UK asbestos imports and mortality due to idiopathic pulmonary fibrosis

Our plain-English summary of UK asbestos imports and mortality due to idiopathic pulmonary fibrosis, by C.M. Barber, R.E. Wiggans, C. Young, et al (Occupational Medicine, 2016).

The study

• Authors: C.M. Barber, R.E. Wiggans, C. Young, D. Fishwick
• Journal: Occupational Medicine
• Published: 2016;66(2):106-11
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Previous studies have demonstrated that the rising mortality due to mesothelioma and asbestosis can be predicted from historic asbestos usage. Mortality due to idiopathic pulmonary fibrosis (IPF) is also rising, without any apparent explanation.

Aims: To compare mortality due to these conditions and examine the relationship between mortality and national asbestos imports.

Methods: Mortality data for IPF and asbestosis in England and Wales were available from the Office for National Statistics. Data for mesothelioma deaths in England and Wales and historic UK asbestos import data were available from the Health & Safety Executive. The numbers of annual deaths due to each condition were plotted separately by gender, against UK asbestos imports 48 years earlier. Linear regression models were constructed.

Results: For mesothelioma and IPF, there was a significant linear relationship between the number of male and female deaths each year and historic UK asbestos imports. For asbestosis mortality, a similar relationship was found for male but not female deaths. The annual numbers of deaths due to asbestosis in both sexes were lower than for IPF and mesothelioma.

Conclusions: The strength of the association between IPF mortality and historic asbestos imports was similar to that seen in an established asbestos-related disease, i.e. mesothelioma. This finding could in part be explained by diagnostic difficulties in separating asbestosis from IPF and highlights the need for a more accurate method of assessing lifetime occupational asbestos exposure.

© Crown copyright 2015.

In plain English

This study compared national death counts with historic asbestos imports. The authors took yearly numbers of deaths in England and Wales from idiopathic pulmonary fibrosis (IPF, lung scarring with no identified cause), asbestosis and mesothelioma, separately for men and women. They compared these with total UK imports of chrysotile, amosite and crocidolite 48 years earlier. How closely deaths tracked imports was measured with a statistic called adjusted R2. For mesothelioma it was 0.91 in men and 0.87 in women. For asbestosis it was 0.76 in men, with no significant relationship in women, who had very few asbestosis deaths. For IPF it was 0.92 in men and 0.93 in women. The authors stated that this relationship cannot establish causation and may be entirely coincidental. They concluded that it raises the question of whether some IPF deaths are in fact due to unrecognized asbestos exposure. They noted limits in the data: the import figures were crude UK totals that could not show whether asbestos was used or stored, and the 48-year lag was taken from a US model.

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-level comparison of national death statistics with historic national asbestos import figures, using correlation and linear regression
• Who was studied: Annual numbers of male and female deaths in England and Wales: IPF (1962 to 2012) and asbestosis (1967 to 2012) as the underlying cause, from the Office for National Statistics. Mesothelioma deaths (1968 to 2012, any mention on the death certificate) came from the Health & Safety Executive.
• Exposure: Total yearly UK imports of chrysotile, amosite and crocidolite, 1914 to 1965, in hundreds of tonnes. These were compared with deaths 48 years later, a latent period taken from a previous US asbestosis model.
• Main results:
  • Mesothelioma deaths showed a significant linear relationship with imports 48 years earlier in both men (adjusted R2 0.91, P less than 0.001) and women (adjusted R2 0.87, P less than 0.001). Asbestosis deaths showed a significant relationship in men (adjusted R2 0.76, P less than 0.001) (Table 1).
  • There was no significant relationship between imports and asbestosis deaths in women (adjusted R2 0.00), who had very low numbers of asbestosis deaths each year.
  • IPF deaths were also significantly related to imports 48 years earlier in men (adjusted R2 0.92, P less than 0.001) and women (adjusted R2 0.93, P less than 0.001) (Table 1).
  • Yearly deaths from mesothelioma and from IPF rose together. The Pearson correlation coefficient was 0.98 for men and 0.97 for women (both P less than 0.001).
  • The ratio of asbestosis deaths to IPF deaths stayed fairly constant in men, at about 1:16 in 1967 and 1:13 in 2012.
  • In women, the ratio of asbestosis deaths to IPF deaths went from about 1:38 in 1967 to 1:381 in 2012.
  • In women, yearly IPF deaths were consistently higher than mesothelioma deaths.
• The authors' conclusion: The authors concluded that the link between IPF deaths and historic asbestos imports raises the question of whether a proportion of IPF deaths are in fact due to unrecognized asbestos exposure. They also called for a British asbestos job-exposure matrix to aid diagnosis.
• Limitations the authors state:
  • The relationship cannot establish causation and may be entirely coincidental.
  • Total UK imports were used because figures for England and Wales alone were not available.
  • The import estimate was crude: total tonnage rather than per head, with no allowance for whether imported asbestos was used or stored, or for exposure to existing asbestos products.
  • The 48-year latent period was taken from a US asbestosis model rather than chosen to best fit this study's data.

Topics

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

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

Related studies

• Idiopathic pulmonary fibrosis and asbestos use — C.M. Barber, D. Fishwick (2019)
• Estimating Lifetime Asbestos Exposure in Patients With Idiopathic Pulmonary Fibrosis — C.M. Barber, R.E. Wiggans, et al. (2016)
• Occupational exposures and idiopathic pulmonary fibrosis — G.I. Walters (2020)
• Smoking, occupational exposures, and idiopathic pulmonary fibrosis among Swedish construction workers — M. Andersson, P.D. Blanc, et al. (2021)
• Occupational and environmental risk factors for idiopathic pulmonary fibrosis in Australia: case-control study — M.J. Abramson, T. Murambadoro, et al. (2020)
• Radiological characteristics, histological features and clinical outcomes of lung cancer patients with coexistent idiopathic pulmonary fibrosis — K.A. Khan, M.P. Kennedy, et al. (2015)

Browse more research in Occupational Medicine, or return to medical research.