A RETROSPECTIVE MORTALITY STUDY WITHIN OPERATING SEGMENTS OF A PETROLEUM COMPANY

This retrospective mortality study was conducted among 34,597 oil industry workers in diverse operating segments. Employees were traced through Statistics Canada, and overall mortality (SMR = 0.85) was lower than general population rates and similar to other petrochemical cohorts. The most notable finding was a significant excess of malignant melanoma [observed deaths (N) = 16, SMR = 1.87, 95% CI = 1.07, 3.04], which concentrated among upstream workers (N = 6, SMR = 6.00, 95% CI = 2.19, 13.06), and was directly related to employment duration and latency. Specific substances or hydrocarbon (HC) streams could not be implicated, although possible explanations include dermal HC exposure, ultraviolet light exposure, or a synergistic effect between these two factors. Marketing/transportation workers showed a non-significant excess of multiple myeloma (SMR = 1.81), which was also related to employment duration, latency, and commencement of employment before 1950. Lymphatic cancer, skin cancer, and kidney cancer mortality was not elevated in refinery workers, a finding at odds with some previous refinery worker studies. Although the malignant melanoma and possibly the multiple myeloma mortality patterns are consistent with an occupational link, further studies are needed to investigate the relationship of these diseases with particular exposures.