Proportionate mortality among unionized construction ironworkers

Our plain-English summary of Proportionate mortality among unionized construction ironworkers, by F.B. Stern, M.H. Sweeney, E. Ward (American Journal of Industrial Medicine, 1997).

The study

• Authors: F.B. Stern, M.H. Sweeney, E. Ward
• Journal: American Journal of Industrial Medicine
• Published: 1997;31(2):176-87
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This report presents the results of proportionate mortality ratios (PMR) and proportionate cancer mortality ratios (PCMR) among 13,301 members of the International Union of Bridge, Structural, and Ornamental Ironworkers who had been members for a minimum of 1 year, were actively paying dues into the death beneficiary fund, and had died between 1984-1991. Using the United States proportionate mortality rates as the comparison population, statistically significant elevated risks, using 95% confidence intervals (CI), were observed for several types of injuries: falls (N = 259, PMR = 3.57, CI = 3.15-4.03), transportation injuries (N = 363, PMR = 1.22, CI = 1.10-1.35), and other types of injuries (N = 225, PMR = 1.63, CI = 1.43-1.86). The deaths due to falls were significantly elevated for each 10-year age group under age 60 (PMR > 7.00) and for those workers with < 20 years in the union (PMR > 6.00). Elevated mortality risks were also observed for all malignant neoplasms combined (N = 3,682, PMR = 1.09, CI = 1.06-1.13) as well as for site-specific malignant neoplasms of the lung (N = 1,523, PMR = 1.28, CI = 1.21-1.35), pleural mesothelioma (N = 7, PMR = 1.67, CI = 0.67-3.44) and "other and unspecified sites" (N = 307, PMR = 1.29, CI = 1.15-1.44). The category "pneumoconiosis and other respiratory diseases" was also significantly elevated (N = 690, PMR = 1.11, CI = 1.03-1.20); in this category, deaths due to asbestosis had the greatest elevated risk (N = 10, PMR = 3.56, CI = 1.70-6.54). No elevation in risk was found for kidney cancer or for chronic nephritis which were of interest because of Ironworkers' potential exposure to lead. The present study underscores the importance of fall protection and other injury prevention efforts in the construction industry, as well as the need to control airborne exposures to asbestos, welding fumes and other respirable disease hazards.

In plain English

This study looked at causes of death among 13,301 members of the International Association of Bridge, Structural, and Ornamental Ironworkers who died in the United States between 1984 and 1991. Only deaths were available, not the whole membership. So the authors used proportionate mortality ratios (PMRs), which compare the share of deaths from each cause with the share expected from U.S. death patterns. Fatal falls were the most elevated cause (259 deaths, PMR 3.57, 95% CI 3.15 to 4.03). Lung cancer was elevated (1,523 deaths, PMR 1.28, CI 1.21 to 1.35), and so was asbestosis (10 deaths, PMR 3.56, CI 1.70 to 6.54). Seven deaths were coded as pleural mesothelioma (PMR 1.67), but the confidence interval, 0.67 to 3.44, included 1. A further 35 mesotheliomas not specified as pleural or peritoneal were counted under "other and unspecified sites". Kidney cancer and chronic nephritis were not elevated. The authors concluded that the lung cancer excess was probably due to welding fumes and asbestos, though smoking could not be entirely ruled out. They noted that exposures were never measured.

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: Proportionate mortality study of deceased union members: proportionate mortality ratios (PMR), proportionate cancer mortality ratios (PCMR), and a multiple-cause-of-death analysis, compared with U.S. population death patterns
• Who was studied: 13,301 deceased members of the International Association of Bridge, Structural, and Ornamental Ironworkers who died in the United States between January 1, 1984 and December 31, 1991, after at least one continuous year of dues-paying membership. The group was 12,846 white males, 434 nonwhite males and 21 females. Deaths outside the United States and deaths without a death certificate were excluded.
• Exposure: Work as a union ironworker (shopmen, rodmen, welders, structural ironworkers, riggers and others). The potential job-site exposures named include inorganic lead, welding fumes, asbestos, solvents and carbon monoxide. Individual exposures were not measured.
• Main results:
  • Deaths from falls among all members studied: 259 deaths, PMR 3.57, 95% CI 3.15 to 4.03.
  • Deaths from falls by length of union membership: PMR 8.36 in the first 10 years of membership and 6.53 in years 10 to 19.
  • Lung cancer deaths among all members studied: 1,523 deaths, PMR 1.28, 95% CI 1.21 to 1.35. Lung cancer remained significantly elevated in the proportionate cancer mortality analysis.
  • Pleural mesothelioma as the underlying cause of death: 7 deaths, PMR 1.67, 95% CI 0.67 to 3.44. The interval included 1, and the result was not marked as statistically significant in the table.
  • Cancer of other and unspecified sites: 307 deaths, PMR 1.29, 95% CI 1.15 to 1.44. This category included 35 mesotheliomas not specified as pleural or peritoneal.
  • Asbestosis deaths: 10 deaths, PMR 3.56, 95% CI 1.70 to 6.54. This was within the broader category of pneumoconiosis and other respiratory diseases: 690 deaths, PMR 1.11, 95% CI 1.03 to 1.20.
  • No elevation was found for kidney cancer or chronic nephritis. These causes were examined because of possible lead exposure.
• The authors' conclusion: The authors concluded that the excess lung cancer risk was probably due directly to welding fumes and asbestos exposure, and/or possibly indirectly to coal tar pitch, asphalt production, diesel exhaust or another toxic agent. They added that excess cigarette smoking could not be entirely ruled out.
• Limitations the authors state:
  • Exposures were not monitored, so the type, intensity and length of each member's exposures were unknown.
  • Death certificate data carry little information on possible confounders such as tobacco, alcohol use and socioeconomic status. Smoking could not be ruled out as a confounder for the lung cancer results.
  • Members who left the union before retirement or death were not included, so cancer deaths may have been underestimated.
  • In the PMR method, the ratio for each cause depends on the ratios for other causes. For example, a low share of heart disease deaths can push other causes up.

Topics

Medical terms in this study, explained in our Lexicon: confidence interval, Neoplasm, Pleural Mesothelioma, Pneumoconiosis.

Related studies

• Proportionate mortality among unionized roofers and waterproofers — F.B. Stern, A.M. Ruder, et al. (2000)
• Proportionate mortality study of the United Association of Journeymen and Apprentices of the Plumbing and Pipe Fitting Industry — E.J. Lehman, M.J. Hein, et al. (2008)
• Proportionate mortality among construction laborers — F. Stern, P. Schulte, et al. (1995)
• Cancer risks among iron and steel workers in Anshan, China, Part I: Proportional mortality ratio analysis — Z. Xu, G.W. Pan, et al. (1996)
• Assessment of mortality in the construction industry in the United States, 1984-1986 — C. Robinson, F. Stern, et al. (1995)
• Mortality among unionized construction plasterers and cement masons — F. Stern, E. Lehman, et al. (2001)

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