A Potential Threat

Elimination of some 5,000 radionuclide radiation devices, used for a host of medical, research, and industrial purposes in the U.S., was recommended by a National Research Council panel.

In a report ordered by Congress because of terrorism concerns, the panel recommended the phaseout begin with equipment that uses high-activity cesium-137 in the form of radioactive cesium chloride. The cesium salt is easily dispersible in dirty bombs and is water-soluble, panel members noted, adding that some 1,300 such devices are in use in the U.S., primarily for blood irradiation and research.

With a half-life of 30 years, these cesium chloride devices are reaching the end of their useful lives, warned Leonard W. Connell, a panel member and staff member at Sandia National Laboratories. He also noted that the U.S. currently does not yet have an ultimate national disposal facility or repository for radioactive waste.

"We think it is possible to get rid of most of the 5,000 high-activity radiation devices over the next 10 to 20 years if there was a national policy to encourage it," says Theodore L. Phillips, panel chair and professor of radiation oncology at the University of California, San Francisco. "There are replacements" for such devices, he stressed, adding that "some are not practical or economically attractive today, but most are improving and could be so in time."

For cesium chloride, an energetic gamma emitter, Phillips urged replacement with non-radionuclide, mechanical X-ray generators, or less hazardous forms of radioactive materials.