Exposure to asbestos: past, present and future

Our plain-English summary of Exposure to asbestos: past, present and future, by E. Pira, F. Donato, L. Maida, et al (Journal of Thoracic Disease, 2018).

The study

• Authors: E. Pira, F. Donato, L. Maida, G. Discalzi
• Journal: Journal of Thoracic Disease
• Published: 2018;10(Suppl 2):S237-S245
• Type of article: Review
• Cited by: 41 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

This paper summarises the past, present and future of asbestos exposure. The future scenarios as to the mesothelioma incidence in countries, where asbestos has been banned, are discussed.

In plain English

This article is a narrative review of the history, current situation and possible future of asbestos exposure. It reported no new data. It drew on historical sources, production figures, exposure limits and earlier studies. Citing International Ban Asbestos Secretariat data, it reported world asbestos production of 2,026,000 tons in 2015, close to the 2,070,000 tons of 2000. Use fell in Europe but rose in Asia, Africa and some Latin-American countries. The review described exposure limits that were drastically reduced over time. It gave approximate workplace fibre levels that fell from above 100 fibres/mL before the 1930s to 1 fibre/mL in the 1980s. Citing earlier work, it noted that new mesothelioma cases rise with time since first exposure even when there is no further exposure. The authors concluded that, because of mesothelioma's long latency, the epidemic could last more than four decades even after a ban. They also said that removing asbestos products still in place should be discussed. Two authors disclosed personal fees from law firms for the defence in asbestos litigation.

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 article; no original study data
• Who was studied: Not a study of a specific population. The review covers asbestos production, use, exposure limits and disease worldwide, including countries that have and have not banned asbestos, with ban information as of July 2017.
• Exposure: Occupational and environmental exposure to asbestos. The fibre types named are chrysotile (serpentine group) and the amphiboles crocidolite, amosite and anthophyllite. Actinolite and tremolite are described as only natural pollutants.
• Main results:
  • Citing International Ban Asbestos Secretariat data, the review reported world asbestos production of 2,026,000 tons in 2015, almost the same as in 2000 (2,070,000 tons).
  • Asbestos use in European countries dropped from 2,500,000 tons in 1990 to 530,000 tons in 2000. At the same time, use increased in non-EU countries, especially China and India, as well as Africa and some Latin-American countries.
  • The exposure limits (threshold limit values) proposed by the American Conference of Governmental Industrial Hygienists were drastically reduced over time as evidence on the cancer-causing effects of asbestos accumulated.
  • The authors gave approximate average workplace fibre concentrations: above 100 fibres/mL before the 1930s, 100 fibres/mL in 1935 to 1950, 20 fibres/mL in the 1960s, 5 fibres/mL in 1975 and 1 fibre/mL in the 1980s.
  • Citing earlier work, the review stated that new mesothelioma cases are proportional to the 3rd or 4th power of time from first exposure, whatever the age at first exposure and even with no further exposure.
  • A previously published pooled analysis of six occupational cohorts and two high environmental exposure cohorts, cited by the review, showed a log-linear relationship between pleural mesothelioma incidence and latency, at least for the first 45 to 50 years. That analysis did not show a correlation between mesothelioma incidence and duration of exposure.
  • In countries that banned asbestos, the review stated that the diseases that declined were mainly asbestosis and lung cancer, which it described as clearly dose-dependent with a relatively short latency.
  • Citing other sources, the review reported risk estimates for the general population. Agencies broadly agreed on a lifetime risk (under 80 years of age) of one additional mesothelioma case per 100,000 people at 1 fibre/litre. The US National Research Council gave a lifetime risk of 15.6 cases per 100,000 at 0.4 fibres/litre.
  • The review described the Helsinki Criteria for identifying people who in all probability had occupational asbestos exposure. Examples include over 0.1 million amphibole fibres longer than 5 µm per gram of dry lung tissue, or over 1,000 asbestos bodies per gram of dry lung tissue.
  • In a WHO table reproduced in the review, airborne asbestos fibres were below 100 fibres per cubic metre in rural areas remote from emission sources. In urban areas, general levels ranged from below 100 to 1,000 fibres per cubic metre.
  • This is a disclosure, not a finding. Two of the authors (E Pira and G Discalzi) reported personal fees from several law firms for the defence in asbestos litigation, outside the submitted work.
• The authors' conclusion: The authors concluded that countries that banned asbestos must manage the residual effects of exposure before the ban, with current mesothelioma cases traceable to occupational exposure in the 1970s to 1980s. In countries without a ban, the mesothelioma epidemic could last more than four decades even if asbestos were banned. They also concluded that public health discussion should cover whether to remove existing asbestos products in place.

Topics

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

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