Risk of cancer associated with residential exposure to asbestos insulation: a whole-population cohort study

Our plain-English summary of Risk of cancer associated with residential exposure to asbestos insulation: a whole-population cohort study, by R.J. Korda, M.S. Clements, B.K. Armstrong, et al (The Lancet. Public Health, 2017).

The study

• Authors: R.J. Korda, M.S. Clements, B.K. Armstrong, H.D. Law, T. Guiver, P.R. Anderson, S.M. Trevenar, M.D. Kirk
• Journal: The Lancet. Public Health
• Published: 2017;2(11):e522-e528
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: The health risks associated with living in houses insulated with asbestos are unknown. Loose-fill asbestos was used to insulate some houses in the Australian Capital Territory (ACT). We compared the incidence of mesothelioma and other cancers in residents of the ACT who did and did not live in these houses.

Methods: Our cohort study included all ACT residents identified using Medicare enrolment data. These data were linked to addresses of affected residential properties in the ACT to ascertain exposure. We followed up residents by linking data to the Australian Cancer Database and National Death Index. Outcomes were diagnosis of mesothelioma and selected other cancers. Effects were estimated for males and females separately using standardised incidence ratios (SIRs), adjusting for age and calendar time of diagnosis.

Findings: Between Nov 1, 1983, and Dec 31, 2013, 1 035 578 ACT residents were identified from the Medicare database. Of these, 17 248 (2%) had lived in an affected property, including seven (2%) of 285 people diagnosed with mesothelioma. The adjusted incidence of mesothelioma in males who had lived at an affected property was 2·5 times that of unexposed males (SIR 2·54, 95% CI 1·02-5·24). No mesotheliomas were reported among females who had lived at an affected property. Among individuals who had lived at an affected property, there was an elevated incidence of colorectal cancer in women (SIR 1·73, 95% CI 1·29-2·26) and prostate cancer in men (1·29, 1·07-1·54); colorectal cancer was increased, although not significantly, in males (SIR 1·32, 95% CI 0·99-1·72), with no significant increase in the other cancers studied.

Interpretation: Residential asbestos insulation is likely to be unsafe. Our findings have important health, social, financial, and legal implications for governments and communities in which asbestos has been used to insulate houses.

Funding: ACT Government.

Copyright © 2017 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.

In plain English

This whole-population cohort study examined residents of the Australian Capital Territory (ACT), where some houses had loose-fill asbestos (largely amosite with some crocidolite) blown into roof spaces. Using Medicare records linked to cancer and death registers, the authors identified 1 035 578 ACT residents from November 1983 to December 2013. Of these, 17 248 (2%) had ever lived in an affected house. Of 285 mesothelioma cases, seven were in people who had lived in an affected house before diagnosis, and all seven were men. Adjusted for age and calendar period, the standardised incidence ratio (SIR) for mesothelioma in exposed versus unexposed men was 2.54 (95% CI 1.02 to 5.24). No mesothelioma was recorded among exposed women. Colorectal cancer was raised in exposed women (SIR 1.73, 95% CI 1.29 to 2.26) and, though not statistically significantly, in exposed men (SIR 1.32, 95% CI 0.99 to 1.72). Prostate cancer was raised in exposed men (SIR 1.29, 95% CI 1.07 to 1.54). The authors called the colorectal and prostate findings uncertain and could not adjust for smoking. They concluded that residential asbestos insulation is likely to be unsafe.

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: Whole-population retrospective cohort study using linked records (Medicare enrolment, a register of affected houses, the Australian Cancer Database and the National Death Index), with standardised incidence ratios adjusted for age and calendar period
• Who was studied: 1 035 578 people with an ACT address in Medicare enrolment records between Nov 1, 1983, and Dec 31, 2013. Of these, 17 248 (2%) had lived at an affected residential property and were classified as exposed. 1 034 059 people were included in the main mesothelioma analysis.
• Exposure: Having ever lived in a house insulated with crushed loose-fill asbestos (largely amosite with some crocidolite) blown into the roof space, as listed on the ACT Asbestos Response Taskforce register. A 10-year lag was applied between first exposure and diagnosis.
• Main results:
  • Of 285 mesothelioma cases, nine were in people who had ever lived at an affected property. Two of these were diagnosed before living there. Seven had lived at an affected property before diagnosis.
  • All seven exposed cases were men, as were 239 of the 278 unexposed cases.
  • The article states that the cases were diagnosed with pleural mesothelioma. The sentence is interrupted by figure text in the source.
  • Among the exposed cases, the time from first exposure to an affected property to mesothelioma diagnosis ranged from 12.8 to 24.9 years. The authors noted this is probably a minimum.
  • Crude mesothelioma incidence was 2.25 cases per 100 000 person-years in unexposed males (95% CI 1.97 to 2.56) and 8.26 per 100 000 person-years in exposed males (95% CI 3.32 to 17.0).
  • After adjusting for age and calendar period, mesothelioma incidence in exposed males was two and a half times that in unexposed males (SIR 2.54, 95% CI 1.02 to 5.24).
  • An estimated 4.2 excess mesothelioma cases (95% CI 0.06 to 11.7) occurred in male residents of affected properties between 1984 and 2013.
  • No mesothelioma cases occurred in exposed females.
  • Colorectal cancer incidence was higher in exposed females (SIR 1.73, 95% CI 1.29 to 2.26). It was also higher in exposed males (SIR 1.32, 95% CI 0.99 to 1.72), but the male figure was not statistically significant.
  • Of the other six asbestos-associated cancers examined, only colorectal cancer incidence was significantly elevated in exposed residents.
  • Prostate cancer incidence was higher in exposed men than in unexposed men (SIR 1.29, 95% CI 1.07 to 1.54).
  • Bladder cancer, kidney cancer and melanoma incidence did not differ between exposed and unexposed residents.
  • In sensitivity analyses, the mesothelioma association was maintained but with considerable uncertainty.
  • Excluding people with post office box addresses substantially reduced the strength of the colorectal and prostate cancer associations.
• The authors' conclusion: The authors concluded that residential asbestos insulation is likely to be unsafe. They also concluded that living in a loose-fill asbestos house could be associated with some mesotheliomas in men, possibly because men entered and renovated roof spaces.
• Limitations the authors state:
  • The authors described the colorectal and prostate cancer associations as somewhat unexpected and said they should be regarded as uncertain.
  • Medicare records began in 1983, while exposure may have occurred from 1968. People exposed before 1983 who did not live in an affected house after that date may have been misclassified or missed. The authors said this would likely bias results toward the null.
  • People whose address was a post office box may have been wrongly classified as unexposed.
  • Cancer cases before mandatory reporting began in the ACT in 1994, or in people living outside Australia at diagnosis, may have been missed.
  • The authors could not account for confounding other than by age and sex, such as occupational asbestos exposure or prostate cancer screening.
  • The lack of smoking information limited interpretation of the lung cancer findings.
  • The study lacked statistical power for the rarer cancers.

Topics

Medical terms in this study, explained in our Lexicon: Cohort Study, Mesothelioma, Standardized Incidence Ratio (SIR), Colorectal Cancer.

Related studies

• Case-control study on lung cancer and residential radon in western Germany — L. Kreienbrock, M. Kreuzer, et al. (2001)
• Increased risk of malignant mesothelioma of the pleura after residential or domestic exposure to asbestos: a case-control study in Casale Monferrato, Italy — C. Magnani, P. Dalmasso, et al. (2001)
• Non-occupational exposure to asbestos and risk of pleural mesothelioma: review and meta-analysis — G.M. Marsh, A.S. Riordan, et al. (2017)
• Risk of cancer among Danish utility workers--a nationwide cohort study — C. Johansen, J.H. Olsen (1998)
• Relationships of Lower Lung Fibrosis, Pleural Disease, and Lung Mass with Occupational, Household, Neighborhood, and Slate Roof-Dense Area Residential Asbestos Exposure — D. Kang, Y.Y. Kim, et al. (2018)
• A cohort study on mortality among wives of workers in the asbestos cement industry in Casale Monferrato, Italy — C. Magnani, B. Terracini, et al. (1993)

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