Asbestos-associated cancers in the Ontario refinery and petrochemical sector

Our plain-English summary of Asbestos-associated cancers in the Ontario refinery and petrochemical sector, by M.M. Finkelstein (American Journal of Industrial Medicine, 1996).

The study

• Author: M.M. Finkelstein
• Journal: American Journal of Industrial Medicine
• Published: 1996;30(5):610-5
• Cited by: 24 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos has been widely used in the refinery and petrochemical sector. Mesothelioma has occurred among maintenance employees, and it was hypothesized that mesothelioma is a marker for exposures which might increase lung cancer risk. A death certificate-based case-control study of mesothelioma and lung cancer from 1980 to 1992 was conducted in an Ontario county with a substantial presence of these industries. Each of the 17 men who died of mesothelioma and 424 with lung cancer were matched with controls who died of other causes. The Job and Industry fields on the death certificates were abstracted. Employment as a maintenance worker in the refinery and petrochemical sector was associated with an increased risk of mesothelioma (odds ratio: 24.5; 90% confidence interval 3.1-102). The risk of lung cancer among petrochemical workers, in comparison with all other workers in the county, was 0.88. In an internal comparison of maintenance employees with other blue-collar workers in the refinery and petrochemical sector, the odds ratio for lung cancer was 1.73 (90% confidence interval 0.83-3.6). This finding is consistent with no difference in risk between maintenance and other employees, but it is also compatible with study power being too low to achieve statistical significance. The hypothesis of increased lung cancer risk could be examined more fully with nested case-control studies in existing cohorts. Meanwhile, it would be prudent to reinforce adherence to asbestos control measures in the refinery and petrochemical sector.

In plain English

This death certificate-based case-control study examined men's deaths in Lambton County, Ontario, from 1980 to 1992. Job and industry entries were compared for 17 men who died of mesothelioma versus 46 controls, and 424 men aged 45 to 74 who died of lung cancer versus 431 controls. Six of the 17 men with mesothelioma had been maintenance workers in the refinery and petrochemical sector, versus 1 of 46 controls. The odds ratio was 24.5 (90% confidence interval 3.1 to 102). Compared with all other county workers, sector workers had a lung cancer odds ratio of 0.88 (95% confidence interval 0.61 to 1.3, a range that includes 1). Within the sector, maintenance workers had a lung cancer odds ratio of 1.73 (90% confidence interval 0.83 to 3.6) compared with other blue-collar sector workers. This difference was not statistically significant. The author cited small sample size and the lack of data on smoking or on the length or extent of asbestos exposure. The author concluded that mesothelioma among maintenance employees may be a marker for increased respiratory cancer risk from asbestos exposure.

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: death certificate-based case-control study
• Who was studied: Men who died in Lambton County, Ontario, 1980-1992. The usable data covered 17 men with mesothelioma and 46 controls, and 424 men aged 45 to 74 with lung cancer and 431 controls. Controls had died of any cause other than lung cancer, mesothelioma, or leukemia.
• Exposure: Occupation and industry as recorded on death certificates. The groups compared were employment in the refinery and petrochemical sector, maintenance work in that sector, and work as an insulation worker or pipefitter. No fiber types or doses were measured.
• Main results:
  • Among the 17 men with mesothelioma, 6 had been maintenance workers in the refinery and petrochemical sector. Among the 46 controls, 1 had been.
  • Maintenance work in the refinery and petrochemical sector was associated with mesothelioma: odds ratio 24.5 (90% confidence interval 3.1-102).
  • Men whose jobs were insulation worker or pipefitter (57 subjects, 35 with lung cancer) had a lung cancer odds ratio of 1.67 compared with all other occupations, and 1.59 compared with other blue-collar occupations.
  • Refinery and petrochemical sector workers (134 subjects, 63 with lung cancer) had a lung cancer odds ratio of 0.88 compared with all other workers in the county. Table II gives the confidence interval as 0.61-1.3; under the stated methods this is a 95% interval.
  • Restricted to men in blue-collar occupations, the lung cancer odds ratio for sector workers was 0.92.
  • Sector maintenance workers (50 subjects, 28 with lung cancer) had a lung cancer relative risk of 1.30 compared with all Lambton residents, and 1.19 compared with blue-collar workers.
  • Neither excess for maintenance workers compared with other county residents (1.30 and 1.19) was statistically significant.
  • In the internal comparison within the sector, maintenance workers had a lung cancer odds ratio of 1.73 (90% confidence interval 0.83-3.6) compared with other blue-collar workers in the sector.
  • The internal comparison of maintenance workers with other blue-collar workers in the sector was not statistically significant (p = 0.12, one-tailed test).
  • Among other county sectors with 10 or more lung cancer deaths, increased lung cancer risk was seen in construction workers (odds ratio 1.39) and fiberglass factory employees (odds ratio 4.15).
• The authors' conclusion: The author concluded that mesothelioma among maintenance employees in the refinery and petrochemical sector may be a marker for increased respiratory cancer risk associated with asbestos exposure, and that this could be examined further with nested case-control studies in existing cohorts.
• Limitations the authors state:
  • The sample size was too small. The author estimated that 127 lung cancer cases would be needed for 90% power to detect a relative risk of 1.5; there were 49 lung cancer deaths among blue-collar workers in the sector.
  • Job titles on death certificates were used to classify potential asbestos exposure.
  • There were no data on personal smoking habits or on the length or extent of asbestos exposure.
  • Some death certificates were not imaged and could not be accessed. Others gave nonspecific job entries such as "retired", which reduced the number of usable subjects.
  • It could not be determined which, if any, fiberglass workers had been exposed to asbestos.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Lung Cancer, Death Certificate, Case-Control Study, Odds Ratio, confidence interval, Statistical Significance.

Related studies

• Maintenance work and asbestos-related cancers in the refinery and petrochemical sector — M.M. Finkelstein (1999)
• Maintenance work and asbestos-related cancers in the refinery and petrochemical sector — M.M. Finkelstein (1999)
• Occupational associations with lung cancer in two Ontario cities — M.M. Finkelstein (1995)
• Mortality among maintenance employees potentially exposed to asbestos in a refinery and petrochemical plant — S.P. Tsai, L.C. Waddell, et al. (1996)
• Radiographic asbestosis is not a prerequisite for asbestos-associated lung cancer in Ontario asbestos-cement workers — M.M. Finkelstein (1997)
• Retrospective exposure assessment of airborne asbestos related to skilled craftsmen at a petroleum refinery in Beaumont, Texas (1940-2006) — P. Williams, D. Paustenbach, et al. (2007)

Browse more research in American Journal of Industrial Medicine, or return to medical research.