Health findings from a mortality and morbidity surveillance of refinery employees

PURPOSE: To present results from a prospective mortality (1973-1998) and mo rbidity (1990-1998) surveillance of a refinery population in California. METHODS: Mortality and illness-absence data were extracted from the Shell O il Company's Health Surveillance System (HSS). Mortality data were compared to the United States, the state of California, and Contra Costa County, wh ere the refinery is located. Morbidity data were compared to other company manufacturing employees. The standardized mortality/morbidity ratio (SMR/SM bR) was used as a measure of risk. Morbidity frequency and duration of abse nce were calculated by age, sex, and four health risk factors (smoking, hig h blood pressure, hypercholesterolemia, and obesity). RESULTS: With the United States as a comparison, the all causes combined SM R was 0.84 [95% confidence interval (CI) = 0.78-0.90], and the SMR for all cancer was 0.75 (95% Cl = 0.64-0.88). Statistically significant deficits in mortality were found for lung cancer (SMR = 0.60) and leukemia (SMR = 0.26 ). Morbidity frequency and duration of absence among smokers were substanti ally higher than those of nonsmokers. Similar results were also noted for o bese employees when compared to those of normal weight. CONCLUSIONS: Regardless of the comparison population, significantly fewer d eaths were seen for all causes combined, all cancer, lung cancer, and leuke mia. The study also showed no increased mortality from cancer of the stomac h, kidney, skin, prostate, and brain. The increased morbidity frequency and duration of absence were associated with the presence of known health risk factors. These study findings are useful in setting priorities for medical programs and directing efforts Such as health promotion and disease preven tion strategies. (C) 2001 Elsevier Science Inc. All rights reserved.