Clinical aspects of asbestos-related diseases--what are the unresolved topics?

Our plain-English summary of Clinical aspects of asbestos-related diseases--what are the unresolved topics?, by D.E. Banks (Journal of Occupational and Environmental Medicine, 2014).

The study

• Author: D.E. Banks
• Journal: Journal of Occupational and Environmental Medicine
• Published: 2014;56 Suppl 10:S8-S12
• Type of article: Review
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: Despite awareness of the health risks associated with asbestos fiber inhalation and the decline in U.S. utilization (about 0.1% of the yearly peak amount), illnesses associated with exposure persist. Those with disease typically describe excessive exposures in the remote past, yet excessive exposures can occur today, most likely related to careless asbestos abatement procedures. The intent is to address unanswered questions associated with asbestos exposure.

Methods: The author summarizes clinical information addressing the case definition of asbestosis, the world-wide rate of mesothelioma, and clinical follow-up for those with exposure.

Results: The author describes information relevant to issues which remain unresolved.

Conclusion: Perhaps somewhat surprisingly, even though there have been a great number of manuscripts reporting on the health risks of asbestos exposure, there remain unanswered questions regarding the pathogenesis of this disease.

In plain English

This article was a narrative review by a single author, not a new study. The author summarized published information on unresolved clinical questions about asbestos: how asbestosis is defined, worldwide mesothelioma rates, and lung cancer screening of exposed workers. The author described a meta-analysis by other researchers. It estimated that, for fibers 10 μm or longer, the mesothelioma risk from chrysotile was between 0 and 1/200th that of crocidolite. On asbestosis, the author wrote that there is no absolute value for a "sufficient exposure and latency period." The author cited a review of mesothelioma deaths in 31 countries that showed no clear-cut decline in 2005 data compared with 1996. Another cited report suggested that global mesothelioma incidence had been underestimated by approximately 20%. The author noted that a large trial of low-dose CT lung cancer screening in heavy smokers did not address asbestos. The author also noted that no evidence-based guidelines for lung cancer screening using low-dose CT take asbestos exposure into account. The author concluded that unanswered questions remain and that the current US exposure limit appears to protect workers.

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: Narrative review / commentary summarizing published studies; no new data were collected
• Who was studied: No study population of its own; the author reviewed published studies of asbestos-exposed workers, national mesothelioma mortality data, and lung cancer screening trials
• Exposure: Asbestos in general, with discussion of amphibole fibers (most often crocidolite; also amosite) versus chrysotile, fiber length and width, and changes over time in US OSHA permissible exposure limits
• Main results:
  • A meta-analysis by Berman et al, described by the author, estimated that for fibers 10 μm or longer the mesothelioma risk from chrysotile was between 0 and 1/200th that of crocidolite
  • The author wrote that there is no absolute value for the "sufficient exposure and latency period" needed for asbestosis. The author cited the 1997 Helsinki Criteria as requiring a latency of at least 10 years.
  • A cited review of 2005 data showed no clear-cut decline in mesothelioma death rates in 31 countries compared with 1996. Rates increased in seven countries (statistically significantly in five), were equivocal in 24, and did not change in the US.
  • More recent information cited by the author suggested that, based on asbestos usage up to 1970, global mesothelioma incidence had been underestimated by approximately 20%
  • US asbestos use fell from 803,000 metric tons in 1973 to an estimated 1060 metric tons in 2012
  • In a cited 2009 follow-up of 2181 sheet-metal workers, 5.3% had radiographic changes consistent with asbestosis. No worker who began employment after 1970 had parenchymal interstitial fibrosis.
  • In the National Lung Screening Trial of heavy smokers, low-dose CT reduced the risk of dying from lung cancer by approximately 20%, with an absolute risk reduction of 0.33%. The trial did not address asbestos-attributable cancer risk.
  • The author stated that there are no evidence-based guidelines for lung cancer screening with low-dose CT that take asbestos exposure into consideration
• The authors' conclusion: The author concluded that, despite many published papers, unanswered questions remain about asbestos-related disease. The author wrote that the current permissible exposure limit appears to protect the worker, and that low-dose CT screening may lessen lung cancer mortality in asbestos-exposed people.
• Limitations the authors state:
  • The author noted that the cross-sectional asbestosis studies compared across decades in Figure 1 may not be entirely comparable because of different follow-up periods
  • Not all of the unanswered questions listed in Table 1 were discussed in the report

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: Abatement, Asbestos Exposure, Mesothelioma.

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