A first-of-its-kind study of more than 53,000 nuclear power workers in the United States has found that employees in the commercial nuclear industry are less likely than the general population to die from cancer or non-cancer diseases due, in large measure, to the so-called "healthy worker effect."
The study by Columbia University's Mailman School of Public Health tracked workers from 15 nuclear utilities in the United States for periods of up to 18 years between 1979 and 1997. Mortality rates of these workers showed that they were 60 percent lower than cause-specific U.S. mortality rates for a population similar in terms of gender, age and calendar year. In order to work in the nuclear industry, workers have to be healthy and are usually required to have annual medical check-ups.
The most important results of this study were findings with respect to radiation-related leukemia and radiation-related other cancers. According to the records, which were maintained by the facilities themselves and by the Nuclear Regulatory Commission and the Department of Energy, positive, although non-statistically-significant, associations with radiation were seen for mortality from some forms of leukemia and other cancers as a whole. The magnitude of these associations is very similar to those from other radiation studies on which current radiation safety standards are based, indicating that the standards are appropriate.
The researchers did report, however, a strong positive and statistically significant association between radiation dose and death from arteriosclerotic heart disease, including coronary heart disease.
Geoffrey Howe, professor of epidemiology at the Mailman School and principal investigator of the study, noted, "While associations with heart disease have been reported by some other occupational studies, the magnitude of the present association is not consistent with them, and, therefore, needs cautious interpretation and merits further attention."
According to Howe, "With a mean age of 45 years, this cohort is still relatively young, which explains the small number of deaths. Further follow-up and data from an ongoing analysis of nuclear workers from 15 countries will provide an additional opportunity for studying the effects of low-dose radiation exposures and greater power to evaluate the present findings."
This study represents the culmination of efforts by individuals in industry, government and academia to combine available sources of information on occupational radiation doses received by U.S. commercial nuclear workers. Currently, there is no single depository of radiation doses in the United States, and researchers believe one is desirable.
The study, "Analysis of the Mortality Experience Amongst U.S. Nuclear Power Industry Workers After Chronic Low-Dose Exposure to Ionizing Radiation," is published in the November issue of Radiation Research, the official journal of the American Radiation Research Society. The 15 nuclear utilities voluntarily participated in the study.