Mortality and cancer incidence among Lithuanian cement producing workers

Our plain-English summary of Mortality and cancer incidence among Lithuanian cement producing workers, by G. Smailyte, J. Kurtinaitis, A. Andersen (Occupational and Environmental Medicine, 2004).

The study

• Authors: G. Smailyte, J. Kurtinaitis, A. Andersen
• Journal: Occupational and Environmental Medicine
• Published: 2004;61(6):529-34
• Cited by: 55 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Aims: To investigate mortality and cancer incidence of cement producing workers.

Methods: A total of 2498 cement workers who have been employed at Portland cement producing departments for at least one year from 1956 to 2000 were followed up from 1 January 1978 to 31 December 2000. The cohort contributed 43,490 person-years to the study. Standardised incidence ratios (SIR) and standardised mortality ratios (SMR) were calculated as ratios between observed and expected numbers of cancers and deaths. The expected numbers were based on sex specific incidence and mortality rates for the total Lithuanian population.

Results: Significantly increased SMRs were found for all malignant neoplasms (SMR 1.3, 95% CI 1.0 to 1.5) and for lung cancer (SMR 1.4, 95% CI 1.0 to 1.9) among male cement workers. SIR for all cancer sites was 1.2 (95% CI 1.0 to 1.4). Excess risk was found for cancer of the lung (SIR 1.5, 95% CI 1.1 to 2.1). The SIR for urinary bladder cancer was also increased (SIR 1.8, 95% CI 0.9 to 3.5). The overall cancer incidence was not increased among females (SIR 0.8, 95% CI 0.6 to 1.1). With increasing cumulated exposure to cement dust, there were indications of an increasing risk of lung and stomach cancers among males.

Conclusions: This study supported the hypothesis that exposure to cement dust may increase the lung and bladder cancer risk. A dose related risk was found for stomach cancer, but no support was found for an increased risk of colorectal cancer.

In plain English

This cohort study compared deaths and cancers from 1978 to 2000 among 2498 workers (1727 men, 771 women), each employed at least a year in Portland cement production at Lithuania's only cement factory, with national rates. Among men, deaths from all cancers (SMR 1.3, 95% CI 1.0 to 1.5) and lung cancer (SMR 1.4, 95% CI 1.0 to 1.9) exceeded expectations, as did lung cancer incidence (SIR 1.5, 95% CI 1.1 to 2.1). Men's bladder cancer SIR was 1.8 (95% CI 0.9 to 3.5). Women's overall cancer incidence was not increased. Men's lung cancer was significantly raised in the two highest cumulative dust groups (trend p = 0.3). Stomach cancer in men rose with cumulative dust exposure (trend p less than 0.05), although overall incidence was below expected (SIR 0.7, 95% CI 0.4 to 1.3; 11 cases). Excluding 389 workers also employed in asbestos cement, men's lung cancer SIR was 1.4 (95% CI 1.0 to 2.0; 34 cases). One man had mesothelioma (0.3 expected) and no known asbestos exposure at the factory. The authors, lacking individual smoking data, concluded cement dust may increase lung and bladder cancer risk.

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 study of mortality (standardised mortality ratios) and cancer incidence (standardised incidence ratios), compared with the total Lithuanian population
• Who was studied: 2498 workers (1727 males, 771 females) of 2662 identified, employed at least 12 months in cement producing departments of the Akmenes cementas factory, Naujoji Akmene, Lithuania, between 1956 and 2000. Administration staff were excluded. Follow-up ran from 1 January 1978 to 31 December 2000 (43 490 person-years).
• Exposure: Cement dust from Portland cement production. It was estimated from stationary annual total dust measurements by department from 1975, which were used to calculate individual cumulative exposure. 389 of the workers had also worked in asbestos cement production at the same enterprise.
• Main results:
  • Overall mortality among male cement workers was not increased (SMR 1.0, 95% CI 0.9 to 1.1).
  • Among males, death from malignant neoplasms was increased (SMR 1.3, 95% CI 1.0 to 1.5), mainly due to lung cancer mortality (SMR 1.4, 95% CI 1.0 to 1.9). The discussion calls the lung cancer mortality excess borderline significant.
  • No excess mortality from non-malignant respiratory diseases was found among males (SMR 0.8, 95% CI 0.5 to 1.3).
  • Male cement workers had 141 cancer cases observed against 115.3 expected (SIR 1.2, 95% CI 1.0 to 1.4).
  • Lung cancer incidence among male workers was significantly increased (44 cases; SIR 1.5, 95% CI 1.1 to 2.1).
  • Among males, the SIR for skin cancer was 1.4 (95% CI 0.8 to 2.5) and the SIR for urinary bladder cancer was 1.8 (95% CI 0.9 to 3.5; 8 cases).
  • Among males, stomach cancer cases were lower than expected overall: 11 cases, SIR 0.7. Table 4 gives the 95% CI as 0.4 to 1.3; the results text prints 0.2 to 2.1.
  • Among female workers, overall cancer incidence was not increased (SIR 0.8, 95% CI 0.6 to 1.1).
  • One case of mesothelioma was found among males versus 0.3 expected. It occurred in a 42-year-old worker with less than two years of exposure in raw material preparation, and he had no known asbestos exposure at the factory.
  • When the 389 workers who had also worked in asbestos cement production were excluded, the lung cancer SIR was 1.4 (95% CI 1.0 to 2.0; 34 cases) in males and 2.0 (95% CI 0.7 to 6.3; 3 cases) in females.
  • Among male workers, stomach cancer showed an increasing trend with increasing cumulative dust exposure (p less than 0.05).
  • Among males, lung cancer risk was significantly increased in the two highest cumulative exposure groups (55.4 to 130.2: SIR 2.0, 95% CI 1.2 to 3.4; above 130.2: SIR 1.8, 95% CI 1.1 to 3.0). The test for trend was not significant (p = 0.3).
• The authors' conclusion: The authors concluded that the study supported the hypothesis that cement dust exposure may increase the risk of lung and bladder cancer. They found a dose-related risk for stomach cancer and no support for an increased risk of colorectal cancer. They added that more studies are needed before a final conclusion.
• Limitations the authors state:
  • Cumulative dust exposure was probably misclassified. It was based on stationary department-level measurements, with all workers in a department given the same level, so differences between job tasks were not reflected.
  • No individual smoking data were available.
  • The whole Lithuanian population was used as the reference. Blue collar workers smoke more, and using them as the reference would have brought the results closer to unity.
  • The observed excess of bladder cancer suggests that smoking could have been a confounder.
  • Loss to follow-up was a problem, especially before 1978.
  • Results for specific cancer sites among females were based on few cases.

Topics

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

Medical terms in this study, explained in our Lexicon: Standardized Incidence Ratio (SIR), Neoplasm, Lung Cancer, Stomach Cancer, Colorectal Cancer.

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• Radiographic asbestosis is not a prerequisite for asbestos-associated lung cancer in Ontario asbestos-cement workers — M.M. Finkelstein (1997)
• Respiratory health in Turkish asbestos cement workers: the role of environmental exposure — I. Akkurt, B. Onal, et al. (2006)

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