TOKAIMURA, JAPAN--As life here returns to normal this week after the country's worst-ever nuclear accident, the worker blasted with the highest radiation dose is being readied for an experimental therapy that may be his best chance for surviving the accident. He is scheduled to receive a transfusion of his brother's blood stem cells on Wednesday.
The 30 September incident at a nuclear fuel processing facility 110 kilometers northeast of Tokyo began when workers inadvertently set off a nuclear chain reaction. They overloaded a sedimentation tank with 16 kilograms of uranium, seven times the amount approved for the procedure. That was enough to unleash a runaway chain reaction, which plant workers finally were able to halt 18 hours later. Early reports of an explosion that released radioactive material were false, officials said, and radiation levels quickly returned to normal once the reaction ceased.
Three workers were hospitalized and more than 60 others, including three rescue workers and seven golfers on a neighboring course, were found to have been exposed to high levels of radiation. The most critically ill of the workers, Hisashi Ouchi, 35, was exposed to about 17 sieverts of radiation, according to the Science and Technology Agency's National Institute of Radiological Sciences in Chiba, near Tokyo. Normal background radiation produces a dose of about 2 to 4 millisieverts annually, and doses of more than 5 sieverts have typically been fatal.
Radiation destroyed Ouchi's lymphatic cells, white blood cells critical to the body's immune system. Ouchi is scheduled to receive blood stem cells, donated by his brother, in a first-ever procedure for radiation victims. Hisamaru Hirai, a cell transplant specialist at the University of Tokyo Hospital, where the procedure will take place, says the stem cell transplant promises to restore Ouchi's blood-generating capability more quickly than a bone marrow transplant. The treatment has been used as a nonsurgical alternative to bone marrow transplants for those undergoing cancer therapy. The donor is given a growth factor for several days before the procedure to boost the number of stem cells in the blood. Hirai says the second hospitalized victim, who received 10 sieverts of radiation, has received a transfusion of blood stem cells drawn from a newborn's umbilical cord because of the absence of a suitable donor.