Cancer mortality and incidence of mesothelioma in a cohort of wives of asbestos workers in Casale Monferrato, Italy

Our plain-English summary of Cancer mortality and incidence of mesothelioma in a cohort of wives of asbestos workers in Casale Monferrato, Italy, by D. Ferrante, M. Bertolotti, A. Todesco, et al (Environmental Health Perspectives, 2007).

The study

• Authors: D. Ferrante, M. Bertolotti, A. Todesco, D. Mirabelli, B. Terracini, C. Magnani
• Journal: Environmental Health Perspectives
• Published: 2007;115(10):1401-5
• Cited by: 97 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Family members of asbestos workers are at increased risk of malignant mesothelioma (MM). Although the hazard is established, the magnitude of the risk is uncertain, and it is unclear whether risk is also increased for other cancers. Few cohort studies have been reported.

Objective: The "Eternit" factory of Casale Monferrato (Italy), active from 1907 to 1986, was among the most important Italian plants producing asbestos-cement (AC) goods. In this article we present updated results on mortality and MM incidence in the wives of workers at the factory.

Methods: We studied a cohort of 1,780 women, each married to an AC worker during his employment at the factory but not personally occupationally exposed to asbestos. Cohort membership was defined starting from the marital status of each worker, which was ascertained in 1988 from the Registrar's Office in the town where workers lived. At the end of follow-up (April 2003), 67% of women were alive, 32.3% dead, and 0.7% lost to follow-up. Duration of exposure was computed from the husband's period of employment. Latency was the interval from first exposure to the end of follow-up.

Results: The standardized mortality ratio (SMR) for pleural cancer [21 observed vs. 1.2 expected; SMR = 18.00; 95% confidence interval (CI), 11.14-27.52] was significantly increased. Mortality for lung cancer was not increased (12 observed vs. 10.3 expected; SMR = 1.17; 95% CI, 0.60-2.04). Eleven incident cases of pleural MM were observed (standardized incidence ratio = 25.19; 95% CI, 12.57-45.07).

Conclusions: Household exposure, as experienced by these AC workers' wives, increases risk for pleural MM but not for lung cancer.

In plain English

This updated cohort study followed, until April 2003, 1,780 women married to Eternit asbestos-cement workers in Casale Monferrato, Italy, during their husbands' employment. Women who had worked at the plant were excluded. The plant used chrysotile and crocidolite; work clothes were taken home for cleaning. Deaths before age 80 in 1965 to 2003 were compared with Piedmont regional rates. The wives had 21 pleural cancer deaths against 1.2 expected (SMR 18.00; 95% CI 11.14 to 27.52). There were 12 lung cancer deaths against 10.3 expected (SMR 1.17; 95% CI 0.60 to 2.04), not a statistically significant increase. In 1990 to 2001, among women under 80, 11 pleural mesothelioma cases occurred against 0.44 expected (SIR 25.19; 95% CI 12.57 to 45.07); one further case was observed after age 80. Pleural cancer risk rose with exposure duration and was significantly raised from 30 years after first exposure. The authors had no household exposure measurements. They noted that environmental exposure in the town may have contributed to the risk. The authors concluded that the increase was limited to pleural mesothelioma and was not seen for lung cancer.

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: Cohort study (update of an earlier study of the same cohort) of cause-specific mortality and mesothelioma incidence, comparing observed with expected numbers (standardized mortality and incidence ratios) based on Piedmont regional rates
• Who was studied: 1,780 women married to male asbestos-cement workers at the Eternit plant in Casale Monferrato, Italy, at some time during the husband's employment there. The workers were employed on 1 January 1950 or hired between 1950 and 1986. Women who had worked at the plant were excluded. Follow-up ran to 30 April 2003, beyond the plant's closure in 1986. Mortality analyses covered 1965 to 2003 and ages under 80, giving 51,873 person-years.
• Exposure: Domestic (household) exposure through the husband's work at an asbestos-cement plant that used chrysotile and crocidolite. Work clothes were taken home for cleaning. Duration of exposure was estimated from the overlap of marriage and the husband's employment (mean 15.0 years).
• Main results:
  • In the cohort of wives, mortality from all causes and from all malignant neoplasms was near expectations (all causes: 396 observed vs 389.3 expected, SMR 1.02, 95% CI 0.92 to 1.12).
  • Pleural cancer mortality among the wives was significantly increased: 21 observed vs 1.2 expected, SMR 18.00 (95% CI 11.14 to 27.52).
  • Lung cancer mortality among the wives was not significantly increased: 12 observed vs 10.3 expected, SMR 1.17 (95% CI 0.60 to 2.04). Peritoneal neoplasm (3 observed vs 1.2 expected) and ovarian cancer (11 observed vs 7.7 expected) also did not show a statistically significant increase.
  • Incidence of histologically or cytologically confirmed pleural mesothelioma in the wives during 1990 to 2001, with women censored at 80 years of age: 11 cases observed vs 0.44 expected, SIR 25.19 (95% CI 12.57 to 45.07). One further incident mesothelioma case was observed after 80 years of age.
  • Pleural cancer SMRs were higher with longer duration of domestic exposure. They were significantly increased from 30 years after first exposure. Only one incident mesothelioma case occurred before 30 years of latency.
  • By calendar period of first exposure there were no statistically significant differences, although there was a suggestion of lower risks in more recent periods.
  • Among the women with mesothelioma, four also had fathers occupationally exposed at the Eternit plant. One had worked as a goldsmith for 12 years, with possible asbestos exposure.
  • Mortality was significantly increased for psychiatric disorders and poorly defined causes, and significantly decreased for diabetes and external causes. The authors stated that none of these causes is thought to be related to asbestos exposure.
• The authors' conclusion: The authors concluded that household exposure among women married to asbestos workers increased the risk of mesothelioma. They found the increase was limited to pleural mesothelioma and was not observed for other diseases associated with occupational asbestos exposure, such as lung cancer.
• Limitations the authors state:
  • There was no quantitative information on the extent of asbestos exposure in the homes.
  • Many women lived in Casale Monferrato, where environmental exposure occurred and may have contributed to the observed risk. Full residential history was not included in the analysis.
  • Statistical power for lung cancer was limited: 53% power to detect a relative risk of 1.65 and 82% power to detect a relative risk of 2.
  • Analyses were limited to ages under 80, and a loss of incident mesothelioma cases at older ages seemed likely. Above age 80 there were 3 pleural cancer deaths against 0.2 expected and 1 lung cancer death against 1.64 expected.
  • The unexposed cohort was not analysed because results were statistically unstable due to small numbers.

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: Mesothelioma, Casale Monferrato, Eternit, Asbestos-Cement, Latency, standardized mortality ratio (SMR), confidence interval, Lung Cancer.

Related studies

• 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)
• 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)
• Mortality and mesothelioma incidence among chrysotile asbestos miners in Balangero, Italy: A cohort study — D. Ferrante, D. Mirabelli, et al. (2020)
• Environmental Health Education for Asbestos-Contaminated Communities in Italy: The Casale Monferrato Case Study — D. Marsili, A. Canepa, et al. (2019)
• Para-occupational exposures to asbestos: lessons learned from Casale Monferrato, Italy — L.T. Stayner (2016)
• Mortality in asbestos cement workers in Pavia, Italy: A cohort study — E. Oddone, D. Ferrante, et al. (2017)

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