Kidney cancer and hydrocarbon exposures among petroleum refinery workers

Our plain-English summary of Kidney cancer and hydrocarbon exposures among petroleum refinery workers, by C. Poole, N.A. Dreyer, M.H. Satterfield, et al (Environmental Health Perspectives, 1993).

The study

• Authors: C. Poole, N.A. Dreyer, M.H. Satterfield, L. Levin, K.J. Rothman
• Journal: Environmental Health Perspectives
• Published: 1993;101 Suppl 6(Suppl 6):53-62
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

To evaluate the hypothesis of increased kidney cancer risk after exposure to hydrocarbons, especially those present in gasoline, we conducted a case-control study in a cohort of approximately 100,000 male refinery workers from five petroleum companies. A review of 18,323 death certificates identified 102 kidney cancer cases, to each of whom four controls were matched by refinery location and decade of birth. Work histories, containing an average of 15.7 job assignments per subject, were found for 98% of the cases and 94% of the controls. To each job, industrial hygienists assigned semiquantitative ratings for the intensity and frequency of exposures to three hydrocarbon categories: nonaromatic liquid gasoline distillates, aromatic hydrocarbons, and the more volatile hydrocarbons. Ratings of "present" or "absent" were assigned for seven additional exposures: higher boiling hydrocarbons, polynuclear aromatic hydrocarbons, asbestos, chlorinated solvents, ionizing radiation, and lead. Each exposure had either no association or a weak association with kidney cancer. For the hydrocarbon category of principal a priori interest, the nonaromatic liquid gasoline distillates, the estimated relative risk (RR) for any exposure above refinery background was 1.0 (95% confidence interval [CI] 0.5-1.9). Analyses of cumulative exposures and of exposures in varying time periods before kidney cancer occurrence also produced null or near-null results. In an analysis of the longest job held by each subject (average duration 9.2 years or 40% of the refinery work history), three groups appeared to be at increased risk: laborers (RR = 1.9, 95% CI 1.0-3.9); workers in receipt, storage, and movements (RR = 2.5, 95% CI 0.9-6.6); and unit cleaners (RR = 2.3, 95% CI 0.5-9.9).

In plain English

This case-control study drew on a combined cohort of about 100,000 male refinery workers from five petroleum companies. A review of 18,323 death certificates found 102 deaths with kidney cancer (renal cell carcinoma). Each was matched with four controls by refinery location and decade of birth. Industrial hygienists rated every job for three hydrocarbon groups and for other agents, including asbestos (rated present or absent). For any exposure above refinery background to nonaromatic liquid gasoline distillates, the main group of interest, the relative risk was 1.00 (95% CI 0.51 to 1.94). For asbestos it was 0.76 (0.40 to 1.44). Cumulative and timing analyses were also null or near-null. By longest-held job, compared with administrative and service staff, three groups appeared to be at increased risk: laborers (1.94; 0.96 to 3.92), receipt, storage and movements workers (2.49; 0.95 to 6.56) and unit cleaners (2.28; 0.53 to 9.93). The authors concluded the exposure-rating results were most consistent with no effect, or one too small to measure precisely. They noted the ratings were not based directly on measurements.

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 nested in a combined cohort of petroleum refinery workers, with job-by-job exposure ratings by industrial hygienists
• Who was studied: Men in a combined cohort of about 100,000 male refinery workers from five petroleum companies. Review of 18,323 death certificates identified 102 kidney cancer (renal cell carcinoma) cases, each matched with four controls by refinery location and decade of birth. Work histories were analysed for 100 cases and 406 controls.
• Exposure: Semiquantitative ratings for three hydrocarbon categories: nonaromatic liquid gasoline distillates, aromatic hydrocarbons, and more volatile hydrocarbons. Present or absent ratings for secondary exposures including higher boiling hydrocarbons, polynuclear aromatic hydrocarbons, asbestos, chlorinated solvents and lead.
• Main results:
  • Any exposure above refinery background to nonaromatic liquid gasoline distillates: relative risk 1.00 (95% CI 0.51-1.94); 87 of 100 cases and 353 of 406 controls ever exposed
  • Asbestos, ever exposed above background: 85 cases and 357 controls exposed vs 15 cases and 49 controls never exposed; relative risk 0.76 (95% CI 0.40-1.44)
  • Analyses of cumulative exposure and of exposure in time periods before kidney cancer gave null or near-null results
  • Longest-held job, laborers vs administration and services: 24 cases, 53 controls; relative risk 1.94 (95% CI 0.96-3.92)
  • Longest-held job, receipt, storage and movements workers vs administration and services: 9 cases, 15 controls; relative risk 2.49 (95% CI 0.95-6.56)
  • Longest-held job, unit cleaners vs administration and services: 3 cases, 5 controls; relative risk 2.28 (95% CI 0.53-9.93)
  • Longest-held job, pipefitters vs administration and services: 4 cases, 49 controls; relative risk 0.33 (95% CI 0.10-1.05)
• The authors' conclusion: The authors concluded that the exposure-rating results were most consistent with no effect on kidney cancer risk, or an effect too small for this study to measure precisely. If the job-category results reflect a real effect, it would have to come from an exposure other than, and not strongly associated with, the exposures examined.
• Limitations the authors state:
  • Exposure ratings were neither quantitative nor based directly on hydrocarbon measurements, so exposure misclassification was possible and could bias results toward no effect
  • Disease classification relied solely on death certificates
  • No information on non-occupational kidney cancer risk factors other than age and gender
  • Laborers, the only sizable group with an elevated relative risk, were the hardest to assess for refinery exposures
  • Unit cleaners and receipt, storage and movements workers were too few for more detailed analysis

Topics

Medical terms in this study, explained in our Lexicon: Case-Control Study, Death Certificate, Relative Risk, confidence interval, Cumulative Exposure, Work History.

Related studies

• An updated mortality study of workers at a petroleum refinery in Beaumont, Texas — G.K. Raabe, K.W. Collingwood, et al. (1998)
• Asbestos-related cancers in refinery workers in the Australian petroleum industry — R. Gun, N.L. Pratt, et al. (2006)
• Asbestos exposure and cancer mortality among petroleum refinery workers: a Poisson regression analysis of updated data — F. Montanaro, M. Ceppi, et al. (2004)
• Renal cell carcinoma — P.A. Godley, M.A. Escobar (1998)
• Long-term follow-up mortality study of petroleum refinery and chemical plant employees — S.P. Tsai, E.L. Gilstrap, et al. (1996)
• Mortality and cancer morbidity in a cohort of Canadian petroleum workers — R.J. Lewis, A.R. Schnatter, et al. (2003)

Browse more research in Environmental Health Perspectives, or return to medical research.