Asbestosis and mesothelioma among British asbestos workers (1971-2005)

Our plain-English summary of Asbestosis and mesothelioma among British asbestos workers (1971-2005), by A.H. Harding, A.J. Darnton (American Journal of Industrial Medicine, 2010).

The study

• Authors: A.H. Harding, A.J. Darnton
• Journal: American Journal of Industrial Medicine
• Published: 2010;53(11):1070-80
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Ascertainment of asbestosis and mesothelioma from underlying cause of death underestimates the burden of these diseases. The aims of this study were to estimate the true frequency of asbestosis and mesothelioma among asbestos workers in Great Britain (GB), and to identify factors associated with the risk of death with these diseases.

Methods: The GB Asbestos Survey was established in 1971 to monitor long-term health outcomes among workers covered by regulations to control asbestos at work. Asbestosis and mesothelioma cases were defined by multiple cause of death, and were ascertained by identifying asbestos workers on the GB Asbestosis and Mesothelioma Registers. Standardized mortality ratios (SMRs) were calculated; the risks of asbestosis and mesothelioma were modeled with Poisson regression analysis. Deaths to the end of 2005 were included.

Results: There were 15,557 deaths between 1971 and 2005 among the 98,912 workers. Altogether 477 asbestosis and 649 mesothelioma cases were identified. The SMR for all causes was 1.42, for asbestosis 51.3, and for mesothelioma 13.5. In multiply adjusted analysis, age, sex, job, and birth cohort were significantly associated with asbestosis and mesothelioma. For asbestosis year of first exposure, and for mesothelioma latency, were also statistically significant.

Conclusions: The asbestos workers experienced high mortality from all causes, asbestosis, and mesothelioma. There was some evidence that the risk of asbestosis and mesothelioma was lower in later birth cohorts and among those first occupationally exposed to asbestos more recently. Due to the long latency of both diseases, further follow-up is required to confirm these trends.

© 2010 Wiley-Liss, Inc.

In plain English

This study followed 98,912 workers in the Great Britain Asbestos Survey, recruited from 1971 mainly in asbestos products manufacturing and later in removal, insulation and other work. The authors linked survey records to national registers of deaths mentioning asbestosis or mesothelioma anywhere on the death certificate, through 2005. Detailed exposure information was not collected, and these workers' fiber types were not reported. Of 15,557 deaths, 477 mentioned asbestosis and 649 mesothelioma. Compared with national rates, standardized mortality ratios were 1.42 (95% CI 1.39 to 1.44) for all causes, 51.3 (46.8 to 56.1) for deaths with asbestosis and 13.5 (12.5 to 14.6) for deaths with mesothelioma. Underlying cause of death alone identified only 24% of asbestosis and 61% of mesothelioma cases. Insulation workers had the highest risks of both diseases, compared with manufacturing workers. Smoking was associated with asbestosis but not mesothelioma. Risk was lower in later birth cohorts for both diseases and, for asbestosis, among those first exposed more recently; the authors called this some evidence. They concluded this may reflect improved exposure controls, but longer follow-up is needed to confirm it.

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: Cohort mortality study (GB Asbestos Survey) with record linkage to the national Asbestosis and Mesothelioma Registers; standardized mortality ratios and Poisson regression
• Who was studied: Asbestos workers in Great Britain taking part in the GB Asbestos Survey, 1971 to 2005: 98,912 workers in the mesothelioma analysis and 98,510 in the asbestosis analysis. Nearly 5% were women, and the median age at entry was 33. Asbestosis deaths were observed only for 1978 to 2005.
• Exposure: Occupational asbestos exposure, grouped by the main job type: manufacturing, stripping/removal, 'other exposed' (shipbuilding, construction, miscellaneous) and insulation work. The article does not report fiber types or exposure measurements for this cohort. Fiber types appear only in references to other studies.
• Main results:
  • Among all workers, 477 deaths had asbestosis recorded on the death certificate, but only 116 of these had asbestosis as the underlying cause.
  • Using the underlying cause of death alone identified only 24% of the workers with asbestosis and 61% of the workers with mesothelioma found through the registers.
  • Compared with the GB population, the asbestos workers had an SMR of 1.42 (95% CI 1.39 to 1.44) for all causes of death, 51.3 (95% CI 46.8 to 56.1) for deaths with asbestosis, and 13.5 (95% CI 12.5 to 14.6) for deaths with mesothelioma.
  • Women in the cohort had higher SMRs than men.
  • Adjusted for age and sex, insulation workers had the highest relative risks compared with manufacturing workers: asbestosis RR 8.22 (95% CI 6.56 to 10.3) and mesothelioma RR 4.03 (95% CI 3.26 to 4.99). Removal workers came next: asbestosis RR 1.72 (95% CI 1.32 to 2.24) and mesothelioma RR 1.92 (95% CI 1.58 to 2.34).
  • For asbestosis, adjusted for age and sex and compared with current smokers, former smokers had RR 0.73 (95% CI 0.60 to 0.90) and never smokers had RR 0.23 (95% CI 0.15 to 0.34).
  • Smoking status was not associated with the relative risk of mesothelioma.
  • Compared with less than 10 years since last exposure, asbestosis risk was RR 0.76 (95% CI 0.62 to 0.93) at 10 to 19 years and RR 0.68 (95% CI 0.51 to 0.92) at 20 to 29 years.
  • For mesothelioma there was little evidence that risk fell with time since last exposure.
  • Mesothelioma risk peaked at 40 to 59 years after first exposure.
  • The final adjusted asbestosis model included age, sex, smoking status, main job, birth cohort and year of first exposure.
  • The final mesothelioma model included age, sex, main job, birth cohort and latency. Year of first exposure was not in this model.
  • In the final adjusted model, asbestosis risk was 87% lower for workers first exposed in the 1960s than for those first exposed before 1930.
  • The authors described the lower risk in later birth cohorts and among those first exposed more recently as 'some evidence'.
  • Among the 17,799 workers born during the 1940s, 7% of the 1,755 deaths observed so far were due to mesothelioma.
• The authors' conclusion: The authors concluded that the risks of asbestosis and mesothelioma declined among those occupationally exposed in recent times. They said this trend may reflect improved measures to control exposure at work, but that longer follow-up is required to confirm it.
• Limitations the authors state:
  • Detailed exposure information was not collected.
  • Few deaths occurred at the longest latencies (over 60 years), so the apparent fall in mesothelioma risk with very long follow-up cannot be regarded as conclusive.
  • For asbestosis, using the time from first exposure to death as 'latency' is likely to overestimate the true latent period substantially.
  • Of the deaths on the Mesothelioma Register during 1996 to 2005, 91 (29%) were not confirmed by cancer incidence data and may have been misclassified.
  • The Asbestosis Register data have not been compared with pathology or histology data.
  • Death certificates often did not specify the site of the mesothelioma (pleural or peritoneal).

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, standardized mortality ratio (SMR), Latency.

Related studies

• Mortality among British asbestos workers undergoing regular medical examinations (1971-2005) — A.H. Harding, A. Darnton, et al. (2009)
• Cardiovascular disease mortality among British asbestos workers (1971-2005) — A.H. Harding, A. Darnton, et al. (2012)
• The effect of smoking on the risk of lung cancer mortality for asbestos workers in Great Britain (1971-2005) — G. Frost, A. Darnton, et al. (2011)
• Cohort mortality study of pulp and paper mill workers in British Columbia, Canada — P.R. Band, N.D. Le, et al. (1997)
• Prediction of mesothelioma, lung cancer, and asbestosis in former Wittenoom asbestos workers — G. Berry (1991)
• Temporal Patterns of Exposure to Asbestos and Risk of Asbestosis: An Analysis of a Cohort of Asbestos Textile Workers — A. Farioli, F.S. Violante, et al. (2018)

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