Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment

Our plain-English summary of Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment, by D. Ferrante, D. Mirabelli, S. Tunesi, et al (Occupational and Environmental Medicine, 2016).

The study

• Authors: D. Ferrante, D. Mirabelli, S. Tunesi, B. Terracini, C. Magnani
• Journal: Occupational and Environmental Medicine
• Published: 2016;73(3):147-53
• Cited by: 70 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Casale Monferrato (north west Italy) is an area with an exceptionally high incidence of mesothelioma caused by asbestos contamination at work and in the general environment from the asbestos-cement Eternit plant that was operational until 1986. The purpose of this study was to quantify the association between pleural malignant mesothelioma (PMM) and asbestos cumulative exposure using individual assessment of environmental and domestic exposure, as well as of occupational exposure.

Methods: This population-based case-control study included cases of PMM diagnosed between January 2001 and June 2006 among residents in the Casale Monferrato Local Health Authority. Population controls were randomly sampled, matched by age and sex to cases. Cumulative exposure was estimated to account for the lifelong exposure history. Analyses were conducted using unconditional logistic regression models adjusting for gender, age at diagnosis and type of interview (direct or proxy respondents).

Results: 200 PMM cases of 223 eligible cases (89.7%) and 348 (63%) of 552 eligible controls accepted to be interviewed. ORs increased with cumulative exposure index (p<0.0001) from 4.4 (CI 95% 1.7 to 11.3) (<1 f/mL-years) to 62.1 (CI 95% 22.2 to 173.2) (≥10 f/mL-years). Among subjects never occupationally exposed, corresponding ORs were 3.8 (CI 95% 1.3 to 11.1) and 23.3 (CI 95% 2.9 to 186.9) (reference: background level of asbestos exposure). ORs of about 2, statistically significant, were observed for domestic exposure and for living in houses near buildings with large asbestos cement parts.

Conclusions: Risk of PMM increased with cumulative asbestos exposure and also in analyses limited to subjects non-occupationally exposed. Our results also provide indication of risk associated with common sources of environmental exposure and are highly relevant for the evaluation of residual risk after the cessation of asbestos industrial use.

Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

In plain English

This population-based case-control study examined pleural malignant mesothelioma around Casale Monferrato, Italy, where the Eternit asbestos-cement plant operated until 1986. It interviewed 200 of 223 eligible cases diagnosed January 2001 to June 2006 and 348 of 552 random local controls matched by age and sex. An expert rater, blind to case status, estimated each person's lifetime cumulative asbestos exposure from work, environment, family and home. Against background exposure, odds ratios rose from 4.4 (95% CI 1.7 to 11.3) at 0.1 to under 1 fibre/mL-years to 62.1 (22.2 to 173.2) at 10 or more. Among people never exposed at work, they rose from 3.8 (1.3 to 11.1) to 23.3 (2.9 to 186.9) (top group: 5 cases, 2 controls). Raised odds were linked to a family member exposed at work (2.2, 1.2 to 4.0), an asbestos-cement roof (2.4, 1.4 to 4.2), asbestos-cement buildings near home (1.9, 1.2 to 3.2) and paving with asbestos-cement tailings (3.4, 1.4 to 8.4). The authors concluded risk rose with cumulative exposure even at low levels, noting possible exposure-assessment error and recall bias for home exposures.

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 case-control study. Cases were pleural malignant mesothelioma diagnosed between 1 January 2001 and 30 June 2006. Controls were a random sample of the local population, matched by date of birth and sex. Analysis used unconditional logistic regression adjusted for sex, age and type of interview (direct or proxy).
• Who was studied: Residents of the Casale Monferrato Local Health Authority area, north west Italy. 200 of 223 eligible cases (89.7%) and 348 of 552 eligible controls (63%) were interviewed. 46% of case interviews and 7.2% of control interviews were with relatives (proxies).
• Exposure: Lifetime cumulative asbestos exposure index (fibre/mL-years) combining all sources: occupational, environmental (living near industrial or natural sources), familial (living with asbestos-exposed workers) and domestic (asbestos-containing materials at home, home repairs, leisure activities). The main local source was the Eternit asbestos-cement plant. The exposure index did not separate fibre types.
• Main results:
  • All subjects, reference group: background exposure level (under 0.1 f/mL-years), with 8 cases and 106 controls.
  • All subjects, 0.1 to under 1 f/mL-years: 26 cases and 108 controls, OR 4.4 (95% CI 1.7 to 11.3).
  • All subjects, 1 to under 10 f/mL-years: 113 cases and 115 controls, OR 17.5 (95% CI 7.3 to 41.8).
  • All subjects, 10 or more f/mL-years: 53 cases and 19 controls, OR 62.1 (95% CI 22.2 to 173.2). The trend across categories had p less than 0.0001.
  • Non-occupationally exposed subjects only (84 cases, 201 controls), 0.1 to under 1 f/mL-years: OR 3.8 (95% CI 1.3 to 11.1).
  • Non-occupationally exposed subjects only, 1 to under 10 f/mL-years: OR 14.8 (95% CI 5.7 to 38.6).
  • Non-occupationally exposed subjects only, 10 or more f/mL-years: OR 23.3 (95% CI 2.9 to 186.9), based on 5 cases and 2 controls.
  • Having any family member occupationally exposed to asbestos (38 cases, 19.0%; 35 controls, 10.1%): OR 2.2 (95% CI 1.2 to 4.0), adjusted for work in the asbestos-cement industry. For an exposed spouse the OR was 2.6 (95% CI 0.9 to 7.5).
  • Garden or courtyard paved with asbestos-cement tailings: OR 3.4 (95% CI 1.4 to 8.4), adjusted for occupational exposure in the asbestos-cement industry.
  • Asbestos-cement roof: OR 2.4 (95% CI 1.4 to 4.2). Asbestos-cement buildings close to the house: OR 1.9 (95% CI 1.2 to 3.2).
  • Use of utensils made of asbestos material: OR 1.3 (95% CI 0.7 to 2.3), not statistically significant.
  • Only 20 cases and 9 controls had worked in the asbestos-cement industry.
  • ORs were higher among subjects interviewed in person than among those with a proxy interview.
• The authors' conclusion: The authors concluded that pleural mesothelioma risk rises with cumulative asbestos exposure, even at low levels. They also concluded that environmental and familial/domestic exposures, including asbestos-cement materials in place in the living environment, contributed to pleural mesothelioma in this population.
• Limitations the authors state:
  • Expert-based exposure assessment has been criticised as not reproducible or transparent.
  • Non-differential error in exposure assessment may have occurred. The authors note that such error tends to weaken the observed exposure-response relationship.
  • Fibre concentration measurements existed for only a minority of exposure circumstances, and only for recent periods; gaps were filled by the assessor's expertise.
  • Exposures from asbestos-containing materials at home depended on self-report and may have been affected by recall bias.
  • In analyses restricted by probability of exposure, the ORs in the corresponding categories had wide and overlapping confidence intervals.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Asbestos Exposure, Case-Control Study, Casale Monferrato, Mesothelioma, Asbestos-Cement, Eternit, Malignant Mesothelioma.

Related studies

• Authors's response: Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment — D. Ferrante, D. Mirabelli, et al. (2016)
• 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)
• Pleural mesothelioma and asbestos exposure: a case-control study with quantitative risk assessment-response to Marsh and Benson's letter — D. Ferrante, D. Mirabelli, et al. (2017)
• Response to: 'Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment' by Ferrante et al — G.M. Marsh, S.M. Benson (2017)
• Response to: Pleural mesothelioma, and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment — P. Boffetta (2016)
• The contribution of environmental monitoring in the epidemiological assessment of exogenous risk. The experience of ARPA in the Emilia-Romagna Region of Italy — A. Zavatti, P. Lauriola (1999)

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