Non-occupational exposure to asbestos and malignant mesothelioma in the Italian National Registry of Mesotheliomas

Our plain-English summary of Non-occupational exposure to asbestos and malignant mesothelioma in the Italian National Registry of Mesotheliomas, by D. Mirabelli, D. Cavone, E. Merler, et al (Occupational and Environmental Medicine, 2010).

The study

• Authors: D. Mirabelli, D. Cavone, E. Merler, V. Gennaro, A. Romanelli, C. Mensi, E. Chellini, C. Nicita, A. Marinaccio, C. Magnani, M. Musti
• Journal: Occupational and Environmental Medicine
• Published: 2010;67(11):792-4
• Cited by: 39 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Malignant mesotheliomas are strictly related to asbestos, but in a proportion of cases no exposure can be recalled. Published estimates of this proportion have important variations. Historical and geographical differences in the fraction of cancer due to any given exposure are to be expected, but incomplete identification of non-occupational exposures may have played a role.

Methods: To assess the role of non-occupational exposures in causing malignant mesotheliomas in Italy, the exposures of cases registered by the national mesothelioma registry (ReNaM) were examined. ReNaM started in 1993 in five regions and currently covers 98% of the Italian population. Information on occupational and non-occupational exposures of cases is collected whenever possible.

Results: From 1993 to 2001 ReNaM registered 5173 malignant mesothelioma cases, and exposures were assessed in 3552 of them. 144 and 150 cases with exposures limited to environmental (living in the neighbourhood of an industrial or natural source of asbestos) or familial (living with a person occupationally exposed to asbestos) circumstances, respectively, were identified, accounting for 8.3% of all cases.

Conclusions: Geographical variations in the proportion of cases due to non-occupational exposures may be explained by the past distribution of asbestos-using industries.

In plain English

This short report used Italy's national mesothelioma registry (ReNaM) to study malignant mesothelioma cases whose asbestos exposure was only non-occupational. Exposure was classed as environmental (living near an industrial or natural asbestos source) or familial (living with someone exposed to asbestos at work). Of 5173 cases registered from 1993 to 2001, exposure was assessed for 3552. Among these, 294 (8.3%) had environmental (144) or familial (150) exposure and no evidence of occupational exposure. By region, this proportion ranged from 24% in Piedmont to 2% in Tuscany. Average age at diagnosis in this group was 65.0 years (95% confidence interval 63.6 to 66.5), versus 67.4 for all registry cases. Women made up 51% of environmental and 84% of familial cases. Living near an asbestos-cement plant was the most common environmental circumstance (74 of 190). The authors concluded that the past location of major asbestos sources explained important regional variations, and that environmental and familial exposures accounted for a substantial proportion of Italian cases. They noted that interview quality may have varied between regions and that anyone with any occupational exposure was excluded, so non-occupational cases were likely underestimated.

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: Short report: descriptive analysis of cases in a national mesothelioma registry (ReNaM), with exposure assessed by structured interview
• Who was studied: Malignant mesothelioma cases registered by the Italian National Mesothelioma Registry between 1993 and 2001. There were 5173 cases (3746 men, 1427 women), and exposure assessment was available for 3552 of them (2702 men, 850 women).
• Exposure: Non-occupational asbestos exposure only. Environmental exposure meant living in the neighbourhood of an industrial or natural source of asbestos. Familial exposure meant living with a person occupationally exposed to asbestos. Cases with any occupational exposure were excluded. Fiber types were not specified in the results.
• Main results:
  • Of the 3552 cases with exposure assessment, 294 (8.3%) had environmental (144 cases) or familial (150 cases) exposure and no evidence of occupational exposure.
  • The proportion of mesothelioma cases with environmental or familial exposure (considered together) varied by region, from 24% in Piedmont to 2% in Tuscany.
  • Cases with non-occupational exposure had an average age at diagnosis of 65.0 years (95% CI 63.6 to 66.5), compared with 67.4 years for all ReNaM cases.
  • Women were 51% of cases with environmental exposure and 84% of cases with familial exposure.
  • Of 190 environmental exposure circumstances, 74 were residence in the neighbourhood of an asbestos-cement plant.
  • Of 181 familial exposure circumstances, most often a close relative (a parent or a spouse) had worked in activities involving asbestos exposure.
  • For 1621 registered cases no interview or exposure information was available. Women were 35.5% of this group, compared with 23.9% of the group with exposure assessment (p less than 0.001).
• The authors' conclusion: The authors concluded that the past distribution of major sources of asbestos pollution explains important regional variations in mesothelioma due to non-occupational exposures. They also concluded that environmental and familial exposures accounted for a substantial proportion of all Italian malignant mesothelioma cases.
• Limitations the authors state:
  • Regional operating centres may have differed in interview quality and in how they applied the criteria for non-occupational exposure. There was no national quality-control panel, so the size of this possible bias could not be estimated.
  • Women were over-represented among cases without exposure information. Because environmental and familial cases were most common among women, this may have led to underestimation.
  • All cases with at least one occupational exposure were excluded, even where the non-occupational exposure might have been the more important cause. The authors judged it likely that they underestimated the role of environmental and familial exposures.

Topics

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

Medical terms in this study, explained in our Lexicon: Non-Occupational Exposure, Malignant Mesothelioma, Mesothelioma.

Related studies

• Epidemiological patterns of asbestos exposure and spatial clusters of incident cases of malignant mesothelioma from the Italian national registry — M. Corfiati, A. Scarselli, et al. (2015)
• Malignant mesothelioma due to non-occupational asbestos exposure from the Italian national surveillance system (ReNaM): epidemiology and public health issues — A. Marinaccio, A. Binazzi, et al. (2015)
• Estimation of Occupational Exposure to Asbestos in Italy by the Linkage of Mesothelioma Registry (ReNaM) and National Insurance Archives. Methodology and Results — C. Airoldi, D. Ferrante, et al. (2020)
• Asbestos Exposure and Malignant Mesothelioma in Construction Workers-Epidemiological Remarks by the Italian National Mesothelioma Registry (ReNaM) — A. Binazzi, D. Di Marzio, et al. (2021)
• Pleural malignant mesothelioma epidemic: incidence, modalities of asbestos exposure and occupations involved from the Italian National Register — A. Marinaccio, A. Binazzi, et al. (2012)
• Incidence of extrapleural malignant mesothelioma and asbestos exposure, from the Italian national register — A. Marinaccio, A. Binazzi, et al. (2010)

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