Biological effects: asbestos-cement manufacturing

Our plain-English summary of Biological effects: asbestos-cement manufacturing, by H. Weill (The Annals of Occupational Hygiene, 1994).

The study

• Author: H. Weill
• Journal: The Annals of Occupational Hygiene
• Published: 1994;38(4):533-8, 413
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Fourteen cohorts of asbestos-cement workers have been studied. These studies have demonstrated exposure-response relationships for lung cancer, mesothelioma and asbestosis. For lung cancer, relatively consistent results have been observed, with risk two-fold or less in 13 of the 14 cohorts. Among New Orleans workers, excess risk was restricted to those with X-ray evidence of asbestosis. Workers employed at least 21 years but without X-ray abnormalities, experienced no elevated risk, while those with small opacities (1/0 or higher) had substantially elevated risk (SMR > 400). Exposures in these two groups had been similar. These results suggest that asbestosis may be a necessary precursor for asbestos-induced lung cancer; if so, then the no-threshold model for lung cancer risk is inappropriate since there is general agreement that very low exposures will not result in radiologically detectable lung fibrosis. Further data on this potential link are needed. As in other industries, mesothelioma risk was strongly related to amphibole exposure, especially to crocidolite in asbestos-cement pipe manufacture. A cluster of cases has recently been reported in a family amosite-cement business. Among New Orleans workers, risk of asbestosis was related to cumulative exposure but there was little evidence of risk below 30 f ml-1-years. Progression of asbestosis in these workers was slow, related to past cumulative exposure and not related to lung function decline. Asbestosis risk is therefore not likely to develop in workers under current controlled exposure conditions.

In plain English

This paper, presented at a 1993 workshop on chrysotile asbestos, was a summary review of published studies on the health of asbestos-cement workers. It included the author's own New Orleans cohort. Asbestos-cement workers in general were most often exposed to mixed fibres, usually chrysotile and crocidolite, but also amosite. Across 14 studies, an overall excess of lung cancer, when found, was approximately two-fold or less, with one exception, and was related to length of employment. Two studies of almost exclusively chrysotile exposure found no excess lung cancer. In New Orleans workers, a four-fold increase in lung cancer was limited to those with X-ray evidence of asbestosis at the start of follow-up. That cohort showed little X-ray evidence of asbestosis below 30 to 40 fibres per cubic centimetre-years, and crocidolite exposure was linked to more asbestosis. Mesothelioma risk was strongly influenced by amphibole exposure. The author concluded that asbestosis and asbestos-attributable lung cancer are not likely risks under current low exposure, and that chrysotile's role in mesothelioma, with or without tremolite, needs further study.

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: Summary review of published studies (paper read at a workshop), including the author's own New Orleans cohort studies
• Who was studied: Asbestos-cement workers in 14 published cohort studies from Europe and North America, mostly published in the 1980s, including New Orleans asbestos-cement workers from two plants
• Exposure: Occupational exposure in asbestos-cement manufacturing, which for workers in the industry was most often to mixed fibres: usually chrysotile and crocidolite, and also amosite. In New Orleans, crocidolite was used in the pipe plant.
• Main results:
  • In the reviewed studies, an overall excess risk of lung cancer, when found, was approximately two-fold or less, with one exception (Finkelstein, 1984), and was related to duration of employment
  • In one study (Neuberger and Kundi, 1990) that could account for smoking, lung cancer risk was related primarily to smoking, not asbestos exposure
  • In two studies (Thomas et al., 1982; Gardner et al., 1986) where exposure was stated to be almost exclusively to chrysotile, no excess lung cancer risk was found
  • In the New Orleans prospective mortality study, there was a four-fold increase in lung cancer risk, limited to workers with radiographic evidence of asbestosis at the start of follow-up
  • New Orleans workers without X-ray evidence of lung fibrosis, or with only pleural effects, did not have a later significant excess of lung cancer deaths
  • Without radiographic information, lung cancer risk in New Orleans workers appeared linearly related to estimated past asbestos exposure
  • Among New Orleans asbestos-cement workers there was little radiographic evidence of asbestosis below 30 to 40 fibres per cubic centimetre-years
  • Progression of asbestosis in affected New Orleans workers was slow and correlated with past cumulative asbestos exposure
  • In the New Orleans cohort, radiographic progression or estimated past exposure did not influence the course of lung function during the 1970s
  • In the New Orleans cohort, crocidolite exposure was associated with greater prevalence and greater probability of progression of asbestosis, after total fibre exposure was taken into account
  • The author stated there is little remaining doubt that amphibole exposures strongly influence mesothelioma risk in the asbestos-cement sector
  • A reviewed report (Otte et al., 1990) described a familial cluster of mesothelioma cases where amosite was used to make asbestos cement in a small family business in the home
  • A reviewed cohort study (Magnani et al., 1993) found a mesothelioma risk in spouses of Italian asbestos-cement workers who had substantial crocidolite exposure
  • In New Orleans workers, mesothelioma odds ratios were related to duration of exposure and to the proportion of time spent in the pipe plant, where crocidolite was used
  • The author stated that, on present evidence, mesothelioma risk can be greatly reduced by not using amphibole fibres in asbestos-cement products
• The authors' conclusion: The author concluded that asbestosis and asbestos-attributable lung cancer are not likely to be risks for those working under current conditions of low fibre exposure
• Limitations the authors state:
  • Where the lung cancer dose-response line meets the axes could not be accurately determined; both threshold and non-threshold models fit the data adequately
  • Confirmatory data are needed on the link between asbestosis and lung cancer risk, and on exposure levels free of asbestosis risk after a working lifetime
  • The role of chrysotile, with or without contaminating tremolite, in causing mesothelioma requires further investigation

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Lung Cancer, Mesothelioma, Fibrosis, Amphibole Group, Crocidolite, Asbestos-Cement Pipe, Amosite.

Related studies

• Influence of dose and fiber type on respiratory malignancy risk in asbestos cement manufacturing — H. Weill, J. Hughes, et al. (1979)
• Radiographic asbestosis is not a prerequisite for asbestos-associated lung cancer in Ontario asbestos-cement workers — M.M. Finkelstein (1997)
• Absence of radiographic asbestosis and the risk of lung cancer among asbestos-cement workers: Extended follow-up of a cohort — M.M. Finkelstein (2010)
• Asbestos lung burden and asbestosis after occupational and environmental exposure in an asbestos cement manufacturing area: a necropsy study — C. Magnani, F. Mollo, et al. (1998)
• Trends in Airborne Chrysotile Asbestos Fibre Concentrations in Asbestos Cement Manufacturing Factories in Zimbabwe from 1996 to 2016 — B. Mutetwa, D. Moyo, et al. (2021)
• Colorectal cancer in asbestos cement workers in Denmark — E. Raffn, E. Villadsen, et al. (1996)

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