Dr. Eugene Saenger, the Ohio radiologist who contributed greatly to medical knowledge about the effects of radiation on the human body, and was sued for his role in controversial 1960s studies on cancer patients, died Sept. 30. He was 90 and had been suffering from bladder cancer.

"Eugene Saenger was one of the real pioneers in assessing the acute effects of radiation," said Dr. Henry N. Wellman of the Indiana University Medical Center.

His work in the 1950s "led to an understanding of biologic indicators of dosimetry, categorization of various acute radiation syndromes, and the development of triage procedures for radiation accident victims," Wellman said.

Saenger was among the first to report on the growth of cancer cells in children following irradiation for benign conditions, and he published a landmark paper in 1968 demonstrating that, contrary to popular belief, radioiodine therapy was not associated with an increased incidence of leukemia.

That legacy was tarnished, however, by the experiments in which Saenger administered high levels of whole-body radiation to more than 90 poor, black, uneducated patients with inoperable tumors.

Saenger maintained that the tests were designed to relieve pain and perhaps shrink the tumors, but critics contended that their sole purpose was to determine the deleterious effects of radiation on the human body for the benefit of the U.S. military, which provided the bulk of the funding for the studies.

As many as 20 of the patients might have died as a result of the radiation, and the majority suffered intense pain, persistent nausea and a variety of other ill effects from the radiation.

"These people were sick," Saenger said in 1993. "They had far advanced cancer. We gave them this treatment to see ... whether we could improve their condition. It was called palliative therapy. It was not intended to be curative therapy."

He added, "These are studies of which we are very proud."

In 1999, however, a federal judge approved a $4 million settlement to the families of the patients. That settlement included the installation of a plaque at Cincinnati's University Hospital commemorating the experiment and listing the names of 70 of the patients.

"He did some great things, I think," said Dr. David Egilman of Brown University, who has studied workplace hazards such as radiation and was one of Saenger's harshest critics. "He also did some horrible things, I think."

Saenger is survived by a son, four grandchildren and two great-grandchildren.