Multicentric study on malignant pleural mesothelioma and non-occupational exposure to asbestos

Our plain-English summary of Multicentric study on malignant pleural mesothelioma and non-occupational exposure to asbestos, by C. Magnani, A. Agudo, C.A. González, et al (British Journal of Cancer, 2000).

The study

• Authors: C. Magnani, A. Agudo, C.A. González, A. Andrion, A. Calleja, E. Chellini, P. Dalmasso, A. Escolar, S. Hernandez, C. Ivaldi, D. Mirabelli, J. Ramirez, D. Turuguet, M. Usel, B. Terracini
• Journal: British Journal of Cancer
• Published: 2000;83(1):104-11
• Cited by: 124 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Insufficient evidence exists on the risk of pleural mesothelioma from non-occupational exposure to asbestos. A population-based case-control study was carried out in six areas from Italy, Spain and Switzerland. Information was collected for 215 new histologically confirmed cases and 448 controls. A panel of industrial hygienists assessed asbestos exposure separately for occupational, domestic and environmental sources. Classification of domestic and environmental exposure was based on a complete residential history, presence and use of asbestos at home, asbestos industrial activities in the surrounding area, and their distance from the dwelling. In 53 cases and 232 controls without evidence of occupational exposure to asbestos, moderate or high probability of domestic exposure was associated with an increased risk adjusted by age and sex: odds ratio (OR) 4.81, 95% confidence interval (CI) 1.8-13.1. This corresponds to three situations: cleaning asbestos-contaminated clothes, handling asbestos material and presence of asbestos material susceptible to damage. The estimated OR for high probability of environmental exposure (living within 2000 m of asbestos mines, asbestos cement plants, asbestos textiles, shipyards, or brakes factories) was 11.5 (95% CI 3.5-38.2). Living between 2000 and 5000 m from asbestos industries or within 500 m of industries using asbestos could also be associated with an increased risk. A dose-response pattern appeared with intensity of both sources of exposure. It is suggested that low-dose exposure to asbestos at home or in the general environment carries a measurable risk of malignant pleural mesothelioma.

In plain English

This population-based case–control study took place in six areas of Italy, Spain and Switzerland. It examined malignant pleural mesothelioma and asbestos exposure outside work. It included 215 people with histologically confirmed pleural mesothelioma and 448 controls. In the Spanish centres the controls were hospital patients. Industrial hygienists, who did not know which subjects were cases, rated exposure at home and from nearby industry using residential histories. The main analysis covered 53 cases and 232 controls with no evidence of work exposure. In this group, a middle or high probability of exposure at home was associated with an odds ratio of 4.81 (95% CI 1.77–13.1). Having lived within 2000 m of an asbestos mine or asbestos works was associated with an odds ratio of 11.5 (95% CI 3.47–38.2). Low-probability categories showed raised but not statistically significant risks, and odds ratios rose with exposure intensity. The authors concluded that their results suggest non-occupational exposure to relatively low doses of asbestos is a hazard that may contribute to mesothelioma. They noted small numbers, the lower quality of answers from relatives, and possible overestimation of risk.

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: Multicentre population-based case–control study. Controls were a random population sample in the Italian centres and Geneva, and hospital patients in the Spanish centres. Exposure was rated by a panel of industrial hygienists.
• Who was studied: 215 new histologically confirmed cases of malignant pleural mesothelioma and 448 controls from Torino, Casale Monferrato and Firenze/Prato (Italy), Barcelona and Cádiz (Spain), and Geneva (Switzerland). Cases were mainly diagnosed 1995–1996; Barcelona also included 1993–1994 and Torino recruited until April 1997. The non-occupational analysis covered 53 cases and 232 controls with no evidence of occupational exposure.
• Exposure: Domestic exposure (e.g. cleaning asbestos-contaminated work clothes, handling asbestos material at home, asbestos material at home such as asbestos roofs) and environmental exposure (living near asbestos mines, asbestos cement plants, asbestos textile plants, shipyards, brake factories, or industries using asbestos). Each was rated by probability and intensity. Fiber types were not specified for this study's subjects.
• Main results:
  • In all subjects, odds ratios for occupational exposure were 1.6 (95% CI 0.9–2.9) for low probability, 3.0 (95% CI 1.8–5.1) for middle or high probability, and 7.9 (95% CI 4.8–13.1) for certain probability.
  • Among subjects without occupational exposure, middle or high probability of domestic exposure applied to 16 cases (30.2%) and 15 controls (6.5%), with an odds ratio of 4.81 (95% CI 1.77–13.1).
  • Among subjects without occupational exposure, high probability of environmental exposure (having lived within 2000 m of a mine or asbestos works) applied to 17 cases (32.1%) and 21 controls (9.1%), with an odds ratio of 11.5 (95% CI 3.47–38.2).
  • Low-probability environmental exposure (living 2000–5000 m from asbestos industries, or within 500 m of industries using asbestos) was associated with an increased but not statistically significant risk (odds ratio 2.70, 95% CI 0.87–8.37).
  • Odds ratios rose with increasing exposure scores for both sources. For high intensity, the odds ratio was 7.83 (95% CI 1.69–36.2) for domestic exposure (9 cases, 4 controls) and 45.0 (95% CI 6.38–318.0) for environmental exposure (6 cases, 3 controls).
  • In the combined analysis (41 cases, 182 controls), subjects with the highest category of both domestic and environmental exposure had an odds ratio of 21.9 (95% CI 4.2–114.1), which the authors described as quite high but imprecise.
  • Eight cases had asbestos at home as their only known source of exposure. Six of them, all in Barcelona, had an asbestos roof. The authors called this an observation that requires confirmation.
• The authors' conclusion: The authors concluded that their results suggest non-occupational exposure to relatively low doses of asbestos is a hazard that may contribute to the burden of mesothelioma over the next few decades. They stated that the study confirms neighbourhood risk in Casale Monferrato and suggests a corresponding risk in Barcelona and Torino.
• Limitations the authors state:
  • Risk estimates were based on small numbers, and the confidence intervals for environmental and domestic exposure overlapped.
  • Information from proxy respondents (relatives of cases who had died) was of lower quality.
  • Cases or their relatives may have recalled exposures better than controls, which would overestimate risk.
  • The authors could not rule out overestimated odds ratios for domestic or environmental exposure.
  • For the asbestos-roof finding, the authors could not rule out other explanations: another exposure source, the use of hospital controls, or inaccurate information from relatives.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Non-Occupational Exposure, Case-Control Study, Asbestos Exposure, Environmental Exposure, Occupational Exposure, Odds Ratio, confidence interval.

Related studies

• 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)
• Occupational and environmental exposures and lung cancer in an industrialised area in Italy — V. Fano, P. Michelozzi, et al. (2004)
• Occupation and risk of malignant pleural mesothelioma: A case-control study in Spain — A. Agudo, C.A. González, et al. (2000)
• Non-occupational exposure to asbestos and malignant mesothelioma in the Italian National Registry of Mesotheliomas — D. Mirabelli, D. Cavone, et al. (2010)
• Mesothelioma and non-occupational environmental exposure to asbestos — C. Magnani, G. Borgo, et al. (1991)

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