A Review of the Literature on Dose-Response Relationships for Non-Malignant Asbestos-Related Diseases

Our plain-English summary of A Review of the Literature on Dose-Response Relationships for Non-Malignant Asbestos-Related Diseases, by G.K. Sluis-Cremer (1978).

The study

• Author: G.K. Sluis-Cremer
• Published: Proceedings of Asbestos Symposium, Johannesburg October 3-7. Published by the National Institute for Metallurgy p.49-64 (1978)
• Type of article: Conference paper
• 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 paper was a review of published research on how the amount of asbestos exposure relates to non-malignant asbestos diseases. It was presented at a 1977 symposium in Johannesburg. The author examined three ways of measuring a response: crackling lung sounds (crepitations), chest X-ray changes, and loss of lung function. The paper also discussed pleural changes and autopsy findings. The reviewed studies covered workers exposed to chrysotile, crocidolite, amosite and mixtures of fibres. The author noted that not everyone with X-ray signs of asbestosis had crepitations. At the Medical Bureau for Occupational Diseases, Johannesburg, 27 out of 64 people with parenchymal asbestosis (42 per cent) had them. The studies had measured exposure in different ways, which made comparison difficult. Routine autopsies of Black asbestos miners showed a fall in asbestosis over 18 years, but some workers still had asbestosis that X-rays had not shown. The author concluded that no single measure identified all cases, that a combined index would be ideal, and that there was no definitive evidence that some fibre types cause more scarring than others. A record of discussion by other speakers followed the paper.

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: Literature review, with some data from the author's own institutions in South Africa (Medical Bureau examinations and autopsy records); followed by a record of symposium discussion by other participants
• Who was studied: Published studies of asbestos-exposed worker populations, including chrysotile miners and millers in Quebec, Cyprus and Italy (Balangero), U.S. insulation workers, British naval-dockyard workers, asbestos-cement workers near Turin and New Orleans, and South African amphibole-exposed workers; plus people examined at the Medical Bureau for Occupational Diseases, Johannesburg, and autopsies of Black asbestos miners in the Northern Transvaal and North-western Cape
• Exposure: Occupational asbestos dust: pure chrysotile (Quebec, Cyprus, Italy), pure crocidolite and amosite (South Africa), and mixed exposures in other studies; exposure measured variously in particle counts, fibre counts or dust mass
• Main results:
  • The reviewed literature showed that not everyone with X-ray changes of asbestosis, even advanced asbestosis, had crepitations
  • Among persons with parenchymal asbestosis who had Benefit Examinations at the Medical Bureau for Occupational Diseases, Johannesburg, over the past year, 27 out of 64 (42 per cent) had crepitations
  • In the same Medical Bureau examinations, crepitations were found in 16 per cent of those with pleural change only
  • Comparison between radiological studies was hampered because dust exposures had been calculated in different ways
  • The author considered that, for epidemiological purposes, both rounded and irregular X-ray opacities should be regarded as responses to asbestos
  • The author reported that a deficit in lung function may occur in asbestos-exposed persons before X-ray change can be detected
  • At routine autopsy of Black asbestos miners, the prevalence of total and slight asbestosis fell over the last 18 years as dust counts improved (North-western Cape total asbestosis: 71,5 per cent of 87 in 1959 to 1964, and 40 per cent of 108 in 1975 to 1977, as printed in Table 1)
  • An important proportion of these workers still had asbestosis that X-rays had not shown and that was first found at autopsy
• The authors' conclusion: The authors concluded that none of the major measures (crepitations, radiological change, lung function) can identify all cases of asbestosis, and that crepitations alone are inappropriate for defining dose-response. They considered that the ideal approach would be a combined index of the three measures. They also concluded that there is at present no definitive evidence of differences in fibrogenicity (ability to cause lung scarring) between fibre varieties.
• Limitations the authors state:
  • Radiology is inaccurate for estimating a worker's response to asbestos during life, as shown by asbestosis first found at autopsy
  • The significance of the many cases of slight asbestosis found at post-mortem is unknown, including whether they would progress if exposure ceased
  • The author could not find the full publication of one study (Regan et al.) on fibre-type differences despite a thorough search

Topics

Medical terms in this study, explained in our Lexicon: Dose-response relationship, Asbestos Exposure, Chest X-Ray, Autopsy, Chrysotile, Crocidolite, Amosite, Occupational Disease.

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