Mortality among British asbestos workers

Our plain-English summary of Mortality among British asbestos workers, by B. Sjögren (Occupational and Environmental Medicine, 2009).

The study

• Author: B. Sjögren
• Journal: Occupational and Environmental Medicine
• Published: 2009;66(12):854-5
• Type of article: Letter, Comment
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

In this letter, the author responded to a study by Harding and coworkers of 98 117 British asbestos workers followed for 1 779 580 person-years. That study found increased mortality from ischaemic heart disease (IHD), with an SMR of 1.40 (95% CI 1.36 to 1.44) and 4183 IHD deaths among 15 496 deaths in total. The author noted that factors such as length of exposure, latency, smoking status and main job category had been taken into account for several cancers, asbestosis and cerebrovascular disease, but IHD was not analysed further. He argued for closer study. He cited evidence that particulate air pollution is associated with cardiovascular hospital admissions and deaths, possibly with no threshold. He stated that whether inhaled asbestos fibres cause IHD is an unsolved question. He then summarised earlier studies. These reported increased circulatory or IHD mortality among US chrysotile textile workers (SMR 1.20, 95% CI 1.10 to 1.32), US asbestos company retirees, Italian chrysotile miners (SMR 1.48) and more heavily exposed Quebec miners and millers. Other studies linked pleural changes or plaques with heart disease. Swedish shipyard workers with asbestosis or suspected asbestosis had a higher risk of IHD death (RR 3.1, 95% CI 1.5 to 6.4). He cited raised inflammatory markers in patients with asbestosis. He proposed that inhaled particles cause low-grade inflammation and increased clotting agents, raising IHD risk. He encouraged the original authors to examine asbestos exposure and IHD in internal analyses.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This is a letter to the editor, not an original study. The author responded to a study by Anne-Helen Harding and coworkers of 98 117 British asbestos workers. That study had reported more deaths than expected from ischaemic heart disease (IHD), with a standardised mortality ratio of 1.40 (95% CI 1.36 to 1.44), based on 4183 IHD deaths among 15 496 deaths. The author noted that IHD, unlike several cancers, asbestosis and cerebrovascular disease, was not analysed further in that study. The author called the question of whether inhaled asbestos fibres can cause IHD unsolved and reviewed earlier research. Several worker studies found raised heart disease deaths, though the author called their comparisons with the total population biased. One textile factory cohort found a small increase that was not statistically significant. Among Swedish shipyard workers, men with asbestosis or suspected asbestosis had a relative risk of IHD death of 3.1 (95% CI 1.5 to 6.4) compared with men without asbestosis. The author proposed that low-grade lung inflammation might raise clotting risk and hoped Harding and coworkers would explore the link further.

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: Letter to the editor (commentary reviewing earlier published studies); no new data
• Who was studied: No population studied by the author. The letter commented on Harding and coworkers' cohort of 98 117 British asbestos workers followed for 1 779 580 person-years, and cited other published cohorts.
• Exposure: Inhaled asbestos fibres (including chrysotile and crocidolite in cited cohorts) in relation to ischaemic heart disease; particulate air pollution was discussed for comparison
• Main results:
  • Harding and coworkers' study (not this letter) reported increased IHD mortality among British asbestos workers: SMR 1.40 (95% CI 1.36 to 1.44), with 4183 IHD deaths out of 15 496 total deaths
  • The author pointed out that IHD was not analysed further in Harding and coworkers' study, unlike several cancers, asbestosis and cerebrovascular disease
  • The author cited several earlier studies showing a relationship between asbestos exposure and IHD, some between pleural plaques and IHD, and one between asbestosis and IHD
  • Cited study: in an expanded cohort of 3072 US chrysotile textile workers followed through 2001, an increased risk of IHD was reported (SMR 1.20, 95% CI 1.10 to 1.32)
  • Cited study: in a cohort of 3211 men at a Rockdale asbestos textile factory, a small but not statistically significant increase in circulatory disease deaths was reported
  • Cited study: among 1725 Swedish male shipyard workers, men with asbestosis or suspected asbestosis had a relative risk of dying from IHD of 3.1 (95% CI 1.5 to 6.4) compared with men without asbestosis, after stratification for age and smoking. Men with pleural plaques had a relative risk of 1.3 (95% CI 0.8 to 2.0).
  • Cited study: non-smoking asbestosis patients had significantly higher serum levels of the inflammatory markers C reactive protein and interleukin-6 than healthy controls. The author linked this to a hypothesis that low-grade lung inflammation raises clotting agents and the risk of IHD.
• The authors' conclusion: The author hoped these arguments would encourage Harding and coworkers to explore further, through internal analysis, the relationship between asbestos exposure and IHD
• Limitations the authors state:
  • The author noted that the earlier studies linking asbestos exposure and IHD relied on a biased comparison with the total population

Topics

Medical terms in this study, explained in our Lexicon: Latency, Chrysotile, Inflammation, Asbestos Exposure.

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)
• Occupational exposure to particulate air pollution and mortality due to ischaemic heart disease and cerebrovascular disease — K. Torén, I.A. Bergdahl, et al. (2007)
• Mortality among U.S. military participants at eight aboveground nuclear weapons test series — J.D. Boice, S.S. Cohen, et al. (2022)
• Occupational exposure to dust: inflammation and ischaemic heart disease — B. Sjögren (1997)
• Cohort mortality study of pulp and paper mill workers in British Columbia, Canada — P.R. Band, N.D. Le, et al. (1997)

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