Update of the Texaco mortality study 1947-93: part I. Analysis of overall patterns of mortality among refining, research, and petrochemical workers

Objective-To update information on the workers of the Texaco mortality study to determine if the patterns of mortality have changed with 16 additional years of follow up. Subjects and methods-Ah workers were employed for greater than or equal to 5 years at company refineries, petrochemical plants, and research laboratories from 1947-93. The cohort now consists of 28 480 employees with an average of greater than or equal to 20 years of follow up. Results-The overall mortality, and most cause specific mortalities were lower than or similar to those for the general population of the United States. For white men (86% of the cohort), there were 8873 observed deaths and 11 181 expected resulting in a significantly lower standardised mortality ratio (SMR) of 79. There were significant deficits for all the leading causes of death in the United States including all cancers, cancer of the lung, stroke, heart disease, respiratory disease, and accidents. Slightly increased mortality was found for cancer of the pancreas, cancer of the brain and central nervous system, leukaemia, and cancer of other lymphatic tissue. For cancer of the bone, the SMR was 162 (95% confidence interval (95% CI) 86 to 278), and for benign and unspecified neoplasms, it was 152 (95% CI 109 to 206). Overall mortality patterns for non-white men and women were similar to those for white men. Mortality patterns for white men were also examined by duration of employment, time first employed, location, and by job and process unit. There were significantly increased SMRs for brain cancer for those people employed as laboratory workers and on units with motor oil and for cancer of other lymphatic tissue for people employed on the fluid catalytic cracking unit. Conclusions-The results of the updated study showed a favourable mortality experience for employees in the Texaco mortality study compared with the United States population. There were a few increases found consistently including, but not limited to, brain cancer and cancer of other lymphatic tissue. These increases led to additional analyses that will be discussed in the accompanying paper.