McDonald, J.S. Fry, et al. (1984)
• Evaluation of the exposure, dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos in a 90-day quantitative inhalation toxicology study - Interim results Part 1: Experimental design, aerosol exposure, lung burdens and BAL — D.M. Bernstein, B. Toth, et al. (2020)
• Evaluation of the dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos in a 90-day quantitative inhalation toxicology study - Interim results Part 2: Histopathological examination, Confocal microscopy and collagen quantification of the lung and pleural cavity — D.M. Bernstein, B. Toth, et al. (2020)
• Increased lung cancer mortality among chrysotile asbestos textile workers is more strongly associated with exposure to long thin fibres — D. Loomis, J.M. Dement, et al. (2012)
• Dust control in a conventional asbestos textile factory — H.C. Lewinsohn, C.A. Kennedy, et al. (1979)

Browse more research in British Journal of Industrial Medicine, or return to medical research.