A cohort mortality study of construction workers

Our plain-English summary of A cohort mortality study of construction workers, by J. Sun, E. Shibata, N. Hisanaga, et al (American Journal of Industrial Medicine, 1997).

The study

• Authors: J. Sun, E. Shibata, N. Hisanaga, M. Kamijima, G. Ichihara, J. Huang, M. Toida, Y. Takeuchi
• Journal: American Journal of Industrial Medicine
• Published: 1997;32(1):35-41
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This report presents a mortality study among the 17,344 members of the Construction Workers' Health Insurance Society of Mie Prefecture in Japan. The study period was between 1973 and 1993. During this period, 480 members died. Age-specific mortality rates of Mie Prefecture were used as comparison standards. Significantly elevated standardized mortality ratio (SMR) and proportionate mortality ratio (PMR) were observed for "accidents and adverse effects." In addition, the PMRs of all cancers and "cancers of trachea, bronchus and lung" were also significantly elevated. The job classifications were reorganized into three groups, according to the frequency of asbestos exposure the workers experienced on the construction sites. The asbestos exposure was based on job classifications among 7,411 workers who had completed a self-administered survey questionnaire. In the frequent-exposure group, the PMR was significantly elevated for all cancers. In the medium-exposure group, the SMRs were significantly elevated for all cancers and "cancer of trachea, bronchus and lung." The PMR was significantly elevated for "cancer of trachea, bronchus and lung." In the less-exposure, group, the PMR was significantly elevated for "accidents and adverse effects." This study provided support for the hypothesis that working in the construction industry might be associated with high risks for asbestos-associated cancers and accidental deaths.

In plain English

This cohort study followed 17,344 men in the Construction Workers' Health Insurance Society of Mie Prefecture, Japan, each a member for at least one year between 1973 and 1993. Standardized mortality ratios (SMRs) compared the 479 analysed deaths with numbers expected from Mie Prefecture age-specific death rates. Proportionate mortality ratios (PMRs) compared each cause's share of deaths with its share in Mie Prefecture. Trades were grouped by asbestos-exposure frequency (frequent, medium, less) using a 1987 questionnaire of 7,411 members. Accident and adverse-effect deaths were significantly raised cohort-wide (SMR 1.30, 95% CI 1.02 to 1.62, 75 deaths). PMRs were significantly raised for all cancers (1.35, 95% CI 1.17 to 1.55, 197 deaths) and for cancers of trachea, bronchus and lung (1.55, 95% CI 1.09 to 2.15, 36 deaths). In the medium-exposure group, the SMR for cancers of trachea, bronchus and lung was 2.03 (95% CI 1.05 to 3.54, 12 deaths). The authors concluded the study supported the hypothesis that construction work might be associated with high risks for asbestos-associated cancers and accidental deaths. They noted that 30% of members left early, which could bias results.

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: Historical (retrospective) cohort mortality study. Standardized mortality ratios (SMRs) compared observed deaths with deaths expected from Mie Prefecture age-specific mortality rates. Proportionate mortality ratios (PMRs) compared the proportions of deaths from each cause, using total deaths in place of person-years.
• Who was studied: 17,344 male members, aged 20 to 75, of the Construction Workers' Health Insurance Society of Mie Prefecture, Japan, who each belonged for at least one year between April 2, 1973 and April 1, 1993; 480 died, of whom 479 deaths were analysed
• Exposure: Construction work, with trades grouped by reported frequency of asbestos dust exposure in a 1987 self-administered questionnaire of 7,411 members. Group I (frequent exposure) was carpenters and sheet metal workers. Group II (medium exposure) was interior finish workers, steel-frame workers, electricians, painters, plasterers and plumbers. Group III (less exposure) was the remaining 35 job categories. No fiber types or doses were measured for this cohort.
• Main results:
  • Whole cohort: the SMR for accidents and adverse effects was 1.30 (95% CI 1.02 to 1.62, 75 deaths), the only cause with a significantly elevated SMR
  • Whole cohort: the PMR for all cancers was 1.35 (95% CI 1.17 to 1.55, 197 deaths)
  • Whole cohort: the PMR for cancer of trachea, bronchus and lung was 1.55 (95% CI 1.09 to 2.15, 36 deaths)
  • Whole cohort: deaths from all causes, heart failure and cerebrovascular disease were significantly lower than expected (all-cause SMR 0.86, 95% CI 0.78 to 0.94)
  • Frequent-exposure group (carpenters and sheet metal workers): the PMR for all cancers was 1.40 (95% CI 1.14 to 1.70, 103 deaths)
  • Medium-exposure group: the SMR for all cancers was 1.35 (95% CI 1.00 to 1.78, 50 deaths)
  • Medium-exposure group: the SMR for cancers of trachea, bronchus and lung was 2.03 (95% CI 1.05 to 3.54), based on 12 deaths
  • Medium-exposure group: the PMR for cancers of trachea, bronchus and lung was 2.01 (95% CI 1.04 to 3.51), based on 12 deaths
  • Less-exposure group: the PMR for accidents and adverse effects was 1.76 (95% CI 1.06 to 2.75, 19 deaths)
  • Less-exposure group: the SMR for accidents and adverse effects was 1.55 (95% CI 0.93 to 2.42), which was not statistically significant
• The authors' conclusion: The authors concluded that the study supported the hypothesis that working in the construction industry might be associated with high risks for asbestos-associated cancers and accidental deaths
• Limitations the authors state:
  • 30% of members (5,237) withdrew from the Society before follow-up ended and were treated as lost to follow-up
  • Because of withdrawals, the authors thought the raised accident SMR might be overestimated and the raised cancer SMRs in the medium-exposure group underestimated
  • Exposure grouping came from a survey of a single year (1987), while the study covered 20 years
  • The number of deaths was too small to assess risk by individual job
  • Statistical power was lower for Groups II and III than for Group I
  • PMRs are affected by changes in deaths from other causes

Topics

Medical terms in this study, explained in our Lexicon: standardized mortality ratio (SMR), Bronchus, Asbestos Exposure.

Related studies

• All-cause and cause specific mortality in a cohort of 20 000 construction workers; results from a 10 year follow up — V. Arndt, D. Rothenbacher, et al. (2004)
• Protest and survive, the U.K. Construction Safety Campaign: a case study of workers' and victims' family action and legal and regulatory inaction on construction health and safety — M. Holder, T. O'Brien (2007)
• Assessment of mortality in the construction industry in the United States, 1984-1986 — C. Robinson, F. Stern, et al. (1995)
• Mortality among North Carolina construction workers, 1988-1994 — E. Wang, J.M. Dement, et al. (1999)
• Proportionate mortality among construction laborers — F. Stern, P. Schulte, et al. (1995)
• A historical cohort mortality study of workers exposed to asbestos in a refitting shipyard — N. Kurumatani, Y. Natori, et al. (1999)

Browse more research in American Journal of Industrial Medicine, or return to medical research.