Paraphrased by
Steve Waldrop
May 4, 2004

Potential deaths and decontamination costs tied to "dirty bombs" - conventional explosives laced with radioactive materials - have been underestimated, says prominent researcher Peter Zimmerman.

Zimmerman of London's King College, is the former chief scientist for the U.S. Senate Foreign Relations Committee. He discussed the threat at the American Physical Society meeting earlier this week.

Public fears about terrorists armed with such devices increased in 2002 with the arrest of suspected al-Qaeda associate Jose Padilla. Law enforcement officials said that Padilla was involved in a plot to trigger a dirty bomb in the USA.

At the time of Padilla's arrest, officials suggested that such a device could "cause mass death and injury." However, radiation experts later testified that deaths from a dirty bomb probably would be few and would come from the explosion, not radiation.

"The truth is somewhere in the middle," Zimmerman says.

He discussed a National Defense University report that based its estimate of deaths from a dirty bomb on a 1987 radioactive waste incident in Brazil. Radioactive cesium powder, released by accident after it was stolen from a medical lab, killed five people and forced 112,000 people to have screening for contamination.

Past estimates of deaths based on the Brazilian incident failed to account for people breathing in or eating dust after a dirty-bomb attack, Zimmerman says, increasing their radiation dose and the death toll. He advises that simple steps to avoid the dust should be provided to the public if such an attack occurs.

Similar amounts of radioactive material released by a dirty bomb would kill about 150 people from radiation and contaminate more acres of land than was affected in New York by the Sept. 11 terrorist attacks, according to Zimmerman.

The Environmental Protection Agency has reported that U.S. firms lost track of nearly 1,500 radioactive sources in the five decades before 1996, recovering only half of them.

The cleanup costs from a dirty bomb would be enormous, says Jaime Yassif of the Federation of American Scientists, who addressed the physicists. "And the public may still refuse to return to a contaminated area."

Yassid went on to say that more planning must be made for cleanup after a dirty bomb attack.