Mesothelioma surveillance to locate sources of exposure to asbestos

Our plain-English summary of Mesothelioma surveillance to locate sources of exposure to asbestos, by K. Teschke, M.S. Morgan, H. Checkoway, et al (Canadian Journal of Public Health = Revue Canadienne de Santé Publique, 1997).

The study

• Authors: K. Teschke, M.S. Morgan, H. Checkoway, G. Franklin, J.J. Spinelli, G. van Belle, N.S. Weiss
• Journal: Canadian Journal of Public Health = Revue Canadienne de Santé Publique
• Published: 1997;88(3):163-8
• Cited by: 58 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

To determine whether there were previously unrecognized sources of asbestos exposure in British Columbia, incident mesothelioma cases (n = 51) and population-based controls (n = 154) were interviewed about their occupational histories and asbestos exposures. The following occupations were at elevated risk: sheet metal workers (OR = 9.6, 95% CI: 1.5-106), plumbers and pipefitters (OR = 8.3, 95% CI: 1.5-86), shipbuilding workers (OR = 5.0, 95% CI: 1.2-23), painters (OR = 4.5, 95% CI: 1.0-24), welders (OR = 3.9, 95% CI: 0.8-22), gardeners (OR = 3.9, 95% CI: 0.8-22), bricklayers (OR = 3.5, 95% CI: 0.9-14), miners (OR = 3.4, 95% CI: 0.9-13), machinists (OR = 3.2, 95% CI: 1.0-11), construction foremen (OR = 3.1, 95% CI: 0.9-11), and electricians (OR = 3.0, 95% CI: 0.8-12). In a reanalysis excluding subjects who worked in occupations or processes considered strongly a priori at risk, three groups remained of interest: non-asbestos miners (OR = 9.6, 95% CI: 1.8-53), bricklayers (OR = 5.4, 95% CI: 1.0-28), and construction labourers (OR = 2.8, 95% CI: 0.7-10.6).

In plain English

This British Columbia case-control study looked for previously unrecognized sources of asbestos exposure. It compared the job histories of 51 people with pleural mesothelioma, registered by the British Columbia Cancer Agency from September 1990 to August 1992, with those of 154 controls from the provincial voters list. Sheet metal workers (odds ratio 9.6, 95% confidence interval 1.5 to 106), plumbers and pipefitters (8.3, 1.5 to 86.3) and shipbuilding workers (5.0, 1.2 to 22.7) had statistically significant raised odds of mesothelioma. Reported occupational asbestos exposure had an odds ratio of 9.3 (4.0 to 23.8). The authors then removed people who had held the strongest known at-risk jobs or processes, leaving 19 cases and 128 controls. In that analysis, miners, drillers and blasters (9.6, 1.8 to 53.0) and bricklayers, plasterers and cement workers (5.4, 1.0 to 27.5) still had raised estimates. None of the miner cases had mined asbestos. The authors concluded that most cases were explainable by sources of asbestos exposure well known in the literature. Apart from non-asbestos mining, the associations not previously linked to mesothelioma involved small numbers, so judging whether they were causal would be speculative.

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: Population-based case-control study used as surveillance for unrecognized asbestos exposure sources; part of a larger investigation that also included nasal and bladder cancer
• Who was studied: 51 interviewed cases of histologically confirmed pleural mesothelioma aged 19 or more, registered by the British Columbia Cancer Agency from September 1, 1990 to August 31, 1992 (58 were eligible), and 154 controls randomly selected from the provincial voters list (190 were eligible), British Columbia, Canada. 47 of the cases (92.2%) were male. 17 case interviews (33.3%) and 21 control interviews (13.6%) were with next-of-kin.
• Exposure: Occupational history, grouped into 57 occupational groups (ever employed for six or more months), plus self-reported occupational asbestos exposure and specific processes such as shipbuilding, insulation, plumbing and heating, furnace or boiler work, building demolition or renovation, and brake lining work. Fiber types were not specified.
• Main results:
  • All cases and controls: sheet metal workers OR 9.6 (95% CI 1.5-106; 6 cases/2 controls), plumbers and pipefitters OR 8.3 (1.5-86.3; 7/2), and shipbuilding workers not elsewhere classified OR 5.0 (1.2-22.7; 7/5) were statistically significant and rose with duration of employment.
  • All cases and controls: eight other occupational groups had ORs of 3.0 or higher, all with confidence intervals reaching 1.0 or below: painters 4.5 (1.0-23.7), welders 3.9 (0.8-21.8), gardeners 3.9 (0.8-21.9), bricklayers, plasterers and cement workers 3.5 (0.9-14.0), miners, drillers and blasters 3.4 (0.9-13.1), machinists 3.2 (1.0-11.1), construction foremen 3.1 (0.9-11.0), and electricians and electrical equipment installers 3.0 (0.8-11.6).
  • All cases and controls: reported occupational asbestos exposure, OR 9.3 (95% CI 4.0-23.8; 30 cases/25 controls); 10.8 (4.4-28.6) with the most recent 20 years removed.
  • Reanalysis excluding at-risk jobs and processes (19 cases, 128 controls): miners, drillers and blasters OR 9.6 (95% CI 1.8-53.0), and none of the miner cases had mined asbestos. Bricklayers, plasterers and cement workers OR 5.4 (1.0-27.5). Construction labourers OR 2.8 (0.7-10.6; 5 cases/15 controls).
  • Reanalysis: occupational building demolition or renovation OR 2.8 (95% CI 0.6-11.9), and 4.6 (0.9-22.1) with the 20-year latency taken into account.
  • Brake lining installation or repair did not appear to be associated with mesothelioma: OR 0.3 (95% CI 0-1.4) in the all-subjects analysis. Vehicle mechanics had OR 0.8 (0.2-2.3).
  • 44 of the 51 cases (86%) had held jobs in categories previously linked to mesothelioma in the literature.
  • 21 cases did not recall occupational asbestos exposure; 14 of these had held jobs identified in the analyses as having high relative risks.
• The authors' conclusion: The authors concluded that most cases were explainable by well-known asbestos sources: shipbuilding, insulation, plumbing and heating, and construction trades. They identified several occupations not previously linked to mesothelioma. All except non-asbestos mining involved small numbers, so in their view judging whether these associations were causal would be speculative.
• Limitations the authors state:
  • Small study size made risk estimates imprecise for some occupational groups.
  • Grouping of occupations was likely to cause non-differential misclassification, usually biasing estimates toward no effect.
  • Next-of-kin interviewees knew exposure data and dates less well and recalled about 19% fewer jobs.
  • Possible biased recall of asbestos exposure by cases, because many physicians know of the asbestos-mesothelioma association.
  • Possible bias if physicians were more likely to diagnose mesothelioma in patients reporting asbestos exposure.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Asbestos Exposure, Pipefitter.

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• Surveillance of respiratory diseases among construction and trade workers at Department of Energy nuclear sites — J.M. Dement, L. Welch, et al. (2003)
• Evaluation of the national health surveillance program of workers previously exposed to asbestos in Spain (2008) — M.G. Gómez, R. Castañeda, et al. (2012)
• Identification of occupational cancer risks in British Columbia, Canada: a population-based case-control study of 1,155 cases of colon cancer — R. Fang, N. Le, et al. (2011)
• Occupations and industries in France at high risk for pleural mesothelioma: A population-based case-control study (1998-2002) — P. Rolland, C. Gramond, et al. (2010)

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