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Mortality and cancer morbidity in a cohort of Canadian petroleum workers
  1. R J Lewis1,
  2. A R Schnatter1,
  3. I Drummond2,
  4. N Murray2,
  5. F S Thompson2,
  6. A M Katz2,
  7. G Jorgensen1,
  8. M J Nicolich1,
  9. D Dahlman2,
  10. G Thériault3
  1. 1ExxonMobil Biomedical Sciences, Inc., 1545 Route 22, PO Box 971, Room LF 264, Annandale, NJ 08801-0971, USA
  2. 2Imperial Oil Limited, 111 St Clair Ave, Toronto, Ontario, Canada M5W 1K3
  3. 3McGill University, Joint Dept of Epidemiology & Biostatistics, and Occupational Health, 1020 Pine Avenue West, Montreal, Quebec, Canada H3A 1A2
  1. Correspondence to:
 Dr R J Lewis
 ExxonMobil Biomedical Sciences, Inc., 1545 Route 22, PO Box 971, Room LF 264, Annandale, NJ 08801-0971, USA;


Aims: To assess mortality and cancer morbidity in Canadian petroleum workers and explore exposure-response relations for specific petroleum agents.

Methods: A total of 25 292 employees hired between 1964 and 1994 were linked to the Canadian tumour registry and national mortality database. Exposure-response trends were assessed for hydrocarbon solvents/fuels, hydrocarbon lubricants, petroleum coke/spent catalyst, and hydrogen sulphide (H2S).

Results: External comparison analyses (mortality and incidence) showed deficits for all causes and all malignant neoplasms combined and were consistent with expectation for most malignant and non-malignant sites analysed. Gall bladder cancer mortality was increased among males based on four deaths, but cases had no common job assignments and the increase was focused in workers employed <10 years. Mesothelioma incidence was increased. Most exposure-specific analyses were compromised by small numbers. Statistically significant increases were observed for H2S exposure and a subgroup of accidental deaths as well as for petroleum coke/spent catalyst exposure and lung cancer. While both findings have a degree of biologic plausibility, the H2S association, which exhibited a clearer exposure-response pattern, could be subject to unmeasured confounders. Additionally, interpretation was complicated by the high correlation between hydrocarbon and H2S exposures. With regard to lung cancer, the analysis could not adequately control for smoking, was based on small numbers, and exhibited a tenuous exposure-response pattern.

Conclusion: The findings for mesothelioma suggest the need for continued attention to asbestos in the petroleum industry. The relation between accidental deaths and H2S exposure deserves closer scrutiny in similarly exposed populations. Further analyses of lung cancer are underway and will be reported separately.

  • petroleum workers
  • hydrocarbon solvents and fuels
  • hydrocarbon lubricants
  • petroleum coke/spent catalyst
  • H2S
  • cancer incidence
  • mortality
  • CCDB, Canadian Cancer Database
  • CE, cumulative exposure
  • CMDB, Canadian Mortality Data Base
  • ETHIS, exposure tracking and health information system
  • GEP, good epidemiology practice
  • HRMS, human resources management system
  • IARC, International Agency for Research on Cancer
  • ICD, International Classification of Diseases
  • LHC, lymphohaematopoietic cancer
  • NDI, National Death Index
  • OCMAP, Occupational Cohort Mortality Analysis Program
  • OEL, occupational exposure limit
  • PAH, polycyclic aromatic hydrocarbons
  • RR, relative rate
  • SC, Statistics Canada
  • SEG, similar exposure group
  • SIR, standardised incidence ratios
  • SMR, standardised mortality ratios

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