Excess leukemia in a refinery population.

A retrospective follow-up mortality study of white male employees of an oil refinery located in southern illinois revealed a statistically significant excess number of deaths due to leukemia compared with the experience of U.S. white males (standardized mortality ratio [SMR] = 213; 95% confidence interval [Cl], 117 to 358). The excess was due mainly to acute myeloid leukemia (AML) (SMR = 394; 95% Cl, 172 to 788). From 1973 to 1982, fourteen leukemia deaths were identified; eight of the cancers were of the AML cell type. The work histories of the decedents were examined for the potential for benzene exposure. Although specificity of the work histories was limited, the investigation has shown that the subjects did not work in jobs identified as having the highest benzene exposures. At this time, the excess leukemia remains unexplained.