'Environment' in cancer causation and etiological fraction: limitations and ambiguities

Our plain-English summary of 'Environment' in cancer causation and etiological fraction: limitations and ambiguities, by D. Mirabelli, E. Merler (Carcinogenesis, 2008).

The study

• Authors: D. Mirabelli, E. Merler
• Journal: Carcinogenesis
• Published: 2008;29(5):1083
• Type of article: Comment, Letter
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This is a letter to the editor, not an original study. The authors responded to a 2007 paper by Boffetta and colleagues on how much cancer can be attributed to the environment. They focused on mesothelioma after environmental (non-occupational) asbestos exposure. Boffetta et al. had quoted a combined relative risk of 3.5 (95% CI 1.8–7.0). An earlier review had reported 7.0 (95% CI 4.7–11) for neighbourhood exposure. The authors wrote that the reason for the change was unclear because no analysis details were given. After excluding two of 11 relative risks listed in a 2003 Boffetta paper, they computed a simple case-weighted average of 8.1. They questioned which of several relative risks from a Casale Monferrato, Italy, study should be used, and regretted that studies of Wittenoom residents were left out. They cited the Italian mesothelioma register, where 10% of 3552 mesotheliomas from 1993–2001 with assessable exposure were due to residential and household exposure. The authors concluded that the burden of mesothelioma from environmental asbestos exposure may be substantial where industrial asbestos use has been relevant.

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: Letter to the editor commenting on a published paper (Boffetta et al. 2007); no original study data
• Who was studied: No study population of its own. The letter re-examined relative risks from 11 studies of environmental asbestos exposure quoted in a 2003 paper by Boffetta et al., and discussed other published studies and registry data.
• Exposure: Environmental (non-occupational: neighbourhood, residential and household) exposure to asbestos, in relation to mesothelioma risk; crocidolite in the Wittenoom studies mentioned
• Main results:
  • Boffetta et al. quoted a meta-analytic relative risk of 3.5 (95% CI 1.8–7.0), while an earlier review had reported 7.0 (95% CI 4.7–11) after neighbourhood exposure. The authors stated that the reasons for the shift were not clear because no details on data analysis were given.
  • Excluding the relative risk of 40.9 (mainly peculiar household exposures) and the relative risk of 182 (number of cases not reported), the authors computed a simple weighted average (weighted by number of cases) of the remaining relative risks of 8.1.
  • For the Casale Monferrato (Italy) case-control study, the authors noted several possible relative risks. One was 14.6, as given in the 2003 review's table but not in the original text. Others were by distance from the factory: 27.7 up to 500 m, 22 for 500 to 1499 m, and 21 for 1500 to 2500 m. They asked which one should be used in a meta-analysis.
  • The authors cited earlier studies, the Wittenoom residents cohort (crocidolite) and a French case-control study, as giving consistent results showing increased mesothelioma risk at low cumulative exposures. They said these studies had been left out of the Boffetta reviews.
  • Citing the Italian Mesothelioma Register, the authors reported that among 3552 mesotheliomas occurring in 1993–2001 whose exposure could be assessed, 10% were due to non-occupational residential and household asbestos exposure.
  • The authors stated that if a relative risk of 8.1 instead of 3.5 were applied, the estimates of environmental mesothelioma cases (200 per year in Great Britain, 500 in the European Union) would be more than doubled.
• The authors' conclusion: The authors concluded that the burden of mesothelioma due to environmental asbestos exposure may be substantial in populations where industrial asbestos use has been relevant. They also said such cases are concentrated in communities near past sources of asbestos pollution.

Topics

Medical terms in this study, explained in our Lexicon: Causation.

Related studies

• 'Environment' in cancer causation and etiological fraction: limitations and ambiguities — P. Boffetta, J.K. McLaughlin, et al. (2007)
• Children's environment in Central Europe: threats and chances — S. Böse-O'Reilly, U. Heudorf, et al. (2007)
• Evaluation of asbestos exposure in the working environment. Recommendation of subcommittee on asbestosis of the permanent commission and international association on occupational health — (1972)
• Elongate mineral particles in the natural environment — M.E. Gunter (2018)
• Unbiased vs. conservative estimators of etiological fractions: examples of misclassification from studies of occupational lung cancer — O. Olsen (1995)
• Value of a multinational approach in determining the causation of cancer — C.S. Muir (1986)

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