Mortality from cancer and other causes in the Balangero cohort of chrysotile asbestos miners

Our plain-English summary of Mortality from cancer and other causes in the Balangero cohort of chrysotile asbestos miners, by E. Pira, C. Pelucchi, P.G. Piolatto, et al (Occupational and Environmental Medicine, 2009).

The study

• Authors: E. Pira, C. Pelucchi, P.G. Piolatto, E. Negri, T. Bilei, C. La Vecchia
• Journal: Occupational and Environmental Medicine
• Published: 2009;66(12):805-9
• Cited by: 43 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: To provide further information on mortality from cancer and other causes among chrysotile asbestos miners several years after exposure ceased, we updated the analyses from the Balangero mine worker cohort with follow-up to the end of 2003.

Methods: The cohort included 1056 men, for a total of 34 432 man-years of observation. We obtained employment data from factory personnel records, and ascertained vital status and causes of death through population registers and death certificates from municipal registration offices. We computed expected numbers of deaths and standardised mortality ratios (SMRs) for relevant causes using the province of Turin and national death rates, for each 5-year calendar period and age group.

Results: We found a significant excess mortality from pleural cancer only (4 deaths, SMR 4.67) and pleural and peritoneal cancers combined (5 deaths, SMR 3.16). All pleural and peritoneal cancer deaths occurred 30 or more years after first exposure. The SMRs were 1.27 for lung cancer (45 deaths), 1.82 for laryngeal cancer (8 deaths) and 1.12 for all cancers (142 deaths). Cumulative dust exposure and the various time factors considered did not show a clear pattern of risk associated with mortality from lung cancer. There were 57 deaths from cirrhosis (SMR 2.94) and 54 from accidents and violence (SMR 1.88). Overall, we observed a total of 590 deaths as compared to 412.9 expected (SMR 1.43).

Conclusions: This updated analysis, with almost 60% of the cohort having died, confirmed the excess mortality from pleural and peritoneal cancers and from several alcohol-related causes.

In plain English

This study updated the follow-up of 1056 men who worked at the Balangero chrysotile asbestos mine near Turin, Italy, tracking deaths to the end of 2003 or age 80, whichever came first (34 432 man-years). Exposure was estimated in cumulative fibre-years. There were 590 deaths against 412.9 expected (standardised mortality ratio, SMR, 1.43). Deaths from pleural cancer (4 observed vs 0.9 expected, SMR 4.67) and from pleural and peritoneal cancers combined (5 vs 1.6, SMR 3.16) were significantly raised. All five occurred 30 or more years after first exposure. Lung cancer (45 deaths, SMR 1.27) and laryngeal cancer (8 deaths, SMR 1.82) were higher than expected, but not statistically significantly so. Lung cancer showed no clear pattern with cumulative dust exposure. There were 21 asbestosis deaths. Cirrhosis (57 deaths, SMR 2.94) and accidents and violence (54 deaths, SMR 1.88) were significantly raised. The authors concluded that the update confirmed excess deaths from pleural and peritoneal cancers and from several alcohol-related causes. They noted that reliance on death certificates, small numbers of cases and uncertain early exposure estimates limited the analysis.

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: Retrospective cohort mortality study; an update of an existing cohort, with deaths compared to expected numbers (standardised mortality ratios) based on Turin province and Italian national death rates
• Who was studied: 1056 men who started work at the Balangero mine (about 30 km north west of Turin, Italy) between 1 January 1930 and 31 December 1975. Follow-up ran from 1946 (or first employment) to 31 December 2003 or age 80, whichever came first, for 34 432 man-years in total. Deaths and man-years beyond age 80 were excluded. By the end, 590 (56%) had died, 422 (40%) were alive and 44 (4%) had emigrated or were lost to follow-up.
• Exposure: Chrysotile asbestos from mining, measured as cumulative inhaled fibres in fibre-years. These were estimated from environmental measurements from 1969 onwards and from artificially recreated working conditions for earlier periods. The authors report that samples showed no detectable fibrous amphibole contamination. A fibrous silicate called balangeroite made up 0.2 to 0.5% of the mine's chrysotile.
• Main results:
  • Whole cohort, pleural cancer: 4 deaths observed vs 0.9 expected, SMR 4.67 (95% CI 1.27 to 11.96), statistically significant
  • Whole cohort, pleural and peritoneal cancers combined: 5 deaths observed vs 1.6 expected, SMR 3.16 (95% CI 1.02 to 7.36), statistically significant
  • All five pleural and peritoneal cancer deaths occurred 30 or more years after first exposure
  • Four of the five pleural and peritoneal cancer deaths occurred in men who had been exposed for 20 or more years, first exposed before 1946, and in the highest cumulative exposure category (400 fibre-years or more)
  • Whole cohort, lung cancer: 45 deaths observed vs 35.5 expected, SMR 1.27 (95% CI 0.93 to 1.70), not statistically significant
  • Lung cancer showed no clear pattern of risk with cumulative dust exposure or the time factors considered
  • Lung cancer SMRs by cumulative dust exposure were 0.83 below 100 fibre-years, 1.57 for 100 to below 400 fibre-years, and 1.37 for the highest category. The authors described this as an inverted U shape.
  • Whole cohort, laryngeal cancer: 8 deaths observed vs 4.4 expected, SMR 1.82 (95% CI 0.78 to 3.59), not statistically significant
  • Whole cohort, all cancers: 142 deaths observed vs 126.3 expected, SMR 1.12 (95% CI 0.95 to 1.33), not statistically significant
  • There were 21 deaths from asbestosis. COPD and asbestosis combined: 40 deaths vs 17.4 expected, SMR 2.30 (95% CI 1.64 to 3.13).
  • Whole cohort, cirrhosis: 57 deaths vs 19.4 expected, SMR 2.94 (95% CI 2.23 to 3.81)
  • Whole cohort, accidents and violence: 54 deaths vs 28.8 expected, SMR 1.88 (95% CI 1.41 to 2.45)
  • Whole cohort, all causes: 590 deaths vs 412.9 expected, SMR 1.43 (95% CI 1.32 to 1.55)
  • The authors stated the study does not support an association with stomach and colorectal cancers. Stomach: 15 deaths, SMR 0.97. Intestine: 9 deaths, SMR 0.77.
• The authors' conclusion: The authors concluded that this update, with almost 60% of the cohort dead, confirmed excess mortality from pleural and peritoneal cancers and from several alcohol-related causes. They also attributed the laryngeal cancer increase at least in part to high alcohol consumption in the cohort.
• Limitations the authors state:
  • The exposure factors linked to pleural and peritoneal cancer were closely inter-related and cases were few, so their separate effects could not be distinguished
  • Using death certificates rather than cancer registries has inherent limitations. For example, one mesothelioma case known from a regional registry was recorded on the death certificate as lung cancer.
  • Dust exposure estimates were uncertain, especially before fibre counts began in 1969. The authors suggested this may explain the lack of a clear lung cancer trend.
  • The validity of the asbestosis diagnoses was unclear, given the large asbestosis excess without a large lung cancer excess
  • There was no employment end-date information after 1987. Workers still employed then were assumed to have stayed until production ceased in 1990.
  • Other possible explanations for the modest lung cancer association included exclusion of contract workers, healthy or unhealthy worker effects, and differences in smoking habits compared with the general population

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Balangero mine, Balangero, about 20 km north of Turin, Piedmont

All asbestos mines

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Balangero Mine, Death Certificate, Lung Cancer, Laryngeal Cancer.

Related studies

• An update of cancer mortality among chrysotile asbestos miners in Balangero, northern Italy — G. Piolatto, E. Negri, et al. (1990)
• Mortality from cancer and other causes among Italian chrysotile asbestos miners — E. Pira, C. Romano, et al. (2017)
• Mortality and mesothelioma incidence among chrysotile asbestos miners in Balangero, Italy: A cohort study — D. Ferrante, D. Mirabelli, et al. (2020)
• The 1891-1920 birth cohort of Quebec chrysotile miners and millers: development from 1904 and mortality to 1992 — F.D. Liddell, A.D. McDonald, et al. (1997)
• Mortality of Talc Miners and Millers From Val Chisone, Northern Italy: An Updated Cohort Study — E. Pira, M. Coggiola, et al. (2017)
• An update of cancer mortality among chrysotile asbestos miners in Balangero, northern Italy — R. Calisti, P. De Giuli, et al. (1992)

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