Past and current asbestos exposure and future mesothelioma risks in Britain: The Inhaled Particles Study (TIPS)

Our plain-English summary of Past and current asbestos exposure and future mesothelioma risks in Britain: The Inhaled Particles Study (TIPS), by C. Gilham, C. Rake, J. Hodgson, et al (International Journal of Epidemiology, 2018).

The study

• Authors: C. Gilham, C. Rake, J. Hodgson, A. Darnton, G. Burdett, J. Peto Wild, M. Newton, A.G. Nicholson, L. Davidson, M. Shires, T. Treasure, J. Peto, TIPS Collaboration
• Journal: International Journal of Epidemiology
• Published: 2018;47(6):1745-1756
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Occupational and environmental airborne asbestos concentrations are too low and variable for lifetime exposures to be estimated reliably, and building workers and occupants may suffer higher exposure when asbestos in older buildings is disturbed or removed. Mesothelioma risks from current asbestos exposures are therefore not known.

Methods: We interviewed and measured asbestos levels in lung samples from 257 patients treated for pneumothorax and 262 with resected lung cancer, recruited in England and Wales. Average lung burdens in British birth cohorts from 1940 to 1992 were estimated for asbestos-exposed workers and the general population.

Results: Regression analysis of British mesothelioma death rates and average lung burdens in birth cohorts born before 1965 suggests a lifetime mesothelioma risk of approximately 0.01% per fibre/mg of amphiboles in the lung. In those born since 1965, the average lung burden is ∼1 fibre/mg among those with no occupational exposure.

Conclusions: The average lifetime mesothelioma risk caused by recent environmental asbestos exposure in Britain will be about 1 in 10 000. The risk is an order of magnitude higher in a subgroup of exposed workers and probably in occupants in the most contaminated buildings. Further data are needed to discover whether asbestos still present in buildings, particularly schools, is a persistent or decreasing hazard to workers who disturb it and to the general population, and whether environmental exposure occurs predominantly in childhood or after beginning work. Similar studies are needed in other countries to estimate continuing environmental and occupational mesothelioma hazards worldwide, including the contribution from chrysotile.

In plain English

The authors counted asbestos fibres by electron microscopy in lung samples from 262 lung cancer and 257 pneumothorax (collapsed lung) patients in England and Wales born in 1940 or later. Average lung burdens were compared with British mesothelioma death rates by birth year. Analyses used amphibole fibres; chrysotile's effect could not be estimated. In men, average lung burden fell from 62 fibres per milligram of dry lung (born 1940–44) to 11 (born 1960–64). Male mesothelioma deaths per million by age 50 fell from 184 to 35. Using the women's data, judged more reliable, lifetime risk was estimated at 0.010% per fibre/mg. With only environmental exposure, average burdens fell from 17 (born 1940–54) to 1 (born 1975–84). Twelve occupationally exposed people born since 1965, with two or more amphibole fibres counted in about 0.3 mg of lung tissue, averaged 11 fibres/mg; the authors said this implies a 1 in 1000 lifetime risk. The authors concluded that if the average lung burden from environmental exposure stays at 1 fibre/mg by age 30, average lifetime risk will be of the order of 1 in 10 000.

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: Lung fibre burden study: fibre counts in stored lung samples, plus telephone interviews about lifetime jobs, compared by regression with national mesothelioma death rates by birth cohort
• Who was studied: Asbestos was measured in lung samples from 257 pneumothorax patients and 262 resected lung cancer patients, recruited in England and Wales and born in 1940 or later. The Methods describe tissue taken from 271 pneumothorax patients treated in 2002–10: a random sample of 251 plus 20 extra men born since 1965 who had worked in construction. The lung cancers were resected in 1999–2010.
• Exposure: Amphibole asbestos fibres in the lung (mainly amosite and crocidolite), counted by transmission electron microscopy. Chrysotile is shown only in Table 3 and Figure 3. Jobs were grouped by mesothelioma risk; people who never worked in these jobs were called environmentally exposed.
• Main results:
  • Men: average amphibole lung burden fell from 62 f/mg (born 1940–44) to 11 f/mg (born 1960–64).
  • Men: British mesothelioma risk per million to age 50 fell from 184 to 35 over the same birth cohorts.
  • Women: average lung burden fell from 18 to 9 f/mg (born 1940–44 to 1960–64), and risk per million to age 50 fell from 33 to 16.
  • Mesothelioma risk to age 50 per f/mg: 0.00032% (95% CI 0.00026% to 0.00040%) in men and 0.00019% (95% CI 0.00014% to 0.00024%) in women.
  • Estimated lifelong mesothelioma mortality: 0.017% per f/mg in men.
  • Estimated lifetime risk: 0.010% per f/mg from the women's data, which the authors considered more reliable.
  • Born 1940–64: 19% (14/75) of men in the three highest-risk job categories had lung burdens over 200 f/mg.
  • Born 1940–64: lung burdens over 200 f/mg were found in 2% (3/152) of other men and 1% (1/109) of women. No one born since 1965 exceeded 60 f/mg.
  • Born 1965–74: average burden was 1.8 f/mg in carpenters and 1.7 f/mg in unexposed men and women, but 9.1 f/mg in plumbers, painters and electricians.
  • Environmental exposure only (men and women): average burden fell from 17 f/mg (born 1940–54) to 1 f/mg (born 1975–84), P less than 0.001.
  • Born since 1965: 12 people in occupational-exposure job groups had two or more amphibole fibres counted in approximately 0.3 mg of lung tissue. They were plumbers, electricians and decorators, other construction workers, and medium-risk workers. Their mean of 11 f/mg implies a lifetime risk of 1 in 1000.
• The authors' conclusion: The authors concluded that if the average lung burden by age 30 from environmental exposure is now 1 f/mg and stays at that level, there will be a continuing lifetime mesothelioma risk of the order of 1 in 10 000, averaged across the population. They put the risk an order of magnitude higher in a subgroup of exposed workers.
• Limitations the authors state:
  • Most subjects born before 1965 (78%) were lung cancer patients from an earlier study. Differences between lung cancer and pneumothorax patients might cause error in predicting future rates.
  • Lung samples came from different sites: apical (top of the lung) in pneumothorax patients and various sites in lung cancers.
  • The effect of chrysotile could not be estimated because it does not stay in the lung long enough.
  • The only direct evidence of recent environmental exposure is very imprecise.
  • The lung cancer risk estimate used to adjust lung burdens is very imprecise.
  • No asbestos removal workers were included.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Mesothelioma, Pneumothorax, Lung Cancer, Amphibole Group, Occupational Exposure, Environmental Exposure, Chrysotile.

Related studies

• Commentary: Past and current asbestos exposure and future mesothelioma risks in Britain — B. Terracini (2018)
• Mesothelioma risk and environmental exposure to asbestos: past and future trends in Japan — K. Azuma, I. Uchiyama, et al. (2009)
• Pleural mesothelioma and lung cancer risks in relation to occupational history and asbestos lung burden — C. Gilham, C. Rake, et al. (2016)
• A ban on asbestos must be based on a comparative risk assessment — M. Camus (2001)
• Are current or future mesothelioma epidemics in Hong Kong the tragic legacy of uncontrolled use of asbestos in the past? — L.A. Tse, I.T. Yu, et al. (2010)
• The effect of smoking on the risk of lung cancer mortality for asbestos workers in Great Britain (1971-2005) — G. Frost, A. Darnton, et al. (2011)

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