Mortality in a cohort of cement workers in a plant of Central Italy

Our plain-English summary of Mortality in a cohort of cement workers in a plant of Central Italy, by F. Giordano, V. Dell'orco, F. Fantini, et al (International Archives of Occupational and Environmental Health, 2012).

The study

• Authors: F. Giordano, V. Dell'orco, F. Fantini, F. Grippo, V. Perretta, A. Testa, I. Figà-Talamanca
• Journal: International Archives of Occupational and Environmental Health
• Published: 2012;85(4):373-9
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: Workers of cement production are exposed to alkaline dust with irritant effects on the respiratory system. Most previous studies have examined workers in cement/asbestos factories, but there is limited information of the effects of exposures to Portland cement alone. The present study examines the effects of cement dust in a cohort of Portland cement workers through the analyses of their mortality records.

Methods: Using the records of a cement plant, we reconstructed the work history of all 748 male employees between 1956 and 2006. SMRs were computed for overall mortality and for specific causes of death for the cohort compared with the reference population. The analysis was also performed by subdividing the cohort in low- and high-exposure groups on the basis of the task of the worker and the length of his exposure.

Results: The overall mortality of the cohort (SMR = 0.87) as well as the mortality from all cancers (SMR = 0.64) and from cancers of the respiratory system (SMR = 0.56) was significantly lower compared to the reference population. Workers of the cement plant with higher exposures did not have an increased mortality risk from any cause. The only significantly elevated risk observed among these workers was for cancer of the respiratory system (SMR = 2.86), exclusively in the small subgroup of 39 workers with previous exposure to a cement/asbestos plant.

Conclusions: Portland cement workers had a statistically significant reduced risk of overall mortality and of all cancers mortality probably due to the healthy workers effect. The study confirmed an increased risk of respiratory system cancer only in the subgroup with previous work exposure in a cement/asbestos plant.

In plain English

This retrospective cohort study examined deaths among 748 male workers at a Portland cement plant in the district of Rome, Italy. The plant never made cement–asbestos products. By June 30, 2006, 280 men had died. Death rates were compared with the Latium region's. Overall mortality was lower than expected (SMR 0.87; 95% CI 0.77–0.98). So was mortality from all cancers (SMR 0.64; 95% CI 0.48–0.82) and from cancers of the larynx, trachea, bronchus and lung (SMR 0.56; 95% CI 0.32–0.89). Deaths from non-cancer respiratory diseases were above expected (SMR 1.41; 95% CI 0.95–2.03), significant only at the 10% level, not the usual 5% level. No exposure subgroup had a statistically significant increase in all-cause deaths. The 39 men who had previously worked or lived in Casale Monferrato, a town with a cement–asbestos plant, had a non-significant all-cause SMR of 1.19 (95% CI 0.84–1.62) and 9 respiratory cancer deaths (SMR 2.86; 95% CI 1.30–5.42). No mesothelioma was reported in this group. The authors concluded that the low overall mortality was probably due to a 'healthy worker effect'. They noted that the records lacked smoking information.

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 using standardized mortality ratios (SMRs), with the Latium region as the main reference population
• Who was studied: 748 male workers of a Portland cement plant in the district of Rome, Italy. Work history was reconstructed for 1940–2006 and vital status followed to June 30, 2006. 280 had died, and the cause of death was unknown for 9. Cause-specific SMRs covered 1969–2006.
• Exposure: Portland cement dust. 'High exposure' meant unskilled production workers with at least 10 years of exposure; everyone else was 'low exposure'. The plant never manufactured cement–asbestos products, but 39 cohort members had previously worked or lived in Casale Monferrato, a town with a cement–asbestos plant. These 39 were analyzed separately and excluded from the high/low analysis. No fiber type is named.
• Main results:
  • Whole cohort: all-cause mortality was significantly lower than in the reference population (SMR 0.87; 95% CI 0.77–0.98; 280 observed vs 320.4 expected, 1956–2006).
  • Whole cohort: mortality from all cancers was significantly lower than expected (SMR 0.64; 95% CI 0.48–0.82; 59 observed vs 92.9 expected).
  • Whole cohort: cancers of the larynx/trachea/bronchus/lung were significantly lower than expected (SMR 0.56; 95% CI 0.32–0.89; 17 observed).
  • Whole cohort: malignant neoplasms of lymphoid/hematopoietic tissue were elevated but not statistically significant (SMR 1.42; 95% CI 0.65–2.70).
  • Whole cohort: diseases of the respiratory system were elevated (SMR 1.41; 95% CI 0.95–2.03; 29 observed vs 20.5 expected). This was not significant at the 95% level but was significant at the 10% level (p less than 0.10).
  • Exposure subgroups: the authors reported no increase in all-cause mortality in any subgroup. Table 3 shows the high-exposure group's all-cause SMR was 0.84 (95% CI 0.73–0.96, 1956–2006). The prior cement–asbestos subgroup had an elevated but not statistically significant all-cause SMR: 1.19 (95% CI 0.84–1.62) for 1956–2006 and 1.26 (95% CI 0.89–1.74) for 1969–2006.
  • Respiratory disease mortality was higher in both the low- and high-exposure groups without previous asbestos exposure, but the increase was not statistically significant.
  • Subgroup of 39 with previous exposure to the Casale Monferrato cement–asbestos plant: 9 deaths from respiratory system cancer (SMR 2.86; 95% CI 1.30–5.42). All-cancer mortality in this subgroup was SMR 1.49 (95% CI 0.82–2.50), not statistically significant.
  • No case of mesothelioma was reported in the subgroup previously exposed to asbestos.
• The authors' conclusion: The authors concluded that the Portland cement workers did not show increased overall mortality, probably because of a 'healthy worker effect'. They also found no increase in all-cancer or respiratory cancer mortality. They confirmed a respiratory cancer risk in the subgroup with previous exposure to a cement/asbestos plant. They described the increase in non-cancer respiratory disease mortality as associated with Portland cement exposure, though not statistically significant.
• Limitations the authors state:
  • The workers' records did not include information on smoking.
  • Using the general population as the reference may introduce a 'healthy worker effect' bias. The authors say this could be avoided by comparing with similar workers not exposed to cement production.

Topics

Medical terms in this study, explained in our Lexicon: Occupational History.

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)
• A mortality cohort study among workers in a graphite electrode production plant in Italy — D.F. Merlo, S. Garattini, et al. (2004)
• Mortality in asbestos cement workers in Pavia, Italy: A cohort study — E. Oddone, D. Ferrante, et al. (2017)
• Cumulative asbestos exposure and mortality from asbestos related diseases in a pooled analysis of 21 asbestos cement cohorts in Italy — F. Luberto, D. Ferrante, et al. (2019)
• Mortality among workers in the geothermal power plants at Larderello, Italy — E. Pira, M. Turbiglio, et al. (1999)
• Cohort mortality study of rock salt workers in Italy — M. Tarchi, D. Orsi, et al. (1994)

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