Over forty years ago, 12-year-old Ronald Beaulieu and dozens of other students attending a Waltham school unwittingly ate breakfast cereal laced with radioactive isotopes as part of a government experiment.

Now, the 56-year-old Somerville resident wants those responsible to pay.

Beaulieu filed a class action suit Monday against the state, the Fernald School and other individuals and agencies who oversaw the experiments.

Two former Harvard Medical School faculty members, Clemens E. Benda and Earle Chapman, are among the defendants named in the suit, said Jeffrey Petrucelly, Beaulieu's attorney.

Benda, who was also the medical director at Fernald, died in 1975. Chapman's whereabouts are unknown, Petrucelly said.

The suit was filed in Suffolk Superior Court on behalf of at least 53 other participants in the so-called Fernald Science Club.

The subjects were given radioactive isotopes in their breakfast cereal without parental notification or consent.

A presidential panel investigating some 4,000 Cold War-era radiation experiments recommended that the subjects receive an apology but no financial compensation.

It did find "sufficient evidence that wrongs were committed against the children who participated in the experiments at the Fernald School."

The Beaulieus, who learned of the experiments only last October, are asking the defendants to pay for medical monitoring of the test subjects and to provide financial compensation for their spouses.

The suit names the former superintendent and medical director at Fernald, four MIT scientists, the two Harvard Medical School doctors, three former employees at Fernald, a representative of the U.S. Atomic Energy Commission, the state Department of Mental Retardation and the Quaker Oats Co., which helped fund the experiments.

Beaulieu claimed his civil rights were violated and his privacy invaded as a result of the experiments. He also said the experiments were a form of battery.

"They had a very willing population here," Petrucelly said. "These are institutionalized minor children who had low IQs and parents who weren't right there to know what was going on."

The students who cooperated were rewarded with Christmas parties and trips to Fenway Park.

Gerald Ryan, a spokesperson for both Fernald and the state's Department of Mental Retardation, said the department has identified and contacted the Fernald students--74 in all--who participated in two sets of radiation tests.

A task force which studied the experiments determined that the impact on the subjects was minimal, but committee members were troubled that the tests were performed on "the most vulnerable people in society," Ryan said.

This story was written with Associated Press wire dispatches