Multiple myeloma and diesel and other occupational exposures in swedish construction workers

Our plain-English summary of Multiple myeloma and diesel and other occupational exposures in swedish construction workers, by W.J. Lee, D. Baris, B. Järvholm, et al (International Journal of Cancer, 2003).

The study

• Authors: W.J. Lee, D. Baris, B. Järvholm, D.T. Silverman, I.A. Bergdahl, A. Blair
• Journal: International Journal of Cancer
• Published: 2003;107(1):134-8
• Cited by: 35 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

We examined the relationships between occupational exposures and the risk of multiple myeloma among male construction workers in Sweden. A total of 446 myeloma subjects were identified among 365,424 male workers followed from 1971 to 1999. Occupational exposure was assessed using a semiquantitative job-exposure matrix, based on a survey carried out by the Construction Industry's Organization for Working Environment, Occupational Safety and Health in Sweden. Rate ratios (RRs) in the exposed groups relative to the unexposed groups were estimated by Poisson regression. We found an increased risk (RR = 1.3, 95% CI 1.04-1.71) among construction workers exposed to diesel exhaust. Adjustment for other occupational exposures did not change this estimate (RR = 1.3, 95% CI 1.00-1.77). However, there was no monotonic increase in risk with estimated level of exposure (RR for low = 1.4, moderate = 1.1, high = 1.4). There was no evidence of increased risk associated with the other occupational exposures among these construction workers, including asbestos, asphalt, cement dust, metal dust, mineral wool, organic solvents, stone dust and wood dust. Occupational exposure to diesel exhaust in the Swedish construction industry may present a small risk of multiple myeloma, but lack of an exposure-response trend tempers our ability to draw clear conclusions.

Copyright 2003 Wiley-Liss, Inc.

In plain English

This cohort study followed 365,424 male Swedish construction workers who joined an industry health program between 1971 and 1993. They were tracked through 1999 using the Swedish National Cancer Registry, and 446 developed multiple myeloma. Workplace exposures in the mid-1970s were estimated from job titles using a job-exposure matrix. These included diesel exhaust, asbestos (fiber type not specified), asphalt, cement dust, metal dust, mineral wool, organic solvents, stone dust and wood dust. Workers ever exposed to diesel exhaust had a rate ratio of 1.3 (95% CI 1.00–1.77) after adjustment for age, body mass index and other workplace exposures, but risk did not rise with exposure level. Workers ever exposed to asbestos (12 cases) had a rate ratio of 0.9 (95% CI 0.37–1.94). The authors reported that multiple myeloma was not associated with asbestos or the other non-diesel exposures. They concluded that they saw a small increase in risk with potential diesel exposure, but that the lack of a clear exposure-response gradient made clear conclusions difficult. They noted possible exposure misclassification and had no data on exposure duration or latency.

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 study with linkage to the national cancer registry; rate ratios estimated by Poisson regression
• Who was studied: 365,424 male Swedish construction workers who entered the Bygghälsan occupational health program in 1971–1993, followed through 31 December 1999 (7,062,984 person-years); 446 incident multiple myeloma cases
• Exposure: Job-exposure matrix ratings of exposures in the mid-1970s for over 300 job codes: diesel exhaust, asbestos (fiber type not specified), organic solvents, metal dust, asphalt, wood dust, stone dust, mineral wool and cement dust. Diesel exposure was graded never, low, moderate or high.
• Main results:
  • Workers ever exposed to diesel exhaust (79 cases): rate ratio 1.3 (95% CI 1.04–1.71) adjusted for age and BMI; 1.3 (95% CI 1.00–1.77) after further adjustment for other occupational exposures
  • Workers ever exposed to asbestos (12 cases; 384 never-exposed cases): rate ratio 0.8 (95% CI 0.42–1.34) adjusted for age and BMI; 0.9 (95% CI 0.37–1.94) also adjusted for other exposures. Asphalt, cement dust, metal dust, mineral wool, organic solvents, stone dust and wood dust were also not associated with multiple myeloma.
  • No exposure-response pattern for diesel exhaust (fully adjusted): low exposure (52 cases) rate ratio 1.4 (95% CI 0.99–1.92), moderate (10 cases) 1.1 (95% CI 0.56–2.04), high (17 cases) 1.4 (95% CI 0.77–2.59)
  • Drivers not exposed to diesel exhaust (5 cases) had a rate ratio of 1.2 (95% CI 0.48–2.82), similar to drivers exposed to diesel (22 cases, 1.2, 95% CI 0.77–2.00). Diesel-exposed non-drivers (57 cases) had 1.4 (95% CI 0.99–1.86).
• The authors' conclusion: The authors saw a small increase in multiple myeloma risk with potential diesel exhaust exposure and no association with the other substances, but concluded that the lack of a clear exposure-response gradient made it difficult to draw clear conclusions
• Limitations the authors state:
  • Some nondifferential misclassification of exposure may have occurred, which would bias results toward no effect and might explain some negative findings
  • There was no information on duration of exposure or date of first exposure, so risk by duration or latency could not be analyzed
  • Diesel exhaust exposure levels in the cohort were low, making an effect hard to discern

Topics

Medical terms in this study, explained in our Lexicon: Myeloma, Occupational Exposure, rate ratio.

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