Risk of asbestosis in crocidolite and amosite mines in South Africa: an erratum

Our plain-English summary of Risk of asbestosis in crocidolite and amosite mines in South Africa: an erratum, by L.M. Irwig, R.S. du Toit, G.K. Sluis-Cremer, et al (American Journal of Industrial Medicine, 1984).

The study

• Authors: L.M. Irwig, R.S. du Toit, G.K. Sluis-Cremer, R.G. Thomas
• Journal: American Journal of Industrial Medicine
• Published: 1984;5(6):479-83
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000548).

In plain English

This short article was an erratum to the authors' 1979 study of white and mixed-race (Coloured) men who worked at some time between 1970 and 1975 in crocidolite and amosite asbestos mines and mills in South Africa. Their chest X-rays had been read for pleural and parenchymal (lung tissue) abnormality. The authors reported that a computer program error had made the average fibre concentrations in the original paper 3.7 times too low. They stated that this did not affect their conclusions about pleural abnormality, which had not been related to average fibre concentration, but it did affect the original results on parenchymal abnormality. They reanalysed those data using corrected categories of up to 20, 20.01 to 50, and more than 50 short fibres per millilitre. Age, years of asbestos exposure and average short fibre concentration were each independently and significantly associated with parenchymal abnormality. Among men with more than 15 years of exposure at more than 50 short fibres per millilitre, 13 of 38 (34.2%) had parenchymal abnormality. A new analysis of long fibres (longer than 5 micrometres) showed a similar pattern.

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: Erratum (published correction) with reanalysis of data from the authors' earlier X-ray prevalence study
• Who was studied: All white and mixed-race (Coloured) miners employed at some time between 1970 and 1975 in crocidolite and amosite asbestos mines and mills in South Africa (the population of the authors' 1979 study)
• Exposure: Work in crocidolite and amosite mines and mills. The measures were years of asbestos exposure and average fibre concentration (cumulative exposure divided by duration), for short fibres (visible under the light microscope and shorter than 5 micrometres) and long fibres (longer than 5 micrometres)
• Main results:
  • A programming error caused a 3.7-fold proportional underestimation of the average fibre concentration in the original paper.
  • The original categories for short fibre concentration should be corrected by multiplying by 3.7. For example, 'less than 10 short fibres/ml' should read 'less than 37 short fibres/ml'.
  • In the reanalysis, age, duration of asbestos exposure and average short fibre concentration were each independently and highly significantly associated with the prevalence of parenchymal abnormality. For short fibre concentration, the partial chi-square was 12.6 on 2 degrees of freedom, with a probability of 0.0018.
  • A similar result was obtained when duration of exposure and short fibre concentration were used as continuous variables in a logistic regression.
  • Among men with more than 15 years of asbestos exposure at more than 50 short fibres per ml, 13 of 38 (34.2%) had parenchymal abnormality, an excess prevalence of 27.1%.
  • A new analysis of average long fibre concentration showed a pattern similar to that for short fibres. For long fibre concentration, the partial chi-square was 6.1 on 2 degrees of freedom, with a probability of 0.0485.
• The authors' conclusion: The authors stated that the error did not affect any of their conclusions about pleural abnormality, because pleural abnormality had not been related to average fibre concentration. The error did affect the original information on fibre concentration and parenchymal abnormality (Table 7 and Figure 7 of the 1979 paper).

Topics

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

Medical terms in this study, explained in our Lexicon: Crocidolite, Amosite.

Related studies

• Risk of asbestosis in crocidolite and amosite mines in South Africa — L.M. Irwig, R.S. du Toit, et al. (1979)
• Excess mortality from stomach cancer, lung cancer, and asbestosis and/or mesothelioma in crocidolite mining districts in South Africa — J.L. Botha, L.M. Irwig, et al. (1986)
• Re: "Excess mortality from stomach cancer, lung cancer, and asbestosis and/or mesothelioma in crocidolite mining districts in South Africa" — H.P. Hart (1987)
• Health effects of amosite mining and milling in South Africa — J. Murray, G. Nelson (2008)
• The mortality of amphibole miners in South Africa, 1946-80 — G.K. Sluis-Cremer, F.D. Liddell, et al. (1992)
• Asbestosis in South Africa--certain geographical and environmental considerations — G.K. Sluis-Cremer (1965)

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