Objective: To assess patterns and trends in mortality among men employed in U.S. operating segments of a petroleum company.
Methods: We defined a cohort of 127,266 men with at least 1 day of employment during the period of 1979 through 2000. Computerized human resources databases were the basis of the cohort definition as well as the source of demographic and most work history information. Standardized mortality ratios (SMR) and 95% confidence intervals (CI) were calculated for 94 causes of death, including analyses by operating segment and job type.
Results: Most SMR results are below unity. The main exception is mesothelioma (SMR = 1.49; 95% CI = 1.15 to 1.90), which has elevations three times greater than expectation among some groups of men working in manufacturing sites who were hired before 1960. SMRs for cancers of the blood and blood-forming organs are generally close to unity, whereas men in the chemicals segment have 17 deaths due to acute non-lymphocytic leukemia (SMR = 1.81; 95% CI = 1.06 to 2.90), with no temporal or job type patterns. Men in the downstream segment have an elevation of aplastic anemia (SMR = 2.19; 95% CI = 0.95 to 4.32), based on eight deaths. There are eight deaths from malignant melanoma among downstream drivers (SMR = 2.46; 95% CI = 1.06 to 4.84), and motor vehicle accident rates are slightly elevated among some groups of younger and shorter-term operators.
Conclusions: This comprehensive study indicates an overall favorable mortality profile for this workforce. For a few elevations, the study helps guide decisions about future surveillance, focused studies, and other follow-up actions.