Vic Sidel, MD

Radiopharmaceuticals are extremely important in medical care, but adverse public health consequences must be carefully avoided.  The medical isotope technetium 99, useful in the examination of organs such as hearts, lungs and kidneys, is used in approximately 80-85 percent of the world's diagnostic imaging procedures (cardiac perfusion scans and bone scans among them) and 12 million procedures in the United States alone.  But use of highly enriched uranium (HEU) to produce technetium 99 is a significant and unnecessary public health hazard that may lead to nuclear weapons proliferation and nuclear terrorism.

Technetium 99 is derived from molybdenum 99, which is made in nuclear reactors from HEU, which contains more than 90 percent uranium 235. Placing HEU "targets" in or near nuclear reactor cores produces about 95 percent of the global supply of the radioisotope. The radioactive cores produce high neutron fluxes that flood the targets and produce molybdenum 99, a short-lived fission product with a half-life of 2.7 days that decays into technetium 99. However, less than 5 percent of these "targets" are consumed; the rest is stockpiled as waste in Canada, Europe and South Africa, where companies use about 85 kilograms of HEU per year to make molybdenum 99. While the isotope producers provide security for HEU transport and storage, it's unclear whether the security is stringent enough to eliminate the risk of theft. If a sophisticated terrorist group acquired about 50 kilograms of this waste, they could build a simple Hiroshima-type nuclear bomb

Conversely, low-enriched uranium (LEU) contains less than 20 percent uranium 235 and cannot be used to make a nuclear bomb. But it still can be used to make molybdenum 99.  Conversion of use of HEU in production to use of low-enriched uranium, which is not directly usable for weapons, is technically feasible and readily achievable.  Converting facilities to use LEU is relatively inexpensive.  The security cost savings alone would help defray the cost.  This should prompt a global effort to replace HEU with LEU in medical isotope production.

Health professionals have an opportunity and an ethical obligation to close one of the most vulnerable pathways to a terrorist nuclear bomb by ending the use of HEU in the production of radiopharmaceuticals.