Physician Robert P. Gale said yesterday a new medical treatment that stimulates division of bone-marrow cells appears to have helped the first people on whom it has been tested -- victims of a radiation accident in Brazil.

Gale, a bone-marrow specialist from the University of California at Los Angeles, flew to the Soviet Union last year to perform bone-marrow transplants on victims of the nuclear accident at Chernobyl, but more recently joined specialists from six countries treating radiation victims in Goiania, Brazil.

Speaking at a meeting of the American Society of Hematology, Gale said the treatment, involving a genetically engineered hormone produced two years ago, was administered for the first time to eight victims of a radiation accident in Goiania.

Brazil suffered its worst nuclear contamination accident in mid-September, after thieves stole an abandoned radiotherapy machine from a demolished hospital and sold it to a scrap metal dealer in Goiania, 650 miles northwest of Rio de Janeiro.

The metal dealer, unaware that the machine contained radioactive cesium 137 powder -- used to bombard cancer patients with radiation to kill malignant cells -- broke open the lead container holding the cesium. Fascinated by the glowing, reddish-blue powder, he handed it out to friends and relatives, who fell ill a few days later.

Gale said 30 people were hospitalized after they ingested or touched the substance. Four people, including a 6-year-old girl who ate some of the cesium, have died from radiation illnesses or from infections.

Gale said 18 people who were exposed to the radioactive substance suffered bone-marrow failure, in which the body stops producing critical white blood cells needed to fight infections and help blood to clot.

In eight of these patients the condition is potentially reversible, Gale said, because the marrow cells that produce the white blood cells were not destroyed. These eight were given a hormone called granulocyte-macrophage colony-stimulating factor.

"It stimulates primitive bone-marrow cells to divide and thereby shortens the period of bone-marrow failure," Gale said of the treatment. The colony-stimulating factor is produced naturally in the human body, but in minute quantities.

"There's no question that these people responded to" the treatment, Gale said, adding that within 12 hours there was a rapid increase in critical white-blood-cell counts.

"These people are going to recover now," Gale said.

Gale said that because cesium 137 is excreted in sweat, the radiation victims have become "health nuts" and are on heavy exercise regimes to sweat the cesium out of their bodies. They also are given diuretics to help speed excretion of the radioactive material.

Gale said that in the long run as many as 5,000 people may be at risk of suffering cancer from direct or indirect exposure to the radiation in Brazil. He said 135,000 face the risk as a result of the Chernobyl accident.