Increasing exposure to ionizing radiation boosts the risk of multiple myeloma, a rare but often fatal cancer of blood-forming tissues, especially among people exposed later in life, according to a new study of workers at four U.S. Department of Energy plants.
The study, conducted by University of North Carolina at Chapel Hill researchers, analyzed radiation exposures among plant employees and compared them to health records. Older workers with cumulative radiation doses of five rem or more were almost three-and-a-half times more likely to die from multiple myeloma than workers at the same plants whose cumulative exposures were less than one rem.
The current occupational limit for radiation workers is five rem per year. Average background radiation is between a tenth and a third of a rem per year depending on what is being counted, such as radon.
A report on the findings appears in the April issue of Annals of Epidemiology, a scientific journal. UNC-CH School of Public Health authors are Dr. Steve Wing, associate professor; Dr. David Richardson, postdoctoral fellow; Suzanne Wolf, research associate; and programmer Joy L. Wolf, all of epidemiology, and Drs. Douglas J. Crawford-Brown, professor, and Gary Mihlan, research assistant, both of environmental sciences and engineering.
"Workers exposed to ionizing radiation at older ages appeared to be more sensitive than younger workers," Wing said. "However, that does not mean that it is safe for young workers to be exposed to radiation. Exposures during the child-bearing ages might lead to genetic mutations that could affect children and future generations."
UNC-CH researchers identified 98 workers who died of multiple myeloma and 391 age-matched controls from a combined roster of 115,143 people hired before 1979 at the Hanford (Wash.), Los Alamos National Laboratory (N.M.), Oak Ridge National Laboratory (Tenn.) and the Savannah River (S.C.) nuclear facilities, he said. Information on work history,
Contact: David Williamson
University of North Carolina at Chapel Hill