Increased risk of malignant mesothelioma of the pleura after residential or domestic exposure to asbestos: a case-control study in Casale Monferrato, Italy

Our plain-English summary of Increased risk of malignant mesothelioma of the pleura after residential or domestic exposure to asbestos: a case-control study in Casale Monferrato, Italy, by C. Magnani, P. Dalmasso, A. Biggeri, et al (Environmental Health Perspectives, 2001).

The study

• Authors: C. Magnani, P. Dalmasso, A. Biggeri, C. Ivaldi, D. Mirabelli, B. Terracini
• Journal: Environmental Health Perspectives
• Published: 2001;109(9):915-9
• Cited by: 121 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The association of malignant mesothelioma (MM) and nonoccupational asbestos exposure is currently debated. Our study investigates environmental and domestic asbestos exposure in the city where the largest Italian asbestos cement (AC) factory was located. This population-based case-control study included pleural MM (histologically diagnosed) incidents in the area in 1987-1993, matched by age and sex to two controls (four if younger than 60). Diagnoses were confirmed by a panel of five pathologists. We interviewed 102 cases and 273 controls in 1993-1995, out of 116 and 330 eligible subjects. Information was checked and completed on the basis of factory and Town Office files. We adjusted analyses for occupational exposure in the AC industry. In the town there were no other relevant industrial sources of asbestos exposure. Twenty-three cases and 20 controls lived with an AC worker [odds ratio (OR) = 4.5; 95% confidence interval (CI), 1.8-11.1)]. The risk was higher for the offspring of AC workers (OR = 7.4; 95% CI, 1.9-28.1). Subjects attending grammar school in Casale also showed an increased risk (OR = 3.3; 95% CI, 1.4-7.7). Living in Casale was associated with a very high risk (after selecting out AC workers: OR = 20.6; 95% CI, 6.2-68.6), with spatial trend with increasing distance from the AC factory. The present work confirms the association of environmental asbestos exposure and pleural MM, controlling for other sources of asbestos exposure, and suggests that environmental exposure caused a greater risk than domestic exposure.

In plain English

This population-based case-control study examined pleural malignant mesothelioma around Casale Monferrato, Italy. Its Eternit asbestos cement factory (1907 to 1985) reported using 15,000 tons of asbestos (10% crocidolite) in 1981. Interviews reached 102 of 116 eligible cases (1987 to mid-1993) and 273 of 330 matched controls. Ever versus never working in the asbestos cement industry gave a crude odds ratio of 7.3 (95% CI 3.2 to 16.4). Among those never employed there, living with a relative in that industry had an odds ratio of 4.5 (1.8 to 11.1). With a parent it was 7.4 (1.9 to 28.1); with a spouse, 3.1 (0.6 to 17.7). Home asbestos items showed no statistically significant increase. For non-workers, residence in Casale, counting only homes before the 20 years preceding diagnosis, gave an odds ratio of 20.6 (6.2 to 68.6) against people without such residence in Casale or nearby municipalities, adjusted for relatives' work in the industry. Estimates were raised at every distance, with some evidence of a spatial trend. The authors concluded environmental exposure was associated with pleural mesothelioma, suggesting greater risk than domestic exposure.

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 (conditional logistic regression on matched sets)
• Who was studied: Residents of the Local Health Authority of Casale Monferrato, Italy (48 towns, 100,000 inhabitants, 40,000 of them in Casale). Cases were pleural malignant mesothelioma recorded from 1 January 1987 to 30 June 1993, with controls matched by sex, birth date and vital status. 116 cases and 330 controls were eligible, and 102 cases and 273 controls were interviewed in 1993 to 1995. 102 matched sets (345 subjects) were analysed.
• Exposure: Asbestos from a large Eternit asbestos cement factory active from 1907 to 1985, which in 1981 reported using 15,000 tons of asbestos (10% crocidolite). The study looked at work in the asbestos cement industry, living with a relative who worked there, asbestos-containing items at home, grammar school attendance in Casale, and the distance of the home from the factory.
• Main results:
  • Ever working in the asbestos cement industry: 27 cases and 13 controls, crude ORC 7.3 (95% CI 3.2 to 16.4). The reference group was subjects never engaged in that industry.
  • Any relative employed in the asbestos cement industry during cohabitation: 23 cases and 20 controls. Crude ORC 3.3 (95% CI 1.6 to 6.5). Among subjects with no occupation in the asbestos cement industry, ORC 4.5 (95% CI 1.8 to 11.1).
  • Father and/or mother employed in the asbestos cement industry: 9 cases and 5 controls. Crude ORC 4.6 (95% CI 1.5 to 13.9). Among subjects with no occupation in the asbestos cement industry, ORC 7.4 (95% CI 1.9 to 28.1).
  • Spouse employed in the asbestos cement industry: 6 cases and 8 controls. Crude ORC 1.5 (95% CI 0.5 to 4.5). Among subjects with no occupation in the asbestos cement industry, ORC 3.1 (95% CI 0.6 to 17.7).
  • Domestic exposure from asbestos-containing items (subset of 78 cases and 174 controls): any indoor and/or outdoor exposure had an ORC of 1.5 (0.7 to 3.0). Individual items ranged from 0.6 to 2.5, and none was statistically significant.
  • Attending grammar school in Casale, among subjects who never worked in the asbestos cement industry: ORC 3.3 (95% CI 1.4 to 7.7), based on five cases and 10 controls.
  • Ever living in Casale at any distance from the factory: ORC 20.6 (95% CI 6.2 to 68.6), with asbestos cement workers selected out. Residence was classified by the home closest to the factory, and the last 20 years before diagnosis (for controls, before the matched case's diagnosis) were ignored. The reference group was subjects who never worked in the asbestos cement industry and had no such residence in Casale or its surrounding municipalities. The model adjusted for relatives' occupational exposure.
  • Residential exposure was classified ignoring the last 20 years before the date of diagnosis (for controls, the diagnosis date of the matched case).
  • Odds ratios for residence were above 1 and statistically significant at all distances from the factory, with some evidence of a spatial trend.
  • Residence less than 500 m from the factory (closest home, outside the last 20 years before diagnosis): 5 cases and 2 controls, ORC 27.7 (95% CI 3.1 to 247.7). The comparison was with people in none of the other categories (never in the asbestos cement industry, no such residence in Casale or the surrounding municipalities).
  • Residence more than 2,500 m from the factory: 4 cases and 9 controls, ORC 11.1 (95% CI 1.8 to 67.2), against the same reference group.
  • Work in agriculture was associated with a lower risk among subjects who never worked in the asbestos cement industry (ORC 0.4; 95% CI 0.3 to 0.8, based on 21 cases).
• The authors' conclusion: The authors concluded that the study confirmed the association of environmental asbestos exposure with pleural malignant mesothelioma, after controlling for other sources of asbestos exposure. They suggested that in Casale environmental exposure caused a greater risk than domestic exposure.
• Limitations the authors state:
  • The study could not take into account people's movement within the city, which would tend to average out exposure from geographically defined sources.
  • Work in the asbestos cement industry was used as a stand-in for occupational exposure, and its sensitivity may be lower than its specificity.
  • The increased risk linked to attending grammar school in Casale is a new finding that requires confirmation. Numbers were too small to estimate risk by school location.
  • Other possible sources of exposure in the town, such as asbestos cement residues used in playgrounds or loft insulation, are known only from anecdotal reports and were not quantified.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Pleura, Case-Control Study, Casale Monferrato, Asbestos Exposure, Asbestos-Cement, Occupational Exposure, Odds Ratio.

Related studies

• Cancer mortality and incidence of mesothelioma in a cohort of wives of asbestos workers in Casale Monferrato, Italy — D. Ferrante, M. Bertolotti, et al. (2007)
• 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)
• Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment — D. Ferrante, D. Mirabelli, et al. (2016)
• Para-occupational exposures to asbestos: lessons learned from Casale Monferrato, Italy — L.T. Stayner (2016)
• Environmental Health Education for Asbestos-Contaminated Communities in Italy: The Casale Monferrato Case Study — D. Marsili, A. Canepa, et al. (2019)
• Residential proximity to naturally occurring asbestos and mesothelioma risk in California — X.L. Pan, H.W. Day, et al. (2005)

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