Lung cancer risk among workers in the construction industry: results from two case-control studies in Montreal

Our plain-English summary of Lung cancer risk among workers in the construction industry: results from two case-control studies in Montreal, by A. Lacourt, J. Pintos, J. Lavoué, et al (BMC Public Health, 2015).

The study

• Authors: A. Lacourt, J. Pintos, J. Lavoué, L. Richardson, J. Siemiatycki
• Journal: BMC Public Health
• Published: 2015;15:941
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Given the large number of workers in the construction industry, it is important to derive accurate and valid estimates of cancer risk, and in particular lung cancer risk. In most previous studies, risks among construction workers were compared with general populations including blue and white collar workers. The main objectives of this study were to assess whether construction workers experience excess lung cancer risk, and whether exposure to selected construction industry exposures carries excess risks. We wished to address these objectives within the sub-population of blue collar workers.

Methods: Two case-control studies were conducted in Montreal. Combined, they included 1593 lung cancer cases and 1427 controls, of whom 1304 cases and 1081 controls had been blue collar workers. Detailed lifetime job histories were obtained and translated by experts into histories of exposure to chemical agents. The two key analyses were to estimate odds ratio (OR) estimates of lung cancer risk: a) for all blue-collar construction workers compared with other blue-collar workers, and b) for construction workers exposed to each of 20 exposure agents found in the construction industry compared with construction workers unexposed to those agents. All analyses were conducted using unconditional logistic regression adjusted for socio-demographic factors and smoking history.

Results: The OR for all construction workers combined was 1.11 (95 % CI: 0.90-1.38), based on 381 blue collar construction workers. Analyses of specific exposures were hampered by small numbers and imprecise estimates. While none of 20 occupational agents examined was significantly associated with lung cancer, the following agents manifested non-significantly elevated ORs: asbestos, silica, Portland cement, soil dust, calcium oxide and calcium sulfate.

Conclusions: Compared with other blue collar workers, there was only a slight increased risk of lung cancer for subjects who ever held an occupation in the construction industry. The analyses of agents within the construction industry produced imprecise estimates of risk, but nevertheless pointed to some plausible associations. Excess risks for asbestos and silica were in line with previous knowledge. The possible excess risks with the other inorganic dusts require further corroboration.

In plain English

This study pooled two population-based case-control studies of lung cancer in the Montreal area: Study I (1979 to 1986) and Study II (cases diagnosed 1996 to 1998). The analyses covered men only: 1,593 lung cancer cases and 1,427 controls. Experts who did not know which men had cancer turned each man's lifetime job history into estimated exposures to chemical agents. Among blue-collar workers, men who had ever worked in construction had an odds ratio for lung cancer of 1.11 (95% CI 0.90 to 1.38) compared with blue-collar men outside construction, after adjustment for smoking and other factors. Longer construction employment was not linked to higher risk. Within construction workers only, the authors examined 20 agents. Substantial asbestos exposure had an odds ratio of 1.9 (95% CI 0.8 to 4.6), based on 25 cases and 12 controls. Soil dust, crystalline silica, Portland cement, calcium oxide and calcium sulfate also showed raised estimates. The authors said the numbers were small and the estimates imprecise. They concluded that their study suggests only a slight increased risk of lung cancer for men who had ever worked in construction.

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: Pooled analysis of two population-based case-control studies, using expert assessment of lifetime job histories
• Who was studied: Men in the greater Montreal area. Study I (1979 to 1986) contributed 857 male lung cancer cases and 533 male controls. Study II (cases diagnosed 1996 to 1998) contributed 736 cases and 894 controls. Women were excluded because few worked in construction. Construction workers were defined as men who had held at least one job in the construction industry. In the blue-collar analysis, Table 2 gives 1,313 cases and 1,081 controls.
• Exposure: Two exposures were studied. The first was ever having worked in the construction industry. The second was each of 20 agents found in construction, including asbestos (fiber type not specified), crystalline silica, soil dust, Portland cement, calcium oxide and calcium sulfate. Exposure was assessed by chemists and industrial hygienists. 'Substantial' exposure meant likely or definite exposure at medium or high concentration, for more than 5% of the workweek, for at least 5 years.
• Main results:
  • Blue-collar men who ever worked in construction (381 cases, 288 controls) had an odds ratio for lung cancer of 1.11 (95% CI 0.90 to 1.38) compared with blue-collar men never in construction.
  • Construction workers compared with all other workers had an odds ratio of 1.15 (95% CI 0.94 to 1.41).
  • Within construction workers, the comparison group was construction workers never exposed to asbestos. Men ever exposed to asbestos (122 cases, 97 controls) had an odds ratio of 1.2 (95% CI 0.9 to 1.5). Men substantially exposed (25 cases, 12 controls) had an odds ratio of 1.9 (95% CI 0.8 to 4.6).
  • Among construction workers with substantial exposure, other agents had these odds ratios: soil dust 1.9 (95% CI 1.1 to 3.4), crystalline silica 1.7 (1.0 to 3.0), Portland cement 1.7 (0.9 to 3.2), calcium oxide (lime) 2.0 (1.0 to 4.2) and calcium sulfate (gypsum) 1.5 (0.9 to 2.5).
  • Workers with long-term construction employment did not show higher risks than those with shorter employment.
  • Smoking changed the apparent effect only for silica. For asbestos there was no evidence of interaction: among substantially exposed men, the odds ratio was 2.3 (95% CI 0.4 to 14.5) in never or low smokers and 1.8 (0.7 to 4.9) in medium-heavy smokers. For silica, the effect appeared stronger in non and low smokers.
  • Adding asbestos, crystalline silica and diesel engine emissions as extra adjustment factors did not materially change the odds ratios for the agents.
• The authors' conclusion: The authors concluded that their study suggests only a slight increased risk of lung cancer for men who ever worked in construction. They saw suggestions of increased risk with soil dust, asbestos, crystalline silica, Portland cement, calcium oxide and calcium sulfate. For asbestos and silica in construction, they considered this stronger evidence than earlier studies spanning many industries. For the other agents, they said corroborating evidence is needed.
• Limitations the authors state:
  • Restricting the agent analyses to construction workers meant small numbers and imprecise risk estimates.
  • The expert exposure assessment involves measurement error. The authors expected it to be similar for cases and controls because the experts did not know disease status.
  • The lack of a duration effect may reflect a healthy worker effect, if susceptible workers left construction for other industries.
  • Within-industry estimates for the agents may slightly underestimate true risks if construction work as a whole carries a general excess risk.
  • The sensitivity analyses could not settle whether socioeconomic status should be treated as a confounder or as a collider.
  • Men in the study area may have moved between construction and other industries more than elsewhere. The authors offered this as a possible reason for associations weaker than in some earlier studies.

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Odds Ratio.

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