Emerging evidence that the ban on asbestos use is reducing the occurrence of pleural mesothelioma in Sweden

Our plain-English summary of Emerging evidence that the ban on asbestos use is reducing the occurrence of pleural mesothelioma in Sweden, by B. Järvholm, A. Burdorf (Scandinavian Journal of Public Health, 2015).

The study

• Authors: B. Järvholm, A. Burdorf
• Journal: Scandinavian Journal of Public Health
• Published: 2015;43(8):875-81
• Cited by: 46 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Aims: Several countries have banned the use of asbestos. The future health impacts of previous use have been modeled but there are to our knowledge no convincing studies showing a decreased occurrence of asbestos-related diseases due to a ban. The aim of our study was to estimate the effects of the ban and other measures to decrease the use of asbestos in Sweden.

Methods: The effect was measured through comparing the incidence of pleural malignant mesothelioma in birth cohorts who started to work before and after the decrease in the use of asbestos, i.e. in mid-1970s. Cases were identified through the Swedish Cancer Registry and the analysis was restricted to persons born in Sweden.

Results: Men and women born 1955-79 had a decreased risk of malignant pleural mesothelioma compared to men and women born 1940-49 (RR 0.16, 95% CI 0.11-0.25; and RR 0.47, 95% CI 0.23-0.97 respectively). The decreased use of asbestos prevented each year about 10 cases in men and two cases in women below the age of 57 years in 2012.

Conclusions: The ban and decreased use of asbestos in Sweden can be measured today in birth cohorts that started their working career after the decrease.

© 2015 the Nordic Societies of Public Health.

In plain English

The authors used the national Swedish Cancer Register to examine whether Sweden's cut in asbestos use from the mid-1970s, and its 1982 ban, reduced malignant pleural mesothelioma. They compared people born in Sweden in birth cohorts who started work before and after asbestos imports fell sharply. Most of the imported asbestos was chrysotile. The total number of new cases each year had been fairly stable since 1995. Compared with people born 1940–49, men born 1955–79 had a relative risk of 0.16 (95% CI 0.11–0.25), and women born 1955–79 had a relative risk of 0.47 (95% CI 0.23–0.97). Through 2012, 35 cases were observed among people born 1955–79, against 155.6 expected if they had the same age-specific risk as the 1940s cohorts. The authors estimated that about 12 cases a year (about 10 in men and two in women) at ages up to 57 were avoided in 2008–2012. They concluded that the effect of the ban can now be measured in cohorts who began working after the decrease. They noted that the estimate covered only pleural mesothelioma and assumed similar ages at first exposure across cohorts.

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: Population-based registry analysis comparing incidence of pleural malignant mesothelioma by birth cohort, with observed versus expected cases and Poisson regression
• Who was studied: Cases of pleural malignant mesothelioma reported to the Swedish Cancer Register, with data until 2012. The analysis was restricted to persons born in Sweden, and the main comparison was between the 1940–49 and 1955–79 birth cohorts.
• Exposure: National asbestos use, estimated from imports of raw asbestos (mostly chrysotile). Asbestos spraying was prohibited in 1973 and crocidolite was banned in 1975. A construction industry agreement led to a sharp decline in 1976, asbestos was banned in most activities in 1982, and a total ban followed in 1986. Individual exposure was not measured; birth cohort served as the marker of starting work before or after the decrease.
• Main results:
  • Overall age-adjusted incidence for 1995–2013 decreased slightly in men (APC −1.3%) but not in women (APC 0.6%).
  • The highest incidences were among people born 1935–49, and later-born cohorts showed lower incidence.
  • Compared with people born 1940–49, the relative risk for people born 1955–79 was 0.16 (95% CI 0.11–0.25) in men and 0.47 (95% CI 0.23–0.97) in women.
  • Through 2012, the observed and expected cases among those born 1955–79 were: men 23 observed vs 131.0 expected; women 12 vs 24.6; total 35 vs 155.6. That is about 121 fewer cases than expected.
  • The gap between expected and observed cases was 1.7 in 1988–92 and 62.7 in 2008–2012, which is about 12 cases per year in the latter period (about 10 in men and two in women).
  • Men compared with women: relative risk 7.55 (95% CI 5.78–9.86) in the 1940–49 cohort and 1.91 (95% CI 0.98–3.72) in the 1955–79 cohort.
  • Fewer than 10% of cases were among persons not born in Sweden, and these cases occurred mostly toward the end of the observation period.
• The authors' conclusion: The authors concluded that the effect of the ban and the decreased use of asbestos in Sweden can now be measured in birth cohorts that started their working careers after the decrease.
• Limitations the authors state:
  • The analysis assumes that people in each birth cohort, on average, started exposure at similar ages.
  • The full effect of the ban cannot yet be evaluated, because that requires cohorts who started work in the 1990s.
  • The impact estimate covers only pleural malignant mesothelioma, not other asbestos-related diseases.
  • The analysis was restricted to people born in Sweden; immigrants with different exposure patterns could cause some bias.
  • Effects of the ban on environmental exposure are harder to evaluate because the numbers are small.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Malignant Mesothelioma, Cancer Registry.

Related studies

• The risk of lung cancer after cessation of asbestos exposure in construction workers using pleural malignant mesothelioma as a marker of exposure — B. Järvholm, E. Aström (2014)
• Pleural mesothelioma in Sweden: an analysis of the incidence according to the use of asbestos — B. Järvholm, A. Englund, et al. (1999)
• Smoking, occupational exposures, and idiopathic pulmonary fibrosis among Swedish construction workers — M. Andersson, P.D. Blanc, et al. (2021)
• The impact of asbestos exposure in Swedish construction workers — B. Järvholm, A. Englund (2014)
• Incidence and familial risk of pleural mesothelioma in Sweden: a national cohort study — J. Ji, J. Sundquist, et al. (2016)
• Explaining differences in incidence rates of pleural mesothelioma between Sweden and the Netherlands — A. Burdorf, B. Järvholm, et al. (2005)

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