NYC officials are concerned that trace amounts of a radioactive material commonly found in hospitals could be used by terrorists to make a dirty bomb.

That's because many hospitals use irradiators containing a small amount of the isotope cesium-137, which is used in blood transfusions and cancer research, but also has the potential to be utilized by terrorists in a dirty bomb attack.

According to the US Nuclear Regulatory Commission, the explosion itself would be more immediately harmful than the cesium-137, but the contamination—and ensuing panic—caused by the presence of radioactive material would make for a chaotic and costly cleanup.

"If this were released in a high-density area, an area like the Financial District for example, the number of people who might be affected by a dirty bomb would be in the hundreds of thousands," NYC's Health Department Commissioner Dr. Mary Bassett told reporters at a press conference yesterday. Cesium-137 isotope bonds exceptionally well with concrete, so the affected area would be "no longer fit for human habitation." The medical effects and the sanitizing process would take years.

That's why Basset and officials from the U.S. Department of Energy met at Mt. Sinai hospital to announce their new plan to remove all cesium-137 irradiators from the New York area by 2020.

While Basset stressed that such a dirty bomb attack was "highly unlikely," but that the department's "goal is always to eliminate, where possible, serious risks to the public.

David Huizenga, who works as the acting deputy administrator for the Defense Nuclear Nonproliferation in the Department of Energy, said that new non-radioactive x-ray equipment had rendered the cesium-137 irradiators obsolete.

"You don't really have to make any sacrifices in terms of performance for research, or for safety," Huizenga said.

According to Huizenga, some cesium-137 irradiators have already been removed from New York area hospitals and replaced with alternative equipment. He estimated that it will cost approximately $250,000 for the removal and replacement of each irradiator, with the Department of Energy covering half of the cost, and individual hospitals responsible for the rest. There are about 28 devices left in the city.