Causes of death in former asbestos-cement workers in the state of São Paulo, Brazil

Our plain-English summary of Causes of death in former asbestos-cement workers in the state of São Paulo, Brazil, by G.A. Fernandes, E. Algranti, V. Wunsch-Filho, et al (American Journal of Industrial Medicine, 2021).

The study

• Authors: G.A. Fernandes, E. Algranti, V. Wunsch-Filho, L.F. Silva, T.N. Toporcov
• Journal: American Journal of Industrial Medicine
• Published: 2021;64(11):952-959
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: In low- and middle-income countries, such as Brazil, studies on the causes of death in asbestos-exposed workers are scarce.

Methods: A cohort study was performed involving 988 males who had worked in the asbestos-cement industry in the state of São Paulo, with a total of 12,217 person-years of observation between 1995 and 2016. The standardized mortality ratio (SMR) stratified by age was calculated as the ratio between the observed rate and the expected rate in the state of São Paulo.

Results: Increased SMRs were observed for overall mortality (SMR 1.1, 95% confidence interval [CI], 0.98-1.23) and mortality due to pleural malignant neoplasms (MN) (SMR, 69.4; 95% CI, 22.55-162.1), asbestosis (SMR, 975.7; 95% CI, 396.4-2031), peritoneal MN (SMR, 5.0; 95% CI, 0.13-27.78), laryngeal MN (SMR, 1.4; 95% CI, 0.30-4.20), and pulmonary MN (SMR, 1.5; 95% CI, 0.82-2.64).

Conclusion: The present study highlights the damage caused by asbestos exposure and reinforces the existing evidence of a causal association between exposure and increased mortality due to pleural MN, pulmonary MN, and asbestosis.

© 2021 Wiley Periodicals LLC.

In plain English

This cohort study followed 988 men who had worked at an asbestos-cement plant in Osasco, São Paulo state, Brazil. The plant operated from 1941 to 1992. Chrysotile was the main fiber used there, and amphibole fibers, used mainly in tubes, stopped in 1979. The men joined the study between 1995 and 2016 and contributed 12,217 person-years of observation. Their deaths were compared with the number expected among men in São Paulo state. By the end of follow-up, 298 had died and 329 could not be traced. Deaths were raised for pleural malignant neoplasms (five deaths; SMR 69.4, 95% CI 22.55–162.1), asbestosis (seven deaths; SMR 975.7, 95% CI 396.4–2031) and respiratory organ cancers (SMR 1.9, 95% CI 1.20–2.96). Overall deaths (SMR 1.1, 95% CI 0.98–1.23) and lung cancer deaths (SMR 1.5, 95% CI 0.82–2.64) were higher than expected, but these intervals included 1. The authors concluded that the study reinforces existing evidence of an association between fiber exposure and increased deaths from pleural cancer, lung cancer and asbestosis. They noted possible selection bias and that about one-third of the men were lost to follow-up.

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 mortality study using standardized mortality ratios (SMRs), with the state of São Paulo as the comparison population; the cohort was a convenience sample
• Who was studied: 988 male former workers of an asbestos-cement plant in Osasco, São Paulo state, Brazil (plant operated 1941–1992), enrolled from June 1995 to December 31, 2016 through the Brazilian Association of Asbestos Exposed (ABREA); 12,217 person-years of observation. Eight women and two men with inconsistent data were excluded.
• Exposure: Work in an asbestos-cement plant making flat and corrugated sheets, tubes, water tanks and small molded roofing items. Chrysotile was the main fiber. Amphibole fibers, used mainly in tubes, were used until 1979. Only chrysotile was used from 1979 to 1992. 53.2% of the men were exposed for less than 10 years.
• Main results:
  • At the end of follow-up, 361 (36.5%) of the 988 men were alive, 298 (30.2%) had died and 329 (33.3%) had been lost to follow-up.
  • Pleural malignant neoplasms in the cohort: five deaths, SMR 69.4 (95% CI 22.55–162.1).
  • Asbestosis in the cohort: seven deaths, SMR 975.7 (95% CI 396.4–2031).
  • Respiratory organ malignant neoplasms in the cohort: SMR 1.9 (95% CI 1.20–2.96).
  • Overall mortality in the cohort: SMR 1.1 (95% CI 0.98–1.23; table p value 0.10).
  • Pulmonary (lung) malignant neoplasms in the cohort: SMR 1.5 (95% CI 0.82–2.64), based on 13 observed deaths in the table.
  • Peritoneal malignant neoplasm in the cohort: one death, SMR 5.0 (95% CI 0.13–27.78).
  • Laryngeal malignant neoplasms in the cohort: SMR 1.4 (95% CI 0.30–4.20).
  • In a sensitivity analysis, the cohort's death rates were applied to 4,111 male workers registered at the plant (1955–1992). Results were similar for asbestos-related diseases. The SMR for laryngeal cancer was low, and the SMR for digestive organ cancers was significantly elevated.
• The authors' conclusion: The authors concluded that the study highlights the negative consequences of asbestos exposure in these former asbestos-cement workers. They concluded that it reinforces existing evidence of an association between fiber exposure and increased mortality from pleural malignant neoplasms, pulmonary malignant neoplasms and asbestosis. They recommended surveillance of causes of death among such workers in countries still using asbestos.
• Limitations the authors state:
  • The cohort was a convenience sample, so selection bias is possible. In 1995 and 1996, older and more exposed men tended to enroll.
  • Findings for digestive organ cancers and laryngeal cancer were poorly reproduced in the sensitivity analysis, possibly due to selection bias. The authors advised caution in interpreting them.
  • About one-third of the cohort was lost to follow-up. Those lost were younger and had shorter exposure, and the authors judged it unlikely that they consistently skewed the findings.
  • Mortality analyses are not sensitive for diseases with long survival, such as laryngeal cancer.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Cohort Study, standardized mortality ratio (SMR), confidence interval, Neoplasm, Asbestos Exposure.

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