Updated mortality among diverse operating segments of a petroleum company

Objectives-To update mortality for 34 560 employees from diverse operating segments of a Canadian petroleum company; and to investigate potential rela tions with occupational factors. Methods-Employees from 1964-83 were linked to the Canadian mortality data b ase to provide 11 years additional follow up. There were 6760 deaths and 75 0 683 person-years of follow up compared with 3909 and 428 190, respectivel y, in the earlier study. Analyses used standardised mortality ratios (SMRs) to compare worker cause specific mortality with the Canadian general popul ation. Duration of employment and latency analyses were performed for cause s previously found to be increased in this and other petroleum cohorts, as well as any findings of interest. Results-For the period 1964-94, employees experienced significantly low ove rall mortality (SMR=0.86 men, SMR=0.80 women). Kidney cancer, which has bee n increased in some studies of petroleum workers, was not increased. Acute nonlymphocytic leukaemia in exposed operating segments was consistent with the expected or only slightly, non-significantly increased. The most notabl e finding was increased deaths from mesothelioma among refinery and petroch emical workers (SMR 8.68; 95% confidence interval (95% CI) 5.51 to 13.03), most of whom were long term employees in jobs with presumed exposure to asb estos (mechanical and pipefitters). Deaths from multiple myeloma among mark eting and distribution workers, which were previously increased, remained i ncreased (SMR 2.08; 95% CI 0.95 to 3.95) in the update period 1984-94; howe ver, there was no clear pattern by duration of employment or latency. Aorti c aneurysms, which also were previously significantly increased among marke ting and distribution workers approached the expected in the update period (SMR 1.18; 95% CI 0.65-1.98), Analyses by duration of employment showed sug gestive trends for aortic aneurysms, but earlier studies of this cohort hav e not found a relation between aortic aneurysms and exposure to hydrocarbon s. Conclusion-The additional 2851 deaths and 322 493 person-years of follow up strengthened the assessment of mortality patterns relative to occupational factors. With the exception of mesothelioma, no clear work related increas es in disease were identified.