Proportionate mortality among unionized roofers and waterproofers

Our plain-English summary of Proportionate mortality among unionized roofers and waterproofers, by F.B. Stern, A.M. Ruder, G. Chen (American Journal of Industrial Medicine, 2000).

The study

• Authors: F.B. Stern, A.M. Ruder, G. Chen
• Journal: American Journal of Industrial Medicine
• Published: 2000;37(5):478-92
• Cited by: 33 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: The United Union of Roofers, Waterproofers, and Allied Workers (UURWAW) is one of the 15 building and construction trades departments in the AFL-CIO. The U.S. roofing industry, including both roofing and waterproofing applications, both unionized and nonunionized, comprises about 25,000 firms, employing approximately 300,000 people, about 200,000 of whom are involved in the application of roofs. The specific toxins to which roofers may be exposed at the job site include, among others, bitumens (asphalt and/or coal tar pitch) as well as asbestos and fiberglass from roof removal operations. Excess deaths from occupational injuries are also of concern.

Methods: This study evaluated causes of mortality among 11,144 members of the UURWAW. Age-adjusted proportionate mortality ratios (PMRs) were computed with 95% confidence intervals (CI) using U.S. age-, gender-, and race-specific proportional mortality rates for the years of the study, 1950-1996.

Results: Statistically significant increased PMRs were found for all injuries (PMR = 142, CI = 134-150), especially falls (PMR = 464, CI = 419-513) and other injuries (PMR = 121, CI = 107-137), cancers of the lung (PMR = 139, CI = 131-148), bladder (PMR = 138, CI = 111-170), esophagus (PMR = 134, CI = 107-166), larynx (PMR = 145, CI = 106-193), and cancers of other and unspecified sites (PMR = 130, CI = 112-149), pneumoconioses and other nonmalignant respiratory diseases (PMR = 115, CI = 103-128), and homicides (PMR = 153, CI = 135-172). The occupational exposures which may have contributed to the excess risks of malignant and nonmalignant respiratory diseases include, among others, asphalt fumes, coal tar pitch volatiles and asbestos; however, cigarette smoking must also be considered a contributing factor.

Conclusions: The present study underscores the need to control airborne exposures to hazardous substances and especially to examine fall prevention efforts within the roofing industry. Am. J. Ind. Med. 37:478-492, 2000. Published 2000 Wiley-Liss, Inc.

In plain English

This study examined deaths among 11,144 male members of the United Union of Roofers, Waterproofers, and Allied Workers who died from 1950 to 1996. It used the union's death benefit records and death certificates but had no information on individual members' exposures or smoking. As a proportionate mortality ratio (PMR) study, it compared each cause's share of deaths with the share expected from U.S. death rates. Fall deaths were much higher than expected (PMR 464, 95% CI 419 to 513). Lung cancer was raised (1,071 deaths, PMR 139, 95% CI 131 to 148), as were cancers of the bladder, esophagus and larynx, pneumoconiosis and other respiratory diseases (PMR 115, 95% CI 103 to 128), and homicide. In a separate 1960 to 1996 analysis, asbestosis caused 2 deaths (PMR 141, 95% CI 17 to 507), not statistically significant. Six pleural mesothelioma deaths were found. The authors concluded that the cancer excesses may have come from asphalt or coal tar pitch fumes. They said tearing off old asbestos-containing roofing may also have exposed roofers, and smoking could not be ruled out.

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 ratio (PMR) study using existing union death benefit records and death certificates; causes of death were compared with U.S. male proportional mortality
• Who was studied: 11,144 deceased male members of the United Union of Roofers, Waterproofers, and Allied Workers (UURWAW) in the United States who died between January 1, 1950, and December 31, 1996: 10,042 white males and 1,102 nonwhite males
• Exposure: Work as a union roofer or waterproofer. Potential exposures named by the authors included bitumens (asphalt and/or coal tar pitch), and asbestos and fiberglass from roof removal operations. Individual members' exposure types, intensity and duration were unknown.
• Main results:
  • Among all 11,144 members, deaths from all malignant neoplasms combined were raised (2,691 deaths, PMR 114). Lung cancer had the greatest excess cancer risk (1,071 deaths, PMR 139, 95% CI 131 to 148).
  • Cancers of the esophagus (84 deaths, PMR 134, CI 107 to 166), bladder (89 deaths, PMR 138, CI 111 to 170), larynx (46 deaths, PMR 145, CI 106 to 193) and other and unspecified sites (195 deaths, PMR 130, CI 112 to 149) were also significantly raised among members.
  • Pneumoconiosis and other respiratory diseases were significantly raised among members (326 deaths, PMR 115, 95% CI 103 to 128). This category had a PMR of 120 for white males and 72 for nonwhite males.
  • In a separate analysis of deaths from 1960 to 1996, asbestosis showed a non-statistically-significant excess (2 deaths, PMR 141, 95% CI 17 to 507). Cancer of the nasal cavity also showed a non-statistically-significant excess (3 deaths, PMR 399, 95% CI 82 to 1167).
  • The study found two deaths due to asbestosis and six deaths due to pleural mesothelioma. No PMR was reported for mesothelioma.
  • All injuries were raised among members (1,196 deaths, PMR 142, CI 134 to 150), especially falls (381 deaths, PMR 464, CI 419 to 513).
  • In the 1979 to 1993 analysis using National Occupational Mortality Surveillance comparison data, members younger than 65 at death had a PMR of 3442 for falls from a building.
  • Homicide was raised among members (264 deaths, PMR 153, CI 135 to 172). In a random sample of these death certificates, none of the homicides occurred on the job.
  • Some causes were significantly lower than expected among members: skin cancer (33 deaths, PMR 69), diabetes, ischemic heart disease (3,005 deaths, PMR 89), cerebrovascular disease and diseases of the genitourinary system.
  • Nine locals said to do more waterproofing were compared with the other locals. In the waterproofing locals, PMRs for esophageal cancer and pharyngeal cancer were 210 and 186. In the other locals they were 107 and 116, which were not significant. Lung cancer PMRs were 146 in the waterproofing locals and 137 in the other locals.
• The authors' conclusion: The authors concluded that the excess cancers of the lung, bladder, esophagus and larynx may have been due to occupational exposure to asphalt and/or coal tar pitch fumes. They said many roofers may also have been exposed to asbestos when tearing off old roofing materials and from its earlier use in roofing, and that excess cigarette smoking could not be ruled out as a contributing factor. They linked the excess injury deaths, especially falls, possibly to the heights of the work and to inadequate safety training and fall protection.
• Limitations the authors state:
  • No smoking history was available for union members, so the authors could not directly evaluate how much smoking contributed to the lung cancer excess.
  • Death certificate data contain no information on confounding factors such as tobacco, alcohol use and socioeconomic status.
  • Individual exposures could not be assessed because local unions did not track job sites, tasks or exposures, so different types of roofing could not be separated.
  • Former members who stopped paying dues could not be identified or included.
  • If roofers' overall death rate was higher than the U.S. rate, the PMR method would tend to underestimate true risks.
  • Multiple significance testing may produce chance associations.
  • PMR studies are exploratory, so the significant results should be confirmed in further studies.
  • Diseases that are usually not fatal, such as skin cancer, may not show an increase in a mortality study.

Topics

Medical terms in this study, explained in our Lexicon: confidence interval, Proportional mortality, Occupational Exposure.

Related studies

• Proportionate mortality among unionized construction ironworkers — F.B. Stern, M.H. Sweeney, et al. (1997)
• Proportionate mortality among construction laborers — F. Stern, P. Schulte, et al. (1995)
• Mortality among unionized construction plasterers and cement masons — F. Stern, E. Lehman, et al. (2001)
• A proportionate mortality study of bricklayers and allied craftworkers — J. Salg, T. Alterman (2005)
• Proportionate mortality among US shoeworkers, 1966-1977 — P. Decouflé, J. Walrath (1983)
• 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)

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