Maintenance work and asbestos-related cancers in the refinery and petrochemical sector

Our plain-English summary of Maintenance work and asbestos-related cancers in the refinery and petrochemical sector, by M.M. Finkelstein (American Journal of Industrial Medicine, 1999).

The study

• Author: M.M. Finkelstein
• Journal: American Journal of Industrial Medicine
• Published: 1999;35(2):201-5
• Type of article: Review
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

This commentary examined whether maintenance workers in the refinery and petrochemical sector, who have the greatest potential for asbestos exposure, are at increased risk of lung cancer. The author noted that refinery and petrochemical workers overall have lower lung cancer rates than the general population, with one review reporting lung cancer mortality at 77% of the population average. He argued that internal comparisons within plants were therefore needed. He reviewed published evidence on asbestos use, radiographic surveys and mesotheliomas, which have generally been diagnosed in maintenance workers. In one survey of 995 employees, 9% had asbestos-related X-ray changes. He also reviewed the limited data on smoking habits. He then assembled five cohort studies and one case-control study that compared lung cancer among maintenance workers with other blue-collar workers at the same plants. For one study he derived the comparison by subtraction from published tables. Study-specific relative risks ranged from 0.80 to 1.73. He combined them as a weighted average, using the inverse of the squared standard error as the weight. The combined relative risk was 1.40 (95% CI 1.15–1.69) excluding the Hanis et al. 1985 study, and 1.28 (95% CI 1.08–1.52) including it. The author concluded that maintenance employees had a significantly higher lung cancer risk than other blue-collar workers. He judged that smoking differences were unlikely to account for a 30–40% elevation. He considered it reasonable to conclude the excesses were work-related and to reinforce asbestos control measures.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This article was a commentary, not a new study. The author reviewed published research on refinery and petrochemical workers to ask whether maintenance workers, described as having the greatest potential for asbestos exposure, had more lung cancer than other blue-collar workers at the same plants. The author noted that these workers overall had lower lung cancer rates than the general population, so comparisons within the workforce were needed. The author combined five cohort studies and one case-control study, the author's own earlier Ontario study. For one Texas study, the author worked out the comparison from published summary tables and called the results approximations. Combined, maintenance workers had a relative risk of lung cancer of 1.40 (95% confidence interval 1.15 to 1.69) compared with other blue-collar workers when one study was left out. It was 1.28 (1.08 to 1.52) when that study was included using an assumed variance. Smoking data comparing the groups were not available. The author concluded that the excess was significant, unlikely to be explained by smoking, and reasonably considered work-related.

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: Commentary reviewing published studies, with a pooled analysis: a weighted average of study-specific relative risks for maintenance versus other blue-collar workers
• Who was studied: Five cohort studies and one case-control study of workers in the petroleum refinery and petrochemical sector. These covered two oil refineries in Northern Italy, a Texas refinery and petrochemical complex, a refinery in Beaumont, Texas, eight North American styrene-butadiene rubber plants, three Exxon refineries and chemical plants, and Lambton County, Ontario.
• Exposure: Work as a maintenance employee in the refinery and petrochemical sector, treated as the job with the greatest potential for asbestos exposure. No exposure measurements were analyzed. The author cited a 1991 survey that found chrysotile, amosite, or a mixture of the two in samples from these industries.
• Main results:
  • Combined relative risk of lung cancer, maintenance workers versus other blue-collar workers, leaving out the Hanis et al. [1985] study: 1.40 (95% confidence interval 1.15 to 1.69)
  • Combined relative risk including the Hanis et al. [1985] study, whose variance the author assumed to be similar to that of Raabe and colleagues [1998]: 1.28 (95% confidence interval 1.08 to 1.52)
  • Sathiakumar et al. [1998], North American styrene-butadiene rubber plants: relative risk 1.41 (95% CI 1.08 to 1.85) for maintenance versus other blue-collar workers
  • Raabe et al. [1998], Beaumont, Texas refinery: relative risk 1.45 (95% CI 0.98 to 2.15)
  • Tsai et al. [1996b], Texas refinery and petrochemical complex, as recalculated by the author from published tables: relative risk 1.24 (95% CI 0.70 to 2.11)
  • Gennaro et al. [1995], two Northern Italian refineries: relative risk 1.21 (95% CI 0.62 to 2.27)
  • Finkelstein [1996] case-control study, Lambton County, Ontario: odds ratio for lung cancer 1.73 (95% CI 0.74 to 4.2) for maintenance employees versus other blue-collar workers in the sector
  • Hanis et al. [1985], three Exxon refineries and chemical plants: the rate ratio for mechanical workers versus process operators was 0.80. No confidence interval could be computed.
• The authors' conclusion: The author concluded that maintenance employees in the sector had a significantly higher lung cancer risk than other blue-collar workers. In the author's view, smoking differences were unlikely to account for a 30 to 40% elevation in risk. Given that asbestos is a lung carcinogen, the author judged it reasonable to conclude the excesses were work-related and to reinforce asbestos control measures in the sector.
• Limitations the authors state:
  • Comparative information on cigarette smoking between maintenance and other workers was not available.
  • No published information existed on whether the smoking habits of maintenance workers differed from those of other blue-collar workers in the sector.
  • The Tsai comparison was taken from summary tables, so the calculations were only approximations.
  • No confidence interval could be computed for the Hanis study, so its weight in the combined estimate had to be assumed.
  • The populations were relatively small, and the extent of asbestos exposure was likely to vary between studies.
  • Laborers, who may have been exposed to asbestos, were included in the comparison group in some studies but not in others.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Lung Cancer, Mesothelioma, Habit, Case-Control Study, Relative Risk.

Related studies

• Maintenance work and asbestos-related cancers in the refinery and petrochemical sector — M.M. Finkelstein (1999)
• Mortality among maintenance employees potentially exposed to asbestos in a refinery and petrochemical plant — S.P. Tsai, L.C. Waddell, et al. (1996)
• Asbestos-associated cancers in the Ontario refinery and petrochemical sector — M.M. Finkelstein (1996)
• Update of the Texaco mortality study 1947-93: Part II. Analyses of specific causes of death for white men employed in refining, research, and petrochemicals — B.J. Divine, C.M. Hartman, et al. (1999)
• Dangerous and cancer-causing properties of products and chemicals in the oil refining and petrochemical industry: Part V--Asbestos-caused cancers and exposure of workers in the oil refining industry — M.A. Mehlman (1991)
• Asbestos related lung disease in maintenance workers — M. Huncharek, J. Capotorto (1988)

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