A furor has been growing in Europe for weeks over contentions that some allied troops contracted leukemia from exposure to the depleted uranium used to strengthen NATO ammunition used in the Balkans campaign, or that European civilians are at risk because they may have breathed uranium-tinged dust near military testing grounds.
But some physicists and medical experts say it is biologically impossible for depleted uranium to have caused the leukemia, and they doubt that the metal caused any illnesses in Europe.
Dr. Frank von Hippel, a physicist and professor of public and international affairs at Princeton University, said depleted uranium was not much of a radioactivity hazard, in part because it is what its name implies–depleted. It is what is left when the more highly radioactive uranium 235 has been removed from its more abundant atomic cousin, uranium 238.
Uranium 235 is used to fuel nuclear reactors and make nuclear weapons. Uranium 238 “is very non-reactive,” von Hippel said.
Even assuming there is a ton of depleted uranium dust for every square kilometer in Kosovo, he said, its radiation would be just one one-hundredth, or 1 percent, of the natural radiation level. “So this is not a very significant hazard,” he said.
Moreover, uranium 238 emits alpha radiation, which does not even penetrate skin, said Dr. Michael Thun, who directs epidemiological research for the American Cancer Society. The radiation that causes leukemia–gamma and X-rays–passes through the body and reaches the marrow, damaging cells and giving rise to disease. Uranium 235 emits gamma particles, and that is one reason it is so dangerous, Thun said.
The World Health Organization said in a preliminary report that not enough information was yet available on the exposure of NATO personnel in Kosovo to make definitive conclusions on the cancer risks they ran.
Uranium is a heavy metal and as such can be toxic. When it enters the body, it lodges in the kidneys, which it can damage. But studies of a handful of gulf war soldiers hit by friendly fire and left with fragments of uranium 238 in their bodies have been reassuring, said Dr. Charles Phelps, the provost at the University of Rochester and a member of an Institute of Medicine committee that reported on the problem last year.
Uranium 238 clearly was leaching into the soldiers’ kidneys, he said. “They had very high levels of uranium salts in their urine,” Phelps said. “But there is no evidence of kidney disease.”
Depleted uranium long has been used for weapons because it is extremely dense, 65 percent more dense than lead. A weapon made with depleted uranium can penetrate even steel-armored tanks. It also ignites when it hits its target.
Because the radiation cannot reach bone marrow, it is biologically impossible for depleted uranium to cause leukemia, said Dr. John Boice, scientific director of the International Epidemiology Institute, a research concern in Rockville, Md., and an expert on radiation and cancer.
“To get leukemia you need to get the radiation to the bone marrow. And uranium 238 will not get to the bone marrow,” Boice said.
Dr. Bruce Boecker, a radiation biologist at the Lovelace Respiratory Research Institute in Albuquerque said, “I don’t think it causes leukemia at all.”
If a person inhales uranium 238, it lodges in the lungs where, in theory, it might cause lung cancer or it might travel to the lymph nodes and theoretically cause lymphoma.
But Boice said extensive studies of uranium workers, some exposed to high levels by breathing uranium dust, did not find any association between inhaling uranium 238 and developing lung cancer or lymphomas.
Lymphomas do not seem to be caused by radiation in any case, Boice said. But lung cancer can be, although the study of uranium workers did not find that.
