The federal government has inadequately considered the long-term health effects of exposure to low-level nuclear radiation, the head of a government task force told a House subcommittee yesterday.

To say that "the government is not handling these problems well" would be an understatement, declared F. Peter Libassi, general counsel of the Health, Education and Welfare Department.

Libassi also deplored a lack of coordination among agencies studying the health effects of radiation and those involved in regulation of nuclear facilities.

But he said he had found no desire on the part of the agencies "to defind the past."

The Libassi task force was established in May after the White House chose HEW as the agency to coordinate a government-wide review of radiation health research and regulatory practices.

The study was ordered, a White House memorandum said at the time, to develop "a coordinated response to the growing agency ad congressional concern about the effects of radiation exposure on participants in nuclear (weapons) tests and workers in nuclear-related projects."

Members of the House Government Operations subcommittee on the environment, energy and natural resources interpreted Libassi's testimony yesterday as criticism of the Environmental Protection Agency, an organization they had helped establish through a reorganization act passed in 1970.

"We understood that EPA was the agency at the helm," subcommittee Chairman Leo J. Ryan (D-Calif) said in opening the session.

He said EPA claimed responsibility for setting environmental radiation standards and "for coordinating and overseeing the radiation protection programs of all the federal agencies."

"The record is clear," Ryan declared, "that the EPA failed in that responsibility."

No representative of EPA testified yesterday.

George Marienthal, deputy assistant secretary of defense for energy, environment and safety, told the subcommitte his office "now serves as the focal point to coordinate DOD review and comment on all newly proposed radiation standards and regulations" - an indication that the Department of Defense has recognized both concern and movement surrounding the subject.

But Marienthal added, "I believe that our past radiation protection programs have served us well."

His statement came shortly after Libassi said that Army officials, in reviewing the use of troops at nuclear weapons tests in the 1950s, told him that if they knew then what they know now, they would have taken far more precautions.

Libassi said his group hopes to give the White House by September recommendations "as to what studies need to be done" based on assessing potential health problems and the groups at risk.

He said the task force also might recommend ways to supervise radiation health responsibility in the future.

"The issues are too important," Libassi said, "to allow this to slip into narrow bureaucratic areas."

To which Ryan added what he termed his "17th law" of government: "That above public health . . . government officials protect their power, their turf and rear ends."