A 50-year mortality follow-up of a large cohort of oil refinery workers in Texas.

To investigate further the possible role of occupational exposures on mortality, an update of a large Texas petroleum refinery cohort was undertaken. Between 1937 and 1987, 6799 deaths were identified among 17,844 employees. Relative to the general population of Texas, the overall standardized mortality ratio (SMR) showed a statistically significant deficit, as did nine other cause-of-death categories. Statistically significant mortality excesses were found for bone cancer (SMR = 207.8: 95% confidence interval [CI], 110.6 to 355.3), acute lymphocytic leukemia (ALL) (SMR = 259.6; 95% CI, 112.1 to 511.5), and benign/unspecified neoplasms (SMR = 194.9; 95% CI, 129.5 to 281.7). However, none of these diseases demonstrated an exposure-response relationship with length of employment. Subcohort mortality analyses by sex and race groups, length of employment, interval since hire, period of hire, and pay status were also performed. Overall, the update findings do not indicate that any excess mortality occurred as a result of employment at the refinery.

Micronucleated erythrocytes as an index of cytogenetic damage in humans: demographic and dietary factors associated with micronucleated erythrocytes in splenectomized subjects.

Erythrocytes containing micronuclei serve as an indicator of genotoxic exposure in splenectomized individuals. Micronucleated erythrocytes, derived from cytogenetically damaged RBC precursors, are not selectively removed from peripheral blood in individuals who lack splenic function. The relationship between micronucleated cell frequencies and demographic, environmental, and dietary factors was examined in 44 subjects with previous splenectomy due to trauma. Their micronucleated cell counts fit a log-normal distribution, with geometric means of 3.3 micronucleus-containing cells/1000 reticulocytes and 2.7/1000 normochromatic erythrocytes. A multiple regression analysis showed that drinking five cups of coffee or tea/day (relative to none) was associated with an approximately 2-fold higher frequency of micronucleated cells. Weaker statistical associations were also noted with micronucleus frequency and the consumption of calcium supplements (associated with a higher frequency) and vitamins A, C, or E (lower frequency). An apparent trend of higher micronucleus counts with age was attenuated when other factors were considered in the regression. Cigarette smoking and decaffeinated coffee consumption were among the factors not associated with elevated micronucleated cell frequencies. Because the occurrence of micronuclei in reticulocytes reflects cytotoxic exposures within the past 3-8 days, it may be possible to test directly the relationship of these factors to micronucleus formation through intervention studies.