Pleural mesothelioma mortality and asbestos exposure mapping in Italy

Our plain-English summary of Pleural mesothelioma mortality and asbestos exposure mapping in Italy, by L. Fazzo, M. De Santis, G. Minelli, et al (American Journal of Industrial Medicine, 2012).

The study

• Authors: L. Fazzo, M. De Santis, G. Minelli, C. Bruno, A. Zona, A. Marinaccio, S. Conti, P. Comba
• Journal: American Journal of Industrial Medicine
• Published: 2012;55(1):11-24
• Cited by: 39 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: An epidemic of asbestos-related diseases is ongoing worldwide. Mortality from malignant pleural neoplasms in Italy was analyzed, to estimate the health impact of asbestos at national and local level.

Methods: Mortality from ICD-9 code 163 was considered, in the time-window 1995-2002, using National Bureau of Statistics data. National and regional standardized rates and municipal Standardized Mortality Ratios (SMR) were calculated. Municipal clusters were identified by applying Spatial Scan Statistics procedure. Relative risks (RR) express the ratio of risk within the cluster to the risk outside the cluster.

Results: The national standardized annual mortality rate was 1.9 per 100,000. Significant clusters corresponded to asbestos-cement industries (Casale Monferrato: RR = 11.63), shipyards (Monfalcone, RR = 7.43), oil refineries (Falconara, RR = 2.52), petrochemical industries (Priolo, RR = 3.81).

Conclusions: The present study confirms malignant pleural neoplasms mortality as a suitable indicator of asbestos exposure at geographic level. In addition to asbestos-cement industries and shipyards, other industrial settings are associated with pleural neoplasm mortality.

Copyright © 2011 Wiley Periodicals, Inc.

In plain English

Using national death records for 1995–2002, the authors mapped deaths from malignant pleural neoplasms (ICD-9 code 163) across all 8,100 Italian municipalities. These deaths were used as a stand-in for pleural mesothelioma. The authors compared observed with expected deaths and searched for geographic clusters. The national standardized annual rate was 1.9 per 100,000, and 202 municipalities had significantly raised standardized mortality ratios. Relative risks compare risk inside a cluster with risk outside it. Men's clusters included the area around the Casale Monferrato asbestos-cement industry (11.63; 21.96 in the women's cluster there), a shipbuilding area including Monfalcone (7.43), the Falconara oil refinery area (2.52), which earlier national studies had not detected, and the Priolo industrial area with a refinery and petrochemical industry (3.81). Women's clusters included fewer municipalities. The authors noted that the death code overcounted mesothelioma by about 20%, though they argued estimated risks were not inflated. They also noted that residence at death only approximates residence at exposure. They concluded that pleural mesothelioma mortality is a suitable population indicator of past asbestos exposure and that most clusters can be explained by occupational 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: Geographic (municipal-level) mortality study using national death data, with standardized mortality ratios for each municipality and a spatial cluster analysis (Spatial Scan Statistics, SatScan software)
• Who was studied: Residents of all 8,100 Italian municipalities, using deaths and population data from the National Bureau of Statistics (ISTAT) for 1995–2002, by 5-year age class and gender
• Exposure: Asbestos exposure was not measured directly. The authors linked clusters to potential local sources of asbestos exposure: asbestos-cement industries, shipbuilding and repair, asbestos textile industries, oil refineries, petrochemical plants, railway carriage construction and repair, and hazardous waste dumping sites. In Biancavilla, the source was naturally occurring fluoro-edenite fibres.
• Main results:
  • The national standardized annual mortality rate from malignant pleural neoplasm was 1.9 per 100,000 inhabitants. In the 40- to 75-year age class it was 4.91 in men and 1.71 in women.
  • Some northern regions had the highest standardized rates: Piemonte 3.3, Lombardia 2.5, Liguria 6.0, and Friuli Venezia Giulia 3.5 per 100,000.
  • 202 municipalities had significantly increased standardized mortality ratios (SMRs).
  • Among the highest municipal SMRs, as printed in the article: Casale Monferrato (asbestos-cement factories), SMR 2,734 (95% CI 2,351–3,161); Monfalcone (shipyards), SMR 757 (95% CI 541–1,031).
  • Biancavilla, where fluoro-edenite fibres naturally occur, had an SMR of 495 (95% CI 237–911).
  • Men's cluster centred on Casale Monferrato (asbestos-cement industry): 132 deaths observed versus 11.91 expected, relative risk 11.63. Women's cluster there: 111 observed versus 5.50 expected, relative risk 21.96.
  • Men's cluster centred on San Pier d'Isonzo, including Monfalcone (shipbuilding and repair): 79 observed versus 11.70 expected, relative risk 7.43. Women's cluster centred on Monfalcone: relative risk 6.18.
  • Men's cluster around Falconara Marittima (oil refinery; shipbuilding and repair): 32 observed versus 12.90 expected, relative risk 2.52. The authors said earlier national mortality studies had not detected it.
  • Men's cluster around Priolo Gargallo (refinery and petrochemical industry; asbestos-cement industry; shipbuilding and repair): 19 observed versus 5.21 expected, relative risk 3.81.
  • There were more significant clusters among men than among women in all macro-areas. The authors said this supports a significant role for occupational exposure.
  • Fifteen of the 27 clusters included municipalities already defined as polluted sites of national interest for environmental remediation.
  • For one women's cluster (Frugarolo), no potential source of asbestos exposure could be identified.
• The authors' conclusion: The authors concluded that pleural mesothelioma mortality at population level is a suitable indicator of previous asbestos exposure. They found excess risk not only near asbestos-cement industries and shipyards but also where oil refineries, petrochemical plants, textile industries, and railway carriage facilities operate. They concluded that most clusters can be explained by occupational asbestos exposure, with environmental exposures possibly contributing in a limited number of sites.
• Limitations the authors state:
  • The ICD-9 code 163 covers all malignant pleural neoplasms and overestimated pleural mesothelioma cases by about 20%. The authors argued that estimated risks would not be overestimated, because the overcount affects both observed and expected figures.
  • Municipal SMRs are vulnerable to random error, partly because of small numbers of observed cases.
  • Because of latency, residence at time of death is only a proxy for residence at the time of the relevant exposure.
  • Death certification for pleural mesothelioma produces both false negatives and false positives.

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, Asbestos Exposure, Neoplasm, standardized mortality ratio (SMR), Relative Risk, Asbestos-Cement, Casale Monferrato.

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• Peritoneal mesothelioma mortality in Italy: Spatial analysis and search for asbestos exposure sources — A. Zona, L. Fazzo, et al. (2019)
• Asbestos-related lung cancer mortality in Piedmont, Italy — M. Martuzzi, P. Comba, et al. (1998)
• Peritoneal mesothelioma in Italy: Trends and geography of mortality and incidence — S. Conti, G. Minelli, et al. (2015)
• The Epidemiological Surveillance of Mesothelioma Mortality in Italy as a Tool for the Prevention of Asbestos Exposure — L. Fazzo, G. Minelli, et al. (2023)

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