Mortality patterns and trends among 49,705 U.S.-based women in a petroleum company: update 1979-2000

To examine mortality patterns and trends in a cohort of women employed in U.S. operating segments of a petroleum company.

Based on human resources databases, we defined a cohort of 49,705 U.S.-based women with at least one day of company employment during 1979 to 2000. These data sources provided demographic and most work history information. Standardized mortality ratios and 95% confidence intervals were calculated for 95 causes of death for the total cohort and with separate analyses by job type and operating segment when numbers allowed.

Cohort women have a 25% lower overall death rate than the general U.S. female population comparison. This lower rate is expected in light of the "healthy worker effect" that influences employee studies. Circulatory diseases have a deficit of 40%, and external causes of death and cancer have deficits of 13% and 9%, respectively. For analyses by job type, office/clerical workers have an elevation in ovarian cancer (standardized mortality ratio = 1.40, 95% confidence interval = 1.02 to 1.87), based on 46 deaths, with no work-related patterns. White-collar groups have generally large overall deficits for noncancer causes of death. In contrast, and based on smaller numbers, operators and laborers have elevations of motor vehicle accidents and other external causes of death, and laborers also have elevations of cerebrovascular disease and chronic obstructive pulmonary disease. These variations by job type are probably associated with differences in lifestyle factors.

This large mortality surveillance study of women in the petroleum industry provides an opportunity for meaningful analysis of many causes of death. The study found an overall favorable mortality profile and, for a small number of elevations, helped identify possible subgroups for health and safety prevention programs and interventions.