Investigators from the University of Pittsburgh determined these individuals' maximum and likely gamma exposure during the 10 days after the accident and combined the results with the interview data as well as mortality data from the Pennsylvania Department of Health. In analyzing the information they used standard calculations such as statistical modeling and standard mortality ratios -- direct comparisons of the number of observed deaths with the expected number of deaths in a general population.
Mortality indicators examined in the study included all heart disease, all malignancies as well as specific cancers that are known to be sensitive to radioactivity: bronchus, trachea and lung; breast (women only); lymphatic and hematopoietic tissue (blood-forming organs), excluding chronic lymphocytic leukemia and Hodgkin's disease; and the central nervous system. Thyroid cancer was considered, but no deaths were reported during the study period.
Initial results indicated a significantly higher mortality from all causes among the TMI population as compared with residents of the surrounding three-county area. The largest contributor to that mortality was heart disease. However, after adjusting for smoking and education, the increases were no longer apparent.
"The effects of smoking and education levels on the incidence of heart disease are well known," said Dr. Talbott. "When we controlled for these risk factors, along with background radiation factors, we found that the elevations in mortality were not note-worthy."
Likewise, elevations in mortality from cancers of the bronchus, trachea and lung were
observed in women, as well as an increase in lymphatic and hematopoietic tissue can
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Contact: Kathryn Duda
dudak@msx.upmc.edu
412-624-2607
University of Pittsburgh Medical Center
27-Apr-2000