Key Issues
Radiation Safety at Nuclear Power Plants: Studies Look at Public, Workers
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Stewart-Kneale Studies
British epidemiologists Alice Stewart and George Kneale published 1977, 1981 and 1993 studies on the effects of low radiation doses on workers at DOE’s Hanford, Wash., nuclear complex. The 1981 analysis covered workers who died no later than 1977. The 1993 analysis included deaths from 1944 through 1986.
Among the questionable 1993 findings: 200 of the workers died or will die from radiation-induced cancer; older workers were at greater risk than younger workers; and doses as low as that from natural background radiation may be more harmful than implied in current radiation exposure standards for workers and the public.
Questions raised about the study’s validity include:
Gilbert Study
In a 1993 study published in Radiation Research, Hanford epidemiologist Ethel Gilbert found fewer cancer deaths in radiation workers than in nonradiation workers. More important, her analysis showed no increase in cancer mortality with higher worker doses.
Stewart-Kneale Studies
British epidemiologists Alice Stewart and George Kneale published 1977, 1981 and 1993 studies on the effects of low radiation doses on workers at DOE’s Hanford, Wash., nuclear complex. The 1981 analysis covered workers who died no later than 1977. The 1993 analysis included deaths from 1944 through 1986.
Among the questionable 1993 findings: 200 of the workers died or will die from radiation-induced cancer; older workers were at greater risk than younger workers; and doses as low as that from natural background radiation may be more harmful than implied in current radiation exposure standards for workers and the public.
Questions raised about the study’s validity include:
- First, a 1992 study by the U.K. Radiological Protection Board of 95,000 nuclear power plant workers—who had received greater occupational doses than the Hanford employees—showed no excess cancers whatever.
- Second, Stewart and Kneale’s results could have been marred by a flaw in their previous studies, in which they ignored exposures of workers to potential carcinogens besides radiation.
- Third, if doses as small as those in the Stewart study affected cancer rates, then 5 million residents of Colorado, where the natural radiation level is high because of the altitude, should show 50,000 excess cancer deaths over their lifetime. But between 1950 and 1988, Colorado residents experienced fewer—not more—leukemia deaths than people at sea level.
Gilbert Study
In a 1993 study published in Radiation Research, Hanford epidemiologist Ethel Gilbert found fewer cancer deaths in radiation workers than in nonradiation workers. More important, her analysis showed no increase in cancer mortality with higher worker doses.
