A case-control study of mesothelioma and employment in the Hawaii sugarcane industry

Our plain-English summary of A case-control study of mesothelioma and employment in the Hawaii sugarcane industry, by T. Sinks, M.T. Goodman, L.N. Kolonel, et al (Epidemiology, 1994).

The study

• Authors: T. Sinks, M.T. Goodman, L.N. Kolonel, B. Anderson
• Journal: Epidemiology
• Published: 1994;5(4):466-8
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

We conducted a case-control study of 93 mesothelioma cases and 281 cancer controls to determine whether sugarcane workers exposed to biogenic silica fibers were at increased risk of mesothelioma. We found no important excess risk of mesothelioma in sugarcane workers [odds ratio (OR) = 1.3; 95% confidence interval (CI) = 0.4-3.8] when we excluded all control subjects with cancer of sites suspected of being associated with asbestos exposure. We could not identify any sugarcane workers who developed mesothelioma and worked in jobs where high exposure levels of biogenic silica fibers have been measured. We did confirm that mesothelioma risk in Hawaii is associated with probable occupational asbestos exposure. Work at the Pearl Harbor Naval Shipyard was associated with a 10-fold increase in mesothelioma when we excluded controls with cancer of sites related to asbestos exposure (OR = 10.1; 95% CI = 2.6-56.6). Work in the medical industry was also associated with an unexpected increased risk for mesothelioma (OR = 4.2; 95% CI = 1.2-15.5).

In plain English

This case-control study asked whether Hawaii sugarcane work, a marker of biogenic silica fiber exposure, was linked to mesothelioma. The authors compared 93 Hawaii Tumor Registry patients diagnosed with mesothelioma from 1960 to 1987 with 281 registry patients with other cancers. Seven cases and 19 controls had worked in sugarcane (odds ratio 1.1, 95% confidence interval 0.4 to 2.9). Excluding controls with cancers of the larynx, trachea, bronchus, lung or stomach gave 1.3 (0.4 to 3.8). Personnel records were found for two sugarcane cases and seven controls. Both cases held jobs involving asbestos, and none of them had operated a harvesting tractor, the job considered to have the greatest fiber exposure. Work at Pearl Harbor Naval Shipyard was associated with mesothelioma (odds ratio 8.2, 2.6 to 30.3). In the final model, medical industry work had an odds ratio of 4.2 (1.2 to 15.5), which the authors could not explain. The authors concluded that sugarcane employment did not appear to be an important risk factor. They noted they lacked detailed work histories for everyone, and that cancer controls may have introduced selection bias.

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: case-control study using cases and cancer controls from a statewide tumor registry
• Who was studied: 93 Hawaii residents with mesothelioma diagnosed 1960 to 1987 and listed in the Hawaii Tumor Registry, compared with 281 controls who had other cancers, randomly selected from the same registry and matched by decade of diagnosis, age group and gender (three controls per case)
• Exposure: Employment in the sugarcane industry, used as a stand-in for exposure to biogenic silica fibers. It was established from death certificates, the 1942 to 1943 Hawaii census, and 1961 to 1988 union membership lists. Occupational asbestos exposure was assessed with a job-exposure matrix and by membership in a previously studied group of Pearl Harbor Naval Shipyard workers.
• Main results:
  • 7 cases and 19 controls had worked in the sugarcane industry: odds ratio 1.1 (95% CI 0.4-2.9) using all controls
  • For sugarcane work, the odds ratio was 1.3 (95% CI 0.4-3.8) in the control subset excluding asbestos-related cancers. The methods and the Table 1 footnote list these as cancers of the larynx, trachea, bronchus, lung or stomach. The results sentence names only the last four.
  • After adjustment for asbestos exposure and medical work, the sugarcane odds ratio was 1.13 (95% CI 0.46-2.80) using all controls, and 1.37 (95% CI 0.52-3.65) using the subset of controls without asbestos-related cancers
  • Personnel records were found for two sugarcane cases and seven sugarcane controls. Both cases had held jobs with asbestos exposure: one was a truck mechanic for 36 years, and the other was a plumber for 2 years around the sugarcane boilers.
  • Following the description of personnel records for two sugarcane cases and seven sugarcane controls, the article states that none of these cases or controls had operated a harvesting tractor, the job considered to have the greatest biogenic silica fiber exposure
  • Occupational asbestos exposure was associated with mesothelioma: the text gives an odds ratio of 1.8 (95% CI 1.0-3.2)
  • Work at the Pearl Harbor Naval Shipyard was associated with mesothelioma: odds ratio 8.2 (95% CI 2.6-30.3) using all controls. The authors attributed this association, presumably, to asbestos exposure.
  • For shipyard work, the odds ratio was 10.1 (95% CI 2.6-56.6) when controls with asbestos-related cancers were excluded
  • Employment in construction was associated with increased risk (odds ratio 2.7, 95% CI 1.3-5.7). The authors believed the increases in construction, machinery and transportation work were related to asbestos rather than to biogenic silica fibers.
  • Six cases (three nurses, two physicians, one office worker) and four controls had worked in medical or science-related jobs: odds ratio 3.4 (95% CI 0.8-17.7)
  • The best-fitting multivariate model included asbestos exposure (odds ratio 2.4, 95% CI 1.3-4.3) and medical industry employment (odds ratio 4.2, 95% CI 1.2-15.5). The authors knew of no exposure peculiar to the medical field that would influence mesothelioma risk.
• The authors' conclusion: The authors concluded that exposure to biogenic silica fibers, as determined by sugarcane employment, does not appear to be an important risk factor for mesothelioma. They said the slight increased risk they saw could be due to asbestos exposure or to chance.
• Limitations the authors state:
  • Detailed employment histories were not collected for all cases and controls
  • Using people with other cancers as controls may have introduced selection bias

Topics

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

Medical terms in this study, explained in our Lexicon: Case-Control Study, Mesothelioma, Odds Ratio, confidence interval, Asbestos Exposure.

Related studies

• Exposure to biogenic silica fibers and respiratory health in Hawaii sugarcane workers — T. Sinks, R. Hartle, et al. (1994)
• Occupational respiratory cancer and exposure to asbestos: a case-control study in a cohort of workers in the electricity and gas industry — E. Imbernon, M. Goldberg, et al. (1995)
• Fine biogenic silica fibres in sugar cane: a possible hazard — R.H. Newman (1986)
• Environmental exposure to tremolite and respiratory cancer in New Caledonia: a case-control study — D. Luce, I. Bugel, et al. (2000)
• Type of asbestos and respiratory cancer in the asbestos industry — P.E. Enterline, V. Henderson (1973)
• Retired and former asbestos workers in Hawaii — G. Fournier-Massey, G. Wong, et al. (1984)

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