Asbestos lung fibre analysis in the United Kingdom, 1976-96

Our plain-English summary of Asbestos lung fibre analysis in the United Kingdom, 1976-96, by G. Berry (The Annals of Occupational Hygiene, 2002).

The study

• Author: G. Berry
• Journal: The Annals of Occupational Hygiene
• Published: 2002;46(6):523-6
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: To summarize data on changes in lung contents of asbestos types between 1976-77 and 1990-96 for mesotheliomas and controls in the UK.

Methods: Data were extracted from published studies of the years 1976, 1977 and 1990-96.

Results: Between 1976-77 and 1990-96 there was a large reduction in the amount of crocidolite in the lungs of both mesotheliomas and controls.

Conclusion: The results are consistent with the use of the different asbestos types in the UK, after taking into account the period of exposure and elimination of fibres from the lung in the time elapsed since exposure.

In plain English

The author combined data from three earlier UK studies that measured asbestos fibres in lung tissue. The 1976 study had 86 mesothelioma cases and 56 controls, the 1977 study had 170 cases and 94 controls, and the 1990–96 study had 69 men aged 36 to 52 with mesothelioma and 57 controls. All three used the same electron microscope method. In mesothelioma cases, median crocidolite fell to 0.2 fibres per microgram of dry tissue in 1990–96, from 1.6 in 1976 and 6.3 in 1977, a highly significant difference. Crocidolite was also lower in controls. Amosite showed no significant differences. Chrysotile was lower in 1990–96, but the 1976 and 1977 studies also differed significantly from each other, which the author said weakens that finding. In every study, cases had at least an order of magnitude more crocidolite and amosite than controls, while chrysotile was similar. The author concluded the results were consistent with UK use of the different asbestos types, allowing for timing of exposure and clearance of fibres from the lung. The author cautioned that the studies selected cases and controls differently.

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: Analysis of data extracted from three previously published UK lung fibre studies (1976, 1977 and 1990–96), comparing the later study with the two earlier ones using trend chi-squared tests
• Who was studied: UK mesothelioma cases and controls whose lung tissue was analysed. 1976: 86 mesotheliomas and 56 controls. 1977: 170 mesotheliomas (145 from Pneumoconiosis Medical Panels, all men, plus 25 from pathologists) and 94 controls from hospital necropsies. 1990–96: 69 men born 1943 or later, aged 36–52, with malignant mesothelioma reported to the SWORD scheme, and 57 controls in the same age range.
• Exposure: Lung content of crocidolite, amosite and chrysotile fibres, measured by analytical transmission electron microscope with energy dispersive X-ray analysis and expressed as fibres per microgram of dry lung tissue
• Main results:
  • Mesothelioma cases, crocidolite: median lung content was 0.2 fibres/µg dry tissue in 1990–96, compared with 1.6 in 1976 and 6.3 in 1977. The difference between 1976 + 1977 and 1990–96 was highly significant (chi-squared 56.31, 1 df, P less than 0.001). The difference between 1976 and 1977 was not significant (P = 0.08).
  • Controls, crocidolite: the difference between 1976 + 1977 and 1990–96 was highly significant (chi-squared 20.04, 1 df, P less than 0.001). The difference between 1976 and 1977 was marginally significant (P = 0.04). There was less crocidolite in 1990–96.
  • Amosite: there were no significant differences between surveys in either mesotheliomas or controls. Median contents in mesotheliomas were 0.9, 0.9 and 2.3 fibres/µg for 1990–96, 1976 and 1977, respectively.
  • Chrysotile: lung content was significantly lower in 1990–96 than in 1976 + 1977 for both mesotheliomas and controls. Because 1976 and 1977 also differed highly significantly from each other, the author considered this reduction attenuated. Median contents in mesotheliomas were 0.6, 0.6 and 4.5 fibres/µg for 1990–96, 1976 and 1977.
  • In each of the three studies, mesothelioma cases had more crocidolite and amosite in their lungs than controls by at least an order of magnitude. Chrysotile amounts were similar in cases and controls.
• The authors' conclusion: The author concluded that the results are consistent with the use of the different asbestos types in the UK, after taking into account the period of exposure and the elimination of fibres from the lung in the time since exposure.
• Limitations the authors state:
  • Cases and controls were selected differently in each survey, so significant differences between years cannot necessarily be ascribed to year.
  • There was limited information on when exposure occurred for the 1976 + 1977 cases, so the author's calculation of exposure duration and fibre elimination could only be illustrative.
  • The lower chrysotile content in controls in 1990–96 is of unclear significance, because 1976 and 1977 also differed significantly.

Topics

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

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